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Definitions

1

ADCA-DN clinical case definition

Adult-onset (typically 30 to 40 years) progressive cerebellar ataxia, sensory neuronal (sensorineural) deafness, and narcolepsy with cataplexy, with dementia developing later, in an individual carrying a heterozygous DNMT1 variant in the C-terminal part of the targeting-sequence domain (classically exon 21). There are no independently validated formal diagnostic criteria; molecular confirmation is central, and the full triad may not be present at onset.

CASE_DEFINITION

Show evidence (3 references)

PMID:22328086 SUPPORT Human Clinical

"Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is characterized by late onset (30-40 years old) cerebellar ataxia, sensory neuronal deafness, narcolepsy-cataplexy and dementia."

The discovery paper gives the defining clinical tetrad and the adult age of onset used in this case definition.

ORPHA:314404 SUPPORT Other

"A rare polymorphic disorder, subtype of autosomal dominant cerebellar ataxia type 1 (ADCA type 1), characterized by ataxia, sensorineural deafness and narcolepsy with cataplexy and dementia."

Orphanet's curated definition independently states the defining features and places ADCA-DN under ADCA type 1.

PMID:22338191 SUPPORT Other

"The diagnosis of DNMT1 disorder is established by identification of a heterozygous pathogenic variant in DNMT1 by molecular genetic testing."

GeneReviews confirms that molecular confirmation, not a clinical score, is what establishes the diagnosis.

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Inheritance

1

Autosomal dominant HP:0000006

ADCA-DN is transmitted as an autosomal dominant trait caused by a single heterozygous DNMT1 missense allele. Onset is strongly age dependent, so penetrance cannot be estimated reliably from the small published pedigrees and is recorded as unknown rather than complete. Expressivity is variable even within one family: in a three-generation kindred carrying p.Ala570Val, the presenting features, presence of cataplexy, and age at onset differed markedly between generations. De novo variants occur, so a negative family history does not exclude the diagnosis.

autosomal dominant inheritance Penetrance: UNKNOWN Expressivity: VARIABLE

Show evidence (4 references)

PMID:22338191 SUPPORT Other

"DNMT1 disorder is inherited in an autosomal dominant manner. Most affected individuals have an affected parent; the proportion of affected individuals with a de novo DNMT1 pathogenic variant is unknown."

GeneReviews states the autosomal dominant mode of inheritance for the DNMT1-related disorder spectrum that contains ADCA-DN, and confirms that the de novo proportion is not established.

PMID:22338191 SUPPORT Other

"Each child of an individual with DNMT1 disorder has a 50% chance of inheriting the pathogenic variant."

Supports the 50% per-pregnancy transmission risk used in counseling.

PMID:40285998 SUPPORT Human Clinical

"ADCA syndrome has a variable phenotype in a same family."

A three-generation p.Ala570Val family directly demonstrates variable expressivity within a single kindred.

+ 1 more reference

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Discussions and Knowledge Gaps

7

Is the narcolepsy of ADCA-DN caused by loss of hypothalamic hypocretin neurons, by dysfunction of surviving hypocretin neurons, or by failure of downstream sleep-wake circuitry?

KNOWLEDGE GAP OPEN gap_adcadn_hypocretin_neuron_pathology

Attached to

pathophysiology#Hypothalamic Hypocretin System Dysfunction biochemical#Cerebrospinal fluid hypocretin-1

In sporadic narcolepsy type 1 the near-complete destruction of hypocretin neurons is established and CSF hypocretin-1 is uniformly low. In DNMT1 disease CSF hypocretin-1 is variously low, intermediate, or normal, and patients can develop progressive polysomnographic abnormalities while their CSF hypocretin-1 remains normal. No neuropathological study has counted hypocretin neurons in an ADCA-DN brain, and PubMed returns no ADCA-DN autopsy series. The pathophysiology node therefore asserts system dysfunction rather than neuron loss, and the distinction matters because it determines whether hypocretin agonist therapy would be expected to work.

Proposed experiments

Quantitative hypothalamic hypocretin neuron counts in ADCA-DN autopsy tissue

exp_adcadn_hypothalamic_hypocretin_neuron_quantification

Recruit ADCA-DN brain donations through an ataxia or narcolepsy brain bank and perform stereological counts of hypocretin-immunoreactive and melanin-concentrating-hormone-immunoreactive neurons in the lateral hypothalamus, comparing against sporadic narcolepsy type 1 and age-matched controls. Pair each brain with the donor's antemortem CSF hypocretin-1 value where available.

Decision criterion

Hypocretin neuron counts comparable to sporadic narcolepsy type 1 would support a cell-loss mechanism; preserved counts with normal or borderline CSF hypocretin-1 would support neuronal dysfunction or downstream circuit failure.

Show evidence (1 reference)

PMID:24727570 SUPPORT Human Clinical

"Remarkably, narcolepsy with or without cataplexy with low/intermediate or normal cerebrospinal fluid hypocretin-1 is present in both diseases."

Documents the heterogeneous CSF hypocretin-1 pattern that motivates this knowledge gap.

What are the ADCA-DN-specific age at onset, survival, and rate of cognitive decline, as opposed to the figures derived from HSAN1E and mixed DNMT1-complex cohorts?

KNOWLEDGE GAP OPEN gap_adcadn_natural_history_scoped_to_hsan1e

Attached to

pathophysiology#Selective Central and Peripheral Neurodegeneration

The most frequently quoted DNMT1 natural-history numbers (mean onset 37.7 years, average survival 53.6 years, significant cognitive deficit in 89 percent by age 45) come from a cohort of nine HSAN1E kinships comprising 45 affected subjects. In the source abstract these figures are attributed explicitly to HSAN1E, not to ADCA-DN. Because HSAN1E and ADCA-DN are discrete clinical entities with different variant positions within the same domain, these values are deliberately not recorded as ADCA-DN prevalence, progression, or prognosis in this entry. No registry-scale ADCA-DN natural history cohort exists, and no variant-specific penetrance estimate is available.

Proposed experiments

International DNMT1 registry stratified by targeting-sequence variant position

exp_adcadn_international_natural_history_registry

Assemble an international registry of genetically confirmed DNMT1 patients with prospective standardized assessment of ataxia scales, audiometry, polysomnography, neuropsychology, and survival, analyzed with strata defined by variant position within the targeting-sequence domain (C-terminal/exon 21 versus middle and N-terminal/exon 20) rather than by clinical label alone.

Decision criterion

Stratified onset, survival, and cognitive-decline curves that differ significantly between variant-position strata would establish ADCA-DN-specific natural history and confirm that pooled DNMT1 figures are not transferable.

Show evidence (2 references)

PMID:25678562 SUPPORT Human Clinical

"The average survival of HSAN1E was 53.6 years."

Shows that the widely cited survival figure is attributed by its source to HSAN1E, which is why it is excluded from the ADCA-DN progression section.

PMID:24727570 SUPPORT Human Clinical

"Phenotypic characterization pinpoints that ADCA-DN and HSAN IE represent two discrete clinical entities belonging to the same disease spectrum, with variable degree of overlap."

Supports the requirement to keep the two entities' natural-history data separate.

Do the existing DNMT1 RFTS knock-in mice model ADCA-DN, given that they carry HSAN1E-equivalent alleles and do not develop narcolepsy, deafness, or cerebellar ataxia?

HUMAN MODEL MISMATCH OPEN mismatch_adcadn_mouse_models_carry_hsan1e_alleles

Attached to

pathophysiology#Relief of RFTS Autoinhibition and DNMT1 Destabilization pathophysiology#Aberrant DNMT1-NSUN2 RNA m5C Methylation pathophysiology#Oxidative Stress and Mitochondrial Dysfunction pathophysiology#Selective Central and Peripheral Neurodegeneration

The only published knock-in mice carry mouse equivalents of the human HSAN1E variants Y495C and D490E-P491Y, which lie in the middle or N-terminal part of the targeting-sequence domain, not the C-terminal exon-21 region that defines ADCA-DN. Since intradomain variant position is the principal determinant separating the two human phenotypes, a model built on HSAN1E alleles cannot be assumed to capture the ADCA-DN phenotype. The heterozygous mice show reduced DNMT1 protein and impaired learning and memory, but the three defining ADCA-DN features (narcolepsy, sensorineural deafness, cerebellar ataxia) have not been demonstrated. Mechanistic conclusions from these mice about RFTS destabilization and cleavage are recorded as PARTIAL support for that reason. A 2025 follow-up using RFTS-mutant mice identified aberrant DNMT1-dependent RNA m5C methylation, oxidative stress, and mitochondrial dysfunction. Its published abstract does not name the mouse RFTS allele or establish translation to classical exon-21 ADCA-DN, so that branch is likewise recorded as provisional, PARTIAL support rather than an established ADCA-DN mechanism.

Proposed experiments

Exon-21-allele knock-in mouse with longitudinal sleep, auditory, and cerebellar phenotyping

exp_adcadn_exon21_knockin_mouse_deep_phenotyping

Generate heterozygous knock-in mice carrying the mouse equivalent of human DNMT1 p.Ala570Val or p.Val606Phe and phenotype them longitudinally with EEG/EMG sleep architecture and cataplexy scoring, hypothalamic hypocretin neuron counts, auditory brainstem responses and distortion-product otoacoustic emissions, rotarod and gait analysis with cerebellar histology, DNA methylome and RNA m5C profiling resolved by cell type, and mitochondrial functional assays. Run the existing HSAN1E-allele lines side by side as comparators.

Decision criterion

Emergence of sleep-onset REM intrusion, cataplexy-like attacks, elevated auditory brainstem response thresholds, and progressive cerebellar degeneration in the exon-21 line but not the HSAN1E lines would establish phenotype dependence on allele position and give the field a genuine ADCA-DN model.

Show evidence (3 references)

PMID:34516921 SUPPORT Model Organism

"We generated Dnmt1-M1 and Dnmt1-M2 knock-in mouse models that are equivalent to Y495C and D490E-P491Y mutation in patients with HSAN1E, respectively."

Confirms that the available mouse models carry HSAN1E-equivalent rather than ADCA-DN alleles.

PMID:25678562 SUPPORT Human Clinical

"Our results indicate that all the mutations causal for HSAN1E are located in the middle part or N-terminus end of the TS domain, whereas all the mutations causal for autosomal dominant cerebellar ataxia, deafness and narcolepsy are located in the C-terminus end of the TS domain."

Establishes that variant position within the domain determines which human phenotype results, which is what makes the allele choice in the mouse models a translational mismatch.

PMID:40328247 SUPPORT INDIRECT Model Organism

"When the DNMT1 RFTS domain is mutated in mice, it triggers aberrant DNMT1-RNA interaction and significantly elevated m5C RNA methylation and RNA stability for a portion of metabolic genes."

Adds the new RNA-methylation mechanism to the model-mismatch question. INDIRECT because the experiment does not establish the branch in human ADCA-DN or in an exon-21 ADCA-DN model.

Does ADCA-DN produce net hypermethylation of normally unmethylated regions, bidirectional change that depends on locus and cell type, or both depending on the tissue examined?

CONTROVERSY OPEN controversy_adcadn_methylome_direction

Attached to

pathophysiology#Cell-Type-Specific Methylome and Transcriptome Disruption

A genome-wide array on DNA from a six-affected ADCA-DN family found a shift out of the lowest and upper-intermediate methylation bins into intermediate and near-complete methylation, with 82 regionally hypermethylated loci, consistent with increased methylation of normally unmethylated promoters and CpG islands. In contrast, patient fibroblasts, iPSCs, and induced neurons showed changes whose direction depended on cell type, including ZFP57 promoter hypomethylation with increased ZFP57 expression. Neither result supports the older global-hypomethylation model, but they are not obviously reconcilable with each other, and the tissue examined differs (peripheral blood-derived DNA versus derived neural cells). Resolving this determines whether any methylation episignature could serve as a diagnostic or pharmacodynamic biomarker.

Proposed experiments

Matched multi-tissue methylome comparison in the same ADCA-DN carriers

exp_adcadn_matched_tissue_methylome_comparison

Profile whole-genome bisulfite methylomes from peripheral blood, skin fibroblasts, and iPSC-derived neurons from the same set of ADCA-DN carriers and matched controls, using one analysis pipeline, and test whether the direction of change at shared loci is concordant across tissues or genuinely dependent on tissue.

Decision criterion

Concordant direction across tissues would indicate that the earlier discrepancy was methodological; discordant direction at shared loci would confirm a genuine dependence on cell type and rule out a single blood-based episignature.

Show evidence (2 references)

PMID:27602171 SUPPORT Human Clinical

"This pattern suggests an increase in methylation of normally unmethylated regions, such as promoters and CpG islands, as well as further methylation of highly methylated gene bodies and intergenic regions."

States the hypermethylation-leaning interpretation from patient DNA.

PMID:37584462 SUPPORT In Vitro

"Furthermore, ZFP57, which is required to maintain gene imprinting through DNA methylation during early development, was hypomethylated in promoters and exhibited upregulated expression in patients with ADCA-DN in both iPSC and iNs."

Provides the contrasting promoter-hypomethylation observation in patient-derived cells.

Which cell populations actually degenerate in the ADCA-DN cerebellum and auditory system, and would that support conformance to the cerebellar_purkinje_degeneration and sensorineural_hair_cell_loss modules?

OPEN QUESTION OPEN open_adcadn_module_conformance_declined

Attached to

pathophysiology#Cerebellar Degeneration pathophysiology#Auditory Pathway Degeneration

Conformance to both modules was evaluated and declined. The cerebellar_purkinje_degeneration module turns on Purkinje neuron degeneration as its central effector, but the only ADCA-DN cerebellar data are MRI atrophy and a raised MR spectroscopy myo-inositol signal, which reflects glial density rather than Purkinje loss; no autopsy series exists. The sensorineural_hair_cell_loss module turns on hair cell mechanotransduction failure and death, whereas the ADCA-DN deafness is described as sensory neuronal and is accompanied by attenuated brainstem auditory evoked potentials, which points to auditory-neural or retrocochlear rather than hair cell pathology. Declaring conformance in either case would assert an effector cell type that has not been demonstrated. Both decisions should be revisited if neuropathological or temporal-bone data appear.

Proposed experiments

Cerebellar and temporal-bone neuropathology in ADCA-DN donors

exp_adcadn_cerebellar_and_temporal_bone_neuropathology

In ADCA-DN brain and temporal-bone donations, perform calbindin and parvalbumin immunohistochemistry with stereological Purkinje cell counts and Bergmann glia assessment in the cerebellar cortex, and cytocochleogram analysis of inner and outer hair cells together with spiral ganglion neuron counts in the temporal bone.

Decision criterion

Significant Purkinje cell loss relative to age-matched controls would justify conformance to cerebellar_purkinje_degeneration; a hair-cell-loss cytocochleogram pattern would justify conformance to sensorineural_hair_cell_loss, whereas isolated spiral ganglion or auditory nerve loss would confirm the retrocochlear interpretation and the decision to decline.

Show evidence (2 references)

PMID:32984563 SUPPORT Human Clinical

"Electrophysiological studies revealed that visual evoked potentials were attenuated with prolonged latencies in both eyes, and brainstem auditory and somatosensory evoked potentials were also attenuated."

The attenuated brainstem auditory evoked potentials are the evidence that points away from a purely cochlear hair cell lesion.

PMID:24709307 SUPPORT Human Clinical

"proton magnetic resonance spectroscopy (MRS) revealed increased cerebellar myoinositol (mI) in both subjects"

The only cellular-level cerebellar evidence in ADCA-DN is a glial marker, not a Purkinje-specific one.

Is there any tractable disease-modifying strategy for ADCA-DN, given that the mechanism combines impaired maintenance methylation with potentially toxic mutant-protein species?

KNOWLEDGE GAP OPEN gap_adcadn_no_disease_modifying_therapy

Attached to

pathophysiology#Mutant DNMT1 Mislocalization and Aggresome Formation

No approved or investigational disease-modifying drug, gene therapy, RNA therapy, or epigenome-editing treatment exists for ADCA-DN, and no disease-specific interventional clinical trial has been registered. The mechanism is not a clean loss of function, so simple gene supplementation is unlikely to be sufficient and broad DNMT inhibition would be expected to be harmful. Allele-selective silencing of the mutant transcript, or pharmacological correction of mutant-protein mislocalization and aggresome formation, are the mechanistically plausible directions but neither has been attempted.

Proposed experiments

Allele-selective mutant DNMT1 knockdown in patient-derived induced neurons

exp_adcadn_allele_selective_knockdown_in_patient_neurons

In induced neurons from ADCA-DN patients carrying p.Ala570Val, p.Gly605Ala, or p.Val606Phe, apply allele-selective antisense oligonucleotides or base editing to reduce the mutant transcript while preserving the wild-type allele, then measure DNMT1 subcellular localization, aggresome burden, autophagic flux, and reversal of the patient methylome and transcriptome signature.

Decision criterion

Normalization of DNMT1 localization and of the patient methylome and transcriptome signature without loss of total maintenance methylation would support allele-selective knockdown as a therapeutic direction.

Show evidence (2 references)

PMID:22338191 SUPPORT Other

"No cure for DNMT1 disorder currently exists."

GeneReviews confirms the absence of any disease-modifying treatment for this disorder.

PMID:25678562 SUPPORT In Vitro

"Our results suggest mutations in DNMT1 result in imbalanced protein homeostasis through aggresome-induced autophagy."

Identifies the proteostasis defect that any mechanism-directed therapy would need to address.

Is cataract a genuine mechanistic consequence of DNMT1 dysfunction in ADCA-DN, or an incidental age-related comorbidity in a small reported series?

OPEN QUESTION OPEN open_adcadn_cataract_unexplained

Attached to

phenotypes#Cataract

Cataract is listed among the variable manifestations of ADCA-DN in two independent sources, but no mechanism links maintenance-methylation failure or the neurodegenerative cascade to lens opacification, and the affected patients are in an age range where cataract is common in the general population. The phenotype is therefore recorded but deliberately left unwired in the pathograph rather than attached to an existing node, which would assert an unsupported causal claim.

Show evidence (1 reference)

PMID:32984563 SUPPORT Human Clinical

"Optic atrophy, cataract, sensory neuropathy, and dementia may develop in the later stages of the disease."

Reports cataract as a late ADCA-DN feature without proposing any mechanism.

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Pathophysiology

12

DNMT1 Exon 21 RFTS Domain Missense Variant

A single heterozygous germline missense variant in exon 21 of DNMT1 alters the C-terminal portion of the replication foci targeting sequence (RFTS, also called targeting sequence or TS) domain of DNA methyltransferase 1, the sole maintenance methyltransferase that restores symmetrical CpG methylation on hemimethylated DNA after replication and during DNA repair. The recurrent ADCA-DN alleles p.Ala570Val, p.Gly605Ala, and p.Val606Phe cluster in close spatial proximity within this region. Variant position within the same TS domain is what separates ADCA-DN from allelic HSAN1E, whose variants lie in the N-terminal-to-middle part of the domain, most often in exon 20.

DNMT1 hgnc:2976

DNA (cytosine-5-)-methyltransferase activity GO:0003886

Downstream

Relief of RFTS Autoinhibition and DNMT1 Destabilization The variant lies within the autoinhibitory RFTS domain itself, so the protein-level consequence follows directly from the amino-acid change.

Show evidence (4 references)

PMID:22328086 SUPPORT Human Clinical

"Our mutations are all located in exon 21 and in very close spatial proximity, suggesting distinct phenotypes depending on mutation location within this gene."

The discovery study localizes all ADCA-DN alleles to a tight cluster in exon 21 and proposes position-dependent phenotype.

PMID:25678562 SUPPORT Human Clinical

"Our results indicate that all the mutations causal for HSAN1E are located in the middle part or N-terminus end of the TS domain, whereas all the mutations causal for autosomal dominant cerebellar ataxia, deafness and narcolepsy are located in the C-terminus end of the TS domain."

A 45-patient genotype-phenotype analysis establishes the intradomain positional split between HSAN1E and ADCA-DN alleles.

PMID:32754641 SUPPORT Other

"DNA methyltransferase 1, encoded by the DNMT1 gene, is the sole methyltransferase for maintaining methylation during DNA replication and DNA repair."

Background statement of the normal enzymatic role that the variant perturbs; cited as framing rather than as ADCA-DN patient data.

+ 1 more reference

Relief of RFTS Autoinhibition and DNMT1 Destabilization

The RFTS domain normally folds back into the catalytic pocket and acts as an endogenous inhibitor of DNMT1 activity. ADCA-DN missense substitutions in this domain weaken that intramolecular interaction. Purified mutant enzyme shows markedly reduced thermal stability, a 2.5 to 3.5-fold increase in DNA binding affinity, and weakened RFTS-mediated inhibition of methylation activity. In knock-in mouse models of the allelic HSAN1E substitutions the destabilized protein is additionally susceptible to proteolytic cleavage within the RFTS domain, generating a truncated species, and steady-state DNMT1 protein is reduced in heterozygotes. The disease mechanism is therefore not simple haploinsufficiency but a mixture of impaired regulation, reduced stability, and potentially toxic mutant-protein species.

DNA (cytosine-5-)-methyltransferase activity GO:0003886 ⚠ ABNORMAL

Downstream

Mutant DNMT1 Mislocalization and Aggresome Formation Reduced conformational stability of the mutant protein underlies its abnormal subcellular handling.

Cell-Type-Specific Methylome and Transcriptome Disruption

Aberrant DNMT1-NSUN2 RNA m5C Methylation A 2025 study identified an additional RFTS-dependent RNA-binding function of DNMT1. The published abstract describes RFTS-mutant mice without naming the allele, and whether classical ADCA-DN exon-21 substitutions perturb this function in the same way remains untested.

Show evidence (5 references)

PMID:31804802 SUPPORT Other

"The replication focus targeting sequence (RFTS) domain, found in the regulatory region, is an endogenous inhibitor of DNMT1 activity."

Background statement of the normal autoinhibitory function of the domain that ADCA-DN variants disrupt.

PMID:31804802 SUPPORT In Vitro

"The mutations significantly decrease the thermal stability of DNMT1, yet the mutant proteins exhibit 2.5-3.5-fold increases in DNA binding affinity."

Biochemical characterization of purified ADCA-DN mutant protein (G589A/V590F in the numbering used by that study) shows destabilization with increased DNA binding.

PMID:31804802 SUPPORT In Vitro

"Taken together, these data suggest these disease-associated mutations decrease protein stability and, at least partially, relieve normal RFTS-mediated autoinhibition of DNMT1."

States the in vitro conclusion that ADCA-DN variants relieve autoinhibition rather than simply abolishing catalysis.

+ 2 more references

Mutant DNMT1 Mislocalization and Aggresome Formation

Mutant DNMT1 protein translocates to the cytoplasm and forms aggresomes while losing its ability to bind heterochromatin during the G2 phase of the cell cycle. The resulting imbalance of protein homeostasis engages aggresome-induced autophagy. This proteostatic burden is the proposed reason why a defect in a ubiquitously required maintenance methyltransferase produces selective rather than global tissue damage.

neuron CL:0000540

inclusion body assembly GO:0070841 ↑ INCREASED autophagy GO:0006914 ↑ INCREASED

aggresome GO:0016235 heterochromatin GO:0000792

Downstream

Selective Central and Peripheral Neurodegeneration

Show evidence (2 references)

PMID:25678562 SUPPORT In Vitro

"Moreover, we show that mutant DNMT1 proteins translocate to the cytoplasm and are prone to form aggresomes while losing their binding ability to heterochromatin during the G2 cell cycle."

Cellular localization experiments on mutant DNMT1 directly demonstrate cytoplasmic mislocalization, aggresome formation, and loss of heterochromatin binding.

PMID:25678562 SUPPORT In Vitro

"Our results suggest mutations in DNMT1 result in imbalanced protein homeostasis through aggresome-induced autophagy."

States the proteostasis-autophagy consequence inferred from the same cellular experiments.

Aberrant DNMT1-NSUN2 RNA m5C Methylation

DNMT1 also binds mRNA and recruits NSUN2 to facilitate 5-methylcytosine (m5C) RNA methylation, which stabilizes transcripts involved in mitochondrial function. In RFTS-mutant mice, DNMT1-RNA interaction, m5C methylation, and stability of a subset of metabolic transcripts are increased. This newly described branch is mechanistically relevant to RFTS-domain disease but remains provisional for classical ADCA-DN because it has not been demonstrated in patients, and the published abstract does not identify the mouse RFTS allele or establish equivalence to a classical exon-21 ADCA-DN allele.

DNMT1 hgnc:2976 NSUN2 hgnc:25994

RNA methylation GO:0001510 ↑ INCREASED

Downstream

Oxidative Stress and Mitochondrial Dysfunction

Show evidence (2 references)

PMID:40328247 SUPPORT In Vitro

"Here, we demonstrated that DNMT1 has the capability to bind to mRNA transcripts and facilitate 5-methylcytosine (m5C) RNA methylation by recruiting NOP2/Sun RNA methyltransferase 2 (NSUN2)."

Establishes the DNMT1-NSUN2 RNA-methylation activity that defines this molecular branch.

PMID:40328247 SUPPORT Model Organism

"When the DNMT1 RFTS domain is mutated in mice, it triggers aberrant DNMT1-RNA interaction and significantly elevated m5C RNA methylation and RNA stability for a portion of metabolic genes."

Demonstrates the abnormal RNA-methylation phenotype in RFTS-mutant mice. PARTIAL because the result has not been shown in human ADCA-DN and the published abstract does not specify the mouse allele.

Oxidative Stress and Mitochondrial Dysfunction

In RFTS-mutant mice, increased metabolic transcript abundance downstream of aberrant RNA m5C methylation produces cumulative oxidative stress and mitochondrial dysfunction associated with neurological abnormalities. This is a model-organism mechanism lead, not an established lesion in classical ADCA-DN patients.

response to oxidative stress GO:0006979 ↑ INCREASED

Downstream

Selective Central and Peripheral Neurodegeneration The mouse study links mitochondrial dysfunction to neurological symptoms, but does not establish which ADCA-DN neuronal populations are affected or whether the same route operates in human disease.

Show evidence (1 reference)

PMID:40328247 SUPPORT Model Organism

"Consequently, increased levels of metabolic RNA transcripts contribute to cumulative oxidative stress, mitochondrial dysfunction, and neurological symptoms."

Supports the transcript-to-mitochondrial-stress sequence in the mutant mice. PARTIAL because human ADCA-DN confirmation is absent.

Cell-Type-Specific Methylome and Transcriptome Disruption

Maintenance CpG methylation becomes abnormal in a manner that depends on cell type and developmental stage rather than producing uniform global hypomethylation. Genome-wide methylation array analysis of an ADCA-DN family carrying p.Ala570Val found a shift out of the extreme methylation bins into intermediate and near-complete methylation, with 82 regionally hypermethylated loci. In patient fibroblasts, induced pluripotent stem cells, and induced neurons carrying p.Ala570Val, p.Gly605Ala, or p.Val606Phe, methylation and expression changes were specific to cell type and negatively correlated, ZFP57 promoters were hypomethylated with increased ZFP57 expression, and PDGFB, PRDM8, and NR2F1 emerged as candidate mediators of the ataxia/psychosis/dementia and deafness/optic atrophy arms respectively.

ZFP57 hgnc:18791 PDGFB hgnc:8800 PRDM8 hgnc:13993 NR2F1 hgnc:7975

DNA modification GO:0006304 ⚠ ABNORMAL epigenetic regulation of gene expression GO:0040029 ⚠ ABNORMAL chromatin organization GO:0006325 ⚠ ABNORMAL

Downstream

Selective Central and Peripheral Neurodegeneration

Show evidence (5 references)

PMID:27602171 SUPPORT Human Clinical

"DNA methylation analysis by high-resolution genome-wide DNA methylation array identified a decrease in CpGs with 0-10 % methylation and 80-95 % methylation and a concomitant increase in sites with 10-30 % methylation and >95 % methylation."

Genome-wide array on DNA from a six-affected ADCA-DN family demonstrates a reproducible redistribution of methylation levels in patients.

PMID:27602171 SUPPORT Human Clinical

"This report identifies robust changes in the DNA methylation patterns in ADCA-DN patients, which is an important step towards elucidating disease pathogenesis."

States the authors' conclusion that patient methylation patterns are robustly altered in ADCA-DN.

PMID:37584462 SUPPORT In Vitro

"We show cell type-specific changes in gene expression and DNA methylation patterns."

Patient-derived fibroblasts, iPSCs, and induced neurons establish that the epigenomic consequence depends on cell type rather than being uniform.

+ 2 more references

Selective Central and Peripheral Neurodegeneration

Despite the ubiquitous requirement for DNMT1, the clinical consequence is restricted degeneration of specific central and peripheral neuronal populations. The pattern in ADCA-DN preferentially involves the hypothalamic hypocretin system, the cerebellum, the auditory pathway, frontosubcortical and cortical networks, the optic nerve, and peripheral sensory axons, with corticospinal (pyramidal) involvement in some patients. The determinants of this selectivity are unknown.

neuron CL:0000540

cerebellum UBERON:0002037

Downstream

Hypothalamic Hypocretin System Dysfunction

Cerebellar Degeneration

Auditory Pathway Degeneration

Cerebral Cortical and Frontosubcortical Degeneration

Optic Nerve and Peripheral Sensory Axon Degeneration

Pyramidal signs Corticospinal tract involvement is reported in a subset of genetically confirmed patients.

Show evidence (2 references)

PMID:22338191 SUPPORT Other

"DNMT1-related disorder is a degenerative disorder of the central and peripheral nervous systems comprising a phenotypic spectrum that includes hereditary sensory and autonomic neuropathy type 1E (HSAN1E) and autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN)."

GeneReviews frames the disorder as a combined central and peripheral nervous system degeneration, which is the claim made by this node.

PMID:31957642 SUPPORT Human Clinical

"Clinical and neurophysiological evaluations reveled signs of cerebellar, pyramidal, peripheral, cognitive involvement, and optical atrophy."

A genetically confirmed exon-21 ADCA-DN patient demonstrates the multi-system distribution of neuronal involvement recorded on this node.

Hypothalamic Hypocretin System Dysfunction

Impaired hypothalamic hypocretin (orexin) signaling destabilizes the sleep-wake and REM-sleep control that hypocretin neurons normally maintain, producing excessive daytime somnolence, cataplexy, and sleep-onset REM periods. Unlike common sporadic narcolepsy type 1, in which CSF hypocretin-1 is usually markedly reduced following extensive hypocretin neuron loss, CSF hypocretin-1 in DNMT1 disease can be low, intermediate, or normal, and cataplexy may be absent. No neuropathological study has demonstrated hypocretin neuron loss in ADCA-DN, so this node records system dysfunction rather than confirmed cell loss.

hypocretin (orexin) neuron CL:0011109

circadian sleep/wake cycle GO:0042745 ⚠ ABNORMAL

hypothalamus UBERON:0001898

Downstream

Excessive daytime somnolence

Cataplexy

Sleep-onset REM periods

Show evidence (2 references)

PMID:24727570 SUPPORT Human Clinical

"Remarkably, narcolepsy with or without cataplexy with low/intermediate or normal cerebrospinal fluid hypocretin-1 is present in both diseases."

Establishes that the DNMT1 sleep phenotype is not accompanied by uniformly low CSF hypocretin-1, which is why this node claims system dysfunction rather than hypocretin neuron destruction.

PMID:23904686 SUPPORT Human Clinical

"CSF hypocretin-1 was 191 pg/mL (normal values > 200 pg/mL)."

A genetically confirmed exon-21 ADCA-DN patient shows a borderline-low CSF hypocretin-1 value, supporting partial hypocretin system involvement.

Cerebellar Degeneration

Progressive degeneration of the cerebellum produces limb and gait incoordination, dysmetria, and tremor, with cerebellar atrophy on structural MRI. Increased cerebellar myo-inositol on proton MR spectroscopy, a marker of glial activity and density, is detectable in presymptomatic carriers and indicates that cerebellar involvement begins before clinical ataxia. The identity of the degenerating cerebellar cell population in ADCA-DN has not been established histologically, so no Purkinje-specific claim is made here.

cerebellum UBERON:0002037

Downstream

Cerebellar ataxia

Gait ataxia

Cerebellar atrophy

Tremor

Show evidence (2 references)

PMID:23904686 SUPPORT Human Clinical

"Mild brain atrophy was observed on MRI, with cerebellar involvement."

Structural imaging in a genetically confirmed ADCA-DN patient documents cerebellar involvement.

PMID:24709307 SUPPORT Human Clinical

"The two asymptomatic carriers of the heterozygous DNMT1 mutation for ADCA-DN, a late-onset neurodegenerative disease, presented with SOREMPs associated with an increase of mI in the brain, a marker of glial cell activity and density characteristic of early stages of neurodegenerative diseases."

Identifies raised cerebellar myo-inositol as a glial neurodegeneration marker present before clinical cerebellar signs.

Auditory Pathway Degeneration

Bilateral progressive sensorineural hearing loss is one of the two earliest manifestations. The discovery report characterized it as sensory neuronal deafness, and electrophysiology in a genetically confirmed patient showed attenuated brainstem auditory evoked potentials alongside attenuated visual and somatosensory evoked potentials, which points to auditory-neural or central pathway involvement. Whether cochlear hair cells are primarily affected has not been determined; there is no temporal-bone or cochlear histopathology in ADCA-DN.

auditory system UBERON:0016490

Downstream

Sensorineural hearing loss

Show evidence (2 references)

PMID:22328086 SUPPORT Human Clinical

"Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is characterized by late onset (30-40 years old) cerebellar ataxia, sensory neuronal deafness, narcolepsy-cataplexy and dementia."

The defining description characterizes the deafness as sensory neuronal rather than conductive or purely cochlear.

PMID:32984563 SUPPORT Human Clinical

"Electrophysiological studies revealed that visual evoked potentials were attenuated with prolonged latencies in both eyes, and brainstem auditory and somatosensory evoked potentials were also attenuated."

Attenuated brainstem auditory evoked potentials indicate involvement of the auditory nerve or central auditory pathway rather than a purely cochlear mechanotransduction defect.

Cerebral Cortical and Frontosubcortical Degeneration

Degeneration of cortical and frontosubcortical networks produces a cognitive syndrome that begins as isolated executive dysfunction with frontal-system features and progresses to globally impaired cognition and dementia, in parallel with neurological deterioration. Psychiatric manifestations including psychosis, hallucinations, depression, and personality change occur, and generalized EEG slowing and epileptic seizures are reported. Structural imaging shows diffuse cerebral atrophy.

neuron CL:0000540

Downstream

Impaired executive functioning

Progressive cognitive decline

Dementia

Cerebral atrophy

Psychosis

Hallucinations

Depression

Seizures

Show evidence (2 references)

PMID:27869457 SUPPORT Human Clinical

"At baseline, 2 individuals demonstrated cognitive profiles with executive difficulties in some areas consistent with frontal-system dysfunction behaviorally and on standardized testing."

Formal neuropsychological testing in an ADCA-DN kindred localizes the early cognitive deficit to frontal systems.

PMID:32984563 SUPPORT Human Clinical

"Magnetic resonance imaging showed diffuse atrophy in the cerebrum and cerebellum without a significant signal change"

Documents diffuse cerebral atrophy accompanying the cerebellar atrophy in a genetically confirmed patient.

Optic Nerve and Peripheral Sensory Axon Degeneration

Involvement of the optic nerve produces optic atrophy, which may be subclinical and detected only on fundoscopy and visual evoked potentials. Degeneration of peripheral sensory axons produces a large- and small-fibre sensory polyneuropathy. Sensory neuropathy is the dominant feature of the allelic HSAN1E phenotype and is variable in ADCA-DN, being absent in some genetically confirmed families.

sensory neuron CL:0000101

Downstream

Optic atrophy

Sensory neuropathy

Show evidence (2 references)

PMID:24727570 SUPPORT Human Clinical

"Other common symptoms and features observed in our cases, involving the central and peripheral nervous system, include deafness, optic neuropathy-previously not reported in HSAN IE-large and small fibres polyneuropathy and lower limbs oedema."

Deep phenotyping of five patients spanning ADCA-DN and HSAN IE documents both optic neuropathy and mixed-fibre polyneuropathy in this DNMT1 spectrum.

PMID:32984563 SUPPORT Human Clinical

"fundoscopy revealed pale discs with an elevated cup-to-disk ratio in both eyes, suggesting optic atrophy"

Direct ophthalmological documentation of optic atrophy in a genetically confirmed ADCA-DN patient.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

20

Ear 1

Sensorineural hearing loss Sensorineural hearing impairment HP:0000407

Laterality: BILATERAL Course: PROGRESSIVE

Show evidence (2 references)

PMID:22328086 SUPPORT Human Clinical

"Narcolepsy and deafness were the first symptoms to appear in all pedigrees, followed by ataxia."

Deafness is one of the two earliest manifestations across all three discovery kindreds.

PMID:31957642 SUPPORT Human Clinical

"A 44-year-old female with personal and familiar longstanding history of progressive bilateral sensorineural deafness, and sensitive cerebellar ataxia"

Confirms the bilateral and progressive character of the hearing loss in a genetically confirmed exon-21 patient.

Eye 2

Optic atrophy HP:0000648

Show evidence (2 references)

PMID:32984563 SUPPORT Human Clinical

"fundoscopy revealed pale discs with an elevated cup-to-disk ratio in both eyes, suggesting optic atrophy"

Direct ophthalmological documentation of optic atrophy in ADCA-DN.

PMID:31957642 SUPPORT Human Clinical

"Clinical and neurophysiological evaluations reveled signs of cerebellar, pyramidal, peripheral, cognitive involvement, and optical atrophy."

Independent report of optic atrophy in an exon-21 ADCA-DN patient.

Cataract HP:0000518

Deliberately not wired into the pathograph. No mechanism has been proposed linking DNMT1 dysfunction or the neurodegenerative cascade to lens opacification, and connecting it to any existing node would assert a causal claim the literature does not support. Recorded here so the manifestation is captured; see the discussions block.

Show evidence (2 references)

PMID:40285998 SUPPORT Human Clinical

"It begins in adulthood, and may also be associated with other variable symptoms as optic atrophy, cataracts, psychosis, depression or sensory neuropathy."

Lists cataract among the recognized variable ADCA-DN manifestations.

PMID:32984563 SUPPORT Human Clinical

"Optic atrophy, cataract, sensory neuropathy, and dementia may develop in the later stages of the disease."

Independent statement that cataract is a late ADCA-DN manifestation.

Nervous System 15

Excessive daytime somnolence HP:0001262

Temporal: CHRONIC Course: PROGRESSIVE

Show evidence (1 reference)

PMID:31957642 SUPPORT Human Clinical

"A 44-year-old female with personal and familiar longstanding history of progressive bilateral sensorineural deafness, and sensitive cerebellar ataxia, presenting with brief episodes of falls while laughing and excessive diurnal somnolence."

Documents excessive daytime somnolence at presentation in a genetically confirmed exon-21 ADCA-DN patient.

Cataplexy HP:0002524

Temporal: RECURRENT

Show evidence (2 references)

PMID:22328086 SUPPORT Human Clinical

"Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is characterized by late onset (30-40 years old) cerebellar ataxia, sensory neuronal deafness, narcolepsy-cataplexy and dementia."

Narcolepsy-cataplexy is part of the defining ADCA-DN phenotype.

PMID:40285998 SUPPORT Human Clinical

"Patient III-1 started at 42 years with narcolepsy with cataplexy, hearing loss and tremor, and patient IV-1 started at 4 years, with mild intellectual disability, and narcolepsy without cataplexy."

Shows cataplexy in one p.Ala570Val carrier but narcolepsy without cataplexy in another from the same family, supporting variable penetrance of the cataplexy component.

Sleep-onset REM periods Abnormal rapid eye movement sleep HP:0002494

Show evidence (1 reference)

PMID:24709307 SUPPORT Human Clinical

"Therefore, SOREMPs may precede the clinical picture of ADCA-DN as an early polysomnographic marker of central nervous system involvement detected by MRS."

Establishes SOREMPs as an ADCA-DN sleep abnormality detectable before clinical onset.

Cerebellar ataxia HP:0001251

Course: PROGRESSIVE

Show evidence (2 references)

PMID:22328086 SUPPORT Human Clinical

"Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is characterized by late onset (30-40 years old) cerebellar ataxia, sensory neuronal deafness, narcolepsy-cataplexy and dementia."

Cerebellar ataxia is one of the defining features of ADCA-DN.

PMID:40285998 SUPPORT Human Clinical

"Ataxia, despite being a cardinal symptom, does not appear at the onset in younger patients, and hearing loss also seems to develop over the years."

Qualifies the timing of ataxia relative to other features within a single p.Ala570Val kindred.

Gait ataxia HP:0002066

Course: PROGRESSIVE

Show evidence (2 references)

PMID:32984563 SUPPORT Human Clinical

"At the age of 38 years, she began experiencing difficulty walking because of ataxic gait."

Documents ataxic gait with a specific age of onset in a genetically confirmed ADCA-DN patient.

PMID:31957642 SUPPORT Human Clinical

"During the 4 years of follow-up her walking ability declined"

Documents progressive decline of walking ability on longitudinal follow-up.

Cerebellar atrophy HP:0001272

Show evidence (2 references)

PMID:40285998 SUPPORT Human Clinical

"Patient II-2 started at 51 years, with ataxia, tremor, epileptic seizures, cerebellar atrophy, narcolepsy without cataplexy, hearing loss, moderate cognitive impairment."

Cerebellar atrophy is recorded in a p.Ala570Val carrier with the full ADCA-DN phenotype.

PMID:23904686 SUPPORT Human Clinical

"Mild brain atrophy was observed on MRI, with cerebellar involvement."

Independent imaging confirmation of cerebellar atrophy.

Tremor HP:0001337

Show evidence (1 reference)

PMID:40285998 SUPPORT Human Clinical

"Patient III-1 started at 42 years with narcolepsy with cataplexy, hearing loss and tremor"

Tremor documented in a genetically confirmed p.Ala570Val carrier.

Cerebral atrophy HP:0002059

Show evidence (1 reference)

PMID:32984563 SUPPORT Human Clinical

"Magnetic resonance imaging showed diffuse atrophy in the cerebrum and cerebellum without a significant signal change"

Documents diffuse cerebral atrophy in a genetically confirmed patient.

Progressive cognitive decline Mental deterioration HP:0001268

Course: PROGRESSIVE

Show evidence (1 reference)

PMID:27869457 SUPPORT Human Clinical

"Cognitive decline occurred in parallel with neurological deterioration."

Directly supports progressive cognitive decline tracking the neurological course in an ADCA-DN kindred.

Dementia HP:0000726

Show evidence (2 references)

PMID:27869457 SUPPORT Human Clinical

"The third individual was further in the disease course and exhibited more globally impaired cognition consistent with a diagnosis of dementia."

Documents dementia in the most advanced member of an ADCA-DN kindred.

PMID:22328086 SUPPORT Human Clinical

"Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is characterized by late onset (30-40 years old) cerebellar ataxia, sensory neuronal deafness, narcolepsy-cataplexy and dementia."

Dementia is part of the defining ADCA-DN phenotype.

Psychosis HP:0000709

Show evidence (1 reference)

PMID:40285998 SUPPORT Human Clinical

"It begins in adulthood, and may also be associated with other variable symptoms as optic atrophy, cataracts, psychosis, depression or sensory neuropathy."

Lists psychosis among the recognized variable manifestations of ADCA-DN specifically.

Hallucinations HP:0000738

Show evidence (1 reference)

PMID:22338191 SUPPORT Other

"Sedative or antipsychotic drugs help to reduce extreme restlessness, roaming behavior, delusions, and hallucinations associated with dementia."

GeneReviews documents hallucinations in DNMT1-related disorder. PARTIAL because the statement covers the whole DNMT1 spectrum (HSAN1E and ADCA-DN) rather than ADCA-DN alone.

Depression HP:0000716

Show evidence (1 reference)

PMID:40285998 SUPPORT Human Clinical

"It begins in adulthood, and may also be associated with other variable symptoms as optic atrophy, cataracts, psychosis, depression or sensory neuropathy."

Lists depression among the recognized variable ADCA-DN manifestations.

Seizures HP:0001250

Show evidence (1 reference)

PMID:40285998 SUPPORT Human Clinical

"Patient II-2 started at 51 years, with ataxia, tremor, epileptic seizures, cerebellar atrophy, narcolepsy without cataplexy, hearing loss, moderate cognitive impairment."

Epileptic seizures documented in a genetically confirmed ADCA-DN patient.

Sensory neuropathy HP:0000763

Show evidence (2 references)

PMID:24727570 SUPPORT Human Clinical

"Other common symptoms and features observed in our cases, involving the central and peripheral nervous system, include deafness, optic neuropathy-previously not reported in HSAN IE-large and small fibres polyneuropathy and lower limbs oedema."

Documents mixed-fibre polyneuropathy in a cohort spanning ADCA-DN and HSAN IE. PARTIAL because the cohort is not restricted to ADCA-DN.

PMID:40285998 SUPPORT Human Clinical

"Sensory neuropathy is not present in any of the cases studied."

A three-generation p.Ala570Val ADCA-DN family had no sensory neuropathy, supporting the description of neuropathy as variable rather than an obligate ADCA-DN feature.

Other 2

Impaired executive functioning HP:0033051

Show evidence (1 reference)

PMID:27869457 SUPPORT Human Clinical

"At baseline, 2 individuals demonstrated cognitive profiles with executive difficulties in some areas consistent with frontal-system dysfunction behaviorally and on standardized testing."

Formal neuropsychological characterization of the early ADCA-DN cognitive profile.

Pyramidal signs Abnormal pyramidal sign HP:0007256

Show evidence (1 reference)

PMID:32984563 SUPPORT Human Clinical

"Here, we report a patient with DNMT1 mutation who presented with mid-age onset of cerebellar ataxia, sensorineural hearing loss, and pyramidal signs."

Pyramidal signs documented in a genetically confirmed ADCA-DN patient.

🧬

Genetic Associations

1

DNMT1 (Causative)

Gene: DNMT1 hgnc:2976 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant

Show evidence (2 references)

PMID:22328086 SUPPORT Human Clinical

"We performed exome sequencing in five individuals from three ADCA-DN kindreds and identified DNMT1 as the only gene with mutations found in all five affected individuals."

Establishes DNMT1 as the causal gene by exome sequencing across three independent ADCA-DN kindreds.

PMID:38970134 SUPPORT Other

"Conversely, several studies have independently confirmed pathogenic mutations within exon 21 of the DNMT1 gene, which encodes the DNA (cytosine-5)-methyltransferase 1 enzyme."

A 2024 systematic review confirms independent replication of pathogenic exon-21 DNMT1 variants.

Variants (3)

Exon 21 TS-domain missense cluster (p.Ala570Val, p.Gly605Ala, p.Val606Phe) Pathogenic

missense variant

The three recurrent ADCA-DN alleles identified in the discovery study, all conserved missense substitutions in exon 21 lying in close spatial proximity within the C-terminal part of the targeting-sequence domain. p.Ala570Val has since been reported repeatedly, including in a six-affected Canadian family and a three-generation Spanish family.

Functional effects

DNA (cytosine-5-)-methyltransferase regulation by the RFTS domain loss-of-function

The substitutions destabilize DNMT1 and relieve RFTS-mediated autoinhibition, so the net effect combines impaired maintenance methylation with abnormal, potentially toxic mutant protein rather than a clean loss of enzyme activity.

mutant DNMT1 protein handling gain-of-function

Mutant protein mislocalizes to the cytoplasm, forms aggresomes, and in RFTS knock-in models is internally cleaved, which has been interpreted as a toxic gain of function superimposed on reduced activity.

Show evidence (4 references)

PMID:22328086 SUPPORT Human Clinical

"Sanger sequencing confirmed the de novo mutation p.Ala570Val in one family, and showed co-segregation of p.Val606Phe and p.Ala570Val, with the ADCA-DN phenotype, in two other kindreds."

Establishes segregation and de novo occurrence for two of the three recurrent alleles.

PMID:22328086 SUPPORT Human Clinical

"An additional ADCA-DN kindred with a p.GLY605Ala mutation was subsequently identified."

Identifies the third recurrent ADCA-DN allele.

PMID:27602171 SUPPORT Human Clinical

"which had been previously reported as pathogenic for ADCA-DN and segregated with disease in the family"

Independent replication of p.Ala570Val with segregation in a six-affected family.

+ 1 more reference

Additional exon 21 alleles (p.Cys596Arg, p.Glu575Lys, p.Glu578Lys) Likely Pathogenic

missense variant

Further pathogenic or likely pathogenic exon-21 substitutions reported in single ADCA-DN patients or families, including a de novo p.Cys596Arg in a Brazilian patient, p.Glu575Lys segregating with disease in an Italian mother and daughter, and p.Glu578Lys in a Taiwanese patient.

Show evidence (3 references)

PMID:23904686 SUPPORT Human Clinical

"The proband had a novel DNMT1 mutation in exon 21, p.Cys596Arg, c.1786T > C."

Reports a novel de novo exon-21 ADCA-DN allele.

PMID:31957642 SUPPORT Human Clinical

"direct sequencing of exons 20 and 21 of the DNMT1 gene was performed revealing the p.Glu575Lys mutation in exon 21 in the proband and her mother."

Reports p.Glu575Lys segregating in an ADCA-DN mother-daughter pair.

PMID:32984563 SUPPORT Human Clinical

"Whole exome sequencing revealed a heterozygous missense mutation in DNMT1 c. 1732G>A (p.E578K), which is the causative gene for autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN)."

Reports p.Glu578Lys as a likely pathogenic exon-21 ADCA-DN allele.

TS-domain positional genotype-phenotype correlation

Variant position within the DNMT1 targeting-sequence domain separates the two allelic phenotypes: ADCA-DN alleles occupy the C-terminal end of the domain (exon 21) whereas HSAN1E alleles occupy the middle or N-terminal part (often exon 20, with Tyr495 a hot spot). The correlation is strong but not absolute, since expanding case series describe overlapping phenotypes and at least one allele outside the domain.

Show evidence (3 references)

PMID:25678562 SUPPORT Human Clinical

"Our results indicate that all the mutations causal for HSAN1E are located in the middle part or N-terminus end of the TS domain, whereas all the mutations causal for autosomal dominant cerebellar ataxia, deafness and narcolepsy are located in the C-terminus end of the TS domain."

The primary statement of the positional genotype-phenotype split.

PMID:23365052 SUPPORT Human Clinical

"Amino acid Tyr495 is a hot spot for HSAN1E, distinct from exon 21 mutations associated with narcolepsy."

Independent confirmation that the HSAN1E hot spot is distinct from the exon-21 narcolepsy-associated region.

PMID:32754641 SUPPORT Human Clinical

"Broader application of WES further expands genotype-phenotype correlations of DNMT1-complex disorder."

Expanded sequencing shows the correlation is a strong tendency rather than an absolute rule, supporting the qualification recorded here.

💊

Medical Actions

7

Symptomatic narcolepsy pharmacotherapy

Action: Pharmacotherapy NCIT:C15986

Agent: modafinil CHEBI:31859

Excessive daytime somnolence and cataplexy are managed with standard narcolepsy therapy under a sleep specialist, typically a wake-promoting agent such as modafinil with anticataplectic treatment where needed, plus scheduled naps, driving and occupational risk counseling, and avoidance of sedating drugs. No ADCA-DN-specific efficacy study or interventional trial exists; this is extrapolated from idiopathic narcolepsy and is symptomatic only. Broad DNA methyltransferase inhibitors used in oncology are not a rational therapy here, because systemic interference with maintenance methylation could be harmful and the disease mechanism includes both deficient function and potentially toxic mutant-protein species.

Target Phenotypes: Excessive daytime somnolence HP:0001262 Cataplexy HP:0002524

Show evidence (1 reference)

PMID:22338191 SUPPORT Other

"No cure for DNMT1 disorder currently exists."

GeneReviews confirms that all management is symptomatic. It supports the framing of this treatment as symptomatic extrapolation rather than supporting a specific agent's efficacy in ADCA-DN.

Hearing aids and assistive communication

Conventional amplification and assistive communication technology are the first-line audiological intervention as sensorineural hearing loss progresses.

Target Phenotypes: Sensorineural hearing impairment HP:0000407

Show evidence (1 reference)

PMID:22338191 SUPPORT Other

"Because hearing loss may be severe, initial use of hearing aids and/or assistive communication methods may be needed."

GeneReviews recommends hearing aids and assistive communication as initial management of the hearing loss in DNMT1-related disorder.

Cochlear implantation

Action: cochlear device implantation Ontology label: Surgical Procedure NCIT:C15329

Cochlear implantation is the clearest reported intervention with an objectively measured benefit in DNMT1-complex disorder, and may be considered for ADCA-DN when amplification becomes inadequate. Direct ADCA-DN-specific outcome evidence is not available.

Target Phenotypes: Sensorineural hearing impairment HP:0000407

Show evidence (3 references)

PMID:32754641 SUPPORT Human Clinical

"Case 4 (p.T497P) underwent left cochlear implant, resulting in significant hearing improvements at all tested frequencies (250-6,000 Hz)."

Quantified audiometric benefit after cochlear implantation. PARTIAL because the patient carried a non-exon-21 DNMT1-complex variant rather than a classical ADCA-DN allele.

PMID:32754641 SUPPORT Human Clinical

"Hearing loss treatment by cochlear implantation is helpful and should be considered."

The authors' explicit management recommendation for DNMT1-complex disorder, of which ADCA-DN is part.

PMID:37199681 SUPPORT Human Clinical

"Cochlear implant was performed at 44 years for the bilateral high frequency sensorineural hearing loss with improvement in hearing and day-to-day function."

A second DNMT1 patient with functional benefit from implantation. PARTIAL because the p.Cys430Tyr variant produced an overlapping HSN1E-cerebellar phenotype rather than classical ADCA-DN.

Neuropsychiatric symptom management

Action: Pharmacotherapy NCIT:C15986

Sedative or antipsychotic medication is used for the restlessness, roaming, delusions, and hallucinations that accompany the dementia phase. Caregiver education and psychological support are considered essential because the behavioral changes and loss of insight impose a substantial caregiver burden.

Target Phenotypes: Hallucinations HP:0000738 Psychosis HP:0000709

Show evidence (2 references)

PMID:22338191 SUPPORT Other

"Sedative or antipsychotic drugs help to reduce extreme restlessness, roaming behavior, delusions, and hallucinations associated with dementia."

GeneReviews directly recommends this symptomatic pharmacotherapy for the neuropsychiatric manifestations.

PMID:22338191 SUPPORT Other

"Because behavioral changes and the loss of insight and judgment often present a considerable burden for partners or other caregivers, information about the disorder and psychological support for partners or other caregivers are essential."

Supports the caregiver-support component of this management arm.

Surveillance and injury prevention for sensory impairment

Action: Supportive Care NCIT:C15747

Annual cognitive assessment and audiometry apply across DNMT1-related disorder. For an ADCA-DN patient who also has sensory neuropathy, daily foot examination and protection of insensate extremities with appropriate socks and shoes and avoidance of hot water follow the broader DNMT1-disorder guidance; these measures are not applicable when sensation is intact.

Show evidence (2 references)

PMID:22338191 SUPPORT Other

"Examination of feet daily for evidence of skin injury; annual routine clinical testing for dementia and audiogram to monitor hearing loss."

The GeneReviews surveillance schedule for DNMT1-related disorder. PARTIAL because foot surveillance is conditional on sensory impairment, which is variable in ADCA-DN.

PMID:22338191 SUPPORT Other

"To prevent injury to extremities with decreased sensation, protect the skin with appropriate socks and shoes and avoid exposure of feet to hot water."

The GeneReviews Agents/Circumstances to Avoid guidance for this disorder, captured as a conditional safety measure for ADCA-DN patients with sensory loss.

Physical therapy, balance training, and fall prevention

Action: Physical Therapy NCIT:C15302

Physiotherapy, gait and balance training, walking aids, home safety review, and occupational therapy address the progressive cerebellar ataxia and falls risk. This is standard rehabilitative practice for progressive hereditary ataxia; no ADCA-DN-specific rehabilitation study exists, so no efficacy evidence is attached.

Target Phenotypes: Gait ataxia HP:0002066

Genetic counseling and reproductive options

Action: Genetic Counseling NCIT:C15240

Counseling covers autosomal dominant transmission with a 50 percent recurrence risk per pregnancy, the availability of prenatal and preimplantation genetic testing once the familial variant is known, and cascade testing of consenting adult relatives. Predictive testing of minors requires careful ethical review because the classical disease is adult-onset and no preventive therapy exists.

Show evidence (2 references)

PMID:22338191 SUPPORT Other

"Once the DNMT1 pathogenic variant has been identified in an affected family member, prenatal and preimplantation genetic testing are possible."

GeneReviews establishes the reproductive testing options offered during counseling.

PMID:22338191 SUPPORT Other

"Each child of an individual with DNMT1 disorder has a 50% chance of inheriting the pathogenic variant."

Supports the recurrence risk figure communicated in counseling.

🔬

Biochemical Markers

2

Cerebrospinal fluid hypocretin-1 (Decreased)

Context: CSF hypocretin-1 (orexin-A) supports the narcolepsy component but, unlike sporadic narcolepsy type 1, it is not uniformly deficient in DNMT1 disease. Reported values in genetically confirmed patients span low, intermediate, and normal, and can remain normal even as polysomnographic abnormalities progress. A normal value therefore does not exclude ADCA-DN.

Show evidence (3 references)

PMID:23904686 SUPPORT Human Clinical

"CSF hypocretin-1 was 191 pg/mL (normal values > 200 pg/mL)."

A quantified borderline-low CSF hypocretin-1 value in a genetically confirmed exon-21 ADCA-DN patient.

PMID:24727570 SUPPORT Human Clinical

"Remarkably, narcolepsy with or without cataplexy with low/intermediate or normal cerebrospinal fluid hypocretin-1 is present in both diseases."

Establishes the variable rather than uniformly deficient CSF hypocretin-1 pattern across the DNMT1 spectrum, which is why presence is qualified in the context field.

PMID:31957642 SUPPORT Human Clinical

"During the 4 years of follow-up her walking ability declined, she became more somnolent and repeated PSG documented REM sleep latency shortening, and finally the evidence of de novo spontaneous SOREMPs, although normal CSF hrct-1 at second revaluation."

Documents a genetically confirmed exon-21 patient whose CSF hypocretin-1 stayed normal while the sleep phenotype progressed.

Cerebellar myo-inositol on proton MR spectroscopy (Increased)

Context: Increased cerebellar myo-inositol, a marker of glial cell activity and density, is detectable by proton MR spectroscopy in clinically unaffected DNMT1 variant carriers with normal structural MRI. It is a research observation in two carriers, not a validated biomarker.

Show evidence (1 reference)

PMID:24709307 SUPPORT Human Clinical

"Sleep recordings found sleep-onset rapid eye movement periods (SOREMPs) and proton magnetic resonance spectroscopy (MRS) revealed increased cerebellar myoinositol (mI) in both subjects."

Directly documents raised cerebellar myo-inositol in presymptomatic DNMT1 carriers.

🔬

Diagnosis

4

DNMT1 molecular genetic testing

Diagnosis is established by identifying a heterozygous pathogenic DNMT1 variant. Targeted approaches sequence exons 20 and 21, which encode the targeting-sequence domain and contain essentially all reported alleles. A known familial variant can be tested directly.

DNMT1 sequencing NCIT:C15709

Results: A heterozygous missense variant in the C-terminal part of the DNMT1 targeting-sequence domain (classically exon 21) confirms ADCA-DN.

Show evidence (2 references)

PMID:22338191 SUPPORT Other

"The diagnosis of DNMT1 disorder is established by identification of a heterozygous pathogenic variant in DNMT1 by molecular genetic testing."

GeneReviews states the molecular basis of diagnosis.

PMID:23904686 SUPPORT Human Clinical

"DNMT1 exons 20 and 21 were sequenced."

Illustrates the targeted two-exon sequencing strategy used in clinical practice.

Exome or genome sequencing for atypical or unresolved presentations

Broad-based sequencing resolves DNMT1-related disease that narrower panel testing misses, particularly in adults presenting to neuromuscular or ataxia clinics with an atypical or overlapping phenotype. Repeat-expansion ataxias require separate targeted testing because standard exome sequencing does not detect them reliably.

Whole Exome Sequencing NCIT:C101295

Show evidence (2 references)

PMID:38392311 SUPPORT Human Clinical

"Here, we use five case examples to illustrate the unique ability of broad-based testing to improve diagnostic yield, resulting in identification of SORD-neuropathy, HADHB-related disease, ATXN2-ALS, MECP2 related progressive gait decline and spasticity, and DNMT1-related cerebellar ataxia,..."

Demonstrates that exome or genome sequencing identified DNMT1-related disease in an adult clinic where narrower testing had not.

PMID:32984563 SUPPORT Human Clinical

"Genetic tests detected no abnormalities such as spinocerebellr ataxia type 1, 2, 3, 6, 7, 17, and dentatorubral -pallidoluysian atrophy."

Shows that repeat-expansion ataxia testing was negative before exome sequencing established the DNMT1 diagnosis, supporting the sequencing pathway for unresolved ataxia.

Polysomnography with multiple sleep latency testing

Overnight polysomnography followed by multiple sleep latency testing documents the narcolepsy component and detects sleep-onset REM periods. Repeat studies are informative because SOREMPs can appear during follow-up.

Polysomnography NCIT:C114185

Show evidence (1 reference)

PMID:23904686 SUPPORT Human Clinical

"Narcolepsy was supported by polysomnographic and multiple sleep latency testing."

Documents the standard sleep-laboratory workup used to establish the narcolepsy component in ADCA-DN.

HLA-DQB1*06:02 typing as non-diagnostic context

HLA-DQB1*06:02 is carried by the great majority of patients with sporadic narcolepsy type 1 but is frequently absent in DNMT1 disease. Its presence or absence can therefore provide context when narcolepsy accompanies deafness or ataxia, but it neither establishes nor excludes ADCA-DN. One genetically confirmed ADCA-DN patient was HLA-DQB1*06:02 positive; molecular DNMT1 testing, not HLA typing, establishes the diagnosis.

HLA-DQB1*06:02 typing NCIT:C15709

Show evidence (2 references)

PMID:24727570 SUPPORT Human Clinical

"The human leukocyte antigen DQB1*06:02 was absent in all patients."

In a five-patient DNMT1 cohort spanning ADCA-DN and HSAN IE, the narcolepsy risk allele was uniformly absent.

PMID:23904686 SUPPORT Human Clinical

"HLA-DQB1*06:02 was positive."

A genetically confirmed exon-21 ADCA-DN patient carried the risk allele, supporting the explicit caveat that a positive HLA result does not exclude ADCA-DN.

📈

Progression

3

Presymptomatic carrier

Age: Third decade (documented in carriers aged 23 and 28)

Clinically unaffected DNMT1 variant carriers can already show sleep-onset REM periods on polysomnography and increased cerebellar myo-inositol on proton MR spectroscopy, while neurological examination, audiometry, ophthalmological evaluation, and structural brain MRI remain normal. These are promising early markers observed in only two carriers and are not validated screening biomarkers.

Show evidence (2 references)

PMID:24709307 SUPPORT Human Clinical

"Sleep recordings found sleep-onset rapid eye movement periods (SOREMPs) and proton magnetic resonance spectroscopy (MRS) revealed increased cerebellar myoinositol (mI) in both subjects."

Documents both presymptomatic markers in two asymptomatic carriers of the familial DNMT1 variant.

PMID:24709307 SUPPORT Human Clinical

"Auditory and ophthalmologic investigations as well as structural brain magnetic resonance imaging (MRI) scans revealed no abnormalities."

Confirms that the sleep and spectroscopic changes precede any detectable auditory, ophthalmological, or structural abnormality.

Early clinical

Age: Fourth to fifth decade

In the original kindreds narcolepsy and deafness were the first manifestations in every pedigree, with ataxia following. The order is not invariable: a six-affected Canadian family developed hearing loss and ataxia first and narcolepsy later, and in a three-generation Spanish family narcolepsy was the presenting symptom in all three affected members while ataxia was absent at onset in the younger patients.

Show evidence (3 references)

PMID:22328086 SUPPORT Human Clinical

"Narcolepsy and deafness were the first symptoms to appear in all pedigrees, followed by ataxia."

Establishes the canonical symptom sequence across the three discovery kindreds.

PMID:27602171 SUPPORT Human Clinical

"We report a family with six individuals affected with ADCA-DN; specifically, patients first developed hearing loss and ataxia, followed by narcolepsy, and cognitive decline."

A six-affected family shows a different ordering, so the canonical narcolepsy-first sequence is typical rather than obligatory.

PMID:40285998 SUPPORT Human Clinical

"Ataxia, despite being a cardinal symptom, does not appear at the onset in younger patients, and hearing loss also seems to develop over the years."

Confirms that the cardinal ataxia and hearing features accrue over years and may be absent at first presentation.

Intermediate to advanced

The course is progressive and lifelong, with no documented spontaneous remission. Gait deteriorates, sleepiness worsens, and sleep abnormalities can appear de novo during follow-up even in patients whose CSF hypocretin-1 remains normal. Cognitive involvement evolves from isolated executive dysfunction to globally impaired cognition and dementia, in parallel with neurological deterioration.

Show evidence (2 references)

PMID:31957642 SUPPORT Human Clinical

"During the 4 years of follow-up her walking ability declined, she became more somnolent and repeated PSG documented REM sleep latency shortening, and finally the evidence of de novo spontaneous SOREMPs, although normal CSF hrct-1 at second revaluation."

A four-year longitudinal follow-up documents progressive motor, sleep, and polysomnographic deterioration in a genetically confirmed ADCA-DN patient.

PMID:27869457 SUPPORT Human Clinical

"This family demonstrated progressive neurodegeneration beginning with isolated areas of executive dysfunction and leading to globally impaired cognition and dementia."

Neuropsychological study of an ADCA-DN kindred defines the cognitive trajectory from executive dysfunction to dementia.

📊

Prevalence

1

Worldwide

Cases In Literature Rare

No population prevalence or incidence estimate exists for ADCA-DN. The published evidence base consists of a small number of individual pedigrees and case reports from European, Brazilian, Taiwanese, Canadian, and other populations, so the entity is best described qualitatively as rare with a worldwide distribution and no ancestry restriction. Orphanet records no epidemiological class for ORPHA:314404. RARE rather than ULTRA_RARE is used here because no source quantifies the rate; the qualitative band is the most that the literature supports.

Show evidence (2 references)

PMID:38970134 SUPPORT Other

"This methylation enzyme is strongly associated with a rare disease defined by autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN)."

A 2024 systematic review characterizes ADCA-DN as a rare disease, which is the level of epidemiological precision the literature supports.

PMID:23904686 SUPPORT Human Clinical

"The Brazilian patient reported here further adds to the worldwide distribution of ADCA-DN."

Supports a worldwide, case-report-level distribution rather than a geographically restricted or founder-based occurrence.

🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Autosomal Dominant Cerebellar Ataxia Deafness and Narcolepsy:

Narcolepsy type 1 (sporadic, HLA-DQB1*06:02 associated)

Overlapping Features Sporadic narcolepsy type 1 shares excessive daytime somnolence, cataplexy, and SOREMPs, but lacks progressive sensorineural deafness, cerebellar ataxia, and dementia. It is strongly HLA-DQB1*06:02 associated and CSF hypocretin-1 is usually markedly reduced, whereas in ADCA-DN HLA-DQB1*06:02 is frequently negative and CSF hypocretin-1 is variable.

Show evidence (1 reference)

PMID:23904686 SUPPORT Human Clinical

"Diagnosing the syndrome can be difficult, as all clinical features may not be present at onset, HLA-DQB1*06:02 is often negative, and sporadic cases occur."

States the diagnostic distinction from sporadic narcolepsy and warns that an incomplete phenotype at onset makes the separation difficult.

Hereditary sensory and autonomic neuropathy type 1E (HSAN1E)

Overlapping Features The allelic DNMT1 disorder, caused by variants in the middle or N-terminal part of the same targeting-sequence domain (often exon 20). It presents with the triad of sensorineural hearing loss, sensory neuropathy with sudomotor failure, and dementia, and typically lacks prominent cerebellar ataxia, although narcolepsy occurs in both. The two are discrete clinical entities within one disease spectrum.

Show evidence (2 references)

PMID:24727570 SUPPORT Human Clinical

"Phenotypic characterization pinpoints that ADCA-DN and HSAN IE represent two discrete clinical entities belonging to the same disease spectrum, with variable degree of overlap."

Directly supports treating HSAN1E as a distinct but allelic differential rather than merging the two entries.

PMID:24727570 SUPPORT Human Clinical

"HSAN IE and ADCA-DN are two extreme phenotypic manifestations of a DNMT1 methylopathy."

Frames the two entities as poles of a single molecular spectrum.

Autosomal dominant spinocerebellar ataxias and other hereditary ataxias

Overlapping Features Repeat-expansion spinocerebellar ataxias (SCA1, 2, 3, 6, 7, 17, DRPLA), Friedreich ataxia, CAPOS syndrome, and mitochondrial disease all overlap with the ataxia plus deafness or optic atrophy presentation.

Show evidence (1 reference)

PMID:32984563 SUPPORT Human Clinical

"The combination of cerebellar ataxia, deafness, pyramidal sign, and optic atrophy indicates differential diagnoses, including cerebellar ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss (CAPOS) syndrome, Friedreich's ataxia (FRDA), and mitochondrial diseases"

Enumerates the principal ataxia differentials considered before the DNMT1 diagnosis was established.

🔬

Clinical Trials

1

NCT01793168 NOT_APPLICABLE RECRUITING

CoRDS is a broad international observational registry for rare and undiagnosed disorders. ClinicalTrials.gov lists Autosomal Dominant Cerebellar Ataxia, Deafness and Narcolepsy among its accepted conditions; it is a registry resource, not an ADCA-DN-specific interventional study.

Show evidence (1 reference)

clinicaltrials:NCT01793168 SUPPORT Human Clinical

"It provides researchers with a centralized, international patient registry for all rare diseases."

Establishes that NCT01793168 is a broad international rare-disease registry rather than an interventional ADCA-DN trial.

🧫

Experimental Models

1

Patient-derived fibroblasts, iPSCs, and induced neurons

Fibroblasts, induced pluripotent stem cells, and induced neurons derived from ADCA-DN patients carrying p.Ala570Val, p.Gly605Ala, or p.Val606Phe. These are the only disease models carrying authentic ADCA-DN alleles and have delineated methylome and transcriptome disruption specific to cell type. Limitations include incomplete neuronal maturation, absence of intact cerebellar and hypothalamic circuits, and inability to reproduce a decades-long degenerative course.

Show evidence (1 reference)

PMID:37584462 SUPPORT In Vitro

"We show cell type-specific changes in gene expression and DNA methylation patterns."

The defining result obtained from the patient-derived cellular model system described here.

🐁

Animal Models

1

Dnmt1-M1 and Dnmt1-M2 RFTS-domain knock-in (heterozygous) Mouse (Mus musculus) Knock-in

CRISPR knock-in mice carrying mouse substitutions equivalent to the human HSAN1E variants Y495C and D490E-P491Y. Heterozygotes are viable with reduced DNMT1 protein and neurodegenerative phenotypes including impaired learning and memory; homozygotes die around embryonic day 10.5. These models support the RFTS-disease mechanism but do not carry ADCA-DN exon-21 alleles and do not reproduce narcolepsy, deafness, or cerebellar ataxia.

Species

Mouse (Mus musculus)

Genotype

Dnmt1-M1 and Dnmt1-M2 RFTS-domain knock-in (heterozygous)

Genes

DNMT1 hgnc:2976

Show evidence (2 references)

PMID:34516921 SUPPORT Model Organism

"We generated Dnmt1-M1 and Dnmt1-M2 knock-in mouse models that are equivalent to Y495C and D490E-P491Y mutation in patients with HSAN1E, respectively."

Describes the only published knock-in mouse models of DNMT1 RFTS disease.

PMID:34516921 SUPPORT Model Organism

"The homozygous mutants die around embryonic day 10.5 and are apparently devoid of DNMT1 proteins."

Documents homozygous embryonic lethality, which constrains modeling strategies to the heterozygous state that matches human disease.

{ }

Source YAML

click to show

name: Autosomal Dominant Cerebellar Ataxia Deafness and Narcolepsy
creation_date: "2026-08-01T00:00:00Z"
category: Mendelian
description: >-
  Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is an
  ultra-rare adult-onset neurodegenerative disorder caused by heterozygous
  missense variants in exon 21 of DNMT1, which encodes the C-terminal portion of
  the replication foci targeting sequence (RFTS, also called targeting sequence
  or TS) domain of DNA methyltransferase 1. Onset is typically in the fourth or
  fifth decade. Narcolepsy with cataplexy and progressive sensorineural deafness
  usually appear first, followed by cerebellar ataxia and progressive cognitive
  and behavioral deterioration ending in dementia; optic atrophy, sensory
  neuropathy, pyramidal signs, psychosis, and seizures broaden the phenotype.
  The disorder is allelic to hereditary sensory and autonomic neuropathy type 1E
  (HSAN1E), whose causal variants lie in exon 20 or the N-terminal-to-middle
  part of the same TS domain; the two are increasingly described together as
  DNMT1-complex disorder, but they remain discrete clinical entities and
  evidence from mixed DNMT1 cohorts should not be attributed to ADCA-DN without
  qualification.

  ADCA-DN is mechanistically distinct from the common sporadic form of
  narcolepsy modeled in the Narcolepsy and Narcolepsy-Cataplexy Syndrome
  entries. Those describe a presumed autoimmune destruction of hypothalamic
  hypocretin/orexin neurons that is strongly HLA-DQB1*06:02 associated and gives
  usually markedly reduced CSF hypocretin-1. In ADCA-DN the sleep phenotype
  arises within a monogenic epigenetic neurodegeneration; HLA-DQB1*06:02 is
  frequently absent, CSF hypocretin-1 is variably low, intermediate, or normal,
  and a full-blown narcolepsy type 1 picture is not always reached.

  Nosologically ADCA-DN is a subtype of autosomal dominant cerebellar ataxia
  type 1 (ADCA type 1). There is no disease-modifying therapy and no
  disease-specific interventional clinical trial; the broad CoRDS rare-disease
  registry accepts ADCA-DN enrollment, and management is symptomatic and
  multidisciplinary.
disease_term:
  preferred_term: autosomal dominant cerebellar ataxia, deafness and narcolepsy
  term:
    id: MONDO:0011397
    label: autosomal dominant cerebellar ataxia, deafness and narcolepsy
parents:
- Hereditary Ataxia
- Neurodegenerative Disease
- Autosomal Dominant Cerebellar Ataxia Type I
synonyms:
- ADCA-DN
- ADCA-DN syndrome
- cerebellar ataxia, deafness, and narcolepsy, autosomal dominant
- Autosomal dominant cerebellar ataxia-deafness-narcolepsy syndrome
- Autosomal dominant cerebellar ataxia-hearing loss-narcolepsy syndrome
- DNMT1-related ADCA-DN
notes: >-
  Module conformance was evaluated and deliberately declined for two candidate
  modules. (1) cerebellar_purkinje_degeneration: the module's central effector
  node is Purkinje neuron degeneration, and no human neuropathological or
  disease-model evidence demonstrates Purkinje cell loss in ADCA-DN. The
  available human data are MRI cerebellar atrophy and an increase in cerebellar
  myo-inositol on MR spectroscopy, which is a glial rather than a Purkinje
  marker; PubMed returns no ADCA-DN autopsy series. Conformance would assert a
  cellular effector the literature has not established. (2)
  sensorineural_hair_cell_loss: the module's central effector node is hair cell
  mechanotransduction failure and death, whereas ADCA-DN deafness is described
  as sensory neuronal deafness and is accompanied by attenuated brainstem
  auditory evoked potentials, pointing to auditory-neural or retrocochlear
  involvement rather than a cochlear hair cell lesion. No study localizes the
  ADCA-DN auditory lesion to hair cells. Both decisions are recorded as open
  questions under discussions and should be revisited if neuropathological or
  temporal-bone data appear.
references:
- reference: PMID:22338191
  title: DNMT1-Related Disorder.
  tags:
  - GeneReviews
inheritance:
- name: Autosomal dominant
  inheritance_term:
    preferred_term: autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  penetrance: UNKNOWN
  expressivity: VARIABLE
  description: >-
    ADCA-DN is transmitted as an autosomal dominant trait caused by a single
    heterozygous DNMT1 missense allele. Onset is strongly age dependent, so
    penetrance cannot be estimated reliably from the small published pedigrees
    and is recorded as unknown rather than complete. Expressivity is variable
    even within one family: in a three-generation kindred carrying p.Ala570Val,
    the presenting features, presence of cataplexy, and age at onset differed
    markedly between generations. De novo variants occur, so a negative family
    history does not exclude the diagnosis.
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      DNMT1 disorder is inherited in an autosomal dominant manner. Most affected
      individuals have an affected parent; the proportion of affected
      individuals with a de novo DNMT1 pathogenic variant is unknown.
    explanation: >-
      GeneReviews states the autosomal dominant mode of inheritance for the
      DNMT1-related disorder spectrum that contains ADCA-DN, and confirms that
      the de novo proportion is not established.
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Each child of an individual with DNMT1 disorder has a 50% chance of
      inheriting the pathogenic variant.
    explanation: Supports the 50% per-pregnancy transmission risk used in counseling.
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ADCA syndrome has a variable phenotype in a same family."
    explanation: >-
      A three-generation p.Ala570Val family directly demonstrates variable
      expressivity within a single kindred.
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Diagnosing the syndrome can be difficult, as all clinical features may not
      be present at onset, HLA-DQB1*06:02 is often negative, and sporadic cases
      occur.
    explanation: >-
      Documents that sporadic (de novo) ADCA-DN occurs, so a negative family
      history does not exclude the dominant disorder.
definitions:
- name: ADCA-DN clinical case definition
  definition_type: CASE_DEFINITION
  derivation_basis: ESTABLISHED_CRITERIA
  description: >-
    Adult-onset (typically 30 to 40 years) progressive cerebellar ataxia,
    sensory neuronal (sensorineural) deafness, and narcolepsy with cataplexy,
    with dementia developing later, in an individual carrying a heterozygous
    DNMT1 variant in the C-terminal part of the targeting-sequence domain
    (classically exon 21). There are no independently validated formal
    diagnostic criteria; molecular confirmation is central, and the full triad
    may not be present at onset.
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is
      characterized by late onset (30-40 years old) cerebellar ataxia, sensory
      neuronal deafness, narcolepsy-cataplexy and dementia.
    explanation: >-
      The discovery paper gives the defining clinical tetrad and the adult age
      of onset used in this case definition.
  - reference: ORPHA:314404
    reference_title: "Autosomal dominant cerebellar ataxia-deafness-narcolepsy syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      A rare polymorphic disorder, subtype of autosomal dominant cerebellar
      ataxia type 1 (ADCA type 1), characterized by ataxia, sensorineural
      deafness and narcolepsy with cataplexy and dementia.
    explanation: >-
      Orphanet's curated definition independently states the defining features
      and places ADCA-DN under ADCA type 1.
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The diagnosis of DNMT1 disorder is established by identification of a
      heterozygous pathogenic variant in DNMT1 by molecular genetic testing.
    explanation: >-
      GeneReviews confirms that molecular confirmation, not a clinical score, is
      what establishes the diagnosis.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: RARE
  notes: >-
    No population prevalence or incidence estimate exists for ADCA-DN. The
    published evidence base consists of a small number of individual pedigrees
    and case reports from European, Brazilian, Taiwanese, Canadian, and other
    populations, so the entity is best described qualitatively as rare with a
    worldwide distribution and no ancestry restriction. Orphanet records no
    epidemiological class for ORPHA:314404. RARE rather than ULTRA_RARE is used
    here because no source quantifies the rate; the qualitative band is the most
    that the literature supports.
  evidence:
  - reference: PMID:38970134
    reference_title: A systematic review on the contribution of DNA methylation to hearing loss.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      This methylation enzyme is strongly associated with a rare disease defined
      by autosomal dominant cerebellar ataxia, deafness and narcolepsy
      (ADCA-DN).
    explanation: >-
      A 2024 systematic review characterizes ADCA-DN as a rare disease, which is
      the level of epidemiological precision the literature supports.
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The Brazilian patient reported here further adds to the worldwide
      distribution of ADCA-DN.
    explanation: >-
      Supports a worldwide, case-report-level distribution rather than a
      geographically restricted or founder-based occurrence.
progression:
- phase: Presymptomatic carrier
  age_range: Third decade (documented in carriers aged 23 and 28)
  notes: >-
    Clinically unaffected DNMT1 variant carriers can already show sleep-onset
    REM periods on polysomnography and increased cerebellar myo-inositol on
    proton MR spectroscopy, while neurological examination, audiometry,
    ophthalmological evaluation, and structural brain MRI remain normal. These
    are promising early markers observed in only two carriers and are not
    validated screening biomarkers.
  evidence:
  - reference: PMID:24709307
    reference_title: "Polysomnographic and neurometabolic features may mark preclinical autosomal dominant cerebellar ataxia, deafness, and narcolepsy due to a mutation in the DNA (cytosine-5-)-methyltransferase gene, DNMT1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Sleep recordings found sleep-onset rapid eye movement periods (SOREMPs)
      and proton magnetic resonance spectroscopy (MRS) revealed increased
      cerebellar myoinositol (mI) in both subjects.
    explanation: >-
      Documents both presymptomatic markers in two asymptomatic carriers of the
      familial DNMT1 variant.
  - reference: PMID:24709307
    reference_title: "Polysomnographic and neurometabolic features may mark preclinical autosomal dominant cerebellar ataxia, deafness, and narcolepsy due to a mutation in the DNA (cytosine-5-)-methyltransferase gene, DNMT1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Auditory and ophthalmologic investigations as well as structural brain
      magnetic resonance imaging (MRI) scans revealed no abnormalities.
    explanation: >-
      Confirms that the sleep and spectroscopic changes precede any detectable
      auditory, ophthalmological, or structural abnormality.
- phase: Early clinical
  age_range: Fourth to fifth decade
  notes: >-
    In the original kindreds narcolepsy and deafness were the first
    manifestations in every pedigree, with ataxia following. The order is not
    invariable: a six-affected Canadian family developed hearing loss and ataxia
    first and narcolepsy later, and in a three-generation Spanish family
    narcolepsy was the presenting symptom in all three affected members while
    ataxia was absent at onset in the younger patients.
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Narcolepsy and deafness were the first symptoms to appear in all
      pedigrees, followed by ataxia.
    explanation: >-
      Establishes the canonical symptom sequence across the three discovery
      kindreds.
  - reference: PMID:27602171
    reference_title: "Identification of a methylation profile for DNMT1-associated autosomal dominant cerebellar ataxia, deafness, and narcolepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a family with six individuals affected with ADCA-DN;
      specifically, patients first developed hearing loss and ataxia, followed
      by narcolepsy, and cognitive decline.
    explanation: >-
      A six-affected family shows a different ordering, so the canonical
      narcolepsy-first sequence is typical rather than obligatory.
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ataxia, despite being a cardinal symptom, does not appear at the onset in
      younger patients, and hearing loss also seems to develop over the years.
    explanation: >-
      Confirms that the cardinal ataxia and hearing features accrue over years
      and may be absent at first presentation.
- phase: Intermediate to advanced
  notes: >-
    The course is progressive and lifelong, with no documented spontaneous
    remission. Gait deteriorates, sleepiness worsens, and sleep abnormalities
    can appear de novo during follow-up even in patients whose CSF hypocretin-1
    remains normal. Cognitive involvement evolves from isolated executive
    dysfunction to globally impaired cognition and dementia, in parallel with
    neurological deterioration.
  evidence:
  - reference: PMID:31957642
    reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      During the 4 years of follow-up her walking ability declined, she became
      more somnolent and repeated PSG documented REM sleep latency shortening,
      and finally the evidence of de novo spontaneous SOREMPs, although normal
      CSF hrct-1 at second revaluation.
    explanation: >-
      A four-year longitudinal follow-up documents progressive motor, sleep, and
      polysomnographic deterioration in a genetically confirmed ADCA-DN patient.
  - reference: PMID:27869457
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN) associated with progressive cognitive and behavioral deterioration."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This family demonstrated progressive neurodegeneration beginning with
      isolated areas of executive dysfunction and leading to globally impaired
      cognition and dementia.
    explanation: >-
      Neuropsychological study of an ADCA-DN kindred defines the cognitive
      trajectory from executive dysfunction to dementia.
pathophysiology:
- name: DNMT1 Exon 21 RFTS Domain Missense Variant
  role: trigger
  biological_scale: MOLECULAR
  description: >-
    A single heterozygous germline missense variant in exon 21 of DNMT1 alters
    the C-terminal portion of the replication foci targeting sequence (RFTS,
    also called targeting sequence or TS) domain of DNA methyltransferase 1, the
    sole maintenance methyltransferase that restores symmetrical CpG methylation
    on hemimethylated DNA after replication and during DNA repair. The recurrent
    ADCA-DN alleles p.Ala570Val, p.Gly605Ala, and p.Val606Phe cluster in close
    spatial proximity within this region. Variant position within the same TS
    domain is what separates ADCA-DN from allelic HSAN1E, whose variants lie in
    the N-terminal-to-middle part of the domain, most often in exon 20.
  gene:
    preferred_term: DNMT1
    term:
      id: hgnc:2976
      label: DNMT1
  molecular_functions:
  - preferred_term: DNA (cytosine-5-)-methyltransferase activity
    term:
      id: GO:0003886
      label: DNA (cytosine-5-)-methyltransferase activity
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our mutations are all located in exon 21 and in very close spatial
      proximity, suggesting distinct phenotypes depending on mutation location
      within this gene.
    explanation: >-
      The discovery study localizes all ADCA-DN alleles to a tight cluster in
      exon 21 and proposes position-dependent phenotype.
  - reference: PMID:25678562
    reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our results indicate that all the mutations causal for HSAN1E are located
      in the middle part or N-terminus end of the TS domain, whereas all the
      mutations causal for autosomal dominant cerebellar ataxia, deafness and
      narcolepsy are located in the C-terminus end of the TS domain.
    explanation: >-
      A 45-patient genotype-phenotype analysis establishes the intradomain
      positional split between HSAN1E and ADCA-DN alleles.
  - reference: PMID:32754641
    reference_title: Expanded genetic insight and clinical experience of DNMT1-complex disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      DNA methyltransferase 1, encoded by the DNMT1 gene, is the sole
      methyltransferase for maintaining methylation during DNA replication and
      DNA repair.
    explanation: >-
      Background statement of the normal enzymatic role that the variant
      perturbs; cited as framing rather than as ADCA-DN patient data.
  - reference: DOI:10.3390/biom14091117
    reference_title: The Role of DNMT Methyltransferases and TET Dioxygenases in the Maintenance of the DNA Methylation Level
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      This review deals with the functional characteristics and biological roles
      of enzymes participating in DNA methylation and demethylation as key
      factors in epigenetic regulation of gene expression.
    explanation: >-
      Background review establishing DNMT-family enzymes as the effectors of
      epigenetic gene regulation whose disruption underlies this disorder.
  downstream:
  - target: Relief of RFTS Autoinhibition and DNMT1 Destabilization
    causal_link_type: DIRECT
    description: >-
      The variant lies within the autoinhibitory RFTS domain itself, so the
      protein-level consequence follows directly from the amino-acid change.
- name: Relief of RFTS Autoinhibition and DNMT1 Destabilization
  biological_scale: MOLECULAR
  description: >-
    The RFTS domain normally folds back into the catalytic pocket and acts as an
    endogenous inhibitor of DNMT1 activity. ADCA-DN missense substitutions in
    this domain weaken that intramolecular interaction. Purified mutant enzyme
    shows markedly reduced thermal stability, a 2.5 to 3.5-fold increase in DNA
    binding affinity, and weakened RFTS-mediated inhibition of methylation
    activity. In knock-in mouse models of the allelic HSAN1E substitutions the
    destabilized protein is additionally susceptible to proteolytic cleavage
    within the RFTS domain, generating a truncated species, and steady-state
    DNMT1 protein is reduced in heterozygotes. The disease mechanism is
    therefore not simple haploinsufficiency but a mixture of impaired
    regulation, reduced stability, and potentially toxic mutant-protein species.
  molecular_functions:
  - preferred_term: DNA (cytosine-5-)-methyltransferase activity
    term:
      id: GO:0003886
      label: DNA (cytosine-5-)-methyltransferase activity
    modifier: ABNORMAL
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:31804802
    reference_title: Disease-Associated Mutations G589A and V590F Relieve Replication Focus Targeting Sequence-Mediated Autoinhibition of DNA Methyltransferase 1.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The replication focus targeting sequence (RFTS) domain, found in the
      regulatory region, is an endogenous inhibitor of DNMT1 activity.
    explanation: >-
      Background statement of the normal autoinhibitory function of the domain
      that ADCA-DN variants disrupt.
  - reference: PMID:31804802
    reference_title: Disease-Associated Mutations G589A and V590F Relieve Replication Focus Targeting Sequence-Mediated Autoinhibition of DNA Methyltransferase 1.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The mutations significantly decrease the thermal stability of DNMT1, yet
      the mutant proteins exhibit 2.5-3.5-fold increases in DNA binding
      affinity.
    explanation: >-
      Biochemical characterization of purified ADCA-DN mutant protein
      (G589A/V590F in the numbering used by that study) shows destabilization
      with increased DNA binding.
  - reference: PMID:31804802
    reference_title: Disease-Associated Mutations G589A and V590F Relieve Replication Focus Targeting Sequence-Mediated Autoinhibition of DNA Methyltransferase 1.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Taken together, these data suggest these disease-associated mutations
      decrease protein stability and, at least partially, relieve normal
      RFTS-mediated autoinhibition of DNMT1.
    explanation: >-
      States the in vitro conclusion that ADCA-DN variants relieve
      autoinhibition rather than simply abolishing catalysis.
  - reference: PMID:34516921
    reference_title: Mutation-induced DNMT1 cleavage drives neurodegenerative disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We found that both mutant heterozygous mice are viable, have reduced DNMT1
      proteins, and exhibit neurodegenerative phenotypes including impaired
      learning and memory.
    explanation: >-
      Knock-in mice carrying HSAN1E-equivalent RFTS substitutions show reduced
      DNMT1 protein and neurodegeneration. PARTIAL because these are not
      ADCA-DN exon-21 alleles.
  - reference: PMID:34516921
    reference_title: Mutation-induced DNMT1 cleavage drives neurodegenerative disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We present the evidence that the mutant DNMT1 proteins are unstable, most
      likely because of cleavage within RFTS domain by an unidentified
      proteinase.
    explanation: >-
      Supports RFTS-variant-induced protein instability and internal cleavage as
      a mechanism, established for HSAN1E-equivalent alleles in mouse.
  downstream:
  - target: Mutant DNMT1 Mislocalization and Aggresome Formation
    causal_link_type: DIRECT
    description: >-
      Reduced conformational stability of the mutant protein underlies its
      abnormal subcellular handling.
  - target: Cell-Type-Specific Methylome and Transcriptome Disruption
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - >-
      Dysregulated recruitment of DNMT1 to replication foci and heterochromatin.
    - >-
      Altered enzymatic activity at hemimethylated CpG substrates during S
      phase.
  - target: Aberrant DNMT1-NSUN2 RNA m5C Methylation
    causal_link_type: DIRECT
    description: >-
      A 2025 study identified an additional RFTS-dependent RNA-binding function
      of DNMT1. The published abstract describes RFTS-mutant mice without naming
      the allele, and whether classical ADCA-DN exon-21 substitutions perturb
      this function in the same way remains untested.
- name: Mutant DNMT1 Mislocalization and Aggresome Formation
  biological_scale: CELLULAR
  description: >-
    Mutant DNMT1 protein translocates to the cytoplasm and forms aggresomes
    while losing its ability to bind heterochromatin during the G2 phase of the
    cell cycle. The resulting imbalance of protein homeostasis engages
    aggresome-induced autophagy. This proteostatic burden is the proposed reason
    why a defect in a ubiquitously required maintenance methyltransferase
    produces selective rather than global tissue damage.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: inclusion body assembly
    term:
      id: GO:0070841
      label: inclusion body assembly
    modifier: INCREASED
  - preferred_term: autophagy
    term:
      id: GO:0006914
      label: autophagy
    modifier: INCREASED
  cellular_components:
  - preferred_term: aggresome
    term:
      id: GO:0016235
      label: aggresome
  - preferred_term: heterochromatin
    term:
      id: GO:0000792
      label: heterochromatin
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:25678562
    reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Moreover, we show that mutant DNMT1 proteins translocate to the cytoplasm
      and are prone to form aggresomes while losing their binding ability to
      heterochromatin during the G2 cell cycle.
    explanation: >-
      Cellular localization experiments on mutant DNMT1 directly demonstrate
      cytoplasmic mislocalization, aggresome formation, and loss of
      heterochromatin binding.
  - reference: PMID:25678562
    reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Our results suggest mutations in DNMT1 result in imbalanced protein
      homeostasis through aggresome-induced autophagy.
    explanation: >-
      States the proteostasis-autophagy consequence inferred from the same
      cellular experiments.
  downstream:
  - target: Selective Central and Peripheral Neurodegeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - >-
      The steps linking chronic aggresome and autophagy burden to the loss of
      specific neuronal populations are not established.
    evidence:
    - reference: PMID:25678562
      reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        This mechanism may explain why mutations in the sole DNA maintenance
        methyltransferase lead to selective central and peripheral
        neurodegeneration.
      explanation: >-
        The authors advance the proteostasis route as an explanation for
        selective neurodegeneration; it is presented as a hypothesis derived
        from cellular experiments, hence PARTIAL.
- name: Aberrant DNMT1-NSUN2 RNA m5C Methylation
  biological_scale: MOLECULAR
  description: >-
    DNMT1 also binds mRNA and recruits NSUN2 to facilitate 5-methylcytosine
    (m5C) RNA methylation, which stabilizes transcripts involved in
    mitochondrial function. In RFTS-mutant mice, DNMT1-RNA interaction, m5C
    methylation, and stability of a subset of metabolic transcripts are
    increased. This newly described branch is mechanistically relevant to
    RFTS-domain disease but remains provisional for classical ADCA-DN because
    it has not been demonstrated in patients, and the published abstract does not
    identify the mouse RFTS allele or establish equivalence to a classical
    exon-21 ADCA-DN allele.
  genes:
  - preferred_term: DNMT1
    term:
      id: hgnc:2976
      label: DNMT1
  - preferred_term: NSUN2
    term:
      id: hgnc:25994
      label: NSUN2
  biological_processes:
  - preferred_term: RNA methylation
    term:
      id: GO:0001510
      label: RNA methylation
    modifier: INCREASED
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:40328247
    reference_title: DNA methyltransferase 1 modulates mitochondrial function through bridging m(5)C RNA methylation.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Here, we demonstrated that DNMT1 has the capability to bind to mRNA
      transcripts and facilitate 5-methylcytosine (m5C) RNA methylation by
      recruiting NOP2/Sun RNA methyltransferase 2 (NSUN2).
    explanation: >-
      Establishes the DNMT1-NSUN2 RNA-methylation activity that defines this
      molecular branch.
  - reference: PMID:40328247
    reference_title: DNA methyltransferase 1 modulates mitochondrial function through bridging m(5)C RNA methylation.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      When the DNMT1 RFTS domain is mutated in mice, it triggers aberrant
      DNMT1-RNA interaction and significantly elevated m5C RNA methylation and
      RNA stability for a portion of metabolic genes.
    explanation: >-
      Demonstrates the abnormal RNA-methylation phenotype in RFTS-mutant mice.
      PARTIAL because the result has not been shown in human ADCA-DN and the
      published abstract does not specify the mouse allele.
  downstream:
  - target: Oxidative Stress and Mitochondrial Dysfunction
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Increased stability and abundance of metabolic transcripts.
- name: Oxidative Stress and Mitochondrial Dysfunction
  biological_scale: CELLULAR
  description: >-
    In RFTS-mutant mice, increased metabolic transcript abundance downstream of
    aberrant RNA m5C methylation produces cumulative oxidative stress and
    mitochondrial dysfunction associated with neurological abnormalities.
    This is a model-organism mechanism lead, not an established lesion in
    classical ADCA-DN patients.
  biological_processes:
  - preferred_term: response to oxidative stress
    term:
      id: GO:0006979
      label: response to oxidative stress
    modifier: INCREASED
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:40328247
    reference_title: DNA methyltransferase 1 modulates mitochondrial function through bridging m(5)C RNA methylation.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Consequently, increased levels of metabolic RNA transcripts contribute
      to cumulative oxidative stress, mitochondrial dysfunction, and
      neurological symptoms.
    explanation: >-
      Supports the transcript-to-mitochondrial-stress sequence in the mutant
      mice. PARTIAL because human ADCA-DN confirmation is absent.
  downstream:
  - target: Selective Central and Peripheral Neurodegeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The mouse study links mitochondrial dysfunction to neurological symptoms,
      but does not establish which ADCA-DN neuronal populations are affected or
      whether the same route operates in human disease.
- name: Cell-Type-Specific Methylome and Transcriptome Disruption
  biological_scale: MOLECULAR
  description: >-
    Maintenance CpG methylation becomes abnormal in a manner that depends on
    cell type and developmental stage rather than producing uniform global
    hypomethylation. Genome-wide methylation array analysis of an ADCA-DN family
    carrying p.Ala570Val found a shift out of the extreme methylation bins into
    intermediate and near-complete methylation, with 82 regionally
    hypermethylated loci. In patient fibroblasts, induced pluripotent stem
    cells, and induced neurons carrying p.Ala570Val, p.Gly605Ala, or
    p.Val606Phe, methylation and expression changes were specific to cell type
    and negatively correlated, ZFP57 promoters were hypomethylated with
    increased ZFP57 expression, and PDGFB, PRDM8, and NR2F1 emerged as candidate
    mediators of the ataxia/psychosis/dementia and deafness/optic atrophy arms
    respectively.
  biological_processes:
  - preferred_term: DNA modification
    term:
      id: GO:0006304
      label: DNA modification
    modifier: ABNORMAL
  - preferred_term: epigenetic regulation of gene expression
    term:
      id: GO:0040029
      label: epigenetic regulation of gene expression
    modifier: ABNORMAL
  - preferred_term: chromatin organization
    term:
      id: GO:0006325
      label: chromatin organization
    modifier: ABNORMAL
  genes:
  - preferred_term: ZFP57
    term:
      id: hgnc:18791
      label: ZFP57
  - preferred_term: PDGFB
    term:
      id: hgnc:8800
      label: PDGFB
  - preferred_term: PRDM8
    term:
      id: hgnc:13993
      label: PRDM8
  - preferred_term: NR2F1
    term:
      id: hgnc:7975
      label: NR2F1
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:27602171
    reference_title: "Identification of a methylation profile for DNMT1-associated autosomal dominant cerebellar ataxia, deafness, and narcolepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      DNA methylation analysis by high-resolution genome-wide DNA methylation
      array identified a decrease in CpGs with 0-10 % methylation and 80-95 %
      methylation and a concomitant increase in sites with 10-30 % methylation
      and >95 % methylation.
    explanation: >-
      Genome-wide array on DNA from a six-affected ADCA-DN family demonstrates a
      reproducible redistribution of methylation levels in patients.
  - reference: PMID:27602171
    reference_title: "Identification of a methylation profile for DNMT1-associated autosomal dominant cerebellar ataxia, deafness, and narcolepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This report identifies robust changes in the DNA methylation patterns in
      ADCA-DN patients, which is an important step towards elucidating disease
      pathogenesis.
    explanation: >-
      States the authors' conclusion that patient methylation patterns are
      robustly altered in ADCA-DN.
  - reference: PMID:37584462
    reference_title: Mutations in human DNA methyltransferase DNMT1 induce specific genome-wide epigenomic and transcriptomic changes in neurodevelopment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We show cell type-specific changes in gene expression and DNA methylation patterns."
    explanation: >-
      Patient-derived fibroblasts, iPSCs, and induced neurons establish that the
      epigenomic consequence depends on cell type rather than being uniform.
  - reference: PMID:37584462
    reference_title: Mutations in human DNA methyltransferase DNMT1 induce specific genome-wide epigenomic and transcriptomic changes in neurodevelopment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In addition, we identified a group of genes associated with clinical
      phenotypes of ADCA-DN, including PDGFB and PRDM8 for cerebellar ataxia,
      psychosis and dementia and NR2F1 for deafness and optic atrophy.
    explanation: >-
      Nominates the specific dysregulated genes recorded on this node as
      candidate mediators of the ADCA-DN phenotype arms.
  - reference: PMID:37584462
    reference_title: Mutations in human DNA methyltransferase DNMT1 induce specific genome-wide epigenomic and transcriptomic changes in neurodevelopment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Furthermore, ZFP57, which is required to maintain gene imprinting through
      DNA methylation during early development, was hypomethylated in promoters
      and exhibited upregulated expression in patients with ADCA-DN in both iPSC
      and iNs.
    explanation: >-
      Documents the ZFP57 promoter hypomethylation and upregulation seen in both
      patient-derived cell types.
  downstream:
  - target: Selective Central and Peripheral Neurodegeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - >-
      How locus-specific methylation change in particular cell types translates
      into the loss of particular neuronal populations decades later is not
      established.
    - >-
      PDGFB, PRDM8, and NR2F1 are candidate but unvalidated mediators.
- name: Selective Central and Peripheral Neurodegeneration
  biological_scale: CELLULAR
  description: >-
    Despite the ubiquitous requirement for DNMT1, the clinical consequence is
    restricted degeneration of specific central and peripheral neuronal
    populations. The pattern in ADCA-DN preferentially involves the hypothalamic
    hypocretin system, the cerebellum, the auditory pathway, frontosubcortical
    and cortical networks, the optic nerve, and peripheral sensory axons, with
    corticospinal (pyramidal) involvement in some patients. The determinants of
    this selectivity are unknown.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: cerebellum
    term:
      id: UBERON:0002037
      label: cerebellum
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      DNMT1-related disorder is a degenerative disorder of the central and
      peripheral nervous systems comprising a phenotypic spectrum that includes
      hereditary sensory and autonomic neuropathy type 1E (HSAN1E) and autosomal
      dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN).
    explanation: >-
      GeneReviews frames the disorder as a combined central and peripheral
      nervous system degeneration, which is the claim made by this node.
  - reference: PMID:31957642
    reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical and neurophysiological evaluations reveled signs of cerebellar,
      pyramidal, peripheral, cognitive involvement, and optical atrophy.
    explanation: >-
      A genetically confirmed exon-21 ADCA-DN patient demonstrates the
      multi-system distribution of neuronal involvement recorded on this node.
  downstream:
  - target: Hypothalamic Hypocretin System Dysfunction
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - >-
      Whether the sleep phenotype reflects hypocretin neuron loss, hypocretin
      neuron dysfunction without loss, or downstream circuit failure is unknown.
  - target: Cerebellar Degeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - >-
      The vulnerable cerebellar cell population has not been identified
      histologically in ADCA-DN.
  - target: Auditory Pathway Degeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - >-
      The site of the auditory lesion (cochlear hair cell, spiral ganglion,
      auditory nerve, or central auditory pathway) is unresolved.
  - target: Cerebral Cortical and Frontosubcortical Degeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Optic Nerve and Peripheral Sensory Axon Degeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Pyramidal signs
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Corticospinal tract involvement is reported in a subset of genetically
      confirmed patients.
- name: Hypothalamic Hypocretin System Dysfunction
  conforms_to: "orexin_arousal_instability#Sleep-Wake State Instability"
  notes: >-
    Conformance is declared at the module's central effector
    (#Sleep-Wake State Instability) and deliberately NOT at its trigger
    (#Loss of Hypothalamic Orexin (Hypocretin) Signal). The module's stated
    entry bar for the trigger is demonstrated CSF hypocretin-1 deficiency,
    postmortem orexin neuron loss, or a causal HCRT/HCRTR variant; ADCA-DN meets
    none of them, since CSF hypocretin-1 here can be low, intermediate, or normal
    and no neuropathological study has shown hypocretin neuron loss. What this
    entry does evidence is the downstream state instability the module makes
    rate-limiting - sleep-onset REM periods alongside excessive daytime
    somnolence and cataplexy - which is exactly the partial conformance the
    module permits for narcolepsy phenotypes without a demonstrated orexin
    lesion. The disorder is a neurodegenerative route into that node rather than
    an autoimmune one, so it also does not inherit the module's immune trigger.
  biological_scale: TISSUE
  description: >-
    Impaired hypothalamic hypocretin (orexin) signaling destabilizes the
    sleep-wake and REM-sleep control that hypocretin neurons normally maintain,
    producing excessive daytime somnolence, cataplexy, and sleep-onset REM
    periods. Unlike common sporadic narcolepsy type 1, in which CSF hypocretin-1
    is usually markedly reduced following extensive hypocretin neuron loss, CSF
    hypocretin-1 in DNMT1 disease can be low, intermediate, or normal, and
    cataplexy may be absent. No neuropathological study has demonstrated
    hypocretin neuron loss in ADCA-DN, so this node records system dysfunction
    rather than confirmed cell loss.
  cell_types:
  - preferred_term: hypocretin (orexin) neuron
    term:
      id: CL:0011109
      label: hypocretin-secreting neuron
  biological_processes:
  - preferred_term: circadian sleep/wake cycle
    term:
      id: GO:0042745
      label: circadian sleep/wake cycle
    modifier: ABNORMAL
  locations:
  - preferred_term: hypothalamus
    term:
      id: UBERON:0001898
      label: hypothalamus
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Remarkably, narcolepsy with or without cataplexy with low/intermediate or
      normal cerebrospinal fluid hypocretin-1 is present in both diseases.
    explanation: >-
      Establishes that the DNMT1 sleep phenotype is not accompanied by uniformly
      low CSF hypocretin-1, which is why this node claims system dysfunction
      rather than hypocretin neuron destruction.
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CSF hypocretin-1 was 191 pg/mL (normal values > 200 pg/mL)."
    explanation: >-
      A genetically confirmed exon-21 ADCA-DN patient shows a borderline-low CSF
      hypocretin-1 value, supporting partial hypocretin system involvement.
  downstream:
  - target: Excessive daytime somnolence
    causal_link_type: DIRECT
  - target: Cataplexy
    causal_link_type: DIRECT
  - target: Sleep-onset REM periods
    causal_link_type: DIRECT
- name: Cerebellar Degeneration
  biological_scale: TISSUE
  description: >-
    Progressive degeneration of the cerebellum produces limb and gait
    incoordination, dysmetria, and tremor, with cerebellar atrophy on structural
    MRI. Increased cerebellar myo-inositol on proton MR spectroscopy, a marker
    of glial activity and density, is detectable in presymptomatic carriers and
    indicates that cerebellar involvement begins before clinical ataxia. The
    identity of the degenerating cerebellar cell population in ADCA-DN has not
    been established histologically, so no Purkinje-specific claim is made here.
  locations:
  - preferred_term: cerebellum
    term:
      id: UBERON:0002037
      label: cerebellum
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mild brain atrophy was observed on MRI, with cerebellar involvement."
    explanation: >-
      Structural imaging in a genetically confirmed ADCA-DN patient documents
      cerebellar involvement.
  - reference: PMID:24709307
    reference_title: "Polysomnographic and neurometabolic features may mark preclinical autosomal dominant cerebellar ataxia, deafness, and narcolepsy due to a mutation in the DNA (cytosine-5-)-methyltransferase gene, DNMT1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The two asymptomatic carriers of the heterozygous DNMT1 mutation for
      ADCA-DN, a late-onset neurodegenerative disease, presented with SOREMPs
      associated with an increase of mI in the brain, a marker of glial cell
      activity and density characteristic of early stages of neurodegenerative
      diseases.
    explanation: >-
      Identifies raised cerebellar myo-inositol as a glial neurodegeneration
      marker present before clinical cerebellar signs.
  downstream:
  - target: Cerebellar ataxia
    causal_link_type: DIRECT
  - target: Gait ataxia
    causal_link_type: DIRECT
  - target: Cerebellar atrophy
    causal_link_type: DIRECT
  - target: Tremor
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Auditory Pathway Degeneration
  biological_scale: TISSUE
  description: >-
    Bilateral progressive sensorineural hearing loss is one of the two earliest
    manifestations. The discovery report characterized it as sensory neuronal
    deafness, and electrophysiology in a genetically confirmed patient showed
    attenuated brainstem auditory evoked potentials alongside attenuated visual
    and somatosensory evoked potentials, which points to auditory-neural or
    central pathway involvement. Whether cochlear hair cells are primarily
    affected has not been determined; there is no temporal-bone or cochlear
    histopathology in ADCA-DN.
  locations:
  - preferred_term: auditory system
    term:
      id: UBERON:0016490
      label: auditory system
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is
      characterized by late onset (30-40 years old) cerebellar ataxia, sensory
      neuronal deafness, narcolepsy-cataplexy and dementia.
    explanation: >-
      The defining description characterizes the deafness as sensory neuronal
      rather than conductive or purely cochlear.
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Electrophysiological studies revealed that visual evoked potentials were
      attenuated with prolonged latencies in both eyes, and brainstem auditory
      and somatosensory evoked potentials were also attenuated.
    explanation: >-
      Attenuated brainstem auditory evoked potentials indicate involvement of
      the auditory nerve or central auditory pathway rather than a purely
      cochlear mechanotransduction defect.
  downstream:
  - target: Sensorineural hearing loss
    causal_link_type: DIRECT
- name: Cerebral Cortical and Frontosubcortical Degeneration
  biological_scale: TISSUE
  description: >-
    Degeneration of cortical and frontosubcortical networks produces a cognitive
    syndrome that begins as isolated executive dysfunction with frontal-system
    features and progresses to globally impaired cognition and dementia, in
    parallel with neurological deterioration. Psychiatric manifestations
    including psychosis, hallucinations, depression, and personality change
    occur, and generalized EEG slowing and epileptic seizures are reported.
    Structural imaging shows diffuse cerebral atrophy.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:27869457
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN) associated with progressive cognitive and behavioral deterioration."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At baseline, 2 individuals demonstrated cognitive profiles with executive
      difficulties in some areas consistent with frontal-system dysfunction
      behaviorally and on standardized testing.
    explanation: >-
      Formal neuropsychological testing in an ADCA-DN kindred localizes the
      early cognitive deficit to frontal systems.
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Magnetic resonance imaging showed diffuse atrophy in the cerebrum and
      cerebellum without a significant signal change
    explanation: >-
      Documents diffuse cerebral atrophy accompanying the cerebellar atrophy in
      a genetically confirmed patient.
  downstream:
  - target: Impaired executive functioning
    causal_link_type: DIRECT
  - target: Progressive cognitive decline
    causal_link_type: DIRECT
  - target: Dementia
    causal_link_type: DIRECT
  - target: Cerebral atrophy
    causal_link_type: DIRECT
  - target: Psychosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Hallucinations
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Depression
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Seizures
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Optic Nerve and Peripheral Sensory Axon Degeneration
  biological_scale: TISSUE
  description: >-
    Involvement of the optic nerve produces optic atrophy, which may be
    subclinical and detected only on fundoscopy and visual evoked potentials.
    Degeneration of peripheral sensory axons produces a large- and small-fibre
    sensory polyneuropathy. Sensory neuropathy is the dominant feature of the
    allelic HSAN1E phenotype and is variable in ADCA-DN, being absent in some
    genetically confirmed families.
  cell_types:
  - preferred_term: sensory neuron
    term:
      id: CL:0000101
      label: sensory neuron
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other common symptoms and features observed in our cases, involving the
      central and peripheral nervous system, include deafness, optic
      neuropathy-previously not reported in HSAN IE-large and small fibres
      polyneuropathy and lower limbs oedema.
    explanation: >-
      Deep phenotyping of five patients spanning ADCA-DN and HSAN IE documents
      both optic neuropathy and mixed-fibre polyneuropathy in this DNMT1
      spectrum.
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      fundoscopy revealed pale discs with an elevated cup-to-disk ratio in both
      eyes, suggesting optic atrophy
    explanation: >-
      Direct ophthalmological documentation of optic atrophy in a genetically
      confirmed ADCA-DN patient.
  downstream:
  - target: Optic atrophy
    causal_link_type: DIRECT
  - target: Sensory neuropathy
    causal_link_type: DIRECT
phenotypes:
- category: Neurological
  name: Excessive daytime somnolence
  description: >-
    Chronic, disabling daytime sleepiness with irresistible sleep episodes. It
    is typically one of the earliest manifestations and worsens over years of
    follow-up.
  phenotype_term:
    preferred_term: Excessive daytime somnolence
    term:
      id: HP:0001262
      label: Excessive daytime somnolence
    temporality: CHRONIC
    clinical_course: PROGRESSIVE
  diagnostic: true
  evidence:
  - reference: PMID:31957642
    reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A 44-year-old female with personal and familiar longstanding history of
      progressive bilateral sensorineural deafness, and sensitive cerebellar
      ataxia, presenting with brief episodes of falls while laughing and
      excessive diurnal somnolence.
    explanation: >-
      Documents excessive daytime somnolence at presentation in a genetically
      confirmed exon-21 ADCA-DN patient.
- category: Neurological
  name: Cataplexy
  description: >-
    Emotion-triggered episodic loss of muscle tone, classically provoked by
    laughter. Cataplexy is a defining feature of the narcolepsy component but is
    not universal: affected family members with narcolepsy without cataplexy are
    described, and prolonged cataplectic spells have been reported in the wider
    DNMT1 spectrum.
  phenotype_term:
    preferred_term: Cataplexy
    term:
      id: HP:0002524
      label: Cataplexy
    temporality: RECURRENT
  diagnostic: true
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is
      characterized by late onset (30-40 years old) cerebellar ataxia, sensory
      neuronal deafness, narcolepsy-cataplexy and dementia.
    explanation: Narcolepsy-cataplexy is part of the defining ADCA-DN phenotype.
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patient III-1 started at 42 years with narcolepsy with cataplexy, hearing
      loss and tremor, and patient IV-1 started at 4 years, with mild
      intellectual disability, and narcolepsy without cataplexy.
    explanation: >-
      Shows cataplexy in one p.Ala570Val carrier but narcolepsy without
      cataplexy in another from the same family, supporting variable penetrance
      of the cataplexy component.
- category: Neurological
  name: Sleep-onset REM periods
  description: >-
    Sleep-onset rapid eye movement periods (SOREMPs) on polysomnography and
    multiple sleep latency testing. SOREMPs can be present in clinically
    unaffected carriers and can also appear de novo during longitudinal
    follow-up of symptomatic patients.
  phenotype_term:
    preferred_term: Sleep-onset REM period
    term:
      id: HP:0002494
      label: Abnormal rapid eye movement sleep
  diagnostic: true
  evidence:
  - reference: PMID:24709307
    reference_title: "Polysomnographic and neurometabolic features may mark preclinical autosomal dominant cerebellar ataxia, deafness, and narcolepsy due to a mutation in the DNA (cytosine-5-)-methyltransferase gene, DNMT1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Therefore, SOREMPs may precede the clinical picture of ADCA-DN as an early
      polysomnographic marker of central nervous system involvement detected by
      MRS.
    explanation: >-
      Establishes SOREMPs as an ADCA-DN sleep abnormality detectable before
      clinical onset.
- category: Auditory
  name: Sensorineural hearing loss
  description: >-
    Bilateral, progressive sensorineural (sensory neuronal) deafness, usually
    one of the first two manifestations and often severe enough to require
    hearing aids, assistive communication, or cochlear implantation.
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
    clinical_course: PROGRESSIVE
    laterality: BILATERAL
  diagnostic: true
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Narcolepsy and deafness were the first symptoms to appear in all
      pedigrees, followed by ataxia.
    explanation: >-
      Deafness is one of the two earliest manifestations across all three
      discovery kindreds.
  - reference: PMID:31957642
    reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A 44-year-old female with personal and familiar longstanding history of
      progressive bilateral sensorineural deafness, and sensitive cerebellar
      ataxia
    explanation: >-
      Confirms the bilateral and progressive character of the hearing loss in a
      genetically confirmed exon-21 patient.
- category: Neurological
  name: Cerebellar ataxia
  description: >-
    Progressive cerebellar incoordination affecting limbs, gait, and speech. It
    is a cardinal feature but is characteristically later than the sleep and
    hearing manifestations and may be absent at onset, particularly in younger
    affected family members.
  phenotype_term:
    preferred_term: Cerebellar ataxia
    term:
      id: HP:0001251
      label: Ataxia
    clinical_course: PROGRESSIVE
  diagnostic: true
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is
      characterized by late onset (30-40 years old) cerebellar ataxia, sensory
      neuronal deafness, narcolepsy-cataplexy and dementia.
    explanation: Cerebellar ataxia is one of the defining features of ADCA-DN.
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ataxia, despite being a cardinal symptom, does not appear at the onset in
      younger patients, and hearing loss also seems to develop over the years.
    explanation: >-
      Qualifies the timing of ataxia relative to other features within a single
      p.Ala570Val kindred.
- category: Neurological
  name: Gait ataxia
  description: >-
    Wide-based, unsteady gait with progressive loss of walking ability, falls,
    and eventual need for walking aids or caregiver assistance.
  phenotype_term:
    preferred_term: Gait ataxia
    term:
      id: HP:0002066
      label: Gait ataxia
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At the age of 38 years, she began experiencing difficulty walking because
      of ataxic gait.
    explanation: >-
      Documents ataxic gait with a specific age of onset in a genetically
      confirmed ADCA-DN patient.
  - reference: PMID:31957642
    reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "During the 4 years of follow-up her walking ability declined"
    explanation: Documents progressive decline of walking ability on longitudinal follow-up.
- category: Imaging
  name: Cerebellar atrophy
  description: Cerebellar volume loss on structural brain MRI.
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  evidence:
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patient II-2 started at 51 years, with ataxia, tremor, epileptic seizures,
      cerebellar atrophy, narcolepsy without cataplexy, hearing loss, moderate
      cognitive impairment.
    explanation: >-
      Cerebellar atrophy is recorded in a p.Ala570Val carrier with the full
      ADCA-DN phenotype.
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mild brain atrophy was observed on MRI, with cerebellar involvement."
    explanation: Independent imaging confirmation of cerebellar atrophy.
- category: Neurological
  name: Tremor
  description: >-
    Action tremor of the hands and, in some patients, head tremor. Reported in
    multiple affected members of a single ADCA-DN kindred.
  phenotype_term:
    preferred_term: Tremor
    term:
      id: HP:0001337
      label: Tremor
  evidence:
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patient III-1 started at 42 years with narcolepsy with cataplexy, hearing
      loss and tremor
    explanation: Tremor documented in a genetically confirmed p.Ala570Val carrier.
- category: Imaging
  name: Cerebral atrophy
  description: Diffuse cerebral volume loss on structural brain MRI.
  phenotype_term:
    preferred_term: Cerebral atrophy
    term:
      id: HP:0002059
      label: Cerebral atrophy
  evidence:
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Magnetic resonance imaging showed diffuse atrophy in the cerebrum and
      cerebellum without a significant signal change
    explanation: Documents diffuse cerebral atrophy in a genetically confirmed patient.
- category: Cognitive
  name: Impaired executive functioning
  description: >-
    Early cognitive involvement takes the form of executive dysfunction with a
    frontal-system profile on standardized neuropsychological testing, before
    global cognitive impairment appears.
  phenotype_term:
    preferred_term: Impaired executive functioning
    term:
      id: HP:0033051
      label: Impaired executive functioning
  evidence:
  - reference: PMID:27869457
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN) associated with progressive cognitive and behavioral deterioration."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At baseline, 2 individuals demonstrated cognitive profiles with executive
      difficulties in some areas consistent with frontal-system dysfunction
      behaviorally and on standardized testing.
    explanation: >-
      Formal neuropsychological characterization of the early ADCA-DN cognitive
      profile.
- category: Cognitive
  name: Progressive cognitive decline
  description: >-
    Cognitive deterioration progressing in parallel with the neurological
    syndrome, from isolated executive deficits to global impairment.
  phenotype_term:
    preferred_term: Mental deterioration
    term:
      id: HP:0001268
      label: Mental deterioration
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:27869457
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN) associated with progressive cognitive and behavioral deterioration."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cognitive decline occurred in parallel with neurological deterioration."
    explanation: >-
      Directly supports progressive cognitive decline tracking the neurological
      course in an ADCA-DN kindred.
- category: Cognitive
  name: Dementia
  description: >-
    Globally impaired cognition meeting criteria for dementia in the later
    stages of the disease.
  phenotype_term:
    preferred_term: Dementia
    term:
      id: HP:0000726
      label: Dementia
  evidence:
  - reference: PMID:27869457
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN) associated with progressive cognitive and behavioral deterioration."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The third individual was further in the disease course and exhibited more
      globally impaired cognition consistent with a diagnosis of dementia.
    explanation: >-
      Documents dementia in the most advanced member of an ADCA-DN kindred.
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is
      characterized by late onset (30-40 years old) cerebellar ataxia, sensory
      neuronal deafness, narcolepsy-cataplexy and dementia.
    explanation: Dementia is part of the defining ADCA-DN phenotype.
- category: Psychiatric
  name: Psychosis
  description: >-
    Psychotic manifestations are a recognized variable feature of ADCA-DN and
    may precede recognition of the neurological syndrome.
  phenotype_term:
    preferred_term: Psychosis
    term:
      id: HP:0000709
      label: Psychosis
  evidence:
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It begins in adulthood, and may also be associated with other variable
      symptoms as optic atrophy, cataracts, psychosis, depression or sensory
      neuropathy.
    explanation: >-
      Lists psychosis among the recognized variable manifestations of ADCA-DN
      specifically.
- category: Psychiatric
  name: Hallucinations
  description: >-
    Auditory or visual hallucinations occur in the DNMT1 disease spectrum,
    including in patients with dementia, and hypnagogic hallucinations may also
    accompany the narcolepsy component.
  phenotype_term:
    preferred_term: Hallucinations
    term:
      id: HP:0000738
      label: Hallucinations
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Sedative or antipsychotic drugs help to reduce extreme restlessness,
      roaming behavior, delusions, and hallucinations associated with dementia.
    explanation: >-
      GeneReviews documents hallucinations in DNMT1-related disorder. PARTIAL
      because the statement covers the whole DNMT1 spectrum (HSAN1E and ADCA-DN)
      rather than ADCA-DN alone.
- category: Psychiatric
  name: Depression
  description: Depression is listed among the variable psychiatric features of ADCA-DN.
  phenotype_term:
    preferred_term: Depression
    term:
      id: HP:0000716
      label: Depression
  evidence:
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It begins in adulthood, and may also be associated with other variable
      symptoms as optic atrophy, cataracts, psychosis, depression or sensory
      neuropathy.
    explanation: Lists depression among the recognized variable ADCA-DN manifestations.
- category: Neurological
  name: Seizures
  description: >-
    Epileptic seizures occur in a subset of patients and can be
    treatment-refractory in the wider DNMT1 spectrum. Generalized EEG slowing
    has also been documented.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patient II-2 started at 51 years, with ataxia, tremor, epileptic seizures,
      cerebellar atrophy, narcolepsy without cataplexy, hearing loss, moderate
      cognitive impairment.
    explanation: Epileptic seizures documented in a genetically confirmed ADCA-DN patient.
- category: Ophthalmological
  name: Optic atrophy
  description: >-
    Optic atrophy with pale discs on fundoscopy, often accompanied by attenuated
    and delayed visual evoked potentials. It may be subclinical and detected
    only on directed ophthalmological assessment.
  phenotype_term:
    preferred_term: Optic atrophy
    term:
      id: HP:0000648
      label: Optic atrophy
  evidence:
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      fundoscopy revealed pale discs with an elevated cup-to-disk ratio in both
      eyes, suggesting optic atrophy
    explanation: Direct ophthalmological documentation of optic atrophy in ADCA-DN.
  - reference: PMID:31957642
    reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical and neurophysiological evaluations reveled signs of cerebellar,
      pyramidal, peripheral, cognitive involvement, and optical atrophy.
    explanation: Independent report of optic atrophy in an exon-21 ADCA-DN patient.
- category: Neurological
  name: Sensory neuropathy
  description: >-
    Large- and small-fibre sensory polyneuropathy. This is the dominant feature
    of the allelic HSAN1E phenotype and is variable in ADCA-DN, being entirely
    absent in some genetically confirmed families.
  phenotype_term:
    preferred_term: Sensory neuropathy
    term:
      id: HP:0000763
      label: Sensory neuropathy
  evidence:
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other common symptoms and features observed in our cases, involving the
      central and peripheral nervous system, include deafness, optic
      neuropathy-previously not reported in HSAN IE-large and small fibres
      polyneuropathy and lower limbs oedema.
    explanation: >-
      Documents mixed-fibre polyneuropathy in a cohort spanning ADCA-DN and
      HSAN IE. PARTIAL because the cohort is not restricted to ADCA-DN.
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sensory neuropathy is not present in any of the cases studied."
    explanation: >-
      A three-generation p.Ala570Val ADCA-DN family had no sensory neuropathy,
      supporting the description of neuropathy as variable rather than an
      obligate ADCA-DN feature.
- category: Neurological
  name: Pyramidal signs
  description: >-
    Corticospinal tract signs including brisk reflexes and spasticity, reported
    in a subset of genetically confirmed patients.
  phenotype_term:
    preferred_term: Abnormal pyramidal sign
    term:
      id: HP:0007256
      label: Abnormal pyramidal sign
  evidence:
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report a patient with DNMT1 mutation who presented with mid-age
      onset of cerebellar ataxia, sensorineural hearing loss, and pyramidal
      signs.
    explanation: Pyramidal signs documented in a genetically confirmed ADCA-DN patient.
- category: Ophthalmological
  name: Cataract
  description: >-
    Cataract is listed among the variable ophthalmological manifestations of
    ADCA-DN and may develop in the later stages.
  phenotype_term:
    preferred_term: Cataract
    term:
      id: HP:0000518
      label: Cataract
  notes: >-
    Deliberately not wired into the pathograph. No mechanism has been proposed
    linking DNMT1 dysfunction or the neurodegenerative cascade to lens
    opacification, and connecting it to any existing node would assert a causal
    claim the literature does not support. Recorded here so the manifestation is
    captured; see the discussions block.
  evidence:
  - reference: PMID:40285998
    reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It begins in adulthood, and may also be associated with other variable
      symptoms as optic atrophy, cataracts, psychosis, depression or sensory
      neuropathy.
    explanation: Lists cataract among the recognized variable ADCA-DN manifestations.
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Optic atrophy, cataract, sensory neuropathy, and dementia may develop in
      the later stages of the disease.
    explanation: Independent statement that cataract is a late ADCA-DN manifestation.
biochemical:
- name: Cerebrospinal fluid hypocretin-1
  presence: Decreased
  context: >-
    CSF hypocretin-1 (orexin-A) supports the narcolepsy component but, unlike
    sporadic narcolepsy type 1, it is not uniformly deficient in DNMT1 disease.
    Reported values in genetically confirmed patients span low, intermediate,
    and normal, and can remain normal even as polysomnographic abnormalities
    progress. A normal value therefore does not exclude ADCA-DN.
  evidence:
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CSF hypocretin-1 was 191 pg/mL (normal values > 200 pg/mL)."
    explanation: >-
      A quantified borderline-low CSF hypocretin-1 value in a genetically
      confirmed exon-21 ADCA-DN patient.
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Remarkably, narcolepsy with or without cataplexy with low/intermediate or
      normal cerebrospinal fluid hypocretin-1 is present in both diseases.
    explanation: >-
      Establishes the variable rather than uniformly deficient CSF hypocretin-1
      pattern across the DNMT1 spectrum, which is why presence is qualified in
      the context field.
  - reference: PMID:31957642
    reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      During the 4 years of follow-up her walking ability declined, she became
      more somnolent and repeated PSG documented REM sleep latency shortening,
      and finally the evidence of de novo spontaneous SOREMPs, although normal
      CSF hrct-1 at second revaluation.
    explanation: >-
      Documents a genetically confirmed exon-21 patient whose CSF hypocretin-1
      stayed normal while the sleep phenotype progressed.
- name: Cerebellar myo-inositol on proton MR spectroscopy
  presence: Increased
  context: >-
    Increased cerebellar myo-inositol, a marker of glial cell activity and
    density, is detectable by proton MR spectroscopy in clinically unaffected
    DNMT1 variant carriers with normal structural MRI. It is a research
    observation in two carriers, not a validated biomarker.
  evidence:
  - reference: PMID:24709307
    reference_title: "Polysomnographic and neurometabolic features may mark preclinical autosomal dominant cerebellar ataxia, deafness, and narcolepsy due to a mutation in the DNA (cytosine-5-)-methyltransferase gene, DNMT1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Sleep recordings found sleep-onset rapid eye movement periods (SOREMPs)
      and proton magnetic resonance spectroscopy (MRS) revealed increased
      cerebellar myoinositol (mI) in both subjects.
    explanation: >-
      Directly documents raised cerebellar myo-inositol in presymptomatic DNMT1
      carriers.
genetic:
- name: DNMT1
  gene_term:
    preferred_term: DNMT1
    term:
      id: hgnc:2976
      label: DNMT1
  association: Causative
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  presence: Present
  features: >-
    ADCA-DN is caused by heterozygous germline missense variants in DNMT1
    (19p13.2), which encodes the sole maintenance DNA methyltransferase. The
    ADCA-DN alleles cluster in exon 21, encoding the C-terminal part of the
    replication foci targeting sequence (RFTS/TS) domain. The recurrent alleles
    are p.Ala570Val, p.Gly605Ala, and p.Val606Phe; additional exon-21 alleles
    include p.Cys596Arg, p.Glu575Lys, and p.Glu578Lys. Position within the TS
    domain is the principal genotype-phenotype determinant separating ADCA-DN
    from allelic HSAN1E. No disease-causing chromosomal abnormality, repeat
    expansion, mitochondrial variant, or validated modifier gene has been
    established, and population allele frequencies for the individual variants
    are not reported.
  inheritance:
  - name: Autosomal dominant
    inheritance_term:
      preferred_term: autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:22328086
    reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We performed exome sequencing in five individuals from three ADCA-DN
      kindreds and identified DNMT1 as the only gene with mutations found in all
      five affected individuals.
    explanation: >-
      Establishes DNMT1 as the causal gene by exome sequencing across three
      independent ADCA-DN kindreds.
  - reference: PMID:38970134
    reference_title: A systematic review on the contribution of DNA methylation to hearing loss.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Conversely, several studies have independently confirmed pathogenic
      mutations within exon 21 of the DNMT1 gene, which encodes the DNA
      (cytosine-5)-methyltransferase 1 enzyme.
    explanation: >-
      A 2024 systematic review confirms independent replication of pathogenic
      exon-21 DNMT1 variants.
  variants:
  - name: Exon 21 TS-domain missense cluster (p.Ala570Val, p.Gly605Ala, p.Val606Phe)
    description: >-
      The three recurrent ADCA-DN alleles identified in the discovery study, all
      conserved missense substitutions in exon 21 lying in close spatial
      proximity within the C-terminal part of the targeting-sequence domain.
      p.Ala570Val has since been reported repeatedly, including in a
      six-affected Canadian family and a three-generation Spanish family.
    clinical_significance: PATHOGENIC
    type: missense variant
    functional_effects:
    - function: DNA (cytosine-5-)-methyltransferase regulation by the RFTS domain
      description: >-
        The substitutions destabilize DNMT1 and relieve RFTS-mediated
        autoinhibition, so the net effect combines impaired maintenance
        methylation with abnormal, potentially toxic mutant protein rather than
        a clean loss of enzyme activity.
      type: loss-of-function
    - function: mutant DNMT1 protein handling
      description: >-
        Mutant protein mislocalizes to the cytoplasm, forms aggresomes, and in
        RFTS knock-in models is internally cleaved, which has been interpreted
        as a toxic gain of function superimposed on reduced activity.
      type: gain-of-function
    evidence:
    - reference: PMID:22328086
      reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Sanger sequencing confirmed the de novo mutation p.Ala570Val in one
        family, and showed co-segregation of p.Val606Phe and p.Ala570Val, with
        the ADCA-DN phenotype, in two other kindreds.
      explanation: >-
        Establishes segregation and de novo occurrence for two of the three
        recurrent alleles.
    - reference: PMID:22328086
      reference_title: Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        An additional ADCA-DN kindred with a p.GLY605Ala mutation was
        subsequently identified.
      explanation: Identifies the third recurrent ADCA-DN allele.
    - reference: PMID:27602171
      reference_title: "Identification of a methylation profile for DNMT1-associated autosomal dominant cerebellar ataxia, deafness, and narcolepsy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        which had been previously reported as pathogenic for ADCA-DN and
        segregated with disease in the family
      explanation: >-
        Independent replication of p.Ala570Val with segregation in a
        six-affected family.
    - reference: PMID:40285998
      reference_title: Cerebellar Ataxia-deafness-narcolepsy (ADCA) syndrome. Description of a variable family phenotype.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Genetic test showed a mutation in DNMT1 gene: variant c.1709 C > T;
        p.Ala570Val in the DNMT1 gene.
      explanation: >-
        Further independent replication of the recurrent p.Ala570Val allele in a
        three-generation kindred.
  - name: Additional exon 21 alleles (p.Cys596Arg, p.Glu575Lys, p.Glu578Lys)
    description: >-
      Further pathogenic or likely pathogenic exon-21 substitutions reported in
      single ADCA-DN patients or families, including a de novo p.Cys596Arg in a
      Brazilian patient, p.Glu575Lys segregating with disease in an Italian
      mother and daughter, and p.Glu578Lys in a Taiwanese patient.
    clinical_significance: LIKELY_PATHOGENIC
    type: missense variant
    evidence:
    - reference: PMID:23904686
      reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The proband had a novel DNMT1 mutation in exon 21, p.Cys596Arg, c.1786T
        > C.
      explanation: Reports a novel de novo exon-21 ADCA-DN allele.
    - reference: PMID:31957642
      reference_title: "Cataplexy and ataxia: red flags for the diagnosis of DNA methyltransferase 1 mutation."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        direct sequencing of exons 20 and 21 of the DNMT1 gene was performed
        revealing the p.Glu575Lys mutation in exon 21 in the proband and her
        mother.
      explanation: Reports p.Glu575Lys segregating in an ADCA-DN mother-daughter pair.
    - reference: PMID:32984563
      reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Whole exome sequencing revealed a heterozygous missense mutation in
        DNMT1 c. 1732G>A (p.E578K), which is the causative gene for autosomal
        dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN).
      explanation: Reports p.Glu578Lys as a likely pathogenic exon-21 ADCA-DN allele.
  - name: TS-domain positional genotype-phenotype correlation
    description: >-
      Variant position within the DNMT1 targeting-sequence domain separates the
      two allelic phenotypes: ADCA-DN alleles occupy the C-terminal end of the
      domain (exon 21) whereas HSAN1E alleles occupy the middle or N-terminal
      part (often exon 20, with Tyr495 a hot spot). The correlation is strong
      but not absolute, since expanding case series describe overlapping
      phenotypes and at least one allele outside the domain.
    evidence:
    - reference: PMID:25678562
      reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Our results indicate that all the mutations causal for HSAN1E are
        located in the middle part or N-terminus end of the TS domain, whereas
        all the mutations causal for autosomal dominant cerebellar ataxia,
        deafness and narcolepsy are located in the C-terminus end of the TS
        domain.
      explanation: The primary statement of the positional genotype-phenotype split.
    - reference: PMID:23365052
      reference_title: DNMT1 mutation hot spot causes varied phenotypes of HSAN1 with dementia and hearing loss.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Amino acid Tyr495 is a hot spot for HSAN1E, distinct from exon 21
        mutations associated with narcolepsy.
      explanation: >-
        Independent confirmation that the HSAN1E hot spot is distinct from the
        exon-21 narcolepsy-associated region.
    - reference: PMID:32754641
      reference_title: Expanded genetic insight and clinical experience of DNMT1-complex disorder.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Broader application of WES further expands genotype-phenotype
        correlations of DNMT1-complex disorder.
      explanation: >-
        Expanded sequencing shows the correlation is a strong tendency rather
        than an absolute rule, supporting the qualification recorded here.
diagnosis:
- name: DNMT1 molecular genetic testing
  description: >-
    Diagnosis is established by identifying a heterozygous pathogenic DNMT1
    variant. Targeted approaches sequence exons 20 and 21, which encode the
    targeting-sequence domain and contain essentially all reported alleles. A
    known familial variant can be tested directly.
  diagnosis_term:
    preferred_term: DNMT1 sequencing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  results: >-
    A heterozygous missense variant in the C-terminal part of the DNMT1
    targeting-sequence domain (classically exon 21) confirms ADCA-DN.
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The diagnosis of DNMT1 disorder is established by identification of a
      heterozygous pathogenic variant in DNMT1 by molecular genetic testing.
    explanation: GeneReviews states the molecular basis of diagnosis.
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "DNMT1 exons 20 and 21 were sequenced."
    explanation: >-
      Illustrates the targeted two-exon sequencing strategy used in clinical
      practice.
- name: Exome or genome sequencing for atypical or unresolved presentations
  description: >-
    Broad-based sequencing resolves DNMT1-related disease that narrower panel
    testing misses, particularly in adults presenting to neuromuscular or ataxia
    clinics with an atypical or overlapping phenotype. Repeat-expansion ataxias
    require separate targeted testing because standard exome sequencing does not
    detect them reliably.
  diagnosis_term:
    preferred_term: Whole Exome Sequencing
    term:
      id: NCIT:C101295
      label: Whole Exome Sequencing
  evidence:
  - reference: PMID:38392311
    reference_title: The Importance of Offering Exome or Genome Sequencing in Adult Neuromuscular Clinics.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we use five case examples to illustrate the unique ability of
      broad-based testing to improve diagnostic yield, resulting in
      identification of SORD-neuropathy, HADHB-related disease, ATXN2-ALS, MECP2
      related progressive gait decline and spasticity, and DNMT1-related
      cerebellar ataxia, deafness, narcolepsy, and hereditary sensory neuropathy
      type 1E.
    explanation: >-
      Demonstrates that exome or genome sequencing identified DNMT1-related
      disease in an adult clinic where narrower testing had not.
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Genetic tests detected no abnormalities such as spinocerebellr ataxia type
      1, 2, 3, 6, 7, 17, and dentatorubral -pallidoluysian atrophy.
    explanation: >-
      Shows that repeat-expansion ataxia testing was negative before exome
      sequencing established the DNMT1 diagnosis, supporting the sequencing
      pathway for unresolved ataxia.
- name: Polysomnography with multiple sleep latency testing
  description: >-
    Overnight polysomnography followed by multiple sleep latency testing
    documents the narcolepsy component and detects sleep-onset REM periods.
    Repeat studies are informative because SOREMPs can appear during follow-up.
  diagnosis_term:
    preferred_term: Polysomnography
    term:
      id: NCIT:C114185
      label: Polysomnography
  evidence:
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Narcolepsy was supported by polysomnographic and multiple sleep latency testing."
    explanation: >-
      Documents the standard sleep-laboratory workup used to establish the
      narcolepsy component in ADCA-DN.
- name: HLA-DQB1*06:02 typing as non-diagnostic context
  description: >-
    HLA-DQB1*06:02 is carried by the great majority of patients with sporadic
    narcolepsy type 1 but is frequently absent in DNMT1 disease. Its presence or
    absence can therefore provide context when narcolepsy accompanies deafness
    or ataxia, but it neither establishes nor excludes ADCA-DN. One genetically
    confirmed ADCA-DN patient was HLA-DQB1*06:02 positive; molecular DNMT1
    testing, not HLA typing, establishes the diagnosis.
  diagnosis_term:
    preferred_term: HLA-DQB1*06:02 typing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  evidence:
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The human leukocyte antigen DQB1*06:02 was absent in all patients."
    explanation: >-
      In a five-patient DNMT1 cohort spanning ADCA-DN and HSAN IE, the
      narcolepsy risk allele was uniformly absent.
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HLA-DQB1*06:02 was positive."
    explanation: >-
      A genetically confirmed exon-21 ADCA-DN patient carried the risk allele,
      supporting the explicit caveat that a positive HLA result does not
      exclude ADCA-DN.
differential_diagnoses:
- name: Narcolepsy type 1 (sporadic, HLA-DQB1*06:02 associated)
  description: >-
    Sporadic narcolepsy type 1 shares excessive daytime somnolence, cataplexy,
    and SOREMPs, but lacks progressive sensorineural deafness, cerebellar
    ataxia, and dementia. It is strongly HLA-DQB1*06:02 associated and CSF
    hypocretin-1 is usually markedly reduced, whereas in ADCA-DN
    HLA-DQB1*06:02 is frequently negative and CSF hypocretin-1 is variable.
  evidence:
  - reference: PMID:23904686
    reference_title: "A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Diagnosing the syndrome can be difficult, as all clinical features may not
      be present at onset, HLA-DQB1*06:02 is often negative, and sporadic cases
      occur.
    explanation: >-
      States the diagnostic distinction from sporadic narcolepsy and warns that
      an incomplete phenotype at onset makes the separation difficult.
- name: Hereditary sensory and autonomic neuropathy type 1E (HSAN1E)
  description: >-
    The allelic DNMT1 disorder, caused by variants in the middle or N-terminal
    part of the same targeting-sequence domain (often exon 20). It presents with
    the triad of sensorineural hearing loss, sensory neuropathy with sudomotor
    failure, and dementia, and typically lacks prominent cerebellar ataxia,
    although narcolepsy occurs in both. The two are discrete clinical entities
    within one disease spectrum.
  evidence:
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Phenotypic characterization pinpoints that ADCA-DN and HSAN IE represent
      two discrete clinical entities belonging to the same disease spectrum,
      with variable degree of overlap.
    explanation: >-
      Directly supports treating HSAN1E as a distinct but allelic differential
      rather than merging the two entries.
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      HSAN IE and ADCA-DN are two extreme phenotypic manifestations of a DNMT1
      methylopathy.
    explanation: Frames the two entities as poles of a single molecular spectrum.
- name: Autosomal dominant spinocerebellar ataxias and other hereditary ataxias
  description: >-
    Repeat-expansion spinocerebellar ataxias (SCA1, 2, 3, 6, 7, 17, DRPLA),
    Friedreich ataxia, CAPOS syndrome, and mitochondrial disease all overlap
    with the ataxia plus deafness or optic atrophy presentation.
  evidence:
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The combination of cerebellar ataxia, deafness, pyramidal sign, and optic
      atrophy indicates differential diagnoses, including cerebellar
      ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss
      (CAPOS) syndrome, Friedreich's ataxia (FRDA), and mitochondrial diseases
    explanation: >-
      Enumerates the principal ataxia differentials considered before the DNMT1
      diagnosis was established.
treatments:
- name: Symptomatic narcolepsy pharmacotherapy
  description: >-
    Excessive daytime somnolence and cataplexy are managed with standard
    narcolepsy therapy under a sleep specialist, typically a wake-promoting
    agent such as modafinil with anticataplectic treatment where needed, plus
    scheduled naps, driving and occupational risk counseling, and avoidance of
    sedating drugs. No ADCA-DN-specific efficacy study or interventional trial
    exists; this is extrapolated from idiopathic narcolepsy and is symptomatic
    only. Broad DNA methyltransferase inhibitors used in oncology are not a
    rational therapy here, because systemic interference with maintenance
    methylation could be harmful and the disease mechanism includes both
    deficient function and potentially toxic mutant-protein species.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: modafinil
      term:
        id: CHEBI:31859
        label: modafinil
  target_phenotypes:
  - preferred_term: Excessive daytime somnolence
    term:
      id: HP:0001262
      label: Excessive daytime somnolence
  - preferred_term: Cataplexy
    term:
      id: HP:0002524
      label: Cataplexy
  notes: >-
    No published ADCA-DN cohort reports treatment response rates for
    wake-promoting or anticataplectic agents.
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "No cure for DNMT1 disorder currently exists."
    explanation: >-
      GeneReviews confirms that all management is symptomatic. It supports the
      framing of this treatment as symptomatic extrapolation rather than
      supporting a specific agent's efficacy in ADCA-DN.
- name: Hearing aids and assistive communication
  description: >-
    Conventional amplification and assistive communication technology are the
    first-line audiological intervention as sensorineural hearing loss
    progresses.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: hearing aid usage
  target_phenotypes:
  - preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Because hearing loss may be severe, initial use of hearing aids and/or
      assistive communication methods may be needed.
    explanation: >-
      GeneReviews recommends hearing aids and assistive communication as initial
      management of the hearing loss in DNMT1-related disorder.
- name: Cochlear implantation
  description: >-
    Cochlear implantation is the clearest reported intervention with an
    objectively measured benefit in DNMT1-complex disorder, and may be
    considered for ADCA-DN when amplification becomes inadequate. Direct
    ADCA-DN-specific outcome evidence is not available.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: cochlear device implantation
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_phenotypes:
  - preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  notes: >-
    Evidence scoping caveat. Both reported implanted patients carried DNMT1
    targeting-sequence variants outside the classical exon-21 ADCA-DN cluster
    (p.T497P and p.Cys430Tyr) and were described within DNMT1-complex disorder
    or HSN1E. The benefit is therefore established for DNMT1-related
    sensorineural hearing loss broadly, and extrapolated to ADCA-DN.
  evidence:
  - reference: PMID:32754641
    reference_title: Expanded genetic insight and clinical experience of DNMT1-complex disorder.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Case 4 (p.T497P) underwent left cochlear implant, resulting in significant
      hearing improvements at all tested frequencies (250-6,000 Hz).
    explanation: >-
      Quantified audiometric benefit after cochlear implantation. PARTIAL
      because the patient carried a non-exon-21 DNMT1-complex variant rather
      than a classical ADCA-DN allele.
  - reference: PMID:32754641
    reference_title: Expanded genetic insight and clinical experience of DNMT1-complex disorder.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hearing loss treatment by cochlear implantation is helpful and should be
      considered.
    explanation: >-
      The authors' explicit management recommendation for DNMT1-complex
      disorder, of which ADCA-DN is part.
  - reference: PMID:37199681
    reference_title: "DNMT1-associated sensory neuropathy and cerebellar ataxia: A novel variant and review of genotype-phenotype correlation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cochlear implant was performed at 44 years for the bilateral high
      frequency sensorineural hearing loss with improvement in hearing and
      day-to-day function.
    explanation: >-
      A second DNMT1 patient with functional benefit from implantation. PARTIAL
      because the p.Cys430Tyr variant produced an overlapping HSN1E-cerebellar
      phenotype rather than classical ADCA-DN.
- name: Neuropsychiatric symptom management
  description: >-
    Sedative or antipsychotic medication is used for the restlessness, roaming,
    delusions, and hallucinations that accompany the dementia phase. Caregiver
    education and psychological support are considered essential because the
    behavioral changes and loss of insight impose a substantial caregiver
    burden.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_phenotypes:
  - preferred_term: Hallucinations
    term:
      id: HP:0000738
      label: Hallucinations
  - preferred_term: Psychosis
    term:
      id: HP:0000709
      label: Psychosis
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Sedative or antipsychotic drugs help to reduce extreme restlessness,
      roaming behavior, delusions, and hallucinations associated with dementia.
    explanation: >-
      GeneReviews directly recommends this symptomatic pharmacotherapy for the
      neuropsychiatric manifestations.
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Because behavioral changes and the loss of insight and judgment often
      present a considerable burden for partners or other caregivers,
      information about the disorder and psychological support for partners or
      other caregivers are essential.
    explanation: Supports the caregiver-support component of this management arm.
- name: Surveillance and injury prevention for sensory impairment
  description: >-
    Annual cognitive assessment and audiometry apply across DNMT1-related
    disorder. For an ADCA-DN patient who also has sensory neuropathy, daily foot
    examination and protection of insensate extremities with appropriate socks
    and shoes and avoidance of hot water follow the broader DNMT1-disorder
    guidance; these measures are not applicable when sensation is intact.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Examination of feet daily for evidence of skin injury; annual routine
      clinical testing for dementia and audiogram to monitor hearing loss.
    explanation: >-
      The GeneReviews surveillance schedule for DNMT1-related disorder.
      PARTIAL because foot surveillance is conditional on sensory impairment,
      which is variable in ADCA-DN.
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      To prevent injury to extremities with decreased sensation, protect the
      skin with appropriate socks and shoes and avoid exposure of feet to hot
      water.
    explanation: >-
      The GeneReviews Agents/Circumstances to Avoid guidance for this disorder,
      captured as a conditional safety measure for ADCA-DN patients with
      sensory loss.
- name: Physical therapy, balance training, and fall prevention
  description: >-
    Physiotherapy, gait and balance training, walking aids, home safety review,
    and occupational therapy address the progressive cerebellar ataxia and falls
    risk. This is standard rehabilitative practice for progressive hereditary
    ataxia; no ADCA-DN-specific rehabilitation study exists, so no efficacy
    evidence is attached.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Physical Therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  target_phenotypes:
  - preferred_term: Gait ataxia
    term:
      id: HP:0002066
      label: Gait ataxia
- name: Genetic counseling and reproductive options
  description: >-
    Counseling covers autosomal dominant transmission with a 50 percent
    recurrence risk per pregnancy, the availability of prenatal and
    preimplantation genetic testing once the familial variant is known, and
    cascade testing of consenting adult relatives. Predictive testing of minors
    requires careful ethical review because the classical disease is adult-onset
    and no preventive therapy exists.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Once the DNMT1 pathogenic variant has been identified in an affected
      family member, prenatal and preimplantation genetic testing are possible.
    explanation: >-
      GeneReviews establishes the reproductive testing options offered during
      counseling.
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Each child of an individual with DNMT1 disorder has a 50% chance of
      inheriting the pathogenic variant.
    explanation: Supports the recurrence risk figure communicated in counseling.
clinical_trials:
- name: NCT01793168
  phase: NOT_APPLICABLE
  status: RECRUITING
  description: >-
    CoRDS is a broad international observational registry for rare and
    undiagnosed disorders. ClinicalTrials.gov lists Autosomal Dominant
    Cerebellar Ataxia, Deafness and Narcolepsy among its accepted conditions;
    it is a registry resource, not an ADCA-DN-specific interventional study.
  notes: >-
    Status and condition-list relevance were rechecked against the live
    ClinicalTrials.gov record on 2026-08-04. The registry is not evidence of a
    treatment or of an ADCA-DN-specific natural-history cohort.
  evidence:
  - reference: clinicaltrials:NCT01793168
    reference_title: Coordination of Rare Diseases at Sanford
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It provides researchers with a centralized, international patient
      registry for all rare diseases.
    explanation: >-
      Establishes that NCT01793168 is a broad international rare-disease
      registry rather than an interventional ADCA-DN trial.
animal_models:
- species: Mouse (Mus musculus)
  genotype: Dnmt1-M1 and Dnmt1-M2 RFTS-domain knock-in (heterozygous)
  category: Knock-in
  genes:
  - preferred_term: DNMT1
    term:
      id: hgnc:2976
      label: DNMT1
  associated_phenotypes:
  - Reduced DNMT1 protein
  - Impaired learning and memory
  - Homozygous embryonic lethality around E10.5
  description: >-
    CRISPR knock-in mice carrying mouse substitutions equivalent to the human
    HSAN1E variants Y495C and D490E-P491Y. Heterozygotes are viable with reduced
    DNMT1 protein and neurodegenerative phenotypes including impaired learning
    and memory; homozygotes die around embryonic day 10.5. These models support
    the RFTS-disease mechanism but do not carry ADCA-DN exon-21 alleles and do
    not reproduce narcolepsy, deafness, or cerebellar ataxia.
  evidence:
  - reference: PMID:34516921
    reference_title: Mutation-induced DNMT1 cleavage drives neurodegenerative disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We generated Dnmt1-M1 and Dnmt1-M2 knock-in mouse models that are
      equivalent to Y495C and D490E-P491Y mutation in patients with HSAN1E,
      respectively.
    explanation: Describes the only published knock-in mouse models of DNMT1 RFTS disease.
  - reference: PMID:34516921
    reference_title: Mutation-induced DNMT1 cleavage drives neurodegenerative disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      The homozygous mutants die around embryonic day 10.5 and are apparently
      devoid of DNMT1 proteins.
    explanation: >-
      Documents homozygous embryonic lethality, which constrains modeling
      strategies to the heterozygous state that matches human disease.
experimental_models:
- name: Patient-derived fibroblasts, iPSCs, and induced neurons
  description: >-
    Fibroblasts, induced pluripotent stem cells, and induced neurons derived
    from ADCA-DN patients carrying p.Ala570Val, p.Gly605Ala, or p.Val606Phe.
    These are the only disease models carrying authentic ADCA-DN alleles and
    have delineated methylome and transcriptome disruption specific to cell
    type. Limitations include incomplete neuronal maturation, absence of intact
    cerebellar and hypothalamic circuits, and inability to reproduce a
    decades-long degenerative course.
  evidence:
  - reference: PMID:37584462
    reference_title: Mutations in human DNA methyltransferase DNMT1 induce specific genome-wide epigenomic and transcriptomic changes in neurodevelopment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We show cell type-specific changes in gene expression and DNA methylation patterns."
    explanation: >-
      The defining result obtained from the patient-derived cellular model
      system described here.
discussions:
- discussion_id: gap_adcadn_hypocretin_neuron_pathology
  prompt: >-
    Is the narcolepsy of ADCA-DN caused by loss of hypothalamic hypocretin
    neurons, by dysfunction of surviving hypocretin neurons, or by failure of
    downstream sleep-wake circuitry?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Hypothalamic Hypocretin System Dysfunction
  - biochemical#Cerebrospinal fluid hypocretin-1
  rationale: >-
    In sporadic narcolepsy type 1 the near-complete destruction of hypocretin
    neurons is established and CSF hypocretin-1 is uniformly low. In DNMT1
    disease CSF hypocretin-1 is variously low, intermediate, or normal, and
    patients can develop progressive polysomnographic abnormalities while their
    CSF hypocretin-1 remains normal. No neuropathological study has counted
    hypocretin neurons in an ADCA-DN brain, and PubMed returns no ADCA-DN
    autopsy series. The pathophysiology node therefore asserts system
    dysfunction rather than neuron loss, and the distinction matters because it
    determines whether hypocretin agonist therapy would be expected to work.
  proposed_experiments:
  - experiment_id: exp_adcadn_hypothalamic_hypocretin_neuron_quantification
    name: Quantitative hypothalamic hypocretin neuron counts in ADCA-DN autopsy tissue
    description: >-
      Recruit ADCA-DN brain donations through an ataxia or narcolepsy brain bank
      and perform stereological counts of hypocretin-immunoreactive and
      melanin-concentrating-hormone-immunoreactive neurons in the lateral
      hypothalamus, comparing against sporadic narcolepsy type 1 and
      age-matched controls. Pair each brain with the donor's antemortem CSF
      hypocretin-1 value where available.
    decision_criterion: >-
      Hypocretin neuron counts comparable to sporadic narcolepsy type 1 would
      support a cell-loss mechanism; preserved counts with normal or borderline
      CSF hypocretin-1 would support neuronal dysfunction or downstream circuit
      failure.
  evidence:
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Remarkably, narcolepsy with or without cataplexy with low/intermediate or
      normal cerebrospinal fluid hypocretin-1 is present in both diseases.
    explanation: >-
      Documents the heterogeneous CSF hypocretin-1 pattern that motivates this
      knowledge gap.
- discussion_id: gap_adcadn_natural_history_scoped_to_hsan1e
  prompt: >-
    What are the ADCA-DN-specific age at onset, survival, and rate of cognitive
    decline, as opposed to the figures derived from HSAN1E and mixed
    DNMT1-complex cohorts?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Selective Central and Peripheral Neurodegeneration
  rationale: >-
    The most frequently quoted DNMT1 natural-history numbers (mean onset 37.7
    years, average survival 53.6 years, significant cognitive deficit in 89
    percent by age 45) come from a cohort of nine HSAN1E kinships comprising 45
    affected subjects. In the source abstract these figures are attributed
    explicitly to HSAN1E, not to ADCA-DN. Because HSAN1E and ADCA-DN are
    discrete clinical entities with different variant positions within the same
    domain, these values are deliberately not recorded as ADCA-DN prevalence,
    progression, or prognosis in this entry. No registry-scale ADCA-DN natural
    history cohort exists, and no variant-specific penetrance estimate is
    available.
  proposed_experiments:
  - experiment_id: exp_adcadn_international_natural_history_registry
    name: International DNMT1 registry stratified by targeting-sequence variant position
    description: >-
      Assemble an international registry of genetically confirmed DNMT1 patients
      with prospective standardized assessment of ataxia scales, audiometry,
      polysomnography, neuropsychology, and survival, analyzed with strata
      defined by variant position within the targeting-sequence domain
      (C-terminal/exon 21 versus middle and N-terminal/exon 20) rather than by
      clinical label alone.
    decision_criterion: >-
      Stratified onset, survival, and cognitive-decline curves that differ
      significantly between variant-position strata would establish
      ADCA-DN-specific natural history and confirm that pooled DNMT1 figures are
      not transferable.
  evidence:
  - reference: PMID:25678562
    reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The average survival of HSAN1E was 53.6 years."
    explanation: >-
      Shows that the widely cited survival figure is attributed by its source to
      HSAN1E, which is why it is excluded from the ADCA-DN progression section.
  - reference: PMID:24727570
    reference_title: Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Phenotypic characterization pinpoints that ADCA-DN and HSAN IE represent
      two discrete clinical entities belonging to the same disease spectrum,
      with variable degree of overlap.
    explanation: >-
      Supports the requirement to keep the two entities' natural-history data
      separate.
- discussion_id: mismatch_adcadn_mouse_models_carry_hsan1e_alleles
  prompt: >-
    Do the existing DNMT1 RFTS knock-in mice model ADCA-DN, given that they
    carry HSAN1E-equivalent alleles and do not develop narcolepsy, deafness, or
    cerebellar ataxia?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Relief of RFTS Autoinhibition and DNMT1 Destabilization
  - pathophysiology#Aberrant DNMT1-NSUN2 RNA m5C Methylation
  - pathophysiology#Oxidative Stress and Mitochondrial Dysfunction
  - pathophysiology#Selective Central and Peripheral Neurodegeneration
  rationale: >-
    The only published knock-in mice carry mouse equivalents of the human
    HSAN1E variants Y495C and D490E-P491Y, which lie in the middle or
    N-terminal part of the targeting-sequence domain, not the C-terminal exon-21
    region that defines ADCA-DN. Since intradomain variant position is the
    principal determinant separating the two human phenotypes, a model built on
    HSAN1E alleles cannot be assumed to capture the ADCA-DN phenotype. The
    heterozygous mice show reduced DNMT1 protein and impaired learning and
    memory, but the three defining ADCA-DN features (narcolepsy, sensorineural
    deafness, cerebellar ataxia) have not been demonstrated. Mechanistic
    conclusions from these mice about RFTS destabilization and cleavage are
    recorded as PARTIAL support for that reason. A 2025 follow-up using
    RFTS-mutant mice identified aberrant DNMT1-dependent RNA m5C methylation,
    oxidative stress, and mitochondrial dysfunction. Its published abstract does
    not name the mouse RFTS allele or establish translation to classical
    exon-21 ADCA-DN, so that branch is likewise recorded as provisional,
    PARTIAL support rather than an established ADCA-DN mechanism.
  proposed_experiments:
  - experiment_id: exp_adcadn_exon21_knockin_mouse_deep_phenotyping
    name: Exon-21-allele knock-in mouse with longitudinal sleep, auditory, and cerebellar phenotyping
    description: >-
      Generate heterozygous knock-in mice carrying the mouse equivalent of human
      DNMT1 p.Ala570Val or p.Val606Phe and phenotype them longitudinally with
      EEG/EMG sleep architecture and cataplexy scoring, hypothalamic hypocretin
      neuron counts, auditory brainstem responses and distortion-product
      otoacoustic emissions, rotarod and gait analysis with cerebellar
      histology, DNA methylome and RNA m5C profiling resolved by cell type, and
      mitochondrial functional assays. Run the existing HSAN1E-allele lines
      side by side as comparators.
    decision_criterion: >-
      Emergence of sleep-onset REM intrusion, cataplexy-like attacks, elevated
      auditory brainstem response thresholds, and progressive cerebellar
      degeneration in the exon-21 line but not the HSAN1E lines would establish
      phenotype dependence on allele position and give the field a genuine
      ADCA-DN model.
  evidence:
  - reference: PMID:34516921
    reference_title: Mutation-induced DNMT1 cleavage drives neurodegenerative disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We generated Dnmt1-M1 and Dnmt1-M2 knock-in mouse models that are
      equivalent to Y495C and D490E-P491Y mutation in patients with HSAN1E,
      respectively.
    explanation: >-
      Confirms that the available mouse models carry HSAN1E-equivalent rather
      than ADCA-DN alleles.
  - reference: PMID:25678562
    reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our results indicate that all the mutations causal for HSAN1E are located
      in the middle part or N-terminus end of the TS domain, whereas all the
      mutations causal for autosomal dominant cerebellar ataxia, deafness and
      narcolepsy are located in the C-terminus end of the TS domain.
    explanation: >-
      Establishes that variant position within the domain determines which human
      phenotype results, which is what makes the allele choice in the mouse
      models a translational mismatch.
  - reference: PMID:40328247
    reference_title: DNA methyltransferase 1 modulates mitochondrial function through bridging m(5)C RNA methylation.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      When the DNMT1 RFTS domain is mutated in mice, it triggers aberrant
      DNMT1-RNA interaction and significantly elevated m5C RNA methylation and
      RNA stability for a portion of metabolic genes.
    explanation: >-
      Adds the new RNA-methylation mechanism to the model-mismatch question.
      INDIRECT because the experiment does not establish the branch in human
      ADCA-DN or in an exon-21 ADCA-DN model.
- discussion_id: controversy_adcadn_methylome_direction
  prompt: >-
    Does ADCA-DN produce net hypermethylation of normally unmethylated regions,
    bidirectional change that depends on locus and cell type, or both depending
    on the tissue examined?
  kind: CONTROVERSY
  status: OPEN
  attaches_to:
  - pathophysiology#Cell-Type-Specific Methylome and Transcriptome Disruption
  rationale: >-
    A genome-wide array on DNA from a six-affected ADCA-DN family found a shift
    out of the lowest and upper-intermediate methylation bins into intermediate
    and near-complete methylation, with 82 regionally hypermethylated loci,
    consistent with increased methylation of normally unmethylated promoters and
    CpG islands. In contrast, patient fibroblasts, iPSCs, and induced neurons
    showed changes whose direction depended on cell type, including ZFP57
    promoter hypomethylation with increased ZFP57 expression. Neither result
    supports the older global-hypomethylation model, but they are not obviously
    reconcilable with each other, and the tissue examined differs (peripheral
    blood-derived DNA versus derived neural cells). Resolving this determines
    whether any methylation episignature could serve as a diagnostic or
    pharmacodynamic biomarker.
  proposed_experiments:
  - experiment_id: exp_adcadn_matched_tissue_methylome_comparison
    name: Matched multi-tissue methylome comparison in the same ADCA-DN carriers
    description: >-
      Profile whole-genome bisulfite methylomes from peripheral blood, skin
      fibroblasts, and iPSC-derived neurons from the same set of ADCA-DN
      carriers and matched controls, using one analysis pipeline, and test
      whether the direction of change at shared loci is concordant across
      tissues or genuinely dependent on tissue.
    decision_criterion: >-
      Concordant direction across tissues would indicate that the earlier
      discrepancy was methodological; discordant direction at shared loci would
      confirm a genuine dependence on cell type and rule out a single
      blood-based episignature.
  evidence:
  - reference: PMID:27602171
    reference_title: "Identification of a methylation profile for DNMT1-associated autosomal dominant cerebellar ataxia, deafness, and narcolepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This pattern suggests an increase in methylation of normally unmethylated
      regions, such as promoters and CpG islands, as well as further methylation
      of highly methylated gene bodies and intergenic regions.
    explanation: States the hypermethylation-leaning interpretation from patient DNA.
  - reference: PMID:37584462
    reference_title: Mutations in human DNA methyltransferase DNMT1 induce specific genome-wide epigenomic and transcriptomic changes in neurodevelopment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Furthermore, ZFP57, which is required to maintain gene imprinting through
      DNA methylation during early development, was hypomethylated in promoters
      and exhibited upregulated expression in patients with ADCA-DN in both iPSC
      and iNs.
    explanation: >-
      Provides the contrasting promoter-hypomethylation observation in
      patient-derived cells.
- discussion_id: open_adcadn_module_conformance_declined
  prompt: >-
    Which cell populations actually degenerate in the ADCA-DN cerebellum and
    auditory system, and would that support conformance to the
    cerebellar_purkinje_degeneration and sensorineural_hair_cell_loss modules?
  kind: OPEN_QUESTION
  status: OPEN
  attaches_to:
  - pathophysiology#Cerebellar Degeneration
  - pathophysiology#Auditory Pathway Degeneration
  rationale: >-
    Conformance to both modules was evaluated and declined. The
    cerebellar_purkinje_degeneration module turns on Purkinje neuron
    degeneration as its central effector, but the only ADCA-DN cerebellar data
    are MRI atrophy and a raised MR spectroscopy myo-inositol signal, which
    reflects glial density rather than Purkinje loss; no autopsy series exists.
    The sensorineural_hair_cell_loss module turns on hair cell
    mechanotransduction failure and death, whereas the ADCA-DN deafness is
    described as sensory neuronal and is accompanied by attenuated brainstem
    auditory evoked potentials, which points to auditory-neural or retrocochlear
    rather than hair cell pathology. Declaring conformance in either case would
    assert an effector cell type that has not been demonstrated. Both decisions
    should be revisited if neuropathological or temporal-bone data appear.
  proposed_experiments:
  - experiment_id: exp_adcadn_cerebellar_and_temporal_bone_neuropathology
    name: Cerebellar and temporal-bone neuropathology in ADCA-DN donors
    description: >-
      In ADCA-DN brain and temporal-bone donations, perform calbindin and
      parvalbumin immunohistochemistry with stereological Purkinje cell counts
      and Bergmann glia assessment in the cerebellar cortex, and cytocochleogram
      analysis of inner and outer hair cells together with spiral ganglion
      neuron counts in the temporal bone.
    decision_criterion: >-
      Significant Purkinje cell loss relative to age-matched controls would
      justify conformance to cerebellar_purkinje_degeneration; a hair-cell-loss
      cytocochleogram pattern would justify conformance to
      sensorineural_hair_cell_loss, whereas isolated spiral ganglion or auditory
      nerve loss would confirm the retrocochlear interpretation and the decision
      to decline.
  evidence:
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Electrophysiological studies revealed that visual evoked potentials were
      attenuated with prolonged latencies in both eyes, and brainstem auditory
      and somatosensory evoked potentials were also attenuated.
    explanation: >-
      The attenuated brainstem auditory evoked potentials are the evidence that
      points away from a purely cochlear hair cell lesion.
  - reference: PMID:24709307
    reference_title: "Polysomnographic and neurometabolic features may mark preclinical autosomal dominant cerebellar ataxia, deafness, and narcolepsy due to a mutation in the DNA (cytosine-5-)-methyltransferase gene, DNMT1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      proton magnetic resonance spectroscopy (MRS) revealed increased cerebellar
      myoinositol (mI) in both subjects
    explanation: >-
      The only cellular-level cerebellar evidence in ADCA-DN is a glial marker,
      not a Purkinje-specific one.
- discussion_id: gap_adcadn_no_disease_modifying_therapy
  prompt: >-
    Is there any tractable disease-modifying strategy for ADCA-DN, given that
    the mechanism combines impaired maintenance methylation with potentially
    toxic mutant-protein species?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Mutant DNMT1 Mislocalization and Aggresome Formation
  rationale: >-
    No approved or investigational disease-modifying drug, gene therapy, RNA
    therapy, or epigenome-editing treatment exists for ADCA-DN, and no
    disease-specific interventional clinical trial has been registered. The
    mechanism is not a clean loss of function, so simple gene supplementation is
    unlikely to be sufficient and broad DNMT inhibition would be expected to be
    harmful. Allele-selective silencing of the mutant transcript, or
    pharmacological correction of mutant-protein mislocalization and aggresome
    formation, are the mechanistically plausible directions but neither has been
    attempted.
  proposed_experiments:
  - experiment_id: exp_adcadn_allele_selective_knockdown_in_patient_neurons
    name: Allele-selective mutant DNMT1 knockdown in patient-derived induced neurons
    description: >-
      In induced neurons from ADCA-DN patients carrying p.Ala570Val,
      p.Gly605Ala, or p.Val606Phe, apply allele-selective antisense
      oligonucleotides or base editing to reduce the mutant transcript while
      preserving the wild-type allele, then measure DNMT1 subcellular
      localization, aggresome burden, autophagic flux, and reversal of the
      patient methylome and transcriptome signature.
    decision_criterion: >-
      Normalization of DNMT1 localization and of the patient methylome and
      transcriptome signature without loss of total maintenance methylation
      would support allele-selective knockdown as a therapeutic direction.
  evidence:
  - reference: PMID:22338191
    reference_title: DNMT1-Related Disorder.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "No cure for DNMT1 disorder currently exists."
    explanation: >-
      GeneReviews confirms the absence of any disease-modifying treatment for
      this disorder.
  - reference: PMID:25678562
    reference_title: Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Our results suggest mutations in DNMT1 result in imbalanced protein
      homeostasis through aggresome-induced autophagy.
    explanation: >-
      Identifies the proteostasis defect that any mechanism-directed therapy
      would need to address.
- discussion_id: open_adcadn_cataract_unexplained
  prompt: >-
    Is cataract a genuine mechanistic consequence of DNMT1 dysfunction in
    ADCA-DN, or an incidental age-related comorbidity in a small reported
    series?
  kind: OPEN_QUESTION
  status: OPEN
  attaches_to:
  - phenotypes#Cataract
  rationale: >-
    Cataract is listed among the variable manifestations of ADCA-DN in two
    independent sources, but no mechanism links maintenance-methylation failure
    or the neurodegenerative cascade to lens opacification, and the affected
    patients are in an age range where cataract is common in the general
    population. The phenotype is therefore recorded but deliberately left
    unwired in the pathograph rather than attached to an existing node, which
    would assert an unsupported causal claim.
  evidence:
  - reference: PMID:32984563
    reference_title: "Autosomal dominant cerebellar ataxia, deafness, and narcolepsy with amenorrhea, subclinical optic atrophy, and electroencephalographic abnormality: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Optic atrophy, cataract, sensory neuropathy, and dementia may develop in
      the later stages of the disease.
    explanation: >-
      Reports cataract as a late ADCA-DN feature without proposing any
      mechanism.

📚

References & Deep Research

References

1

PMID:22338191

DNMT1-Related Disorder.

No top-level findings curated for this source.

Deep Research

1

Falcon ▸

Disease Characteristics Research Template

Edison Scientific Literature 39 citations 2026-07-31T18:45:47.463741

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

Disease Name: Autosomal Dominant Cerebellar Ataxia Deafness and Narcolepsy
MONDO ID: (if available)
Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Autosomal Dominant Cerebellar Ataxia Deafness and Narcolepsy covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

What is the disease? Provide a concise overview.
What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
What are the common synonyms and alternative names?
Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
Risk Factors:

Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases
Genetic risk factors (causal variants, susceptibility loci, modifier genes)
Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
Protective Factors:

Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases
Genetic protective factors (protective variants, modifier alleles)
Environmental protective factors (diet, lifestyle, exposures that reduce risk)
Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene
Pathogenic Variants:
Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
Variant type/class (missense, frameshift, nonsense, splice-site, structural)
Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
Functional consequences (loss of function, gain of function, dominant negative)
Modifier Genes: Genes that modify disease severity or expression
Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases
Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

Search first: CDC databases, WHO, PubMed, NHANES
Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc
Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

Search first: Gene Ontology (GO), Reactome, KEGG, PubMed
Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold
Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA
Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

Search first: ImmPort, Immunome Database, IEDB, Gene Ontology
Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

Search first: PubMed, Gene Ontology, Reactome
Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

Search first: BRENDA, UniProt, KEGG, OMIM, PubMed
Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Molecular Profiling (if available):
Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
Advanced Technologies (if applicable):
Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

Organ Level:
Primary organs directly affected
Secondary organ involvement (complications, secondary effects)
Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT
Tissue and Cell Level:
Specific tissue types affected (epithelial, connective, muscle, nervous)
Specific cell populations targeted (with Cell Ontology terms)

Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB
Subcellular Level:
Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas
Localization:
Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

Onset:
Typical age of onset (congenital, pediatric, adult, geriatric)
Onset pattern (acute, subacute, chronic, insidious)

Search first: OMIM, Orphanet, HPO, PubMed
Progression:
Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
Progression rate (rapid, slow, variable)
Disease course pattern (episodic, relapsing-remitting, progressive, stable)
Disease duration (self-limited, chronic lifelong)

Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM
Patterns:
Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

Epidemiology:
Prevalence (cases per 100,000 at given time)
Incidence (new cases per 100,000 per year)

Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries
For Genetic Etiology:
Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
Population Demographics:
Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
Geographic distribution of specific variants
Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

Clinical Tests:
Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
Genetic Testing:

Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen
Overview of recommended genetic testing approach
Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
FISH > Search first: ClinVar, cytogenetics databases, PubMed
Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
Omics-Based Diagnostics (if applicable):
RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
Clinical Criteria:
Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
Screening:
Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

Survival and Mortality:
Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
Morbidity and Function:
Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
Disease Course:
Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
Prediction:
Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

Pharmacotherapy:
Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
Advanced Therapeutics:
Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
Surgical and Interventional:
Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
Supportive and Rehabilitative:
Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
Experimental:
Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
Treatment Outcomes:
Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
Treatment Strategy:
Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest NCIT (NCI Thesaurus) clinical-intervention terms where applicable.

13. Prevention

Prevention Levels:
Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
Immunization: Vaccine strategies (if applicable)

Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database
Screening and Early Detection:
Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
Behavioral Interventions: Lifestyle modifications to reduce risk

Search first: CDC, WHO, behavioral intervention databases, Cochrane Library
Counseling: Genetic counseling (risk assessment, family planning guidance)

Search first: NSGC resources, ACMG guidelines, GeneReviews
Public Health:
Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
Prophylaxis: Preventive medications or procedures

Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

Taxonomy: Species affected (with NCBI Taxon identifiers)

Search first: NCBI Taxonomy
Breed: Specific breeds affected (with VBO identifiers if applicable)

Search first: VBO (Vertebrate Breed Ontology)
Gene: Orthologous genes in other species (with NCBI Gene IDs)

Search first: NCBI Gene
Natural Disease:
Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
Comparative Biology:
Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
Transmission (if applicable):
Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

Model Types:
Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
Genetic Models:
Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
Model Characteristics:
Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
Applications:
Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
Resources:
Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

Cite primary literature (PMID preferred) for all mechanistic and clinical claims
Prioritize recent reviews and landmark papers
Include direct quotes from abstracts where possible to support key statements
Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, NCIT, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (NCIT terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Autosomal Dominant Cerebellar Ataxia, Deafness and Narcolepsy (ADCA-DN)

Executive summary

ADCA-DN is an ultra-rare, progressive, autosomal-dominant neurodegenerative disorder caused by heterozygous DNMT1 variants, classically missense variants in exon 21 encoding the C-terminal portion of the replication-foci targeting sequence (RFTS) domain. The characteristic sequence is adult-onset narcolepsy with cataplexy and sensorineural hearing loss, usually followed by cerebellar ataxia and cognitive/behavioral decline. Optic atrophy, sensory neuropathy, psychiatric manifestations, seizures, dysautonomia, diabetes, and lymphedema broaden the phenotype. ADCA-DN overlaps clinically and mechanistically with hereditary sensory and autonomic neuropathy type 1E (HSAN1E); collectively these are increasingly called DNMT1-complex disorder. However, evidence from broader DNMT1 cohorts should not automatically be treated as ADCA-DN-specific. (winkelmann2012mutationsindnmt1 pages 1-2, baets2015defectsofmutant pages 13-14, bi2020expandedgeneticinsight pages 1-2)

The most important recent advance is a 2023 study of patient fibroblasts, induced pluripotent stem cells (iPSCs), and induced neurons, which demonstrated cell-type-specific methylomic and transcriptomic abnormalities and nominated phenotype-related genes including PDGFB, PRDM8, NR2F1, and ZFP57. A 2024 systematic review independently reaffirmed exon-21 DNMT1 variants as the strongest monogenic methylation-related association with hearing loss. No disease-modifying treatment or disease-specific clinical trial was identified; care remains multidisciplinary and symptomatic. (davis2023mutationsinhuman pages 1-2, patil2024asystematicreview pages 1-2)

domain	established finding	evidence type/sample	key quantitative detail or variant	source/date/DOI
Identity / IDs	ADCA-DN is a rare Mendelian neurodegenerative syndrome caused by DNMT1; Open Targets maps the disease as MONDO_0011397 and the classic phenotype identifier is OMIM 604121	Disease database mapping plus human discovery families	DNMT1 is the only associated target in Open Targets evidence returned here; OMIM phenotype number 604121 stated in primary literature	Open Targets association, accessed in tool output (OpenTargets Search: autosomal dominant cerebellar ataxia deafness and narcolepsy-DNMT1); Winkelmann et al., 2012, Hum Mol Genet, May 2012, https://doi.org/10.1093/hmg/dds035 (winkelmann2012mutationsindnmt1 pages 1-2)
Synonyms / nomenclature	Common names include “autosomal dominant cerebellar ataxia, deafness and narcolepsy” and “ADCA-DN”; later literature places it within broader “DNMT1-complex disorder” because of overlap with HSAN1E	Narrative disease-level synthesis from human cohorts	Distinction remains useful: ADCA-DN classically maps to exon 21 / C-terminal RFTS variants, HSAN1E more often exon 20 / N-terminal-middle RFTS variants	Baets et al., 2015, Brain, Apr 2015, https://doi.org/10.1093/brain/awv010 (baets2015defectsofmutant pages 13-14, baets2015defectsofmutant pages 1-1, baets2015defectsofmutant pages 14-15); Bi et al., 2020, Neurol Genet, Aug 2020, https://doi.org/10.1212/NXG.0000000000000456 (bi2020expandedgeneticinsight pages 1-2)
Causal gene / variants	The landmark ADCA-DN variants are heterozygous missense DNMT1 exon 21 variants affecting the RFTS domain	Human exome/Sanger family studies	p.Ala570Val, p.Gly605Ala, p.Val606Phe; one report described a de novo exon 21 mutation in a Brazilian patient	Winkelmann et al., 2012, May 2012, https://doi.org/10.1093/hmg/dds035 (winkelmann2012mutationsindnmt1 pages 1-2, winkelmann2012mutationsindnmt1 pages 2-3); Pedroso et al., 2013, Sleep, Aug 2013, https://doi.org/10.5665/sleep.2898
Inheritance / onset	Autosomal dominant inheritance with age-dependent, usually adult onset	Human pedigrees	Typical onset in 30s–40s; narcolepsy-cataplexy and deafness often precede ataxia and dementia	Winkelmann et al., 2012, May 2012, https://doi.org/10.1093/hmg/dds035 (winkelmann2012mutationsindnmt1 pages 1-2, winkelmann2012mutationsindnmt1 pages 2-3); Moghadam et al., 2014, Sleep Med, May 2014, https://doi.org/10.1016/j.sleep.2013.09.028 (moghadam2014polysomnographicandneurometabolic pages 1-2)
Clinical course	Disease is progressive and multisystem neurologic involvement expands over time	Human family cohorts and expanded case series	Early symptoms: narcolepsy/deafness; later cerebellar ataxia, cognitive decline/dementia, optic atrophy, neuropathy, psychiatric manifestations, diabetes mellitus	Winkelmann et al., 2012, May 2012, https://doi.org/10.1093/hmg/dds035 (winkelmann2012mutationsindnmt1 pages 1-2); Davis et al., 2023, Hum Mol Genet, Aug 2023, https://doi.org/10.1093/hmg/ddad123 (davis2023mutationsinhuman pages 1-2)
Core phenotypes	Canonical phenotype triad is narcolepsy/cataplexy, sensorineural deafness, and cerebellar ataxia; dementia is frequent later	Human clinical cohorts	CSF hypocretin-1 reported low/undetectable in the discovery paper; additional features can include optic atrophy, hallucinations, seizures, lymphedema, neuropathy	Winkelmann et al., 2012, May 2012, https://doi.org/10.1093/hmg/dds035 (winkelmann2012mutationsindnmt1 pages 1-2, winkelmann2012mutationsindnmt1 pages 4-5); Baets et al., 2015, Apr 2015, https://doi.org/10.1093/brain/awv010 (baets2015defectsofmutant pages 13-14, baets2015defectsofmutant pages 14-15)
Presymptomatic / early markers	Sleep and metabolic abnormalities may predate overt neurologic symptoms in mutation carriers	Human presymptomatic family study	In 2 asymptomatic daughters, SOREMPs were detected and proton MRS showed increased cerebellar myoinositol despite normal neurologic exam, audiometry, ophthalmology, and structural MRI	Moghadam et al., 2014, May 2014, https://doi.org/10.1016/j.sleep.2013.09.028 (moghadam2014polysomnographicandneurometabolic pages 1-2)
Imaging / neurophysiology	Neuroimaging can show brain or spinal changes; neurophysiology often supports sensory axonal neuropathy	Human case series	Global brain atrophy in 12/14 MRI cases in broader DNMT1 disorder cohort; case reports include T2 hyperintense enhancing lesions, PET hypometabolism, posterior column atrophy, abnormal evoked potentials	Baets et al., 2015, Apr 2015, https://doi.org/10.1093/brain/awv010 (baets2015defectsofmutant pages 1-1); Bi et al., 2020, Aug 2020, https://doi.org/10.1212/NXG.0000000000000456 (bi2020expandedgeneticinsight pages 1-2)
Prognosis / natural history	Available natural-history evidence suggests substantial morbidity and reduced survival, but data are sparse and mostly from aggregated DNMT1-complex cohorts rather than pure ADCA-DN cohorts	Human retrospective cohort	Mean onset 37.7 years and average survival 53.6 years in Baets et al.; cognitive decline in 89% by age 45 in that broader cohort	Baets et al., 2015, Apr 2015, https://doi.org/10.1093/brain/awv010 (baets2015defectsofmutant pages 1-1)
Molecular mechanism	ADCA-DN variants localize to the DNMT1 RFTS domain, disrupting maintenance methylation and protein behavior; disease mechanism is not simple haploinsufficiency	Human genetics, cell biology, mechanistic review	A570V/G605A/V606F weaken RFTS-catalytic domain interaction; mutant DNMT1 can mislocalize, lose heterochromatin binding, aggregate, and drive aggresome/autophagy-related proteostasis defects	Baets et al., 2015, Apr 2015, https://doi.org/10.1093/brain/awv010 (baets2015defectsofmutant pages 1-1); Davletgildeeva & Kuznetsov, 2024, Biomolecules, Sep 2024, https://doi.org/10.3390/biom14091117 (davletgildeeva2024theroleof pages 5-7)
2023 iPSC / iNeuron omics	Patient-derived fibroblasts, iPSCs, and induced neurons show cell-type-specific methylome/transcriptome disruption in ADCA-DN	Human in vitro disease models	Variants studied: Ala570Val, Gly605Ala, Val606Phe; methylation and expression were negatively correlated in iPSCs/iNs; ZFP57 promoter hypomethylation/upregulation; phenotype-linked genes included PDGFB, PRDM8, NR2F1	Davis et al., 2023, Aug 2023, https://doi.org/10.1093/hmg/ddad123 (davis2023mutationsinhuman pages 1-2)
Additional mechanistic models	RFTS mutations can trigger instability and internal cleavage of DNMT1, implying mixed loss- and gain-of-function effects	Mouse and cell models, primarily HSAN1E-oriented but mechanistically relevant to DNMT1 RFTS disease	Specific truncated ~75–80 kDa DNMT1 species near aa ~501 proposed; heterozygous knock-in mice had reduced DNMT1 and impaired learning/memory; homozygous mutants died around E10.5	Wang et al., 2021, Sci Adv, Sep 2021, https://doi.org/10.1126/sciadv.abe8511 (wang2021mutationinduceddnmt1cleavage pages 12-13, wang2021mutationinduceddnmt1cleavage pages 1-2)
Diagnostics	Diagnosis is primarily molecular, supported by characteristic sleep/hearing/ataxia/cognitive phenotype and family history; WES/WGS can be especially useful when phenotype is atypical or overlaps neuromuscular disease	Human genetics case reports and clinic practice article	Sanger sequencing of DNMT1 exon 21 was used in targeted familial testing; later literature emphasizes WES/WGS to improve diagnostic yield in adults	Moghadam et al., 2014, May 2014, https://doi.org/10.1016/j.sleep.2013.09.028 (moghadam2014polysomnographicandneurometabolic pages 1-2); Dratch et al., 2024, Biology, Feb 2024, https://doi.org/10.3390/biology13020093 (dratch2024theimportanceof pages 1-2)
Real-world intervention	Cochlear implantation can improve hearing in DNMT1-complex disorder and is the clearest disease-specific real-world intervention reported in the retrieved evidence	Human case report within clinical series	One patient with p.T497P had “significant hearing improvements at all tested frequencies (250–6,000 Hz)” after left cochlear implant	Bi et al., 2020, Aug 2020, https://doi.org/10.1212/NXG.0000000000000456 (bi2020expandedgeneticinsight pages 1-2)
Supportive care / implementation	Management remains symptomatic and multidisciplinary: sleep medicine, audiology, neurogenetics, rehabilitation, neuropsychology, and genetic counseling	Case-series based care observations	Example supportive measures reported include IV immunoglobulin for hypogammaglobulinemia in one DNMT1-complex case and use of advanced imaging/neurophysiology for surveillance	Bi et al., 2020, Aug 2020, https://doi.org/10.1212/NXG.0000000000000456 (bi2020expandedgeneticinsight pages 1-2); Dratch et al., 2024, Feb 2024, https://doi.org/10.3390/biology13020093 (dratch2024theimportanceof pages 1-2)
Epidemiology gap	Extremely rare disease with very few pedigrees described; robust prevalence/incidence estimates are not available in the retrieved evidence	Literature review and early family reports	Moghadam 2014 states only the original Swedish family plus five further pedigrees recognized worldwide at that time	Moghadam et al., 2014, May 2014, https://doi.org/10.1016/j.sleep.2013.09.028 (moghadam2014polysomnographicandneurometabolic pages 1-2); Patil et al., 2024, Jul 2024, https://doi.org/10.1186/s13148-024-01697-9 (patil2024asystematicreview pages 1-2)
Trials gap	No disease-specific interventional clinical trials for ADCA-DN were identified in the retrieved tool results	Clinical trials search result	Tool search found no relevant ADCA-DN/DNMT1 ataxia-deafness-narcolepsy intervention trial	ClinicalTrials.gov tool search in conversation returned no relevant trials (OpenTargets Search: autosomal dominant cerebellar ataxia deafness and narcolepsy-DNMT1)
Model limitations	Current models are informative but incomplete for ADCA-DN	Mouse/cell model interpretation	2021 knock-in mice modeled HSAN1E-equivalent RFTS mutations and noted that full neuronal phenotypes, “including hearing, remain to be determined”; cognitive defects were modest relative to human disease	Wang et al., 2021, Sep 2021, https://doi.org/10.1126/sciadv.abe8511 (wang2021mutationinduceddnmt1cleavage pages 12-13, wang2021mutationinduceddnmt1cleavage pages 1-2)

Table: This compact table summarizes the most actionable and best-supported findings for autosomal dominant cerebellar ataxia, deafness and narcolepsy across identity, phenotype, mechanism, diagnostics, and care. It emphasizes where evidence is strong, where newer 2023-2024 data add insight, and where important gaps remain.

1. Disease information

Definition and classification

ADCA-DN is a Mendelian, multisystem neurological disorder characterized by narcolepsy-cataplexy, sensorineural deafness, cerebellar ataxia, and later dementia or other cognitive-behavioral deterioration. The landmark molecular study described it as a late-onset disorder, typically beginning at 30–40 years, and identified heterozygous DNMT1 mutations in affected members of several kindreds. (winkelmann2012mutationsindnmt1 pages 1-2, winkelmann2012mutationsindnmt1 pages 2-3)

Recommended identifiers and names

MONDO: MONDO:0011397.
OMIM phenotype: 604121.
Causal gene: DNMT1, Ensembl ENSG00000130816; approved name DNA methyltransferase 1.
Preferred name: autosomal dominant cerebellar ataxia, deafness and narcolepsy.
Synonyms: ADCA-DN; cerebellar ataxia–deafness–narcolepsy syndrome; DNMT1-related ADCA-DN.
Broader grouping: DNMT1-complex disorder, encompassing overlapping ADCA-DN and HSAN1E phenotypes.
Orphanet, MeSH, ICD-10/ICD-11: a dedicated code was not established in the retrieved evidence. In practice, component manifestations may be coded separately, but these are not equivalent to a molecular disease identifier. Open Targets returned DNMT1 as the single associated target for MONDO:0011397, supported by five evidence records. (OpenTargets Search: autosomal dominant cerebellar ataxia deafness and narcolepsy-DNMT1)

The evidence is primarily aggregated disease-level literature derived from small pedigrees and case series, not population-scale EHR data. Individual-patient observations are embedded in those reports, including presymptomatic carriers and sporadic/de-novo cases. (winkelmann2012mutationsindnmt1 pages 1-2, bi2020expandedgeneticinsight pages 1-2, moghadam2014polysomnographicandneurometabolic pages 1-2)

2. Etiology, risk, and protective factors

Primary cause

The established cause is a heterozygous germline pathogenic variant in DNMT1. The original ADCA-DN variants were p.Ala570Val, p.Gly605Ala, and p.Val606Phe, all conserved missense changes in exon 21 and spatially clustered in the RFTS domain. A de-novo occurrence of p.Ala570Val and a separate de-novo exon-21 case demonstrate that a negative family history does not exclude the diagnosis. (winkelmann2012mutationsindnmt1 pages 1-2, winkelmann2012mutationsindnmt1 pages 2-3)

Genetic risk factors

Carrying a pathogenic DNMT1 allele is the dominant risk factor.
Classical ADCA-DN variants occur toward the C-terminal RFTS region; HSAN1E variants tend to occur in exon 20 or the N-terminal/middle RFTS region. This relationship is useful but not absolute because expanding case series show overlapping phenotypes and variants outside the classical region. (davis2023mutationsinhuman pages 1-2, baets2015defectsofmutant pages 1-1, bi2020expandedgeneticinsight pages 1-2)
No validated modifier gene, polygenic risk score, anticipation mechanism, founder allele, or protective allele has been established.
Population allele-frequency estimates for the individual variants were not available in the retrieved evidence. Their rarity, segregation, de-novo occurrence, conservation, and functional effects support pathogenicity; current classification should be checked in ClinVar/gnomAD using the exact transcript and HGVS expression before clinical reporting.

Environmental, lifestyle, infectious, and protective factors

No environmental toxin, infection, diet, smoking behavior, occupation, or lifestyle exposure is established as causing or preventing ADCA-DN. Family history is informative because of dominant inheritance, but is not itself an environmental risk factor. Noise exposure can independently worsen hearing, and common DNMT1/DNMT3A polymorphisms have been studied in noise-induced hearing loss, but that evidence concerns a different, multifactorial condition and should not be interpreted as a demonstrated ADCA-DN gene–environment interaction. The 2024 hearing-loss review concluded that broader evidence for functional methylation effects in complex hearing loss remains limited. (patil2024asystematicreview pages 1-2)

3. Phenotypes

Because reported cohorts are extremely small, robust ADCA-DN-specific percentages generally do not exist. “Common” below means recurrent across pedigrees, not a validated population frequency.

Core and expanded manifestations

Manifestation	Type and typical behavior	Suggested HPO term
Narcolepsy	Symptom/physiological disorder; often an early manifestation in the third to fifth decade; progressive or persistent	Narcolepsy, HP:0030050
Cataplexy	Emotion-triggered episodic loss of muscle tone; may accompany narcolepsy and occasionally be prolonged	Cataplexy, HP:0002524
Excessive daytime sleepiness	Symptom; chronic, functionally disabling	Excessive daytime sleepiness, HP:0002189
Sensorineural hearing loss	Clinical sign; usually bilateral and progressive; frequently early	Sensorineural hearing impairment, HP:0000407
Cerebellar ataxia	Sign; usually follows narcolepsy/deafness and progresses	Cerebellar ataxia, HP:0001251
Gait ataxia/falls	Functional manifestation; progressive, potentially requiring aids or caregiver support	Gait ataxia, HP:0002066
Cognitive decline/dementia	Behavioral/cognitive manifestation; generally later and progressive, sometimes frontotemporal-like	Progressive cognitive impairment, HP:0001268; Dementia, HP:0000726
Sensory axonal neuropathy	Sign/electrophysiological abnormality; variable and progressive	Peripheral axonal neuropathy, HP:0003477; Sensory neuropathy, HP:0000763
Optic atrophy	Ophthalmic sign; variable	Optic atrophy, HP:0000648
Psychiatric/behavioral change	Hallucinations, psychosis, personality change or executive dysfunction; variable	Hallucinations, HP:0000738; Psychosis, HP:0000709
Seizures/myoclonus	Episodic neurological sign; variable, sometimes treatment-refractory	Seizure, HP:0001250; Myoclonus, HP:0001336
Dysautonomia	Sign; variable, especially across DNMT1-complex disorder	Autonomic dysfunction, HP:0002270
Diabetes mellitus	Laboratory/clinical metabolic phenotype; reported but not universal	Diabetes mellitus, HP:0000819
Lower-limb lymphedema	Physical manifestation; reported in some families	Lymphedema, HP:0001004
Brain/cerebellar atrophy	Imaging abnormality; variable and progressive	Cerebral atrophy, HP:0002059; Cerebellar atrophy, HP:0001272

The original report stated that narcolepsy and deafness appeared first in all studied pedigrees, followed by ataxia; low or undetectable CSF hypocretin-1 supported hypothalamic hypocretin-system dysfunction. Additional recognized manifestations include optic atrophy, sensorimotor polyneuropathy, psychosis, dementia, and diabetes mellitus. (winkelmann2012mutationsindnmt1 pages 1-2, davis2023mutationsinhuman pages 1-2)

A presymptomatic study examined two clinically unaffected carriers aged 28 and 23. Both had sleep-onset REM periods and increased cerebellar myoinositol on proton MR spectroscopy despite normal neurological examination, audiometry, ophthalmic evaluation, and structural MRI. The authors concluded: “SOREMPs may precede the clinical picture of ADCA-DN as an early polysomnographic marker.” This is promising but based on only two carriers and is not a validated screening biomarker. (moghadam2014polysomnographicandneurometabolic pages 1-2)

Quality-of-life impact

No ADCA-DN-specific EQ-5D, SF-36, PROMIS, or utility study was found. Expected major burdens are inability to remain awake reliably, driving/work restrictions, communication impairment, imbalance and falls, loss of independent mobility, neuropsychiatric symptoms, and eventual need for assistance with daily activities. In a broader DNMT1 case series, one individual progressed to inability to walk and required caregiver assistance. These are clinically important observations but not standardized quality-of-life measurements. (bi2020expandedgeneticinsight pages 1-2)

4. Genetic and molecular information

Causal gene and protein

DNMT1 encodes the principal maintenance DNA methyltransferase, which preferentially restores symmetrical CpG methylation on hemimethylated DNA after replication and participates in DNA repair, imprint maintenance, genome stability, differentiation, and transcriptional repression. Its RFTS domain regulates recruitment to replication foci and interactions involving UHRF1, ubiquitinated histones, and replication-associated machinery. (bi2020expandedgeneticinsight pages 1-2, wang2021mutationinduceddnmt1cleavage pages 1-2)

Pathogenic variants

The best-established ADCA-DN variants are germline, heterozygous missense variants p.Ala570Val, p.Gly605Ala, and p.Val606Phe. Evidence supports a pathogenic mechanism more complex than simple haploinsufficiency: impaired methyltransferase function coexists with altered folding, localization, stability, aggregation, and possibly toxic cleavage products. No recurrent nonsense variant pattern supports pure loss of function. (winkelmann2012mutationsindnmt1 pages 2-3, davletgildeeva2024theroleof pages 5-7, wang2021mutationinduceddnmt1cleavage pages 12-13)

Broader DNMT1-complex variants include p.C353F, p.T481P, p.P491L, p.Y524D, p.I531N, p.E510K, p.P1546A, p.T497P, and p.Y511H, among others. These should not all be labeled classical ADCA-DN: some were reported in HSAN1E or overlapping phenotypes, and p.P1546A was the first reported outside the targeting-sequence domain. (baets2015defectsofmutant pages 1-1, bi2020expandedgeneticinsight pages 1-2)

No disease-causing chromosomal aneuploidy, translocation, inversion, repeat expansion, mitochondrial variant, or somatic driver has been established. No validated modifier gene or disease-specific methylation “episignature” suitable for routine diagnosis was found.

5. Environmental information

ADCA-DN is not infectious, transmissible, occupational, or toxin-induced. No causal pathogen, radiation exposure, pollutant, diet, alcohol pattern, smoking exposure, or exercise pattern is established. General measures—hearing protection, fall prevention, regular activity within safe limits, sleep scheduling, and avoidance of sedating substances—may reduce secondary harm but do not prevent the genetic disease.

6. Mechanism and pathophysiology

Proposed causal chain

Upstream genetic lesion: a heterozygous missense variant alters the DNMT1 RFTS regulatory domain.
Protein-level dysfunction: altered RFTS conformation weakens regulatory interactions, may reduce catalytic activity, impairs heterochromatin association, promotes abnormal cytoplasmic or nucleolar localization, and can cause protein aggregation or susceptibility to internal cleavage. (baets2015defectsofmutant pages 1-1, davletgildeeva2024theroleof pages 5-7, wang2021mutationinduceddnmt1cleavage pages 12-13)
Epigenomic disturbance: maintenance CpG methylation becomes abnormal in a cell-type-specific manner, producing both hypo- and locus-specific dysmethylation and altered transcription.
Proteostasis and cellular injury: mutant protein may form aggresomes and engage autophagy; cleavage may generate an N-terminal 75–80-kDa product with proposed gain-of-function effects. Neural progenitor maintenance, neuronal survival, and differentiated-neuron gene regulation may consequently fail. (baets2015defectsofmutant pages 1-1, wang2021mutationinduceddnmt1cleavage pages 12-13, wang2021mutationinduceddnmt1cleavage pages 1-2)
Circuit/tissue failure: dysfunction of hypothalamic hypocretin circuitry produces narcolepsy-cataplexy; auditory-system injury causes sensorineural deafness; cerebellar and broader CNS degeneration causes ataxia and cognitive/behavioral deterioration; peripheral sensory neurons may also be involved.
Downstream clinical progression: sleep and hearing abnormalities often precede gait ataxia, dementia, neuropathy, and multisystem disability. (winkelmann2012mutationsindnmt1 pages 1-2, moghadam2014polysomnographicandneurometabolic pages 1-2)

2023 molecular profiling

Davis and colleagues studied fibroblasts, iPSCs, and induced neurons from patients carrying Ala570Val, Gly605Ala, or Val606Phe. They reported cell-type-specific methylation and expression changes, with negative correlation between methylation and expression in iPSCs and induced neurons. ZFP57 promoters were hypomethylated and ZFP57 expression increased; nominated phenotype-associated genes included PDGFB and PRDM8 for ataxia/psychosis/dementia and NR2F1 for deafness/optic atrophy. These are mechanistic candidates, not validated diagnostic or prognostic biomarkers. (davis2023mutationsinhuman pages 1-2)

Suggested GO and Cell Ontology annotations

GO biological processes: maintenance of DNA methylation (GO:0010216); DNA methylation (GO:0006306); regulation of gene expression, epigenetic (GO:0040029); chromatin organization (GO:0006325); neurogenesis (GO:0022008); autophagy (GO:0006914); protein localization to heterochromatin; neuron death (GO:0070997).
GO cellular components: nucleus (GO:0005634), chromatin (GO:0000785), heterochromatin (GO:0000792), replication fork (GO:0005657), nucleolus (GO:0005730), aggresome (GO:0016235).
Candidate CL terms: neuron (CL:0000540), neural stem cell (CL:0000047), cerebellar Purkinje cell (CL:0000121), sensory neuron (CL:0000101), oligodendrocyte (CL:0000128), microglial cell (CL:0000129), regulatory T cell (CL:0000815), and hypothalamic hypocretin/orexin neuron where supported by a local ontology extension.

Immune dysfunction remains speculative for classical ADCA-DN. DNMT1 is important in immune-cell biology and one hypothesis links impaired regulatory T-cell differentiation with hypocretin-neuron vulnerability, but direct proof of an autoimmune causal chain in ADCA-DN is lacking. (winkelmann2012mutationsindnmt1 pages 4-5)

7. Anatomical structures affected

Primary organs/system: central and peripheral nervous systems, with secondary auditory and visual-system involvement.

Hypothalamus/hypocretin system: implicated by narcolepsy and low CSF hypocretin-1. Suggested UBERON: hypothalamus, UBERON:0001898.
Cerebellum: ataxia, cerebellar metabolic change, and possible atrophy. Suggested UBERON: cerebellum, UBERON:0002037.
Cerebral cortex/frontosubcortical networks: cognitive decline, psychosis, executive dysfunction, brain atrophy, and PET hypometabolism.
Auditory apparatus and pathways: bilateral sensorineural hearing loss; precise lesion localization may vary between cochlea, auditory nerve/pathway, and cortex. Suggested UBERON: inner ear, UBERON:0001846; cochlea, UBERON:0001844.
Optic nerve/retinal ganglion-cell pathway: optic atrophy in some patients. Suggested UBERON: optic nerve, UBERON:0000962.
Peripheral sensory nerves and dorsal columns: sensory axonal neuropathy, posterior-column/fasciculus gracilis abnormalities in broader DNMT1-complex cases.

Global brain atrophy occurred in 12 of 14 MRI-evaluated individuals in a broader DNMT1 cohort. A separate five-case series described asymmetric cerebral atrophy, enhancing T2 lesions, regional PET hypometabolism, and posterior-column spinal atrophy. These findings illustrate the spectrum but are neither universal nor specific for classical ADCA-DN. (baets2015defectsofmutant pages 1-1, bi2020expandedgeneticinsight pages 1-2)

There is no characteristic lateralization; manifestations are generally bilateral/systemic, although asymmetric brain atrophy has been reported in an expanded DNMT1 phenotype.

8. Temporal development

Classical onset is chronic and insidious, generally in the fourth or fifth decade, although onset varies and childhood presentations occur in broader DNMT1-complex disorder. Narcolepsy-cataplexy and hearing loss usually emerge first; cerebellar ataxia, neuropathy, cognitive decline, psychiatric disease, and multisystem complications accumulate over years. (winkelmann2012mutationsindnmt1 pages 1-2, bi2020expandedgeneticinsight pages 1-2, moghadam2014polysomnographicandneurometabolic pages 1-2)

A useful nonvalidated staging model is:

Presymptomatic carrier: possible SOREMPs and elevated cerebellar myoinositol.
Early clinical: excessive sleepiness/cataplexy and progressive hearing impairment.
Intermediate: gait/cerebellar ataxia, falls, optic or peripheral sensory involvement.
Advanced: dementia/behavioral deterioration, severe mobility and communication disability, seizures or dysautonomia.

No spontaneous remission is documented. Cataplexy is episodic, but the underlying disease course is progressive and lifelong. The presymptomatic interval might be an intervention window, but no preventive therapy has been validated.

9. Inheritance and population

Inheritance is autosomal dominant. A heterozygous affected individual ordinarily has a 50% probability of transmitting the allele in each pregnancy. Penetrance appears strongly age-dependent, but a precise estimate is unavailable. Expressivity is variable, including within families. No repeat expansion is involved, so genetic anticipation is not established. De-novo disease occurs; germline mosaicism has not been quantified. Consanguinity is not etiologically relevant to dominant transmission. (winkelmann2012mutationsindnmt1 pages 1-2, winkelmann2012mutationsindnmt1 pages 2-3)

ADCA-DN is ultra-rare. As of the 2014 presymptomatic study, only the original Swedish family and five additional pedigrees were recognized worldwide. There are no reliable prevalence, incidence, carrier-frequency, sex-ratio, or ethnicity-specific estimates. Cases have been described in European, Brazilian, Chinese, and other populations, arguing against restriction to one ancestry, but this is case-report geography rather than epidemiology. (moghadam2014polysomnographicandneurometabolic pages 1-2)

10. Diagnostics

Clinical evaluation

Suspect ADCA-DN when adult-onset narcolepsy/cataplexy or unexplained daytime sleepiness co-occurs with progressive sensorineural hearing loss, cerebellar ataxia, dementia, optic atrophy, or sensory neuropathy—especially with dominant family history.

Recommended assessment includes:

Neurological, cerebellar, cognitive, psychiatric, autonomic, and ophthalmic examinations.
Pure-tone and speech audiometry; auditory electrophysiology where indicated.
Overnight polysomnography followed by multiple sleep latency testing for suspected narcolepsy; CSF hypocretin-1 can support narcolepsy type 1 when diagnostic uncertainty remains.
Brain MRI, with attention to cerebellar and cerebral atrophy; spinal MRI if dorsal-column disease is suspected. MRS/PET remain investigational rather than routine.
Nerve-conduction studies/EMG and somatosensory evoked potentials for neuropathy/posterior-column involvement.
EEG if seizures, myoclonus, or episodic altered awareness occur.
Screening guided by phenotype for diabetes, immunoglobulin deficiency, cardiomyopathy, dysautonomia, and lymphedema. (winkelmann2012mutationsindnmt1 pages 1-2, bi2020expandedgeneticinsight pages 1-2, moghadam2014polysomnographicandneurometabolic pages 1-2)

Genetic testing strategy

Known familial variant: targeted Sanger or validated next-generation sequencing assay.
Strong classical phenotype: sequence and deletion/duplication analysis of DNMT1, ensuring high-quality coverage of exons 20–21.
Overlapping ataxia/neuropathy/dementia phenotype: a multigene ataxia, neuropathy, dementia, or sleep-disorder panel that includes DNMT1.
Atypical or unresolved disease: trio/family-aware WES or preferably WGS, with CNV and structural-variant analysis. A 2024 adult neuromuscular-clinic report emphasized that exome/genome sequencing can resolve DNMT1-related disease missed by narrower approaches. (dratch2024theimportanceof pages 1-2)
Repeat expansions: test separately when the differential includes common spinocerebellar ataxias; standard WES may not detect them reliably.

CMA, karyotyping, FISH, and mitochondrial testing are not first-line tests for a classic DNMT1 phenotype unless other findings suggest chromosomal or mitochondrial disease. RNA sequencing, methylome profiling, proteomics, and metabolomics are research tools, not validated clinical diagnostics.

Differential diagnosis

Key alternatives include dominant spinocerebellar ataxias, RFC1-related CANVAS, Friedreich ataxia, POLG/mitochondrial disease, superficial siderosis, multisystem atrophy–cerebellar type, hereditary sensory neuropathies, adult-onset leukodystrophies, autoimmune/paraneoplastic ataxia, and sporadic narcolepsy type 1. The combination of narcolepsy-cataplexy, deafness, ataxia, neuropathy/dementia, and a heterozygous DNMT1 variant is strongly distinguishing.

There are no independently validated formal clinical diagnostic criteria. Molecular confirmation is central.

11. Outcome and prognosis

ADCA-DN causes progressive morbidity involving sleep-wake control, hearing, balance, cognition, and independent living. Recovery of the neurodegenerative syndrome is not expected with current treatment. Quantitative survival data are sparse: in a broader DNMT1-complex cohort, mean onset was 37.7 years, average survival 53.6 years, and cognitive decline was reported in 89% by age 45. These values must not be treated as precise ADCA-DN natural-history estimates because the cohort included phenotypic overlap with HSAN1E. (baets2015defectsofmutant pages 1-1)

Potential complications include falls and injury, loss of communication, immobility, aspiration risk in advanced neurological disease, psychiatric crisis, seizures, autonomic complications, and caregiver burden. No validated prognostic biomarker exists. Earlier onset, severe cognitive involvement, seizures, and widespread CNS/PNS disease may plausibly indicate a more severe course, but formal prognostic models are absent.

12. Treatment and current applications

Disease-modifying treatment

No approved disease-modifying drug, gene therapy, cell therapy, RNA therapy, epigenome-editing treatment, or DNMT1-targeted intervention exists for ADCA-DN. No relevant disease-specific interventional trial was identified by the ClinicalTrials.gov search; an unrelated DNMT1-associated oncology study was excluded.

Symptomatic multidisciplinary care

Narcolepsy/cataplexy: management by a sleep specialist using standard narcolepsy therapies according to local guidelines—wake-promoting medication for excessive sleepiness and anticataplectic therapy where needed—plus scheduled sleep, driving/work risk counseling, and avoidance of sedating drugs. These treatments have not been systematically studied specifically in ADCA-DN.
Hearing loss: hearing aids, assistive communication technology, and cochlear-implant evaluation. In one p.T497P DNMT1-complex case, cochlear implantation produced significant improvement across all tested frequencies from 250 to 6,000 Hz. This is the clearest reported real-world intervention, but it is a single-case result. Suggested NCIT concepts: Hearing Aid Device; Cochlear Implantation. (bi2020expandedgeneticinsight pages 1-2)
Ataxia and mobility: physical therapy, balance/gait training, walking aids, home safety review, fall prevention, and occupational therapy. Suggested NCIT concepts: Physical Therapy; Occupational Therapy; Rehabilitation Therapy.
Speech/swallowing: speech-language therapy, augmentative communication, and swallowing assessment when indicated.
Cognitive/psychiatric disease: neuropsychological monitoring, psychiatric treatment, caregiver education, and advance-care planning.
Neuropathy/dysautonomia: foot and skin surveillance, neuropathic-pain treatment, orthostatic and autonomic management.
Seizures: standard antiseizure treatment individualized to seizure type; one broader DNMT1 case improved after perampanel, but this is not disease-specific efficacy evidence. (bi2020expandedgeneticinsight pages 1-2)

Pharmacogenomic guidance specific to DNMT1 variants is unavailable. Broad DNMT inhibitors used in oncology are not rational routine therapy: systemic interference with maintenance methylation could be harmful, and the disease mechanism includes both deficient function and potentially toxic mutant-protein effects.

13. Prevention

There is no vaccine, prophylactic drug, lifestyle intervention, or population-screening program that prevents ADCA-DN.

Primary prevention: reproductive genetic counseling; options may include preimplantation genetic testing for a known familial variant, prenatal diagnosis, donor gametes, or natural conception with or without testing.
Secondary prevention/early detection: cascade testing of consenting adult relatives after counseling, followed by baseline sleep, hearing, neurological, cognitive, and ophthalmic assessment. Predictive testing of minors requires careful ethical review because classical disease is adult-onset and no preventive therapy exists.
Tertiary prevention: hearing rehabilitation, fall prevention, safe-driving counseling, seizure precautions, mobility support, and surveillance for swallowing, autonomic, metabolic, psychiatric, and caregiver complications.

Population newborn or carrier screening is not justified by current prevalence and actionability data.

14. Other species and natural disease

No naturally occurring veterinary counterpart of ADCA-DN was identified, and no breed-associated syndrome, zoonotic potential, or cross-species transmission applies. DNMT1 orthologues are evolutionarily conserved across mammals and other vertebrates, supporting comparative functional research, but conserved gene function is not evidence of naturally occurring homologous disease. Suggested taxonomy terms for experimental species include Homo sapiens NCBI Taxon 9606 and Mus musculus NCBI Taxon 10090.

15. Model organisms and experimental systems

Human cellular models

The most disease-relevant models currently retrieved are patient fibroblasts, iPSCs, and induced neurons carrying Ala570Val, Gly605Ala, or Val606Phe. These reproduce cell-type-specific methylome and transcriptome disturbances and permit study of developmental stage and neural-cell context. Limitations include incomplete brain maturation, absence of intact cerebellar/hypothalamic circuits, and inability to reproduce decades-long progression. (davis2023mutationsinhuman pages 1-2)

Mouse and cellular knock-in models

Wang and colleagues generated CRISPR knock-in mice modeling HSAN1E-equivalent RFTS variants: mouse Tyr500Cys corresponding to human Y495C and Pro496Tyr corresponding to human D490E/P491Y. Heterozygotes had reduced DNMT1 and impaired learning/memory; homozygotes died around embryonic day 10.5. The study implicated mutation-induced internal cleavage near amino acid 501 and a combination of reduced maintenance methylation with gain-of-function toxicity from truncated protein. (wang2021mutationinduceddnmt1cleavage pages 12-13, wang2021mutationinduceddnmt1cleavage pages 1-2)

These are not exact ADCA-DN variant models. The authors stated that the full spectrum, “including hearing, remain[s] to be determined,” and cognitive defects were milder than in affected humans. Thus they support an RFTS-disease mechanism but do not establish complete recapitulation of narcolepsy, deafness, and cerebellar ataxia. (wang2021mutationinduceddnmt1cleavage pages 12-13)

Relevant resources for future model discovery include MGI, IMPC, KOMP, IMSR/MMRRC, ZFIN, FlyBase, and patient-derived iPSC repositories. A major unmet need is a heterozygous knock-in model carrying an exact ADCA-DN variant and assessed longitudinally for sleep architecture, hypocretin circuitry, auditory function, cerebellar degeneration, cognition, and methylome changes.

Recent developments and evidence gaps

The 2023 patient-derived neural-cell study provides the strongest modern disease-specific mechanistic advance, moving the field from a generic “global hypomethylation” model toward cell-type- and locus-specific dysregulation. The 2024 systematic review found 25 qualifying hearing-loss methylation records from 661 screened articles—12 human methylation studies, five animal studies, and eight DNMT1 mutation studies—and concluded that pathogenic exon-21 DNMT1 variants are independently confirmed, whereas methylation evidence in complex hearing loss remains much less secure. A separate 2024 clinical article highlighted practical implementation of exome/genome sequencing in adults with unresolved neuromuscular phenotypes. (davis2023mutationsinhuman pages 1-2, patil2024asystematicreview pages 1-2, dratch2024theimportanceof pages 1-2)

Critical gaps are the absence of a registry-scale natural-history cohort, variant-specific penetrance estimates, validated biomarkers, standardized outcomes, exact-variant animal models, controlled treatment studies, and disease-specific clinical trials. Accordingly, frequency, prognosis, and treatment claims should be represented in a knowledge base with explicit evidence levels and with ADCA-DN distinguished from the broader DNMT1-complex spectrum.

Key references and publication details

Winkelmann J, et al. “Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.” Human Molecular Genetics. Published May 2012. DOI: https://doi.org/10.1093/hmg/dds035. PMID 22328086. (OpenTargets Search: autosomal dominant cerebellar ataxia deafness and narcolepsy-DNMT1, winkelmann2012mutationsindnmt1 pages 1-2)
Pedroso JL, et al. “A novel de novo exon 21 DNMT1 mutation causes cerebellar ataxia, deafness, and narcolepsy in a Brazilian patient.” Sleep. Published August 2013. DOI: https://doi.org/10.5665/sleep.2898. PMID 23904686. (OpenTargets Search: autosomal dominant cerebellar ataxia deafness and narcolepsy-DNMT1)
Moghadam KK, et al. “Polysomnographic and neurometabolic features may mark preclinical autosomal dominant cerebellar ataxia, deafness, and narcolepsy…” Sleep Medicine. Published May 2014. DOI: https://doi.org/10.1016/j.sleep.2013.09.028. (moghadam2014polysomnographicandneurometabolic pages 1-2)
Baets J, et al. “Defects of mutant DNMT1 are linked to a spectrum of neurological disorders.” Brain. Published April 2015. DOI: https://doi.org/10.1093/brain/awv010. (baets2015defectsofmutant pages 1-1)
Bi H, et al. “Expanded genetic insight and clinical experience of DNMT1-complex disorder.” Neurology Genetics. Published August 2020. DOI: https://doi.org/10.1212/NXG.0000000000000456. PMID 31984424. (OpenTargets Search: autosomal dominant cerebellar ataxia deafness and narcolepsy-DNMT1, bi2020expandedgeneticinsight pages 1-2)
Wang W, et al. “Mutation-induced DNMT1 cleavage drives neurodegenerative disease.” Science Advances. Published September 1, 2021. DOI: https://doi.org/10.1126/sciadv.abe8511. (wang2021mutationinduceddnmt1cleavage pages 12-13, wang2021mutationinduceddnmt1cleavage pages 1-2)
Davis KN, et al. “Mutations in human DNA methyltransferase DNMT1 induce specific genome-wide epigenomic and transcriptomic changes in neurodevelopment.” Human Molecular Genetics. Published August 2023. DOI: https://doi.org/10.1093/hmg/ddad123. (davis2023mutationsinhuman pages 1-2)
Dratch L, et al. “The Importance of Offering Exome or Genome Sequencing in Adult Neuromuscular Clinics.” Biology. Published February 2, 2024. DOI: https://doi.org/10.3390/biology13020093. (dratch2024theimportanceof pages 1-2)
Patil V, et al. “A systematic review on the contribution of DNA methylation to hearing loss.” Clinical Epigenetics. Published July 2024. DOI: https://doi.org/10.1186/s13148-024-01697-9. (patil2024asystematicreview pages 1-2)
Davletgildeeva AT, Kuznetsov NA. “The Role of DNMT Methyltransferases and TET Dioxygenases in the Maintenance of the DNA Methylation Level.” Biomolecules. Published September 2024. DOI: https://doi.org/10.3390/biom14091117. (davletgildeeva2024theroleof pages 5-7)

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(davis2023mutationsinhuman pages 1-2): Kasey N Davis, Ping-Ping Qu, Shining Ma, Ling Lin, Melanie Plastini, Niklas Dahl, Giuseppe Plazzi, Fabio Pizza, Ruth O’Hara, Wing Hung Wong, Joachim Hallmayer, Emmanuel Mignot, Xianglong Zhang, and Alexander E Urban. Mutations in human dna methyltransferase dnmt1 induce specific genome-wide epigenomic and transcriptomic changes in neurodevelopment. Human molecular genetics, 32:3105-3120, Aug 2023. URL: https://doi.org/10.1093/hmg/ddad123, doi:10.1093/hmg/ddad123. This article has 7 citations and is from a domain leading peer-reviewed journal.
(patil2024asystematicreview pages 1-2): Vibha Patil, Patricia Perez-Carpena, and Jose A. Lopez-Escamez. A systematic review on the contribution of dna methylation to hearing loss. Clinical Epigenetics, Jul 2024. URL: https://doi.org/10.1186/s13148-024-01697-9, doi:10.1186/s13148-024-01697-9. This article has 9 citations and is from a peer-reviewed journal.
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(baets2015defectsofmutant pages 1-1): Jonathan Baets, Xiaohui Duan, Yanhong Wu, Gordon Smith, William W. Seeley, Inès Mademan, Nicole M. McGrath, Noah C. Beadell, Julie Khoury, Maria-Victoria Botuyan, Georges Mer, Gregory A. Worrell, Kaori Hojo, Jessica DeLeon, Matilde Laura, Yo-Tsen Liu, Jan Senderek, Joachim Weis, Peter Van den Bergh, Shana L. Merrill, Mary M. Reilly, Henry Houlden, Murray Grossman, Steven S. Scherer, Peter De Jonghe, Peter J. Dyck, and Christopher J. Klein. Defects of mutant dnmt1 are linked to a spectrum of neurological disorders. Brain : a journal of neurology, 138 Pt 4:845-61, Apr 2015. URL: https://doi.org/10.1093/brain/awv010, doi:10.1093/brain/awv010. This article has 152 citations.
(baets2015defectsofmutant pages 14-15): Jonathan Baets, Xiaohui Duan, Yanhong Wu, Gordon Smith, William W. Seeley, Inès Mademan, Nicole M. McGrath, Noah C. Beadell, Julie Khoury, Maria-Victoria Botuyan, Georges Mer, Gregory A. Worrell, Kaori Hojo, Jessica DeLeon, Matilde Laura, Yo-Tsen Liu, Jan Senderek, Joachim Weis, Peter Van den Bergh, Shana L. Merrill, Mary M. Reilly, Henry Houlden, Murray Grossman, Steven S. Scherer, Peter De Jonghe, Peter J. Dyck, and Christopher J. Klein. Defects of mutant dnmt1 are linked to a spectrum of neurological disorders. Brain : a journal of neurology, 138 Pt 4:845-61, Apr 2015. URL: https://doi.org/10.1093/brain/awv010, doi:10.1093/brain/awv010. This article has 152 citations.
(winkelmann2012mutationsindnmt1 pages 2-3): Juliane Winkelmann, Ling Lin, Barbara Schormair, Birgitte R. Kornum, Juliette Faraco, Giuseppe Plazzi, Atle Melberg, Ferdinando Cornelio, Alexander E. Urban, Fabio Pizza, Francesca Poli, Fabian Grubert, Thomas Wieland, Elisabeth Graf, Joachim Hallmayer, Tim M. Strom, and Emmanuel Mignot. Mutations in dnmt1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy. Human molecular genetics, 21 10:2205-10, May 2012. URL: https://doi.org/10.1093/hmg/dds035, doi:10.1093/hmg/dds035. This article has 306 citations and is from a domain leading peer-reviewed journal.
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(dratch2024theimportanceof pages 1-2): Laynie Dratch, Tanya M Bardakjian, Kelsey Johnson, Nareen Babaian, Pedro Gonzalez-Alegre, Lauren B. Elman, Colin C. Quinn, Michael Guo, Steven S Scherer, and Defne A. Amado. The importance of offering exome or genome sequencing in adult neuromuscular clinics. Biology, Feb 2024. URL: https://doi.org/10.3390/biology13020093, doi:10.3390/biology13020093. This article has 2 citations.

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Definitions

Inheritance

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Biochemical Markers

Diagnosis

Progression

Prevalence

Differential Diagnoses

Clinical Trials

Experimental Models

Animal Models

Source YAML

References & Deep Research

References

Deep Research

Disease Characteristics Research Template

Target Disease

Research Objectives

1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

11. Outcome/Prognosis

12. Treatment

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Citation Requirements

Output Format

Autosomal Dominant Cerebellar Ataxia, Deafness and Narcolepsy (ADCA-DN)

Executive summary

1. Disease information

Definition and classification

2. Etiology, risk, and protective factors

Primary cause

Genetic risk factors

Environmental, lifestyle, infectious, and protective factors

3. Phenotypes

Core and expanded manifestations

Quality-of-life impact

4. Genetic and molecular information

Causal gene and protein

Pathogenic variants

5. Environmental information

6. Mechanism and pathophysiology

Proposed causal chain

2023 molecular profiling

Suggested GO and Cell Ontology annotations

7. Anatomical structures affected

8. Temporal development

9. Inheritance and population

10. Diagnostics

Clinical evaluation

Genetic testing strategy

Differential diagnosis

11. Outcome and prognosis

12. Treatment and current applications

Disease-modifying treatment

Symptomatic multidisciplinary care

13. Prevention

14. Other species and natural disease

15. Model organisms and experimental systems

Human cellular models

Mouse and cellular knock-in models

Recent developments and evidence gaps

Key references and publication details

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