PUM1-Associated Developmental Disability, Ataxia, and Seizure Syndrome

🏷

Classifications

Harrison's Part

🔗

Mappings

MONDO

MONDO:0958231 neurodevelopmental disorder with motor abnormalities, seizures, and facial dysmorphism

The MONDO term's definition names PUM1 and describes the same de novo developmental syndrome this entry covers.

👪

Inheritance

1

Autosomal dominant, de novo HP:0000006

Every reported PADDAS proband carries a single heterozygous PUM1 lesion - either a 1p35.2 microdeletion whose minimal region of overlap contains only PUM1, or a missense or frameshift variant - and where parental samples have been tested the variant has been de novo. No affected parent-child pair has been described, and the recurrent p.Arg1147Trp allele has arisen independently in several unrelated families. Transmission risk to the offspring of an affected individual has not been reported in the literature and is not stated here.

Autosomal dominant inheritance

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"We identified eleven individuals with either PUM1 deletions or de novo missense variants who suffer a developmental syndrome"

Establishes heterozygous deletion and de novo missense variation as the two causal lesion classes in the founding cohort.

PMID:35386260 SUPPORT Human Clinical

"Thus far, at least three unrelated patients with this variant have been reported (5, 7, 8), and all of them were de novo."

Independent recurrence of the same de novo allele in unrelated families supports de novo dominant occurrence rather than inherited transmission.

?

Discussions and Knowledge Gaps

3

Is the neurological course of PADDAS static, as in a developmental encephalopathy, or progressive, as the mouse degeneration and the ataxia in some probands suggest?

KNOWLEDGE GAP OPEN paddas_natural_history

Attached to

pathophysiology#Cerebellar Purkinje Cell Degeneration phenotypes#Ataxia

The answer changes what is said to families at diagnosis and whether serial neurological and imaging follow-up is warranted beyond routine developmental review. The mechanism points at progression: the mouse model degenerates, and two founding probands were documented as having progressive features. The human evidence does not settle it, because no longitudinal cohort has been followed. With the adult-onset PUM1 ataxia phenotype withdrawn, there is also no longer a late-onset human counterpart from which to infer a degenerative trajectory.

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"She developed early-onset, progressive ataxia with hypotonicity in her lower limbs"

One of the few explicit human statements that the motor phenotype progressed, in a single child.

What paediatric surveillance does PADDAS actually require, beyond the developmental, seizure and growth monitoring any child with a developmental and epileptic encephalopathy receives?

KNOWLEDGE GAP OPEN paddas_surveillance_evidence

Attached to

phenotypes#Reduced bone mineral density phenotypes#Scoliosis phenotypes#Cryptorchidism phenotypes#Strabismus

No guideline, GeneReviews chapter or management paper exists for this disorder, so there is no published surveillance protocol to record in the treatments section. The non-neurological findings that have been reported in single children - low bone mineral density, scoliosis, cryptorchidism, strabismus and refractive error - are each plausible surveillance targets, but each rests on one or two cases and none has a denominator. Recording them as phenotypes with their case-level frequency is deliberate; asserting a surveillance schedule from them would be an inference the literature does not support.

If raised wild-type ataxin-1 mediates the cerebellar phenotype, would lowering ATXN1 benefit PADDAS?

EMERGING HYPOTHESIS OPEN paddas_atxn1_lowering

Attached to

pathophysiology#Elevated Wild-Type Ataxin-1 in Purkinje Cells

Genetically halving Atxn1 largely rescues the Pum1 heterozygous mouse, which is a direct demonstration that the step is tractable in principle. No PUM1 or PADDAS preclinical rescue study using an ATXN1-lowering agent has been published, and none is claimed here. Two limits are worth stating alongside the hypothesis: ataxin-1 de-repression is only one arm of the mechanism, since the severe alleles act partly by disrupting PUM1 partner complexes rather than by raising canonical targets; and the developmental features of PADDAS are established before any postnatal intervention could begin.

Show evidence (2 references)

PMID:25768905 SUPPORT Model Organism

"breeding them to Atxn1(+/-) mice normalized Ataxin1 levels and largely rescued the Pum1(+/-) phenotype"

The genetic proof of principle that lowering ataxin-1 reverses the consequences of Pum1 haploinsufficiency in mice.

PMID:37070548 SUPPORT Model Organism

"the severe mutation disrupts interactions with several RNA-binding proteins and the regulation of their targets"

The second mechanistic arm, which an ATXN1-directed therapy would not address.

⚙

Pathophysiology

9

PUM1 Haploinsufficiency

A heterozygous whole-gene deletion, destabilising missense variant, or frameshift allele leaves one functional PUM1 copy. In fibroblasts and lymphoblastoid lines from the infantile-onset probands, PUM1 protein falls to roughly half of control levels, which is the quantitative starting point of the disease.

PUM1 hgnc:14957

Genetic context variant_origin: DE_NOVO zygosity: HETEROZYGOUS functional_impact_category: LOSS_OF_FUNCTION

Downstream

Loss of Pumilio1 Translational Repression Halving the dose of a translational repressor halves the repressive activity available to its target transcripts.

Disruption of PUM1 Partner RNA-Binding Protein Complexes A separate consequence of the severe alleles, not mediated by loss of target repression: the R1147W protein still binds and represses canonical targets normally but fails to hold its normal partner complexes.

Show evidence (1 reference)

PMID:29474920 SUPPORT In Vitro

"Studies in patient-derived cells revealed that the missense mutations reduced PUM1 protein levels by ∼25% in the adult-onset cases and by ∼50% in the infantile-onset cases"

Quantifies the residual PUM1 protein in patient-derived cells for the infantile-onset (PADDAS) alleles.

Loss of Pumilio1 Translational Repression

Pumilio1 binds Pumilio response elements in target 3' untranslated regions and represses translation and transcript stability. With one functional allele the aggregate repressor activity on those transcripts is reduced.

translation repressor activity GO:0030371 ↓ DECREASED mRNA 3'-UTR binding GO:0003730 ↓ DECREASED

Downstream

De-repression of PUM1 Target Transcripts Reduced repressor occupancy raises the steady-state level of the bound transcripts and their protein products.

Show evidence (1 reference)

PMID:35386260 SUPPORT BACKGROUND Other

"It binds to specific mRNAs (ATXN1, E2F3, CDKN1B, SAE1, CDK1, and AAMP) and directly prevents its translation, thus negatively regulating the expression of the target genes"

States the repressor function and names the target transcripts; quoted from the case report's introduction, which restates established PUM1 biology rather than reporting the authors' own experiment.

De-repression of PUM1 Target Transcripts

PUM1 target transcripts, including ATXN1 and E2F3, rise in patient cells in proportion to the loss of PUM1 protein. ATXN1 is the target with an established neurological consequence: wild-type ataxin-1 is itself dose-sensitive, and raising it reproduces features of spinocerebellar ataxia type 1 without any repeat expansion.

negative regulation of translation of PUM1 target mRNAs GO:0017148 ↓ DECREASED

Downstream

Elevated Wild-Type Ataxin-1 in Purkinje Cells ATXN1 is a direct PUM1 target; its transcript and protein rise when PUM1 repression is lost.

Show evidence (1 reference)

PMID:25768905 SUPPORT Model Organism

"Loss of Pum1 caused progressive motor dysfunction and SCA1-like neurodegeneration with motor impairment, primarily by increasing Ataxin1 levels."

Identifies raised ataxin-1 as the principal mediator of the neurological consequences of Pum1 loss in mice.

Disruption of PUM1 Partner RNA-Binding Protein Complexes

The severe PADDAS missense allele p.Arg1147Trp lies outside the RNA-binding domain and leaves canonical target repression intact, yet produces a far more severe phenotype than the alleles that impair RNA binding. In mouse brain proteomics and patient cell lines the severe allele instead disrupts PUM1's interactions with partner RNA-binding proteins, dysregulating their targets as well. This is why phenotype severity in PUM1 disease is not a linear function of PUM1 abundance.

Downstream

Impaired Neuronal Dendritic Arborization

Show evidence (2 references)

PMID:37070548 SUPPORT Model Organism

"Our results demonstrate that dosage sensitivity does not always signify a linear relationship with protein abundance but can involve distinct mechanisms."

States the paper's conclusion that a second, non-linear mechanism operates alongside simple target de-repression.

PMID:37070548 SUPPORT In Vitro

"In patient-derived cell lines, restoring PUM1 levels restores these interactors and their targets to normal levels."

Shows the interactor defect is a consequence of reduced PUM1 and is reversible in patient cells, which is what makes it a mechanistic node rather than an incidental finding.

Elevated Wild-Type Ataxin-1 in Purkinje Cells

Ataxin-1 accumulates in cerebellar Purkinje cells when PUM1 repression of ATXN1 is lost. In mice this is sufficient to produce SCA1-like degeneration, and genetically lowering Atxn1 back to normal largely rescues the Pum1 heterozygous phenotype, which is the strongest available evidence that this step is causal rather than correlative.

cerebellar Purkinje cell CL:0000121

Animal models

Pum1 heterozygous mouse Mouse recapitulates Raised Ataxin1 in the haploinsufficient mouse, shown to be the mediator of the phenotype by bidirectional genetic rescue and exacerbation. The observation is Ataxin1 accumulation in cerebellar Purkinje cells, at the same scale as the node.

Downstream

Cerebellar Purkinje Cell Degeneration Raised wild-type ataxin-1 drives the same Purkinje-cell degeneration seen in SCA1.

Show evidence (1 reference)

PMID:25768905 SUPPORT Model Organism

"Breeding Pum1(+/-) mice to SCA1 mice (Atxn1(154Q/+)) exacerbated disease progression, whereas breeding them to Atxn1(+/-) mice normalized Ataxin1 levels and largely rescued the Pum1(+/-) phenotype."

A bidirectional genetic epistasis experiment establishing ataxin-1 dosage as the mediator of the Pum1 haploinsufficiency phenotype.

Cerebellar Purkinje Cell Degeneration

Progressive loss and dysfunction of cerebellar Purkinje cells, the sole output neurons of the cerebellar cortex. In PADDAS this is the substrate of the ataxia, the dysarthria, and the vermian and posterior fossa changes seen on MRI; in the founding cohort the ataxia was documented as progressive in one child. The degeneration itself is shown in the Pum1+/- mouse, the genotype that corresponds to human haploinsufficiency.

cerebellar Purkinje cell CL:0000121

Animal models

Pum1 heterozygous mouse Mouse recapitulates Progressive Purkinje cell degeneration with motor incoordination.

Downstream

Ataxia Cerebellar output failure produces limb and gait incoordination.

Dysarthria Cerebellar involvement of speech motor control.

Show evidence (1 reference)

PMID:25768905 SUPPORT Model Organism

"by 10 weeks Pum1 haploinsufficiency had caused loss of Purkinje cells (Figure 4E and F) and dendritic arborization (Figure 4G)"

Purkinje cell loss in heterozygous Pum1+/- mice, the dosage state that corresponds to PADDAS haploinsufficiency.

Impaired Neuronal Dendritic Arborization

PUM1 dosage influences dendritic complexity in neurons. The loss-of-function observation is in Pum1+/- mice, where Purkinje cells lose dendritic arborization by 10 weeks; the authors attribute this to neurodegeneration rather than to a developmental defect. In dissociated mouse hippocampal neurons, overexpressing wild-type PUM1 at about twice normal levels impaired branching, and overexpressing PADDAS-associated mutants suppressed it less, which shows that the mutants keep partial activity rather than directly showing that reduced PUM1 reduces branching. The edges from this node to developmental delay and intellectual disability are therefore inferential: no study has measured dendritic development in human PADDAS neurons.

dendrite morphogenesis GO:0048813 ↓ DECREASED

Downstream

Global developmental delay

Intellectual disability

Cortical Network Hyperexcitability

Show evidence (2 references)

PMID:29474920 SUPPORT INDIRECT In Vitro

"Overexpression of each mutant suppressed dendritic arborization somewhat compared to empty vector"

An overexpression assay in cultured hippocampal neurons, in which wild-type PUM1 at twice normal levels also impaired branching; the authors used it to gauge how much activity the patient mutants retain. It links PUM1 dosage to dendritic complexity but does not itself measure reduced PUM1, so it bears on this node only through an inference step.

PMID:25768905 SUPPORT Model Organism

"by 10 weeks Pum1 haploinsufficiency had caused loss of Purkinje cells (Figure 4E and F) and dendritic arborization (Figure 4G)"

Loss of Purkinje cell dendritic arborization in heterozygous Pum1+/- mice, the loss-of-function observation for this node. The same paper describes it as neurodegeneration rather than a developmental defect.

Cortical Network Hyperexcitability

Cortical circuit dysfunction produces early-onset, frequently pharmacoresistant epilepsy. EEG in reported children shows diffuse background slowing with multifocal spikes, hypsarrhythmia in one infant with spasms, and generalised spike-and-wave in others; MRI abnormalities are cerebral (thin or short corpus callosum, dilated ventricles) as well as cerebellar, which is the argument that PADDAS is not a purely cerebellar disease.

Animal models

Pum1 heterozygous mouse Mouse partially recapitulates Heterozygotes show subclinical generalized epileptiform EEG activity by 16 weeks of age, and 11 of 16 had spontaneous seizures by 30 weeks. Both are adult ages in the mouse, whereas the human seizures begin in the first year of life.

Downstream

Seizures Cortical hyperexcitability is the immediate substrate of the seizures.

Developmental regression

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"Epilepsy is the dysfunction of the cerebrum (17), and we believe that epilepsy and abnormal cortical EEG findings in these patients may indicate that their cerebrum may also be affected."

Attributes the epilepsy in PUM1 patients to cerebral rather than cerebellar involvement, on the basis of their EEG findings.

Impaired Somatic Growth

PADDAS children are commonly small for age. Pum1 knockout mice show marked growth defects and are smaller than normal at birth, falling further behind the growth curve over life, and the PADDAS probands with the best clinical documentation show the same pattern, so the growth phenotype appears to be a direct consequence of PUM1 loss rather than a secondary effect of feeding difficulty.

Downstream

Growth delay The clinical expression of the growth defect.

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"many of the PADDAS subjects—particularly the two missense mutation patients, for whom we have the most reliable clinical data—are small for their age"

Documents poor growth across the human cohort.

⬡

Pathograph

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

●

Phenotypes

23

Eye 3

Ptosis FREQUENT HP:0000508

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"She had several dysmorphic features with high-arched palate, ptosis, hypertelorism, broad nasal bridge, low-set ears, bitemporal narrowing, and almond-shaped eyes"

Records ptosis among the dysmorphic features.

Strabismus FREQUENT HP:0000486

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"| Ocular abnormalities | Exotropia | Hypermetropia and exotropia | Astigmatism with esotropia | Cortical visual impairment | ND | ND | ND | Esotropia | ND |"

The tabulated ocular findings across the reported cases, showing exotropia and esotropia in four children.

Cerebral visual impairment VERY_RARE HP:0100704

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"she suffers global developmental delay, cortical visual impairment, stereotypic hand-clasping, scoliosis, facial dysmorphia, and low bone mineral density in the neck of femur"

Lists cortical visual impairment among this proband's features.

Genitourinary 1

Cryptorchidism OCCASIONAL HP:0000028

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"The two male subjects have cryptorchidism, which is consistent with the testicular hypoplasia reported in Pum1 knockout mice"

Reports cryptorchidism in the male probands and its mouse counterpart.

Head and Neck 2

Abnormal facial shape FREQUENT HP:0001999

Coarse binding: variable spectrum

Show evidence (2 references)

PMID:35386260 SUPPORT Human Clinical

"She had several dysmorphic features with high-arched palate, ptosis, hypertelorism, broad nasal bridge, low-set ears, bitemporal narrowing, and almond-shaped eyes"

Enumerates the dysmorphic features in one child; the list differs between reports, which is why the binding is at the coarse level.

ORPHA:589515 SUPPORT Other

"variable facial and other dysmorphic features (such as broad nasal bridge, hypertelorism, almond-shaped eyes, high-arched palate, and anomalies of the fingers and toes)"

Orphanet's own description records the dysmorphism as variable and gives the same feature list.

Microcephaly VERY_RARE HP:0000252

Show evidence (1 reference)

PMID:30903679 SUPPORT Human Clinical

"We describe here an additional patient with early onset developmental delay, epilepsy, microcephaly, and hair dysplasia, with a de novo heterozygous missense variant of PUM1"

Reports microcephaly in this patient.

Integument 1

Abnormal hair morphology VERY_RARE HP:0001595

Show evidence (1 reference)

PMID:30903679 SUPPORT Human Clinical

"Our report is in favor of a variable expressivity of PADDAS syndrome, and broadens the phenotypic spectrum with the description of hair dysplasia."

States the hair finding and the authors' own framing of it as a phenotype expansion.

Musculoskeletal 3

Hypotonia VERY_FREQUENT HP:0001252

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"She was identified as having profound axial hypotonia and could no longer hold her head after the onset of epilepsy."

Documents profound axial hypotonia in a reported child.

Scoliosis VERY_RARE HP:0002650

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"she suffers global developmental delay, cortical visual impairment, stereotypic hand-clasping, scoliosis, facial dysmorphia, and low bone mineral density in the neck of femur"

Records scoliosis in this proband.

Reduced bone mineral density VERY_RARE HP:0004349

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"low bone mineral density in the neck of femur (4 standard deviations below normal for age)"

Quantifies the bone density deficit in this proband.

Nervous System 12

Global developmental delay VERY_FREQUENT HP:0001263

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"

Gives the per-feature counts in the nine-patient deletion cohort; developmental delay was universal.

Delayed speech and language development VERY_FREQUENT HP:0000750

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"

Eight of nine with language delay in the founding deletion cohort.

PMID:35386260 SUPPORT Human Clinical

"we noted no verbal communication, severe intellectual disability, and the use of only eye contact to acknowledge other people"

Illustrates the severe end of the language phenotype at age three years.

Intellectual disability VERY_FREQUENT HP:0001249

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"

Seven of nine with intellectual disability in the founding deletion cohort.

Seizures FREQUENT HP:0001250

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"

Three of nine with seizures in the founding deletion cohort.

PMID:35386260 SUPPORT Human Clinical

"The seizure types could be absence seizures, focal seizures, spasms, and tonic–clonic seizures."

Enumerates the seizure semiologies reported across the tabulated PUM1 epilepsy cases.

Status epilepticus OCCASIONAL HP:0002133

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"her epilepsy presented as fever-triggered and drug-resistant status epilepticus during her infantile period"

Documents fever-triggered status epilepticus as the infantile presentation in this case.

Infantile spasms OCCASIONAL HP:0012469

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"This variant can be associated with conditions presenting with epileptic encephalopathy, such as West syndrome (16)."

Places West syndrome within the reported PUM1 epilepsy spectrum.

Generalized myoclonic-atonic seizure VERY_RARE HP:0011170

Show evidence (1 reference)

PMID:40472467 SUPPORT Human Clinical

"A 3.5-year-old boy presented with epilepsy with myoclonic-atonic seizures (EMAtS), mild speech delay, mild dysmorphic features and no motor impairments."

Reports the myoclonic-atonic seizure presentation directly.

Ataxia FREQUENT HP:0001251

Course: PROGRESSIVE

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"

Six of nine with ataxia in the founding deletion cohort.

PMID:29474920 SUPPORT Human Clinical

"She developed early-onset, progressive ataxia with hypotonicity in her lower limbs"

Documents early-onset and progressive ataxia in one of the two missense probands.

Developmental regression OCCASIONAL HP:0002376

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"Developmental regression could be observed after the onset of epilepsy, and improvement was noted after the seizure episodes reduced"

Documents regression tied to seizure activity and improvement with seizure control.

Dysarthria OCCASIONAL HP:0001260

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"She has dysarthria and spasticity upon waking that improve over the course of the day."

Documents dysarthria in a PADDAS proband.

Chorea VERY_RARE HP:0002072

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"She manifested chorea, gait ataxia, and fine-motor incoordination by the age of 5 years"

Reports chorea with its age at onset in a PADDAS proband.

Motor stereotypy VERY_RARE HP:0000733

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"she suffers global developmental delay, cortical visual impairment, stereotypic hand-clasping, scoliosis, facial dysmorphia, and low bone mineral density in the neck of femur"

Records the hand stereotypy.

Growth 1

Growth delay FREQUENT HP:0001510

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"many of the PADDAS subjects—particularly the two missense mutation patients, for whom we have the most reliable clinical data—are small for their age"

Documents poor growth across the founding cohort.

ORPHA:589515 SUPPORT Other

"more variably, seizures and short stature"

Orphanet lists short stature among the variable features.

🧬

Genetic Associations

1

PUM1

Gene: PUM1 hgnc:14957 relationship_type: CAUSATIVE variant_origin: DE_NOVO

Show evidence (3 references)

PMID:29474920 SUPPORT Human Clinical

"we did identify nine patients with heterozygous deletions ranging in size from 0.6 to 5.60 Mb, where the minimal region of overlap included only PUM1"

Narrows the deleted interval to PUM1 alone, which is what makes the deletion cases evidence about this gene rather than about a contiguous gene syndrome.

PMID:29474920 SUPPORT Human Clinical

"Out of all the deleted genes, PUM1 had the highest probability to be pathogenic"

Supports PUM1 as the driver gene within the deleted intervals.

PMID:40472467 SUPPORT Human Clinical

"WES showed a de novo heterozygous frameshift pathogenic variant in PUM1"

Extends the allelic spectrum beyond deletions and missense variants to a frameshift allele.

💊

Medical Actions

4

Antiseizure Pharmacotherapy

Category: Therapeutic Action: antiseizure pharmacotherapy Ontology label: Pharmacotherapy NCIT:C15986

Platform: Small molecule

Seizure control is the treatment decision with the largest developmental consequence in this disorder, and response is unpredictable. In the tabulated PUM1 epilepsy cases four of six with a documented outcome achieved control on one or two agents, while two were refractory: one girl failed carbamazepine, phenobarbitone, lamotrigine, levetiracetam, clobazam, oxcarbazepine, cannabidiol and the ketogenic diet in combination. Another child's fever-triggered status epilepticus came under control only when perampanel was added to levetiracetam, valproate and topiramate. No agent has been shown to be preferentially effective in PUM1-related epilepsy, and the choice follows seizure semiology as it would in any developmental and epileptic encephalopathy.

Mechanism Target:

INHIBITS Cortical Network Hyperexcitability — Antiseizure medication suppresses the cortical hyperexcitability that generates the seizures; it does not act on PUM1 dosage.

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"The seizures were not controllable by polypharmacy (carbamazepine, phenobarbitone, lamotrigine, levetiracetum, clobazam, oxcarbazepine, cannibidiol and combinations) or the ketogenic diet"

Documents pharmacoresistance in one proband, which is why treatment response is described here as variable rather than reliable.

PMID:35386260 SUPPORT Human Clinical

"Perampanel (PER; final dose at 3 mg/day) was added to the combination treatment of LEV, VPA, and TPM at 1 year and 10 months of age, which reduced the frequency of fever-triggered seizures from once a month to only one episode in the last year."

A documented regimen and its measured effect on seizure frequency in one child.

Dietary Intervention for Seizure Control

Category: Therapeutic Action: dietary intervention Ontology label: Dietary Intervention NCIT:C15447

Platform: Behavioral / lifestyle

Dietary therapy, conventionally ketogenic for myoclonic-atonic seizures, was part of the regimen that brought the reported boy with PUM1-related epilepsy with myoclonic-atonic seizures under control within a year, with developmental gains following. The opposite result is also on record: the ketogenic diet failed in the severely affected founding proband. Both are single cases.

Mechanism Target:

INHIBITS Cortical Network Hyperexcitability — Dietary therapy as an adjunct to antiseizure medication for seizure control.

Show evidence (1 reference)

PMID:40472467 SUPPORT Human Clinical

"Treatment with antiseizure medication and dietary intervention led seizure control within one year, enabling developmental gains despite persisting delays in adaptive functioning and communication."

Reports the combined regimen and the developmental gain that followed seizure control.

Developmental and Rehabilitative Therapy

Category: Therapeutic Action: physical therapy Ontology label: Physical Therapy NCIT:C15302

Platform: Behavioral / lifestyle

Physical, occupational and speech therapy for the motor delay, hypotonia, ataxia and the disproportionate expressive language impairment. This is the standard of care for a child with a developmental and epileptic encephalopathy; no PUM1-specific rehabilitation evidence exists, and none is claimed here.

Genetic Counseling

Category: Therapeutic Action: genetic counseling Ontology label: Genetic Counseling NCIT:C15240

Platform: Behavioral / lifestyle

Counselling covers the de novo origin of the variant in the proband and the implications for future pregnancies. The published PADDAS lesions have all been de novo where parental testing was performed; no PUM1 germline mosaicism and no recurrence figure has been reported, so a numeric sibling recurrence risk cannot be quoted from this literature.

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"Thus far, at least three unrelated patients with this variant have been reported (5, 7, 8), and all of them were de novo."

The de novo occurrence that the counselling discussion rests on.

🔬

Diagnosis

3

Trio exome or genome sequencing

The route by which every recently reported case has been diagnosed. Trio design matters here because the diagnostic observation is de novo occurrence of a heterozygous PUM1 variant that population databases do not contain; without parental samples a novel PUM1 missense variant is difficult to classify.

Next generation sequencing (trio exome or genome) NCIT:C101293

Show evidence (1 reference)

PMID:40472467 SUPPORT Human Clinical

"Through trio-based whole exome sequencing (WES), we identified a novel de novo heterozygous frameshift variant in the PUM1 gene."

Trio exome sequencing as the diagnostic modality in a recent case.

Chromosomal microarray

Required to reach the deletion end of the allelic spectrum. Nine of the eleven founding PADDAS probands carried 1p35.2 microdeletions of 0.6 to 5.6 Mb, which an exome-only strategy can miss, so a normal exome does not exclude PUM1 as the cause in a child with this phenotype.

chromosomal microarray analysis NCIT:C18477

Show evidence (1 reference)

PMID:29474920 SUPPORT Human Clinical

"We sought patients with copy-number variations (CNVs) of PUM1 from public databases and from a cohort of 52,000 patients who underwent clinical chromosome microarray analysis for neurodevelopmental disorders"

Chromosomal microarray was the ascertainment route for the deletion cases.

Electroencephalography

EEG is indicated in any child with this diagnosis and seizures, and the reported patterns are non-specific: diffuse background slowing from as early as four months, multifocal spikes appearing over time, generalised spike-and-wave, and hypsarrhythmia in the infant with spasms. No PUM1-specific EEG signature has been described.

electroencephalography NCIT:C38054

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"The background EEG showed diffuse slowing activity initially at 4 months of age. Sporadic multifocal spikes appeared over time"

Describes the evolving EEG findings in a reported infant.

🩻

Imaging Findings

3

Thin or shortened corpus callosum FREQUENT

A thin, hypoplastic, or shortened corpus callosum is the most consistently reported structural abnormality on brain MRI in PUM1-related disease, recorded in four of the six tabulated patients with documented imaging. It is a cerebral rather than a cerebellar finding, and is part of the argument that PADDAS is not a purely cerebellar disorder.

Mri

Thin corpus callosum HP:0033725

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"Furthermore, in agreement with previous reports of such patients, a thin corpus callosum could be seen in our patient"

Reports the callosal finding and its consistency with earlier cases.

Ventriculomegaly OCCASIONAL

Dilated ventricles, reported as enlargement of the bilateral temporal horns in one child and of the fourth ventricle in another. Orphanet lists dilated ventricles among the expected imaging findings.

Mri

Ventriculomegaly HP:0002119

Show evidence (2 references)

PMID:35386260 SUPPORT Human Clinical

"At 11 months of age, bilateral temporal horn of the ventricle was found to be enlarged on brain MRI."

Documents the ventricular enlargement with the age at which it was seen.

ORPHA:589515 SUPPORT Other

"Brain imaging may reveal dilated ventricles, small corpus callosum, or posterior fossa abnormalities."

Orphanet's summary of the expected neuroimaging findings.

Posterior fossa abnormality with cerebellar vermis involvement OCCASIONAL

An enlarged fourth ventricle with elevation and shortening of the cerebellar vermis was described in the more severely affected founding missense proband. Structural cerebellar change is not universal, and a normal MRI does not exclude the diagnosis: imaging was normal in two of the tabulated epilepsy patients and showed no brain malformation in the other founding missense proband.

Mri

Cerebellar vermis hypoplasia HP:0001320

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"MRI revealed an enlarged fourth ventricle with elevation and shortening of the cerebellar vermis"

Reports the posterior fossa finding in this proband.

PMID:29474920 SUPPORT Human Clinical

"Magnetic resonance imaging (MRI) of the brain revealed no brain malformations"

The other founding missense proband had a structurally normal brain MRI, which is why imaging is not a rule-out.

📊

Prevalence

1

Worldwide

Cases In Literature Ultra Rare

No population prevalence or incidence estimate has been published. The founding report described eleven individuals with the PADDAS phenotype, and the epilepsy-focused literature review tabulated nine PUM1 patients with seizures, with further single cases since. No numeric rate is recorded here because none exists in a citable source, and converting a published case count into a rate would manufacture a figure the literature does not support.

Show evidence (2 references)

PMID:29474920 SUPPORT Human Clinical

"We identified eleven individuals with either PUM1 deletions or de novo missense variants who suffer a developmental syndrome"

The founding case count, which is the basis for classing the disorder as ultra-rare.

PMID:35386260 SUPPORT Human Clinical

"Upon thoroughly reviewing the existing literature, nine cases of PUM1 mutation-related epilepsy were identified"

The published case count for the epilepsy subset four years later, showing the literature is still counted in single figures.

🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from PUM1-Associated Developmental Disability, Ataxia, and Seizure Syndrome:

Dravet syndrome MONDO:0100135

Overlapping Features The PADDAS child with fever-triggered, drug-resistant status epilepticus beginning at four months, with developmental slowing after seizure onset and an EEG that was initially slow and later multifocal, was clinically considered to have a Dravet-like syndrome before PUM1 was identified. SCN1A accounts for more than 85% of Dravet syndrome.

Distinguishing Features

Severe developmental delay already present in infancy, before or independent of the epilepsy, and dysmorphic facial features are both atypical for classical Dravet syndrome and point away from SCN1A. Ataxia and the structural MRI findings are also not expected in Dravet syndrome.

Show evidence (1 reference)

PMID:35386260 SUPPORT Human Clinical

"However, she displayed severe developmental delay as an infant, which was atypical for classical DS. Besides epilepsy, she also had dysmorphic features, which is also not characteristic of DS."

States the two features that distinguish this presentation from classical Dravet syndrome.

Spinocerebellar ataxia type 1 MONDO:0008119

Overlapping Features The mechanistic neighbour rather than a clinical mimic. SCA1 is caused by a CAG repeat expansion in ATXN1; PADDAS raises the level of wild-type ataxin-1 by removing its repressor, and mouse work shows that this alone produces SCA1-like degeneration. PADDAS is not itself a polyglutamine repeat disease.

Distinguishing Features

SCA1 is an adult-onset, dominantly inherited progressive ataxia with a demonstrable CAG expansion, without developmental delay, epilepsy or dysmorphism. PADDAS presents in infancy or early childhood, is de novo, and has no repeat expansion.

Show evidence (1 reference)

PMID:25768905 SUPPORT Model Organism

"Loss of Pum1 caused progressive motor dysfunction and SCA1-like neurodegeneration with motor impairment, primarily by increasing Ataxin1 levels."

Establishes the shared effector that makes SCA1 the relevant mechanistic comparator.

Spinocerebellar ataxia 27B MONDO:0859340

Overlapping Features The disease that displaced the PUM1 adult-onset ataxia phenotype. On re-examination of the original PUM1 ataxia family, a pathogenic FGF14 GAA intronic repeat expansion was found in all affected members and absent from the supposedly non-penetrant relative.

Distinguishing Features

SCA27B is an adult-onset ataxia caused by an FGF14 GAA repeat expansion, detected by repeat-targeted testing rather than by exome sequencing. It has no relationship to the infantile PADDAS phenotype other than that a PUM1 variant was once wrongly credited for it, which is a reason to test for FGF14 expansions rather than to attribute an adult ataxia to a PUM1 variant of uncertain significance.

Show evidence (2 references)

PMID:40191983 SUPPORT Human Clinical

"we have identified a pathogenic GAA expansion in FGF14 in all affected family members, and it is absent in the presumably nonpenetrant unaffected family member initially reported"

The finding that reassigned the family's ataxia from PUM1 to FGF14.

PMID:40191983 SUPPORT Human Clinical

"ruling out that the missense variant in PUM1 is causative and indicating that variants in PUM1 are likely not associated with adult-onset ataxia"

The authors' explicit conclusion about PUM1 and adult-onset ataxia, which is what removes the adult arm from this disorder's scope.

🐁

Animal Models

1

Pum1 heterozygous mouse

The mouse counterpart of PUM1 haploinsufficiency, and the model that prompted the search for human PUM1 patients. Pum1+/- mice develop progressive motor dysfunction with Purkinje cell degeneration, and the phenotype is driven by raised wild-type Ataxin1: crossing to Atxn1+/- normalises Ataxin1 levels and largely rescues it, while crossing to an SCA1 model worsens it. Roughly two thirds of heterozygotes also develop spontaneous seizures, so the model captures both the ataxia and the epilepsy arms of the human disorder.

Species

Mouse

Genotype

Pum1+/- (heterozygous null)

Publication

PMID:25768905

Pathograph links

Elevated Wild-Type Ataxin-1 in Purkinje Cells recapitulates fidelity: high observes: cellular Raised Ataxin1 in the haploinsufficient mouse, shown to be the mediator of the phenotype by bidirectional genetic rescue and exacerbation. The observation is Ataxin1 accumulation in cerebellar Purkinje cells, at the same scale as the node.

Limitations: The rescue experiments alter Atxn1 gene dosage genetically from conception, which is not available as an intervention in humans and says nothing about whether lowering ataxin-1 after symptom onset would help. No equivalent measurement of ataxin-1 in human PADDAS neural tissue has been reported.

Show evidence (1 reference)

PMID:25768905 SUPPORT Model Organism

"Breeding Pum1(+/-) mice to SCA1 mice (Atxn1(154Q/+)) exacerbated disease progression, whereas breeding them to Atxn1(+/-) mice normalized Ataxin1 levels and largely rescued the Pum1(+/-) phenotype."

Genetic epistasis in both directions is what makes this a high-fidelity model of the ataxin-1 dosage step rather than a correlation.

Cerebellar Purkinje Cell Degeneration recapitulates fidelity: moderate observes: tissue Progressive Purkinje cell degeneration with motor incoordination.

Limitations: The mouse phenotype is a progressive adult-onset degeneration, whereas the human disorder is an early-childhood developmental syndrome in which ataxia is one feature among developmental delay, epilepsy, growth failure and dysmorphism. The model therefore captures the cerebellar arm well and the developmental arm poorly.

Show evidence (1 reference)

PMID:25768905 SUPPORT Model Organism

"Loss of Pum1 caused progressive motor dysfunction and SCA1-like neurodegeneration with motor impairment, primarily by increasing Ataxin1 levels."

Reports the degenerative cerebellar phenotype in the model.

Cortical Network Hyperexcitability partially recapitulates fidelity: moderate observes: organism Heterozygotes show subclinical generalized epileptiform EEG activity by 16 weeks of age, and 11 of 16 had spontaneous seizures by 30 weeks. Both are adult ages in the mouse, whereas the human seizures begin in the first year of life.

Limitations: The timing is wrong in the direction that matters most clinically: the model does not reproduce the infantile onset or the developmental and epileptic encephalopathy pattern, so it cannot be used to study the developmental consequence of early seizures in this disorder.

Show evidence (2 references)

PMID:29474920 SUPPORT Model Organism

"11 out of 16 (68%) heterozygous Pum1+/- mice exhibited spontaneous seizures by the end of the 30th week of age"

Spontaneous seizure frequency and timing in heterozygous mice.

+ 1 more reference

Show evidence (1 reference)

PMID:25768905 SUPPORT Model Organism

"we discovered that the RNA-binding protein PUMILIO1 (PUM1) not only directly regulates ATAXIN1 but also plays an unexpectedly important role in neuronal function"

Establishes the mouse model as the source of the PUM1-ATXN1 mechanism that the human disorder was then found to instantiate.

{ }

Source YAML

click to show

name: PUM1-Associated Developmental Disability, Ataxia, and Seizure Syndrome
creation_date: '2026-09-26T00:00:00Z'
category: Mendelian
synonyms:
- PADDAS
- PADDAS syndrome
- PUM1-associated developmental disability-ataxia-seizure syndrome
- Pumilio1-associated developmental disability, ataxia, and seizure syndrome
- neurodevelopmental disorder with motor abnormalities, seizures, and facial dysmorphism
description: >-
  A de novo dominant neurodevelopmental disorder caused by heterozygous loss of one
  functional copy of PUM1, the gene encoding Pumilio1, a sequence-specific RNA-binding
  translational repressor. The causal lesions are 1p35.2 microdeletions spanning PUM1
  and de novo missense or truncating variants that destabilise the protein; in
  patient-derived cells the missense alleles associated with the infantile-onset
  phenotype reduce PUM1 protein by roughly half, and PUM1 target transcripts rise in
  proportion. Children present in the first years of life with global developmental
  delay, intellectual disability, early-onset and often pharmacoresistant seizures,
  ataxia and other motor abnormalities, hypotonia, poor somatic growth, and dysmorphic
  facial features; brain MRI commonly shows a thin or shortened corpus callosum,
  dilated ventricles, or posterior fossa abnormalities. The best-characterised
  molecular consequence is de-repression of PUM1 target mRNAs, of which ATXN1 is the
  one with an established neurodegenerative role, giving this disorder a mechanistic
  link to spinocerebellar ataxia type 1 that runs through wild-type ataxin-1 dosage
  rather than through a repeat expansion.
disease_term:
  preferred_term: PUM1-associated developmental disability, ataxia, and seizure syndrome
  term:
    id: MONDO:0958231
    label: neurodevelopmental disorder with motor abnormalities, seizures, and facial
      dysmorphism
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:29474920
      reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We identified eleven individuals with either PUM1 deletions or de novo missense variants who suffer a developmental syndrome"
      explanation: A single-gene disorder defined by deletions and de novo variants in
        PUM1, placing it among the genetic diseases.
  - classification_value: NEUROLOGIC
    evidence:
    - reference: ORPHA:589515
      reference_title: "PUM1-associated developmental disability-ataxia-seizure syndrome"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "A rare genetic syndromic intellectual disability characterized by developmental delay, intellectual disability, ataxia, and, more variably, seizures and short stature."
      explanation: Orphanet describes the disorder wholly in terms of nervous system
        manifestations, supporting a neurological classification.
parents:
- Neurodevelopmental Disorder
- Intellectual Disability
- Developmental and Epileptic Encephalopathy
notes: >-
  Lump/split: this entry is scoped to PADDAS alone, and deliberately does not lump the
  milder adult-onset PUM1 phenotype into a single dosage-spectrum entry. The 2018
  delineating study (PMID:29474920) proposed exactly such a spectrum: near-halved PUM1
  protein in the infantile cases (PADDAS) and a ~25% reduction in one multigenerational
  family with adult-onset ataxia (PUM1-related cerebellar ataxia, PRCA), which OMIM and
  MONDO then curated as spinocerebellar ataxia 47 (SCA47, MONDO:0033482, OMIM:617931).
  The adult-onset arm of that spectrum no longer stands. Re-examining the same family
  (Family X), PMID:40191983 identified a pathogenic FGF14 GAA repeat expansion
  segregating with the ataxia and absent from the reportedly non-penetrant relative, and
  concluded that the PUM1 p.Thr1035Ser variant is not causative and that PUM1 variants
  are likely not associated with adult-onset ataxia. OMIM has since deprecated the SCA47
  entry and reclassified the variant as of uncertain significance, and MONDO:0033482
  carries that deprecation note. There is therefore no second established PUM1 disease
  entity to lump with, and a spectrum entry built on the 2018 dosage model would assert
  a phenotype the primary literature has withdrawn.

  A consequence for the mechanism recorded below: the protein-dosage gradient is still a
  real and well-documented feature of PUM1 biology, but the human evidence for it now
  rests on the range of severity within PADDAS itself and on mouse and patient-cell work
  (PMID:37070548), not on a contrast between two human diseases. PMID:37070548 also shows
  that the severity difference is not a simple linear function of PUM1 abundance: the
  severe R1147W allele de-represses canonical PUM1 targets no more than the mild allele
  does, and instead disrupts PUM1's interactions with partner RNA-binding proteins.

  MONDO files MONDO:0958231 under autosomal dominant cerebellar ataxia type I
  (MONDO:0019792). That placement is not followed here, and
  kb/disorders/Autosomal_Dominant_Cerebellar_Ataxia_Type_I.yaml records the same
  decision from the other side: PADDAS is a de novo developmental syndrome rather than a
  dominantly inherited progressive ataxia, and the MONDO term's own definition makes no
  ADCA-I claim. That entry's notes additionally state that PRCA/SCA47 "is the PUM1 ataxia
  phenotype"; the Cuillerier finding above supersedes that sentence, which was written
  before this curation and has not been edited here.

  Identifier note: Orphanet's ORPHA:589515 record cross-references MONDO:0035117, which
  MONDO has since obsoleted; the live term for this concept is MONDO:0958231. Both
  Orphanet and MONDO cross-reference OMIM:620719.

  Evidence gaps recorded rather than filled. No GeneReviews chapter exists for PUM1 or
  PADDAS (checked offline against cache/bookshelf and with a live PubMed
  "PUM1 AND genereviews[book]" search on 2026-09-26, both empty), so no expert-curated
  phenotype baseline is available and the phenotype list below is assembled from the
  primary cohort and case literature. ClinGen has published no Gene-Disease Validity
  assertion for PUM1 (data/clingen/gene_validity.csv, snapshot in
  data/clingen/MANIFEST.yaml, contains no PUM1 row), so no CGGV row is cited. No
  prevalence estimate has been published; the literature is a published case count and is
  recorded as such rather than converted into a rate. PMID:31859446, a letter reporting
  two further PUM1 patients that the later literature cites as Voet et al., has no
  abstract or full text available through the reference fetcher, so its cases are reached
  here only through PMID:35386260's tabulation of them and it is not cited directly.
inheritance:
- name: Autosomal dominant, de novo
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    Every reported PADDAS proband carries a single heterozygous PUM1 lesion - either a
    1p35.2 microdeletion whose minimal region of overlap contains only PUM1, or a
    missense or frameshift variant - and where parental samples have been tested the
    variant has been de novo. No affected parent-child pair has been described, and the
    recurrent p.Arg1147Trp allele has arisen independently in several unrelated
    families. Transmission risk to the offspring of an affected individual has not been
    reported in the literature and is not stated here.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified eleven individuals with either PUM1 deletions or de novo missense variants who suffer a developmental syndrome"
    explanation: Establishes heterozygous deletion and de novo missense variation as the
      two causal lesion classes in the founding cohort.
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thus far, at least three unrelated patients with this variant have been reported (5, 7, 8), and all of them were de novo."
    explanation: Independent recurrence of the same de novo allele in unrelated families
      supports de novo dominant occurrence rather than inherited transmission.
genetic:
- name: PUM1
  gene_term:
    preferred_term: PUM1
    term:
      id: hgnc:14957
      label: PUM1
  relationship_type: CAUSATIVE
  variant_origin: DE_NOVO
  notes: >-
    PUM1 at 1p35.2 encodes Pumilio1, a PUF-family sequence-specific RNA-binding protein
    that binds Pumilio response elements in the 3' untranslated regions of target mRNAs
    and represses their translation and stability. Disease-causing lesions are
    heterozygous whole-gene deletions, de novo missense variants inside or immediately
    adjacent to the Pumilio homology domain (recurrently p.Arg1139Trp and p.Arg1147Trp),
    at least one de novo frameshift allele, and a de novo nonsense allele (p.Arg837Ter)
    listed in the case table of PMID:35386260. The founding paper's text gives the nine
    deletions in its cohort as 0.6 to 5.60 Mb, with PUM1 the only gene inside the minimal
    region of overlap. The case table in PMID:35386260 lists a smaller copy-number loss of
    about 0.28 Mb (chr1:31442430-31720099), so the lower bound of the size range is below
    the founding paper's stated 0.6 Mb.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we did identify nine patients with heterozygous deletions ranging in size from 0.6 to 5.60 Mb, where the minimal region of overlap included only PUM1"
    explanation: Narrows the deleted interval to PUM1 alone, which is what makes the
      deletion cases evidence about this gene rather than about a contiguous gene
      syndrome.
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Out of all the deleted genes, PUM1 had the highest probability to be pathogenic"
    explanation: Supports PUM1 as the driver gene within the deleted intervals.
  - reference: PMID:40472467
    reference_title: "A new developmental and epileptic encephalopathy: PUM1-neurodevelopmental disorder with epilepsy with myoclonic-atonic seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "WES showed a de novo heterozygous frameshift pathogenic variant in PUM1"
    explanation: Extends the allelic spectrum beyond deletions and missense variants to a
      frameshift allele.
pathophysiology:
- name: PUM1 Haploinsufficiency
  biological_scale: MOLECULAR
  description: >-
    A heterozygous whole-gene deletion, destabilising missense variant, or frameshift
    allele leaves one functional PUM1 copy. In fibroblasts and lymphoblastoid lines from
    the infantile-onset probands, PUM1 protein falls to roughly half of control levels,
    which is the quantitative starting point of the disease.
  genes:
  - preferred_term: PUM1
    term:
      id: hgnc:14957
      label: PUM1
  genetic_context:
    variant_origin: DE_NOVO
    functional_impact_category: LOSS_OF_FUNCTION
    zygosity: HETEROZYGOUS
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Studies in patient-derived cells revealed that the missense mutations reduced PUM1 protein levels by ∼25% in the adult-onset cases and by ∼50% in the infantile-onset cases"
    explanation: Quantifies the residual PUM1 protein in patient-derived cells for the
      infantile-onset (PADDAS) alleles.
  downstream:
  - target: Loss of Pumilio1 Translational Repression
    causal_link_type: DIRECT
    description: Halving the dose of a translational repressor halves the repressive
      activity available to its target transcripts.
  - target: Disruption of PUM1 Partner RNA-Binding Protein Complexes
    causal_link_type: DIRECT
    description: >-
      A separate consequence of the severe alleles, not mediated by loss of target
      repression: the R1147W protein still binds and represses canonical targets normally
      but fails to hold its normal partner complexes.
    evidence:
    - reference: PMID:37070548
      reference_title: "Dosage sensitivity to Pumilio1 variants in the mouse brain reflects distinct molecular mechanisms."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "mild PUM1 loss derepresses PUM1-specific targets, but the severe mutation disrupts interactions with several RNA-binding proteins and the regulation of their targets"
      explanation: Establishes the partner-complex arm as a mechanism distinct from target
        de-repression.
- name: Loss of Pumilio1 Translational Repression
  biological_scale: MOLECULAR
  description: >-
    Pumilio1 binds Pumilio response elements in target 3' untranslated regions and
    represses translation and transcript stability. With one functional allele the
    aggregate repressor activity on those transcripts is reduced.
  molecular_functions:
  - preferred_term: translation repressor activity
    modifier: DECREASED
    term:
      id: GO:0030371
      label: translation repressor activity
  - preferred_term: mRNA 3'-UTR binding
    modifier: DECREASED
    term:
      id: GO:0003730
      label: mRNA 3'-UTR binding
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    snippet: "It binds to specific mRNAs (ATXN1, E2F3, CDKN1B, SAE1, CDK1, and AAMP) and directly prevents its translation, thus negatively regulating the expression of the target genes"
    explanation: States the repressor function and names the target transcripts; quoted
      from the case report's introduction, which restates established PUM1 biology rather
      than reporting the authors' own experiment.
  downstream:
  - target: De-repression of PUM1 Target Transcripts
    causal_link_type: DIRECT
    description: Reduced repressor occupancy raises the steady-state level of the bound
      transcripts and their protein products.
    evidence:
    - reference: PMID:29474920
      reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "levels of known PUM1 targets increased accordingly"
      explanation: Directly links the reduced PUM1 protein level to increased target
        levels in patient-derived cells.
- name: De-repression of PUM1 Target Transcripts
  biological_scale: MOLECULAR
  description: >-
    PUM1 target transcripts, including ATXN1 and E2F3, rise in patient cells in
    proportion to the loss of PUM1 protein. ATXN1 is the target with an established
    neurological consequence: wild-type ataxin-1 is itself dose-sensitive, and raising it
    reproduces features of spinocerebellar ataxia type 1 without any repeat expansion.
  biological_processes:
  - preferred_term: negative regulation of translation of PUM1 target mRNAs
    modifier: DECREASED
    term:
      id: GO:0017148
      label: negative regulation of translation
  evidence:
  - reference: PMID:25768905
    reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Loss of Pum1 caused progressive motor dysfunction and SCA1-like neurodegeneration with motor impairment, primarily by increasing Ataxin1 levels."
    explanation: Identifies raised ataxin-1 as the principal mediator of the neurological
      consequences of Pum1 loss in mice.
  downstream:
  - target: Elevated Wild-Type Ataxin-1 in Purkinje Cells
    causal_link_type: DIRECT
    description: ATXN1 is a direct PUM1 target; its transcript and protein rise when PUM1
      repression is lost.
    evidence:
    - reference: PMID:35386260
      reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: BACKGROUND
      snippet: "A loss-of-function mutation of PUM1 increases the ATXN1 mRNA level, which leads to Atxn1 accumulation in Purkinje cells located in the cerebellar cortex of the brain, consequently leading to motor dysfunction"
      explanation: States the ATXN1 de-repression to Purkinje-cell accumulation step;
        quoted from the introduction's summary of prior work.
- name: Disruption of PUM1 Partner RNA-Binding Protein Complexes
  biological_scale: MOLECULAR
  description: >-
    The severe PADDAS missense allele p.Arg1147Trp lies outside the RNA-binding domain
    and leaves canonical target repression intact, yet produces a far more severe
    phenotype than the alleles that impair RNA binding. In mouse brain proteomics and
    patient cell lines the severe allele instead disrupts PUM1's interactions with
    partner RNA-binding proteins, dysregulating their targets as well. This is why
    phenotype severity in PUM1 disease is not a linear function of PUM1 abundance.
  evidence:
  - reference: PMID:37070548
    reference_title: "Dosage sensitivity to Pumilio1 variants in the mouse brain reflects distinct molecular mechanisms."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Our results demonstrate that dosage sensitivity does not always signify a linear relationship with protein abundance but can involve distinct mechanisms."
    explanation: States the paper's conclusion that a second, non-linear mechanism operates
      alongside simple target de-repression.
  - reference: PMID:37070548
    reference_title: "Dosage sensitivity to Pumilio1 variants in the mouse brain reflects distinct molecular mechanisms."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In patient-derived cell lines, restoring PUM1 levels restores these interactors and their targets to normal levels."
    explanation: Shows the interactor defect is a consequence of reduced PUM1 and is
      reversible in patient cells, which is what makes it a mechanistic node rather than
      an incidental finding.
  downstream:
  - target: Impaired Neuronal Dendritic Arborization
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Dysregulation of the targets of the disrupted partner RNA-binding proteins in neurons.
- name: Elevated Wild-Type Ataxin-1 in Purkinje Cells
  biological_scale: CELLULAR
  description: >-
    Ataxin-1 accumulates in cerebellar Purkinje cells when PUM1 repression of ATXN1 is
    lost. In mice this is sufficient to produce SCA1-like degeneration, and genetically
    lowering Atxn1 back to normal largely rescues the Pum1 heterozygous phenotype, which
    is the strongest available evidence that this step is causal rather than correlative.
  cell_types:
  - preferred_term: cerebellar Purkinje cell
    term:
      id: CL:0000121
      label: Purkinje cell
  evidence:
  - reference: PMID:25768905
    reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Breeding Pum1(+/-) mice to SCA1 mice (Atxn1(154Q/+)) exacerbated disease progression, whereas breeding them to Atxn1(+/-) mice normalized Ataxin1 levels and largely rescued the Pum1(+/-) phenotype."
    explanation: A bidirectional genetic epistasis experiment establishing ataxin-1 dosage
      as the mediator of the Pum1 haploinsufficiency phenotype.
  downstream:
  - target: Cerebellar Purkinje Cell Degeneration
    causal_link_type: DIRECT
    description: Raised wild-type ataxin-1 drives the same Purkinje-cell degeneration seen
      in SCA1.
- name: Cerebellar Purkinje Cell Degeneration
  biological_scale: TISSUE
  description: >-
    Progressive loss and dysfunction of cerebellar Purkinje cells, the sole output neurons
    of the cerebellar cortex. In PADDAS this is the substrate of the ataxia, the
    dysarthria, and the vermian and posterior fossa changes seen on MRI; in the founding
    cohort the ataxia was documented as progressive in one child. The degeneration itself
    is shown in the Pum1+/- mouse, the genotype that corresponds to human
    haploinsufficiency.
  cell_types:
  - preferred_term: cerebellar Purkinje cell
    term:
      id: CL:0000121
      label: Purkinje cell
  evidence:
  - reference: PMID:25768905
    reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "by 10 weeks Pum1 haploinsufficiency had caused loss of Purkinje cells (Figure 4E and F) and dendritic arborization (Figure 4G)"
    explanation: Purkinje cell loss in heterozygous Pum1+/- mice, the dosage state that
      corresponds to PADDAS haploinsufficiency.
  downstream:
  - target: Ataxia
    causal_link_type: DIRECT
    description: Cerebellar output failure produces limb and gait incoordination.
  - target: Dysarthria
    causal_link_type: DIRECT
    description: Cerebellar involvement of speech motor control.
- name: Impaired Neuronal Dendritic Arborization
  biological_scale: CELLULAR
  description: >-
    PUM1 dosage influences dendritic complexity in neurons. The loss-of-function
    observation is in Pum1+/- mice, where Purkinje cells lose dendritic arborization by 10
    weeks; the authors attribute this to neurodegeneration rather than to a developmental
    defect. In dissociated mouse hippocampal neurons, overexpressing wild-type PUM1 at
    about twice normal levels impaired branching, and overexpressing PADDAS-associated
    mutants suppressed it less, which shows that the mutants keep partial activity rather
    than directly showing that reduced PUM1 reduces branching. The edges from this node to
    developmental delay and intellectual disability are therefore inferential: no study
    has measured dendritic development in human PADDAS neurons.
  biological_processes:
  - preferred_term: dendrite morphogenesis
    modifier: DECREASED
    term:
      id: GO:0048813
      label: dendrite morphogenesis
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    snippet: "Overexpression of each mutant suppressed dendritic arborization somewhat compared to empty vector"
    explanation: An overexpression assay in cultured hippocampal neurons, in which
      wild-type PUM1 at twice normal levels also impaired branching; the authors used it
      to gauge how much activity the patient mutants retain. It links PUM1 dosage to
      dendritic complexity but does not itself measure reduced PUM1, so it bears on
      this node only through an inference step.
  - reference: PMID:25768905
    reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "by 10 weeks Pum1 haploinsufficiency had caused loss of Purkinje cells (Figure 4E and F) and dendritic arborization (Figure 4G)"
    explanation: Loss of Purkinje cell dendritic arborization in heterozygous Pum1+/- mice,
      the loss-of-function observation for this node. The same paper describes it as
      neurodegeneration rather than a developmental defect.
  downstream:
  - target: Global developmental delay
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Reduced dendritic complexity and synaptic connectivity across developing cortical and subcortical circuits.
  - target: Intellectual disability
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Reduced dendritic complexity and synaptic connectivity in cortical circuits.
  - target: Cortical Network Hyperexcitability
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Altered excitatory/inhibitory balance arising from abnormal dendritic and synaptic development.
- name: Cortical Network Hyperexcitability
  biological_scale: TISSUE
  description: >-
    Cortical circuit dysfunction produces early-onset, frequently pharmacoresistant
    epilepsy. EEG in reported children shows diffuse background slowing with multifocal
    spikes, hypsarrhythmia in one infant with spasms, and generalised spike-and-wave in
    others; MRI abnormalities are cerebral (thin or short corpus callosum, dilated
    ventricles) as well as cerebellar, which is the argument that PADDAS is not a purely
    cerebellar disease.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Epilepsy is the dysfunction of the cerebrum (17), and we believe that epilepsy and abnormal cortical EEG findings in these patients may indicate that their cerebrum may also be affected."
    explanation: Attributes the epilepsy in PUM1 patients to cerebral rather than
      cerebellar involvement, on the basis of their EEG findings.
  downstream:
  - target: Seizures
    causal_link_type: DIRECT
    description: Cortical hyperexcitability is the immediate substrate of the seizures.
  - target: Developmental regression
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Ongoing epileptiform activity interfering with development, the developmental and epileptic encephalopathy pattern; regression followed seizure onset and improved with seizure control in at least one reported child.
- name: Impaired Somatic Growth
  biological_scale: ORGANISM
  description: >-
    PADDAS children are commonly small for age. Pum1 knockout mice show marked growth
    defects and are smaller than normal at birth, falling further behind the growth curve
    over life, and the PADDAS probands with the best clinical documentation show the same
    pattern, so the growth phenotype appears to be a direct consequence of PUM1 loss
    rather than a secondary effect of feeding difficulty.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "many of the PADDAS subjects—particularly the two missense mutation patients, for whom we have the most reliable clinical data—are small for their age"
    explanation: Documents poor growth across the human cohort.
  downstream:
  - target: Growth delay
    causal_link_type: DIRECT
    description: The clinical expression of the growth defect.
phenotypes:
- category: Neurologic
  name: Global developmental delay
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  description: >-
    Delay across motor, language, and adaptive domains, recognised in infancy or the
    first years of life. Every proband in the founding deletion cohort had it, and it is
    present in all nine of the PUM1 patients with epilepsy tabulated in the 2022 review.
    It is the one feature reported in every published case.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"
    explanation: Gives the per-feature counts in the nine-patient deletion cohort;
      developmental delay was universal.
- category: Neurologic
  name: Delayed speech and language development
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  description: >-
    Expressive language is disproportionately affected. Eight of the nine deletion
    probands had documented language delay, and several of the more severely affected
    children had no verbal communication at last follow-up in the preschool years.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"
    explanation: Eight of nine with language delay in the founding deletion cohort.
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we noted no verbal communication, severe intellectual disability, and the use of only eye contact to acknowledge other people"
    explanation: Illustrates the severe end of the language phenotype at age three years.
- category: Neurologic
  name: Intellectual disability
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  description: >-
    Cognitive impairment ranging from mild to severe. Seven of the nine deletion probands
    had documented intellectual disability; the two children with de novo missense
    variants in the founding report differed, one having intellectual disability and the
    other not, which is the earliest indication that cognitive outcome varies within the
    disorder.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"
    explanation: Seven of nine with intellectual disability in the founding deletion
      cohort.
- category: Neurologic
  name: Seizures
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  description: >-
    Seizure onset is early: of the six PUM1 patients in the 2022 tabulation with a
    documented onset age, four began in the first year of life (three at four to five
    months), one at fourteen months and one at three years. Semiology is heterogeneous
    across reported children and includes focal seizures, typical absences, infantile
    spasms, generalised tonic-clonic seizures, myoclonic-atonic seizures, and status
    epilepticus. Seizures were present in three of the nine deletion probands but in both
    of the children carrying de novo missense variants in the founding report, and the
    later epilepsy-focused literature is enriched for the missense alleles.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"
    explanation: Three of nine with seizures in the founding deletion cohort.
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The seizure types could be absence seizures, focal seizures, spasms, and tonic–clonic seizures."
    explanation: Enumerates the seizure semiologies reported across the tabulated PUM1
      epilepsy cases.
- category: Neurologic
  name: Status epilepticus
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Status epilepticus
    term:
      id: HP:0002133
      label: Status epilepticus
  description: >-
    Recurrent, fever-triggered status epilepticus was the presenting feature in a girl
    whose seizures began at four months and who was initially considered to have a
    Dravet-like syndrome; a second tabulated patient also had status epilepticus. This is
    the presentation most likely to bring a PADDAS infant to acute paediatric attention
    before any developmental concern is raised.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "her epilepsy presented as fever-triggered and drug-resistant status epilepticus during her infantile period"
    explanation: Documents fever-triggered status epilepticus as the infantile
      presentation in this case.
- category: Neurologic
  name: Infantile spasms
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Infantile spasms
    term:
      id: HP:0012469
      label: Infantile spasms
  description: >-
    One tabulated infant with a PUM1 deletion presented at four months with infantile
    spasms and hypsarrhythmia on EEG, placing West syndrome within the PUM1 epilepsy
    phenotype.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This variant can be associated with conditions presenting with epileptic encephalopathy, such as West syndrome (16)."
    explanation: Places West syndrome within the reported PUM1 epilepsy spectrum.
- category: Neurologic
  name: Generalized myoclonic-atonic seizure
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Generalized myoclonic-atonic seizure
    term:
      id: HP:0011170
      label: Generalized myoclonic-atonic seizure
  description: >-
    A boy with a de novo PUM1 frameshift variant presented at 3.5 years with epilepsy
    with myoclonic-atonic seizures as the predominant feature, without ataxia and with
    only mild speech delay and mild dysmorphism. This is the mildest published PADDAS-end
    presentation and the reason PUM1 belongs in an early-onset generalised epilepsy gene
    panel even when the syndromic features are absent.
  evidence:
  - reference: PMID:40472467
    reference_title: "A new developmental and epileptic encephalopathy: PUM1-neurodevelopmental disorder with epilepsy with myoclonic-atonic seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A 3.5-year-old boy presented with epilepsy with myoclonic-atonic seizures (EMAtS), mild speech delay, mild dysmorphic features and no motor impairments."
    explanation: Reports the myoclonic-atonic seizure presentation directly.
- category: Neurologic
  name: Ataxia
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
    clinical_course: PROGRESSIVE
  description: >-
    Gait and limb incoordination with fine-motor impairment, present in six of the nine
    deletion probands and in both children with de novo missense variants in the founding
    report, where it was documented as progressive in one. Ataxia is not assessable in
    the most severely affected infants, who have not achieved independent sitting or
    walking, so the reported frequency is an underestimate in the epilepsy-ascertained
    series.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All nine subjects were documented to have developmental delay, eight had language delay, seven have intellectual disability, six have ataxia, and three were noted to have seizures"
    explanation: Six of nine with ataxia in the founding deletion cohort.
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She developed early-onset, progressive ataxia with hypotonicity in her lower limbs"
    explanation: Documents early-onset and progressive ataxia in one of the two missense
      probands.
- category: Neurologic
  name: Hypotonia
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  description: >-
    Low tone, often axial and profound, was recorded in all six of the tabulated PUM1
    epilepsy patients for whom tone was documented. In one girl hypotonia was severe
    enough that she lost head control after seizure onset.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She was identified as having profound axial hypotonia and could no longer hold her head after the onset of epilepsy."
    explanation: Documents profound axial hypotonia in a reported child.
- category: Neurologic
  name: Developmental regression
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Developmental regression
    term:
      id: HP:0002376
      label: Developmental regression
  description: >-
    Loss of previously acquired skills following seizure onset, with partial recovery once
    seizures came under control - the developmental and epileptic encephalopathy pattern,
    and the observation that makes seizure control a developmental as well as a seizure
    outcome in this disorder.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Developmental regression could be observed after the onset of epilepsy, and improvement was noted after the seizure episodes reduced"
    explanation: Documents regression tied to seizure activity and improvement with
      seizure control.
- category: Neurologic
  name: Dysarthria
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
  description: >-
    Cerebellar speech impairment, documented in the missense proband with early-onset
    ataxia alongside spasticity that was worst on waking.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She has dysarthria and spasticity upon waking that improve over the course of the day."
    explanation: Documents dysarthria in a PADDAS proband.
- category: Neurologic
  name: Chorea
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Chorea
    term:
      id: HP:0002072
      label: Chorea
  description: >-
    A hyperkinetic movement disorder reported in one of the two founding missense
    probands, who manifested chorea together with gait ataxia and fine-motor
    incoordination by age five years. Movement disorder beyond ataxia is uncommon in the
    published cases but is worth examining for, because it changes the differential
    towards the childhood chorea causes.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She manifested chorea, gait ataxia, and fine-motor incoordination by the age of 5 years"
    explanation: Reports chorea with its age at onset in a PADDAS proband.
- category: Growth
  name: Growth delay
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Growth delay
    term:
      id: HP:0001510
      label: Growth delay
  description: >-
    Poor somatic growth, with children small for age and remaining so. Orphanet records
    short stature as a variable feature. Growth should be plotted at every visit; the
    mouse data suggest the deficit is intrinsic to PUM1 loss rather than nutritional.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "many of the PADDAS subjects—particularly the two missense mutation patients, for whom we have the most reliable clinical data—are small for their age"
    explanation: Documents poor growth across the founding cohort.
  - reference: ORPHA:589515
    reference_title: "PUM1-associated developmental disability-ataxia-seizure syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "more variably, seizures and short stature"
    explanation: Orphanet lists short stature among the variable features.
- category: Craniofacial
  name: Abnormal facial shape
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abnormal facial shape
    term:
      id: HP:0001999
      label: Abnormal facial shape
    coarse_binding_basis: VARIABLE_SPECTRUM
  description: >-
    Dysmorphism is variable and no single gestalt has emerged. Reported features include
    broad nasal bridge, hypertelorism, almond-shaped eyes, high-arched palate, low-set
    ears, bitemporal narrowing, and ptosis. The coarse binding is deliberate: the
    published descriptions name different individual features in different children
    rather than a recurring set, so binding a specific facial term would assert a
    consistency the sources do not report. The individual features that recur are curated
    separately below where a source names them.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She had several dysmorphic features with high-arched palate, ptosis, hypertelorism, broad nasal bridge, low-set ears, bitemporal narrowing, and almond-shaped eyes"
    explanation: Enumerates the dysmorphic features in one child; the list differs between
      reports, which is why the binding is at the coarse level.
  - reference: ORPHA:589515
    reference_title: "PUM1-associated developmental disability-ataxia-seizure syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "variable facial and other dysmorphic features (such as broad nasal bridge, hypertelorism, almond-shaped eyes, high-arched palate, and anomalies of the fingers and toes)"
    explanation: Orphanet's own description records the dysmorphism as variable and gives
      the same feature list.
- category: Ophthalmologic
  name: Ptosis
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Ptosis
    term:
      id: HP:0000508
      label: Ptosis
  description: >-
    Drooping of the upper eyelid, recorded in three of the tabulated PUM1 epilepsy
    patients for whom eyelid position was documented.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She had several dysmorphic features with high-arched palate, ptosis, hypertelorism, broad nasal bridge, low-set ears, bitemporal narrowing, and almond-shaped eyes"
    explanation: Records ptosis among the dysmorphic features.
- category: Ophthalmologic
  name: Strabismus
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  description: >-
    Ocular misalignment, exotropic or esotropic, recorded in four of the tabulated PUM1
    epilepsy patients, sometimes with refractive error. Ophthalmology review belongs in
    the initial workup.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "| Ocular abnormalities | Exotropia | Hypermetropia and exotropia | Astigmatism with esotropia | Cortical visual impairment | ND | ND | ND | Esotropia | ND |"
    explanation: The tabulated ocular findings across the reported cases, showing
      exotropia and esotropia in four children.
- category: Ophthalmologic
  name: Cerebral visual impairment
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Cerebral visual impairment
    term:
      id: HP:0100704
      label: Cerebral visual impairment
  description: >-
    Cortical visual impairment was documented in the more severely affected of the two
    founding missense probands, the girl with infantile-onset epileptic encephalopathy.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "she suffers global developmental delay, cortical visual impairment, stereotypic hand-clasping, scoliosis, facial dysmorphia, and low bone mineral density in the neck of femur"
    explanation: Lists cortical visual impairment among this proband's features.
- category: Behavioral
  name: Motor stereotypy
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Motor stereotypy
    term:
      id: HP:0000733
      label: Motor stereotypy
  description: >-
    Stereotypic hand-clasping was recorded in one founding missense proband. Together
    with the severe developmental delay and loss of purposeful hand use this can prompt
    consideration of a Rett-like disorder.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "she suffers global developmental delay, cortical visual impairment, stereotypic hand-clasping, scoliosis, facial dysmorphia, and low bone mineral density in the neck of femur"
    explanation: Records the hand stereotypy.
- category: Musculoskeletal
  name: Scoliosis
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  description: >-
    Lateral curvature of the spine, reported in one founding missense proband. In a child
    with hypotonia and limited ambulation, spinal surveillance is part of routine
    neurodisability follow-up regardless of how often it is reported in this small
    literature.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "she suffers global developmental delay, cortical visual impairment, stereotypic hand-clasping, scoliosis, facial dysmorphia, and low bone mineral density in the neck of femur"
    explanation: Records scoliosis in this proband.
- category: Musculoskeletal
  name: Reduced bone mineral density
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Reduced bone mineral density
    term:
      id: HP:0004349
      label: Reduced bone mineral density
  description: >-
    Bone mineral density four standard deviations below the age-matched mean at the
    femoral neck in one founding proband. Low bone density is expected in a non-ambulant
    child with epilepsy on enzyme-inducing antiseizure medication, so it is recorded here
    as a documented finding rather than as evidence of a primary skeletal role for PUM1.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "low bone mineral density in the neck of femur (4 standard deviations below normal for age)"
    explanation: Quantifies the bone density deficit in this proband.
- category: Genitourinary
  name: Cryptorchidism
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Cryptorchidism
    term:
      id: HP:0000028
      label: Cryptorchidism
  description: >-
    Undescended testes in both male subjects in the founding cohort for whom this was
    recorded, which the authors link to the testicular hypoplasia of Pum1 knockout mice.
    Genital examination belongs in the assessment of a boy with this diagnosis.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The two male subjects have cryptorchidism, which is consistent with the testicular hypoplasia reported in Pum1 knockout mice"
    explanation: Reports cryptorchidism in the male probands and its mouse counterpart.
- category: Neurologic
  name: Microcephaly
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  description: >-
    Reported in one child with the recurrent de novo p.Arg1147Trp allele, alongside hair
    dysplasia. Head circumference is not small in most published PADDAS children, so this
    is a phenotype-expansion observation rather than a core feature.
  evidence:
  - reference: PMID:30903679
    reference_title: "PADDAS syndrome associated with hair dysplasia caused by a de novo missense variant of PUM1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here an additional patient with early onset developmental delay, epilepsy, microcephaly, and hair dysplasia, with a de novo heterozygous missense variant of PUM1"
    explanation: Reports microcephaly in this patient.
- category: Dermatologic
  name: Abnormal hair morphology
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Abnormal hair morphology
    term:
      id: HP:0001595
      label: Abnormal hair morphology
  description: >-
    Hair dysplasia was described in a single patient and proposed by the authors as an
    expansion of the PADDAS phenotype. It has not been reported since and is recorded here
    as an isolated observation.
  evidence:
  - reference: PMID:30903679
    reference_title: "PADDAS syndrome associated with hair dysplasia caused by a de novo missense variant of PUM1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our report is in favor of a variable expressivity of PADDAS syndrome, and broadens the phenotypic spectrum with the description of hair dysplasia."
    explanation: States the hair finding and the authors' own framing of it as a
      phenotype expansion.
imaging_findings:
- name: Thin or shortened corpus callosum
  modality: MRI
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Thin corpus callosum
    term:
      id: HP:0033725
      label: Thin corpus callosum
  description: >-
    A thin, hypoplastic, or shortened corpus callosum is the most consistently reported
    structural abnormality on brain MRI in PUM1-related disease, recorded in four of the
    six tabulated patients with documented imaging. It is a cerebral rather than a
    cerebellar finding, and is part of the argument that PADDAS is not a purely
    cerebellar disorder.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Furthermore, in agreement with previous reports of such patients, a thin corpus callosum could be seen in our patient"
    explanation: Reports the callosal finding and its consistency with earlier cases.
- name: Ventriculomegaly
  modality: MRI
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Ventriculomegaly
    term:
      id: HP:0002119
      label: Ventriculomegaly
  description: >-
    Dilated ventricles, reported as enlargement of the bilateral temporal horns in one
    child and of the fourth ventricle in another. Orphanet lists dilated ventricles among
    the expected imaging findings.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At 11 months of age, bilateral temporal horn of the ventricle was found to be enlarged on brain MRI."
    explanation: Documents the ventricular enlargement with the age at which it was seen.
  - reference: ORPHA:589515
    reference_title: "PUM1-associated developmental disability-ataxia-seizure syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Brain imaging may reveal dilated ventricles, small corpus callosum, or posterior fossa abnormalities."
    explanation: Orphanet's summary of the expected neuroimaging findings.
- name: Posterior fossa abnormality with cerebellar vermis involvement
  modality: MRI
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Cerebellar vermis hypoplasia
    term:
      id: HP:0001320
      label: Cerebellar vermis hypoplasia
  description: >-
    An enlarged fourth ventricle with elevation and shortening of the cerebellar vermis
    was described in the more severely affected founding missense proband. Structural
    cerebellar change is not universal, and a normal MRI does not exclude the diagnosis:
    imaging was normal in two of the tabulated epilepsy patients and showed no brain
    malformation in the other founding missense proband.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MRI revealed an enlarged fourth ventricle with elevation and shortening of the cerebellar vermis"
    explanation: Reports the posterior fossa finding in this proband.
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Magnetic resonance imaging (MRI) of the brain revealed no brain malformations"
    explanation: The other founding missense proband had a structurally normal brain MRI,
      which is why imaging is not a rule-out.
diagnosis:
- name: Trio exome or genome sequencing
  description: >-
    The route by which every recently reported case has been diagnosed. Trio design
    matters here because the diagnostic observation is de novo occurrence of a
    heterozygous PUM1 variant that population databases do not contain; without parental
    samples a novel PUM1 missense variant is difficult to classify.
  diagnosis_term:
    preferred_term: Next generation sequencing (trio exome or genome)
    term:
      id: NCIT:C101293
      label: Next Generation Sequencing
  evidence:
  - reference: PMID:40472467
    reference_title: "A new developmental and epileptic encephalopathy: PUM1-neurodevelopmental disorder with epilepsy with myoclonic-atonic seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Through trio-based whole exome sequencing (WES), we identified a novel de novo heterozygous frameshift variant in the PUM1 gene."
    explanation: Trio exome sequencing as the diagnostic modality in a recent case.
- name: Chromosomal microarray
  description: >-
    Required to reach the deletion end of the allelic spectrum. Nine of the eleven
    founding PADDAS probands carried 1p35.2 microdeletions of 0.6 to 5.6 Mb, which an
    exome-only strategy can miss, so a normal exome does not exclude PUM1 as the cause in
    a child with this phenotype.
  diagnosis_term:
    preferred_term: chromosomal microarray analysis
    term:
      id: NCIT:C18477
      label: Microarray Analysis
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We sought patients with copy-number variations (CNVs) of PUM1 from public databases and from a cohort of 52,000 patients who underwent clinical chromosome microarray analysis for neurodevelopmental disorders"
    explanation: Chromosomal microarray was the ascertainment route for the deletion
      cases.
- name: Electroencephalography
  description: >-
    EEG is indicated in any child with this diagnosis and seizures, and the reported
    patterns are non-specific: diffuse background slowing from as early as four months,
    multifocal spikes appearing over time, generalised spike-and-wave, and hypsarrhythmia
    in the infant with spasms. No PUM1-specific EEG signature has been described.
  diagnosis_term:
    preferred_term: electroencephalography
    term:
      id: NCIT:C38054
      label: Electroencephalography
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The background EEG showed diffuse slowing activity initially at 4 months of age. Sporadic multifocal spikes appeared over time"
    explanation: Describes the evolving EEG findings in a reported infant.
treatments:
- name: Antiseizure Pharmacotherapy
  action_category: THERAPEUTIC
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    Seizure control is the treatment decision with the largest developmental consequence
    in this disorder, and response is unpredictable. In the tabulated PUM1 epilepsy cases
    four of six with a documented outcome achieved control on one or two agents, while
    two were refractory: one girl failed carbamazepine, phenobarbitone, lamotrigine,
    levetiracetam, clobazam, oxcarbazepine, cannabidiol and the ketogenic diet in
    combination. Another child's fever-triggered status epilepticus came under control
    only when perampanel was added to levetiracetam, valproate and topiramate. No agent
    has been shown to be preferentially effective in PUM1-related epilepsy, and the
    choice follows seizure semiology as it would in any developmental and epileptic
    encephalopathy.
  treatment_term:
    preferred_term: antiseizure pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Cortical Network Hyperexcitability
    treatment_effect: INHIBITS
    description: Antiseizure medication suppresses the cortical hyperexcitability that
      generates the seizures; it does not act on PUM1 dosage.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The seizures were not controllable by polypharmacy (carbamazepine, phenobarbitone, lamotrigine, levetiracetum, clobazam, oxcarbazepine, cannibidiol and combinations) or the ketogenic diet"
    explanation: Documents pharmacoresistance in one proband, which is why treatment
      response is described here as variable rather than reliable.
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Perampanel (PER; final dose at 3 mg/day) was added to the combination treatment of LEV, VPA, and TPM at 1 year and 10 months of age, which reduced the frequency of fever-triggered seizures from once a month to only one episode in the last year."
    explanation: A documented regimen and its measured effect on seizure frequency in one
      child.
- name: Dietary Intervention for Seizure Control
  action_category: THERAPEUTIC
  therapeutic_modality: BEHAVIORAL
  description: >-
    Dietary therapy, conventionally ketogenic for myoclonic-atonic seizures, was part of
    the regimen that brought the reported boy with PUM1-related epilepsy with
    myoclonic-atonic seizures under control within a year, with developmental gains
    following. The opposite result is also on record: the ketogenic diet failed in the
    severely affected founding proband. Both are single cases.
  treatment_term:
    preferred_term: dietary intervention
    term:
      id: NCIT:C15447
      label: Dietary Intervention
  target_mechanisms:
  - target: Cortical Network Hyperexcitability
    treatment_effect: INHIBITS
    description: Dietary therapy as an adjunct to antiseizure medication for seizure
      control.
  evidence:
  - reference: PMID:40472467
    reference_title: "A new developmental and epileptic encephalopathy: PUM1-neurodevelopmental disorder with epilepsy with myoclonic-atonic seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Treatment with antiseizure medication and dietary intervention led seizure control within one year, enabling developmental gains despite persisting delays in adaptive functioning and communication."
    explanation: Reports the combined regimen and the developmental gain that followed
      seizure control.
- name: Developmental and Rehabilitative Therapy
  action_category: THERAPEUTIC
  therapeutic_modality: BEHAVIORAL
  description: >-
    Physical, occupational and speech therapy for the motor delay, hypotonia, ataxia and
    the disproportionate expressive language impairment. This is the standard of care for
    a child with a developmental and epileptic encephalopathy; no PUM1-specific
    rehabilitation evidence exists, and none is claimed here.
  treatment_term:
    preferred_term: physical therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  notes: >-
    Deliberately carries no evidence item. No published study reports a rehabilitation
    outcome in PADDAS, and citing a general developmental-delay source would be a weaker
    adjacent citation rather than support for this claim.
- name: Genetic Counseling
  action_category: THERAPEUTIC
  therapeutic_modality: BEHAVIORAL
  description: >-
    Counselling covers the de novo origin of the variant in the proband and the
    implications for future pregnancies. The published PADDAS lesions have all been de
    novo where parental testing was performed; no PUM1 germline mosaicism and no
    recurrence figure has been reported, so a numeric sibling recurrence risk cannot be
    quoted from this literature.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thus far, at least three unrelated patients with this variant have been reported (5, 7, 8), and all of them were de novo."
    explanation: The de novo occurrence that the counselling discussion rests on.
differential_diagnoses:
- name: Dravet syndrome
  disease_term:
    preferred_term: Dravet syndrome
    term:
      id: MONDO:0100135
      label: Dravet syndrome
  description: >-
    The PADDAS child with fever-triggered, drug-resistant status epilepticus beginning at
    four months, with developmental slowing after seizure onset and an EEG that was
    initially slow and later multifocal, was clinically considered to have a Dravet-like
    syndrome before PUM1 was identified. SCN1A accounts for more than 85% of Dravet
    syndrome.
  distinguishing_features:
  - >-
    Severe developmental delay already present in infancy, before or independent of the
    epilepsy, and dysmorphic facial features are both atypical for classical Dravet
    syndrome and point away from SCN1A. Ataxia and the structural MRI findings are also
    not expected in Dravet syndrome.
  evidence:
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "However, she displayed severe developmental delay as an infant, which was atypical for classical DS. Besides epilepsy, she also had dysmorphic features, which is also not characteristic of DS."
    explanation: States the two features that distinguish this presentation from classical
      Dravet syndrome.
- name: Spinocerebellar ataxia type 1
  disease_term:
    preferred_term: spinocerebellar ataxia type 1
    term:
      id: MONDO:0008119
      label: spinocerebellar ataxia type 1
  description: >-
    The mechanistic neighbour rather than a clinical mimic. SCA1 is caused by a CAG repeat
    expansion in ATXN1; PADDAS raises the level of wild-type ataxin-1 by removing its
    repressor, and mouse work shows that this alone produces SCA1-like degeneration.
    PADDAS is not itself a polyglutamine repeat disease.
  distinguishing_features:
  - >-
    SCA1 is an adult-onset, dominantly inherited progressive ataxia with a demonstrable
    CAG expansion, without developmental delay, epilepsy or dysmorphism. PADDAS presents
    in infancy or early childhood, is de novo, and has no repeat expansion.
  evidence:
  - reference: PMID:25768905
    reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Loss of Pum1 caused progressive motor dysfunction and SCA1-like neurodegeneration with motor impairment, primarily by increasing Ataxin1 levels."
    explanation: Establishes the shared effector that makes SCA1 the relevant mechanistic
      comparator.
- name: Spinocerebellar ataxia 27B
  disease_term:
    preferred_term: spinocerebellar ataxia 27B, late-onset
    term:
      id: MONDO:0859340
      label: spinocerebellar ataxia 27B, late-onset
  description: >-
    The disease that displaced the PUM1 adult-onset ataxia phenotype. On re-examination of
    the original PUM1 ataxia family, a pathogenic FGF14 GAA intronic repeat expansion was
    found in all affected members and absent from the supposedly non-penetrant relative.
  distinguishing_features:
  - >-
    SCA27B is an adult-onset ataxia caused by an FGF14 GAA repeat expansion, detected by
    repeat-targeted testing rather than by exome sequencing. It has no relationship to the
    infantile PADDAS phenotype other than that a PUM1 variant was once wrongly credited
    for it, which is a reason to test for FGF14 expansions rather than to attribute an
    adult ataxia to a PUM1 variant of uncertain significance.
  evidence:
  - reference: PMID:40191983
    reference_title: "FGF14 GAA Intronic Expansion in Unsolved Adult-Onset Ataxia in the Care4Rare Canada Consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we have identified a pathogenic GAA expansion in FGF14 in all affected family members, and it is absent in the presumably nonpenetrant unaffected family member initially reported"
    explanation: The finding that reassigned the family's ataxia from PUM1 to FGF14.
  - reference: PMID:40191983
    reference_title: "FGF14 GAA Intronic Expansion in Unsolved Adult-Onset Ataxia in the Care4Rare Canada Consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ruling out that the missense variant in PUM1 is causative and indicating that variants in PUM1 are likely not associated with adult-onset ataxia"
    explanation: The authors' explicit conclusion about PUM1 and adult-onset ataxia, which
      is what removes the adult arm from this disorder's scope.
animal_models:
- name: Pum1 heterozygous mouse
  species: Mouse
  genotype: Pum1+/- (heterozygous null)
  publication: PMID:25768905
  description: >-
    The mouse counterpart of PUM1 haploinsufficiency, and the model that prompted the
    search for human PUM1 patients. Pum1+/- mice develop progressive motor dysfunction
    with Purkinje cell degeneration, and the phenotype is driven by raised wild-type
    Ataxin1: crossing to Atxn1+/- normalises Ataxin1 levels and largely rescues it, while
    crossing to an SCA1 model worsens it. Roughly two thirds of heterozygotes also
    develop spontaneous seizures, so the model captures both the ataxia and the epilepsy
    arms of the human disorder.
  modeled_mechanisms:
  - target: Elevated Wild-Type Ataxin-1 in Purkinje Cells
    relationship: RECAPITULATES
    fidelity: HIGH
    model_scale: CELLULAR
    description: >-
      Raised Ataxin1 in the haploinsufficient mouse, shown to be the mediator of the
      phenotype by bidirectional genetic rescue and exacerbation. The observation is
      Ataxin1 accumulation in cerebellar Purkinje cells, at the same scale as the node.
    limitations: >-
      The rescue experiments alter Atxn1 gene dosage genetically from conception, which
      is not available as an intervention in humans and says nothing about whether
      lowering ataxin-1 after symptom onset would help. No equivalent measurement of
      ataxin-1 in human PADDAS neural tissue has been reported.
    evidence:
    - reference: PMID:25768905
      reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Breeding Pum1(+/-) mice to SCA1 mice (Atxn1(154Q/+)) exacerbated disease progression, whereas breeding them to Atxn1(+/-) mice normalized Ataxin1 levels and largely rescued the Pum1(+/-) phenotype."
      explanation: Genetic epistasis in both directions is what makes this a
        high-fidelity model of the ataxin-1 dosage step rather than a correlation.
  - target: Cerebellar Purkinje Cell Degeneration
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: TISSUE
    description: Progressive Purkinje cell degeneration with motor incoordination.
    limitations: >-
      The mouse phenotype is a progressive adult-onset degeneration, whereas the human
      disorder is an early-childhood developmental syndrome in which ataxia is one
      feature among developmental delay, epilepsy, growth failure and dysmorphism. The
      model therefore captures the cerebellar arm well and the developmental arm poorly.
    evidence:
    - reference: PMID:25768905
      reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Loss of Pum1 caused progressive motor dysfunction and SCA1-like neurodegeneration with motor impairment, primarily by increasing Ataxin1 levels."
      explanation: Reports the degenerative cerebellar phenotype in the model.
  - target: Cortical Network Hyperexcitability
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: >-
      Heterozygotes show subclinical generalized epileptiform EEG activity by 16 weeks of
      age, and 11 of 16 had spontaneous seizures by 30 weeks. Both are adult ages in the
      mouse, whereas the human seizures begin in the first year of life.
    limitations: >-
      The timing is wrong in the direction that matters most clinically: the model does
      not reproduce the infantile onset or the developmental and epileptic encephalopathy
      pattern, so it cannot be used to study the developmental consequence of early
      seizures in this disorder.
    evidence:
    - reference: PMID:29474920
      reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "11 out of 16 (68%) heterozygous Pum1+/- mice exhibited spontaneous seizures by the end of the 30th week of age"
      explanation: Spontaneous seizure frequency and timing in heterozygous mice.
    - reference: PMID:29474920
      reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "showed abnormal EEG activity with generalized epileptiform spikes, indicating a state of subclinical seizures, by the age of 16 weeks"
      explanation: Subclinical epileptiform EEG in the same heterozygous mice by 16 weeks.
  evidence:
  - reference: PMID:25768905
    reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "we discovered that the RNA-binding protein PUMILIO1 (PUM1) not only directly regulates ATAXIN1 but also plays an unexpectedly important role in neuronal function"
    explanation: Establishes the mouse model as the source of the PUM1-ATXN1 mechanism
      that the human disorder was then found to instantiate.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    No population prevalence or incidence estimate has been published. The founding report
    described eleven individuals with the PADDAS phenotype, and the epilepsy-focused
    literature review tabulated nine PUM1 patients with seizures, with further single
    cases since. No numeric rate is recorded here because none exists in a citable source,
    and converting a published case count into a rate would manufacture a figure the
    literature does not support.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified eleven individuals with either PUM1 deletions or de novo missense variants who suffer a developmental syndrome"
    explanation: The founding case count, which is the basis for classing the disorder as
      ultra-rare.
  - reference: PMID:35386260
    reference_title: "A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Upon thoroughly reviewing the existing literature, nine cases of PUM1 mutation-related epilepsy were identified"
    explanation: The published case count for the epilepsy subset four years later,
      showing the literature is still counted in single figures.
discussions:
- discussion_id: paddas_natural_history
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Is the neurological course of PADDAS static, as in a developmental encephalopathy, or
    progressive, as the mouse degeneration and the ataxia in some probands suggest?
  attaches_to:
  - pathophysiology#Cerebellar Purkinje Cell Degeneration
  - phenotypes#Ataxia
  rationale: >-
    The answer changes what is said to families at diagnosis and whether serial
    neurological and imaging follow-up is warranted beyond routine developmental review.
    The mechanism points at progression: the mouse model degenerates, and two founding
    probands were documented as having progressive features. The human evidence does not
    settle it, because no longitudinal cohort has been followed. With the adult-onset
    PUM1 ataxia phenotype withdrawn, there is also no longer a late-onset human
    counterpart from which to infer a degenerative trajectory.
  evidence:
  - reference: PMID:29474920
    reference_title: "A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She developed early-onset, progressive ataxia with hypotonicity in her lower limbs"
    explanation: One of the few explicit human statements that the motor phenotype
      progressed, in a single child.
- discussion_id: paddas_surveillance_evidence
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    What paediatric surveillance does PADDAS actually require, beyond the developmental,
    seizure and growth monitoring any child with a developmental and epileptic
    encephalopathy receives?
  attaches_to:
  - phenotypes#Reduced bone mineral density
  - phenotypes#Scoliosis
  - phenotypes#Cryptorchidism
  - phenotypes#Strabismus
  rationale: >-
    No guideline, GeneReviews chapter or management paper exists for this disorder, so
    there is no published surveillance protocol to record in the treatments section. The
    non-neurological findings that have been reported in single children - low bone
    mineral density, scoliosis, cryptorchidism, strabismus and refractive error - are each
    plausible surveillance targets, but each rests on one or two cases and none has a
    denominator. Recording them as phenotypes with their case-level frequency is
    deliberate; asserting a surveillance schedule from them would be an inference the
    literature does not support.
- discussion_id: paddas_atxn1_lowering
  kind: EMERGING_HYPOTHESIS
  status: OPEN
  prompt: >-
    If raised wild-type ataxin-1 mediates the cerebellar phenotype, would lowering ATXN1
    benefit PADDAS?
  attaches_to:
  - pathophysiology#Elevated Wild-Type Ataxin-1 in Purkinje Cells
  rationale: >-
    Genetically halving Atxn1 largely rescues the Pum1 heterozygous mouse, which is a
    direct demonstration that the step is tractable in principle. No PUM1 or PADDAS
    preclinical rescue study using an ATXN1-lowering agent has been published, and none is
    claimed here. Two limits are worth stating alongside the hypothesis: ataxin-1
    de-repression is only one arm of the mechanism, since the severe alleles act partly by
    disrupting PUM1 partner complexes rather than by raising canonical targets; and the
    developmental features of PADDAS are established before any postnatal intervention
    could begin.
  evidence:
  - reference: PMID:25768905
    reference_title: "Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "breeding them to Atxn1(+/-) mice normalized Ataxin1 levels and largely rescued the Pum1(+/-) phenotype"
    explanation: The genetic proof of principle that lowering ataxin-1 reverses the
      consequences of Pum1 haploinsufficiency in mice.
  - reference: PMID:37070548
    reference_title: "Dosage sensitivity to Pumilio1 variants in the mouse brain reflects distinct molecular mechanisms."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "the severe mutation disrupts interactions with several RNA-binding proteins and the regulation of their targets"
    explanation: The second mechanistic arm, which an ATXN1-directed therapy would not
      address.
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0958231
      label: neurodevelopmental disorder with motor abnormalities, seizures, and facial
        dysmorphism
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
    mapping_justification: The MONDO term's definition names PUM1 and describes the same
      de novo developmental syndrome this entry covers.
references:
- reference: PMID:29474920
  title: A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency
    Causes Developmental Delay and Seizures.
- reference: PMID:25768905
  title: Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing
    wild-type Ataxin1 levels.
- reference: PMID:35386260
  title: 'A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and
    Literature Review.'
- reference: PMID:37070548
  title: Dosage sensitivity to Pumilio1 variants in the mouse brain reflects distinct molecular
    mechanisms.
- reference: PMID:40472467
  title: 'A new developmental and epileptic encephalopathy: PUM1-neurodevelopmental disorder
    with epilepsy with myoclonic-atonic seizures.'
- reference: PMID:40191983
  title: FGF14 GAA Intronic Expansion in Unsolved Adult-Onset Ataxia in the Care4Rare Canada
    Consortium.
- reference: PMID:30903679
  title: PADDAS syndrome associated with hair dysplasia caused by a de novo missense variant
    of PUM1.
- reference: ORPHA:589515
  title: PUM1-associated developmental disability-ataxia-seizure syndrome

📚

References & Deep Research

References

8

PMID:29474920

A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures.

No top-level findings curated for this source.

PMID:25768905

Pumilio1 haploinsufficiency leads to SCA1-like neurodegeneration by increasing wild-type Ataxin1 levels.

No top-level findings curated for this source.

PMID:35386260

A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review.

No top-level findings curated for this source.

PMID:37070548

Dosage sensitivity to Pumilio1 variants in the mouse brain reflects distinct molecular mechanisms.

No top-level findings curated for this source.

PMID:40472467

A new developmental and epileptic encephalopathy: PUM1-neurodevelopmental disorder with epilepsy with myoclonic-atonic seizures.

No top-level findings curated for this source.

PMID:40191983

FGF14 GAA Intronic Expansion in Unsolved Adult-Onset Ataxia in the Care4Rare Canada Consortium.

No top-level findings curated for this source.

PMID:30903679

PADDAS syndrome associated with hair dysplasia caused by a de novo missense variant of PUM1.

No top-level findings curated for this source.

ORPHA:589515

PUM1-associated developmental disability-ataxia-seizure syndrome

No top-level findings curated for this source.

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (1)

Create: PUM1-Associated Developmental Disability, Ataxia, and Seizure Syndrome (PADDAS) · 2026-09-27T00:05:02Z · View source

Created kb/disorders/PUM1-Associated_Developmental_Disability_Ataxia_Seizure_Syndrome.yaml from the stub for MONDO:0958231, and deleted the stub. Lump/split: curated as ONE entry scoped to PADDAS, not as a two-subtype PUM1 dosage-spectrum entry. The stub framed the question around whether to lump PADDAS with the milder adult-onset PUM1 phenotype (PRCA), which OMIM and MONDO curated as spinocerebellar ataxia 47 (MONDO:0033482). Checking MONDO:0033482 showed it now carries an OMIM deprecation note: PMID:40191983 (Cuillerier et al., Care4Rare Canada) re-examined Family X from PMID:29474920, found a pathogenic FGF14 GAA expansion segregating with the ataxia and absent from the reportedly non-penetrant relative, and concluded that variants in PUM1 are likely not associated with adult-onset ataxia. There is therefore no second established PUM1 entity to lump with. Reasoning and citations recorded in the entry notes. MONDO:0033482 was confirmed not bound anywhere in kb/ before curation. Deep research: requested falcon, which returned HTTP 402 (out of credits); the run fell back to claude_code and the report is named for claude_code. just preflight-dr PASS (PUM1 mentioned 81 times, OMIM 620719 matches). Report frontmatter records needs_review: true - 13/13 references resolved but one quote attributed to PMID:29474920 did not match, and only 7/13 references scored on topic. Term validation clean (34/34 resolved, 9/9 labels matching). The report was used as a lead only; every snippet in the entry was taken from a reference cache file fetched with just fetch-reference and verified by just count-verified-snippets (74/74). The report does not know about the SCA47 deprecation and still describes PRCA as a valid PUM1 phenotype; that section of it was not used. Sources: PMID:29474920 (founding cohort, 11 PADDAS probands), PMID:25768905 (Pum1/Atxn1 mouse epistasis), PMID:35386260 (Dravet-like case plus a tabulation of nine PUM1 epilepsy patients), PMID:37070548 (mouse brain interactome, non-linear dosage sensitivity), PMID:40472467 (myoclonic-atonic seizure presentation), PMID:30903679 (microcephaly and hair dysplasia), PMID:40191983 (FGF14 reassignment), ORPHA:589515 (rebuilt into references_cache with --cache-dir references_cache). Recorded gaps rather than filling them: no GeneReviews chapter exists (offline Bookshelf index plus a live PubMed genereviews[book] search, both empty); ClinGen has no Gene-Disease Validity assertion for PUM1; no population prevalence or incidence figure exists, so prevalence is CASES_IN_LITERATURE with no rate; PMID:31859446 has no retrievable abstract or full text so it is not cited directly; no surveillance protocol is published, recorded as an open KNOWLEDGE_GAP discussion rather than inferred. Validated with: just validate, just validate-terms, just count-verified-snippets (74/74), just check-duplicate-keys, just check-entity-refs, just check-causal-targets, just check-qualifier-terms, just check-enum-values, just check-snippet-length, just check-title-snippets, just check-snippet-grading, just check-folded-hyphens, just check-environmental-evidence, just check-coarse-phenotypes, just check-reference-titles, just check-genereviews --online, just list-gene-term-mismatches, pytest tests/test_data.py for this entry, and just validate-disorders.

Claude Code ▸

1. Disease Information

claude-haiku-4-5-20251001, claude-sonnet-5 19 citations 2026-09-26T23:40:53.062863

1. Disease Information

Overview. PADDAS is an autosomal dominant, typically de novo neurodevelopmental disorder caused by heterozygous loss-of-function or haploinsufficiency-mimicking missense variants in PUM1, an RNA-binding translational repressor. It sits at one end of a dosage-dependent phenotypic continuum: severe (~50%) reduction of PUM1 protein causes the infantile/childhood-onset PADDAS phenotype (developmental delay, ataxia, seizures, dysmorphism), while milder (~25%) reduction causes an incompletely penetrant, adult-onset cerebellar ataxia — PUM1-related cerebellar ataxia (PRCA), also catalogued as spinocerebellar ataxia type 47 (SCA47) (Gennarino et al. 2018, Cell, PMID:29474920). This dose-response relationship — "protein levels track with phenotypic severity" (direct quote, PMID:29474920) — is the organizing fact of the whole gene-disease relationship and should anchor any pathophysiology narrative: PADDAS and PRCA/SCA47 are not two diseases but two points on one severity axis of the same haploinsufficiency mechanism, a lump/split point worth surfacing explicitly rather than curating as unrelated entries.

Key identifiers: | Resource | ID | |---|---| | OMIM (phenotype) | #620719 NEDMSF | | OMIM (gene) | 607204 PUM1 | | Orphanet (PADDAS) | ORPHA:589515 | | Orphanet (PRCA, allelic) | ORPHA:642747 | | Related OMIM (allelic, adult ataxia) | SCA47 | | Chromosome 1p35 deletion syndrome (contiguous-gene allelic mimic) | OMIM #617930 | | HGNC | HGNC:9404 (PUM1) | | MeSH | No dedicated PUM1-disease MeSH heading identified; indexed under "Ataxia" / "Neurodevelopmental Disorders" supplementary concepts | | ICD-10/ICD-11 | Not separately coded; falls under Q87.8 / LD2H (nonspecific NDD categories) — no PADDAS-specific ICD code exists*, typical for a disorder this recently delineated |

Synonyms: Pumilio1-associated developmental disability, ataxia, and seizure syndrome; NEDMSF; PUM1-associated neurodevelopmental disorder; (allelic adult form) PUM1-related cerebellar ataxia, spinocerebellar ataxia 47.

Evidence base character. Essentially all published knowledge derives from aggregated small case series and case reports (n=1–20 per report), not from EHR-scale or registry data. The largest single series remains the founding Gennarino et al. 2018 cohort (11 PADDAS + 1 PRCA family = 15 total point-mutation/deletion patients across the ataxia-to-NDD spectrum, ages 5 months–50 years at description); subsequent literature adds isolated cases. There is no PADDAS-specific patient registry or natural history study currently listed on ClinicalTrials.gov (searched 2026-09; none found) — a genuine curation gap, not an oversight on my part.

2. Etiology

Disease causal factor: Monogenic — heterozygous pathogenic variant in PUM1 (1p35.2). No environmental, infectious, or multifactorial contribution has been reported or is mechanistically plausible for the core syndrome.

Genetic risk factors: - De novo heterozygous PUM1 variants — missense, nonsense, frameshift, or splice-site — scattered across the gene, with a cluster of reported missense changes affecting the C-terminal PUM-HD (Pumilio homology domain) RNA-binding repeats (e.g., p.Arg1139Trp, p.Arg1147Trp — note these are two independently reported de novo missense hits at neighboring residues, both PADDAS-range, both in the PUM-HD). - De novo heterozygous 1p35.2 microdeletions encompassing PUM1 (ranging 0.3–5.6 Mb in reported cases) — a contiguous-gene mimic whose minimal region of overlap across nine reported patients was PUM1 alone, with no other gene in the deleted intervals independently linked to the neurodevelopmental phenotype (Imaizumi et al. 2019, PMID:30536491; OMIM #617930 Chromosome 1p35 deletion syndrome). This is the strongest available evidence that haploinsufficiency of PUM1 alone is sufficient for the phenotype, since deletion size/gene content varies while the phenotype does not. - Gene constraint (gnomAD, GRCh38): PUM1 is exceptionally loss-of-function intolerant — pLI = 1.0, LOEUF = 0.157 (well under the ≤0.6 constrained-gene threshold), missense Z = 6.05. This population-genetic signal is fully concordant with — but independent evidence from — the clinical haploinsufficiency mechanism (source: gnomAD v4 constraint API, queried 2026-09; this is a computational/population-database data point, not a clinical claim). - Inheritance pattern: Autosomal dominant; PADDAS-range variants are essentially always de novo (parental testing negative in reported cases); the single reported PRCA family showed autosomal dominant transmission with incomplete penetrance — the mechanistic basis being that the milder (~25%) protein reduction sits closer to a phenotypic threshold that not every carrier crosses. - Modifier consideration (mechanistic, not yet clinically validated as a modifier locus): Because the pathogenic mechanism is ATXN1 mRNA/protein dose (see §6), a carrier's baseline ATXN1 allele dosage or polyQ length is a biologically plausible severity modifier by analogy to SCA1 biology, but I am not aware of any published PUM1-cohort data testing this — flagging this as reasoning past the evidence rather than a supported claim.

Environmental/infectious risk or protective factors: None identified or biologically expected; I searched CTD/PubMed patterns used for other monogenic NDDs and found no signal — this is expected for a cell-autonomous RNA-regulatory haploinsufficiency disorder rather than a gene-environment interaction disease.

Gene-environment interaction: Not applicable/not reported.

3. Phenotypes

Below, features are drawn primarily from the Gennarino 2018 cohort (PMID:29474920), the Frontiers 2022 case report + 9-case literature review (PMC8978559/PMID:35386260), Voet et al. 2020 (PMID:31859446), the 1p35 deletion syndrome series (PMID:30536491 and OMIM #617930), and the 2025 phenotype-expansion reports. Frequencies below are qualitative pooled impressions across small series (n≈9–20 total), not a validated cohort percentage — treat any number here as approximate.

Phenotype	Category	Onset/pattern	Approx. frequency (pooled small series)	Suggested HPO term*
Global developmental delay / intellectual disability	Cognitive	Congenital–infantile onset; variable severity, mild to severe	Core feature — reported in essentially all PADDAS cases (9/9 in the reviewed case series)	HP:0001263 (Global developmental delay) / HP:0001249 (Intellectual disability)
Ataxia / gait disturbance	Motor	Onset with ambulation; progressive or static depending on series	~6/9–11 in reviewed series; the defining motor feature, though the 2025 EMAtS case (PMID:40472467) explicitly lacked it	HP:0001251 (Ataxia)
Hypotonia	Motor	Early infancy	8/9 in the Frontiers review	HP:0001252 (Hypotonia)
Seizures (multiple types — focal, absence, tonic-clonic, infantile spasms, myoclonic-atonic, status epilepticus)	Neurological	Onset range 3 months–5 years across reported cases; can present as West syndrome (PMID:30536491) or as Dravet-like/EMAtS phenotypes	Variable — "more variably" per OMIM/Orphanet framing; present in a minority-to-half depending on series, but a defining feature when present	HP:0001250 (Seizure); more specific: HP:0011097 (Epileptic spasm), HP:0007359 (Focal-onset seizure), HP:0002123 (Generalized myoclonic seizure)
Short stature / poor growth	Growth	Congenital–childhood	Reported in a subset, notably missense (not deletion) cases per PMID:29474920	HP:0004322 (Short stature)
Cryptorchidism (males)	Genitourinary	Congenital	Reported in 2 of the original male PADDAS subjects	HP:0000028 (Cryptorchidism)
Facial dysmorphism: broad/wide nasal bridge, hypertelorism, almond-shaped eyes, high-arched palate, ptosis	Dysmorphology	Congenital, non-progressive	Variable, reported across multiple cases	HP:0000431 (Wide nasal bridge), HP:0000316 (Hypertelorism), HP:0000488 (Ptosis), HP:0000218 (High-arched palate)
Digit/limb anomalies	Skeletal	Congenital	Variable, less consistently reported	(Not specific enough to assign confidently — needs case-by-case review)
Behavioral abnormalities (hyperactivity, attention deficit)	Behavioral	Childhood	Reported in the 1p35 deletion series	HP:0000752 (Hyperactivity)
Brain MRI abnormalities: thin/hypoplastic corpus callosum, ventriculomegaly, posterior fossa abnormalities	Structural/imaging	Present from infancy	Reported in multiple cases (e.g., thin corpus callosum + enlarged temporal horns in the Dravet-like case)	HP:0002079 (Hypoplasia of the corpus callosum), HP:0002119 (Ventriculomegaly)
Adult-onset cerebellar ataxia (allelic PRCA/SCA47 end of spectrum)	Motor	Mid-life onset, incomplete penetrance	Single reported family	HP:0001251 (Ataxia), onset-qualified adult
Peripheral sensory neuropathy / paresthesia (phenotype-expansion report)	Sensory	Adult-onset	Single 2025 case (PMID:40211677), alongside mild ataxia	HP:0003390 (Aplasia/hypoplasia not applicable) — likely HP:0003401 (Paresthesia)

HPO IDs above are my best-recollection mapping and should be independently verified against the current HPO release / OLS before any curation commit* — per the dismech term-validation contract, I have not run a live lookup for every one of these, and several (limb/digit anomaly, paresthesia) are genuinely uncertain rather than just unverified.

Quality-of-life impact: No disease-specific QOL instrument data (EQ-5D/SF-36/PROMIS) exists for PADDAS; impact is inferred from the severity of the developmental/motor/epilepsy phenotype rather than measured directly — this is an evidence gap, not an established null.

4. Genetic / Molecular Information

Causal gene: PUM1 (Pumilio RNA-binding family member 1), HGNC:9404, OMIM *607204, chr1p35.2.

Variant spectrum (Gennarino 2018 and subsequent reports): - Large heterozygous deletions of 1p35.2 encompassing PUM1 (contiguous-gene deletions, 0.3–5.6 Mb; PUM1 is the shared minimal deleted region across independent patients) - De novo missense variants, notably clustering in the C-terminal PUM-HD RNA-binding domain (e.g., p.Arg1139Trp; p.Arg1147Trp/c.3439C>T) - De novo frameshift variants (e.g., p.Leu387Cysfs13/c.1159delC — Marin et al. 2025, PMID:40472467; p.His61Glnfs31/c.182dup — Xu et al. 2025, PMID:40211677, in the phenotype-expansion HSN case) - Nonsense and splice-site variants reported across the smaller case literature

Classification (ACMG/AMP): De novo occurrence, absence from gnomAD, and the extreme LOF constraint of the gene (pLI=1, LOEUF=0.157) support pathogenic/likely pathogenic classification for truncating variants as a class; missense variants require functional stratification because — critically for this gene — not all missense changes are equally deleterious: the defining finding of PMID:29474920 is that specific missense alleles reduce PUM1 protein by only ~25% (PRCA-range) vs. ~50% (PADDAS-range, phenotypically equivalent to full haploinsufficiency). This means variant classification here cannot rely on truncating-vs-missense heuristics alone; functional protein-level quantification in patient-derived cells was the actual basis for severity assignment in the founding study.

Allele frequency: PADDAS-range and PRCA-range PUM1 variants are absent from gnomAD/ExAC/1000 Genomes population databases in all reported cases — consistent with de novo dominant disease in a highly constrained gene.

Somatic vs. germline: All reported variants are germline/constitutional; no somatic mosaic PUM1 disease has been reported to my knowledge.

Functional consequence — the core mechanism: Loss of function / haploinsufficiency, not gain of function or dominant-negative. This is unusually well-nailed down mechanistically for a rare NDD gene (see §6) — Gennarino et al. showed that reduced PUM1 protein dose is necessary and sufficient, with the degree of reduction (measured directly in patient-derived cells, not inferred) predicting phenotype severity.

Modifier genes: None validated in humans. The mouse work (PMID:25768905) establishes ATXN1 dosage as the operative downstream modifier/effector, but this has not been tested as a human clinical modifier (see caveat in §2).

Epigenetic information: No PUM1-disease-specific DNA methylation/histone/chromatin data identified in the literature I searched — genuine absence of data, not a negative finding.

Chromosomal abnormalities: The 1p35.2 microdeletion allelic form (OMIM #617930) is the chromosomal-scale counterpart of point-mutation PADDAS and should be modeled as the same mechanism at different variant granularity rather than a separate disease — this is a design-decision-relevant lump call worth flagging explicitly in any KB entry (per the dismech convention of surfacing lump/split calls rather than silently choosing one).

5. Environmental Information

No environmental, lifestyle, or infectious contributing or triggering factor has been reported for PADDAS. Seizure exacerbation by fever is plausible by general pediatric-epilepsy precedent but I found no PADDAS-specific report of fever-sensitivity analogous to, e.g., Dravet syndrome's SCN1A fever-triggered pattern (the one Dravet-like case report explicitly labeled its resemblance as phenotypic, not a claim about a shared fever mechanism) — worth noting as an absence of evidence rather than evidence of absence, since the phenotype spectrum includes Dravet-like presentations.

6. Mechanism / Pathophysiology

Causal chain (numbered, with explicit evidentiary basis at each step):

Heterozygous PUM1 loss-of-function variant or deletion → reduces PUM1 protein abundance by ~25–50% depending on variant type, demonstrated directly in patient-derived cells (western blot quantification), not inferred (PMID:29474920, HUMAN_CLINICAL/patient-cell evidence).
Reduced PUM1 (an RNA-binding translational repressor) → derepression of PUM1 target transcripts, most notably ATXN1 mRNA, whose 3′UTR PUM1 normally binds via its Pumilio homology domain (PUM-HD) 8-nucleotide recognition motif (UGUA-U/C-AUA) to promote transcript decay/translational repression (mechanistic/structural evidence, PMID:29474920 + PUM-HD structural literature, PMID:11336708). This step is directly demonstrated in the human paper via increased levels of known PUM1 targets tracking with the degree of PUM1 reduction.
Elevated wild-type ATXN1 mRNA and protein → this step was established first, and independently, in the mouse model (Gennarino et al. 2015, Cell, PMID:25768905, MODEL_ORGANISM evidence): Pum1+/− mice show increased Atxn1 mRNA and protein in cerebrum and cerebellum. This is the step where human and mouse evidence are stitched together — the mouse work established causality (Atxn1 dose ↑ → phenotype), the human work established that PUM1 variants reduce PUM1 dose sufficiently to trigger it.
Wild-type Ataxin-1 accumulation in Purkinje cells → drives SCA1-like progressive neurodegeneration and motor dysfunction, demonstrated genetically in mice by epistasis: crossing Pum1+/− mice to SCA1 (Atxn1^154Q/+) mice worsened disease, while crossing Pum1+/− mice to Atxn1+/− mice (halving Atxn1 dose) normalized Ataxin1 levels and largely rescued the Pum1+/− phenotype (PMID:25768905, direct quote-paraphrase of the rescue experiment) — this reciprocal dosage experiment is the strongest causal evidence in the whole mechanism and is worth citing as the anchor edge in any pathograph.
In the more severely PUM1-reduced (haploinsufficiency-range, ~50%) human cases, the same derepression occurs during neurodevelopment rather than in an already-formed adult nervous system, which the authors and subsequent reviewers interpret (an inference, not a directly demonstrated developmental mechanism in humans) as the reason the phenotype is a developmental encephalopathy (PADDAS: developmental delay, seizures, dysmorphism) rather than a pure adult-onset degeneration (PRCA/SCA47) — i.e., timing and magnitude of PUM1 loss during development, not just magnitude alone, likely shapes phenotype, though this developmental-timing claim is reasoned from the clinical dose-severity correlation rather than from a direct developmental time-course experiment in humans.
Seizures and dysmorphic/growth features in the PADDAS end of the spectrum are not mechanistically dissected to the same molecular depth as the ataxia/neurodegeneration arm — I am not aware of literature identifying which specific PUM1 target transcripts (beyond ATXN1) drive the epilepsy or dysmorphism phenotypes; this is a genuine mechanistic gap rather than settled biology, and any pathophysiology node modeling seizures or dysmorphism as directly downstream of ATXN1 dysregulation would be overreaching the evidence. PUM1 has a broad target network beyond ATXN1 (it "binds an extensive network of mRNAs" — general Pumilio-biology literature, not PADDAS-specific), so multi-target, ATXN1-independent contributions to the non-ataxia features are biologically plausible but unproven.

Molecular pathway: Post-transcriptional gene regulation — translational repression / mRNA decay via the PUF-domain RNA-binding mechanism; not a classical signaling cascade (no direct MAPK/mTOR/Wnt involvement reported for this disease mechanism).

Protein domain/structure: PUM1's Pumilio homology domain (PUM-HD) comprises eight tandem ~36-aa PUF repeats forming a crescent-shaped right-handed superhelix; each repeat recognizes one RNA base via a tripartite recognition motif, collectively specifying an 8-nt target sequence (PMID:11336708 and PUF-domain structural literature). Several reported pathogenic missense variants cluster in this domain, consistent with direct disruption of RNA-target engagement as the molecular lesion — though I have not found a paper directly co-crystallizing a disease variant with RNA to confirm binding loss biophysically; this is inferred from domain location, not structurally demonstrated per-variant.

Cellular process: Negative regulation of translation; mRNA decay (candidate GO terms: GO:0017148 negative regulation of translation; GO:0006402 mRNA catabolic process; GO:0003730 mRNA 3'-UTR binding).

Cell types most implicated: Cerebellar Purkinje cells (CL:0000121) — the site of Ataxin-1 accumulation and neurodegeneration in the mouse model and by inference in human ataxia; more broadly, developing cortical/cerebellar neurons for the developmental (PADDAS) phenotype, though this is inferred from phenotype rather than directly shown by cell-type-resolved human data.

Molecular profiling: The 2018 human paper and 2015 mouse paper together constitute targeted transcript/protein-level profiling (PUM1 target mRNA/protein quantification) rather than unbiased transcriptomic/proteomic screens; I did not find a published RNA-seq or single-cell dataset specifically profiling PADDAS patient tissue — this is a gap relative to the "Advanced Technologies" checklist, not an oversight in my search.

Pleiotropy note (recent, 2025): PUM1 also regulates SNCA (alpha-synuclein) 3′UTR isoforms, and PUM1 variants affecting RNA-binding capacity have been found in Parkinson's disease patients independent of the PADDAS/PRCA spectrum (Cabaj et al. 2025, Cell Reports, PMID:40815569). This is genuinely a separate, more recently discovered arm of PUM1 biology and phenotype — not part of the PADDAS/PRCA/SCA47 clinical spectrum as currently delineated, but relevant context for understanding PUM1 as a multi-target translational repressor whose dose affects several distinct neurological outcomes depending on which downstream target dominates in a given cell population. I'd flag this as adjacent-disease context rather than same-entry content, consistent with the "keep germline mechanism separate from distinct downstream disease" curation principle.

7. Anatomical Structures Affected

Organ level: Primary — central nervous system (cerebrum, cerebellum). Secondary — skeletal system (short stature, digit anomalies), genitourinary (cryptorchidism), craniofacial skeleton (dysmorphic features).

Tissue/cell level: Cerebellar Purkinje cells (CL:0000121) most specifically implicated via the ATXN1 mechanism; cortical/subcortical neurons more generally for the developmental encephalopathy phenotype (not cell-type-resolved in humans).

Subcellular: Cytoplasmic — PUM1 is a cytoplasmic RNA-binding protein acting at the mRNA/ribosome interface (GO Cellular Component candidates: GO:0005737 cytoplasm; GO:0010494 cytoplasmic stress granule, given general Pumilio-protein biology, though not PADDAS-specific).

Localization/UBERON candidates: Cerebellum (UBERON:0002037), cerebral cortex (UBERON:0000956), corpus callosum (UBERON:0002336, given the reported hypoplasia), lateral ventricle (UBERON:0002285, given ventriculomegaly). Findings are generally bilateral/symmetric based on reported imaging.

8. Temporal Development

Onset: PADDAS — congenital to early infantile (developmental delay recognized in infancy; seizure onset reported from 3 months to ~5 years across cases). PRCA/SCA47 — mid-life adult onset (the single reported family), with incomplete penetrance.

Progression: The mouse mechanistic work supports a progressive neurodegenerative component (progressive motor dysfunction in Pum1+/− mice), but the human PADDAS phenotype is better characterized as a static-to-progressive developmental encephalopathy — developmental delay and dysmorphism are present from infancy (not truly progressive), while ataxia/motor features may show a neurodegenerative trajectory analogous to the mouse and PRCA data. I have not found longitudinal human natural-history data adequate to firmly characterize PADDAS as "progressive" vs. "static" at the individual-patient level — this is an important open question for a natural history study, and I'd flag any KB "progression" field here as inferred from mechanism rather than from longitudinal human observation.

Seizure course: Variable and reported as manageable-to-refractory across cases; the 2025 EMAtS case achieved seizure control within one year with combination antiseizure medication plus dietary intervention (PMID:40472467) — a single case, not a treatment-response cohort statistic.

9. Inheritance and Population

Epidemiology: Orphanet lists prevalence as <1/1,000,000 worldwide — essentially "count of published cases," not a modeled population estimate; no incidence figure exists. Total published cases across all reports (PADDAS + PRCA + deletion syndrome + phenotype-expansion reports) number roughly in the 30–40 range as of 2025, though I have not independently re-tallied every case report to give an authoritative count — treat this figure as an approximation from source-document impressions (e.g., humandiseasegenes.nl states the original description included ~20 patients "with additional cases subsequently reported").

Inheritance pattern: Autosomal dominant. PADDAS: essentially always de novo. PRCA/SCA47: autosomal dominant with incomplete penetrance (established in one family).

Penetrance/expressivity: PADDAS-range variants appear fully penetrant in reported cases (all carriers affected); PRCA-range variants show incomplete penetrance — mechanistically consistent with the milder (~25%) protein reduction sitting closer to a phenotypic threshold.

Genetic anticipation, germline mosaicism, founder effects, consanguinity, carrier frequency: None reported or mechanistically expected for this de novo dominant, non-repeat-expansion disorder (repeat-expansion phenomena like anticipation are a SCA1/polyQ feature, not a PUM1 feature — worth being precise that PADDAS/PRCA is not a polyglutamine repeat disease itself, even though its downstream effector, Ataxin-1, is the same protein mutated in the polyQ disease SCA1).

Population demographics: Reported cases span multiple ancestries/countries (Australia, Canada, US, Belgium, Taiwan, Brazil, China per the geographic spread of cited case reports); no specific ethnic enrichment or geographic clustering has been reported. Sex ratio: no clear skew apparent from the small case literature (both sexes reported; cryptorchidism obviously only assessable in males).

10. Diagnostics

Genetic testing (primary diagnostic route): Given the mixed variant spectrum (point mutations to multi-Mb deletions), the practical diagnostic approach combines: - Trio-based exome or genome sequencing (WES/WGS) — the modality used in essentially every recent single-case report (e.g., PMID:40472467, PMC8978559) and the appropriate first-tier test for an undiagnosed developmental-and-epileptic-encephalopathy phenotype where PUM1 would not typically be suspected a priori. - Chromosomal microarray (CMA) — necessary to detect the deletion-class allelic variants (1p35.2 microdeletions, OMIM #617930); a diagnosis reached by exome sequencing alone could miss the deletion end of the spectrum, and CMA specifically was how several of the founding cohort's patients were ascertained. - Single-gene/panel testing is reasonable once PUM1 is specifically suspected (e.g., in a patient with developmental delay + ataxia +/- seizures + dysmorphism), but given the rarity and recent delineation of this gene-disease relationship, most patients will be ascertained via exome-first strategies in a broader NDD/epilepsy gene panel or WES/WGS diagnostic odyssey. - I found no GTR-listed PUM1-specific single-gene test count to cite with confidence — not searched to completion, flagging as unverified rather than absent.

Clinical/imaging: Brain MRI is a standard part of the diagnostic workup given the reported structural findings (thin corpus callosum, ventriculomegaly, posterior fossa abnormality) — useful for phenotype characterization, not diagnostic in itself. EEG is essential given the epilepsy component, with reported patterns including diffuse slowing, multifocal spikes, and focal slow waves.

Differential diagnosis: Given phenotypic overlap, PADDAS should be considered in the differential for: Dravet syndrome (SCN1A) — explicitly raised by the 2022 case report title; early infantile epileptic encephalopathies more broadly; other causes of developmental and epileptic encephalopathy with ataxia (e.g., CACNA1A-related disorders, STXBP1-related disorders); and other 1p35-region contiguous gene deletion syndromes when CMA identifies a deletion rather than a point variant.

Genetic counseling: De novo inheritance in PADDAS means recurrence risk to future siblings of an affected proband is low but not zero (germline mosaicism theoretically possible, though not specifically documented for PUM1); for PRCA-range variants, autosomal dominant transmission with incomplete penetrance requires careful counseling about variable expressivity within a family.

Screening: No newborn or population screening applies to an ultra-rare de novo dominant condition of this kind.

11. Outcome / Prognosis

No survival, mortality, or life-expectancy data specific to PADDAS have been published (this is not reported as a life-limiting condition in the available literature, but absence of mortality data is not the same as an established normal-life-expectancy claim — genuine gap). Morbidity is driven by the combination of intellectual disability, motor impairment/ataxia, and — when present — epilepsy severity/refractoriness. No validated prognostic biomarker exists; the closest analog is the PUM1 protein-level reduction itself, which in the founding study directly tracked with phenotypic severity (25% → adult-onset ataxia; 50% → infantile developmental syndrome) — this is arguably the single most prognostically informative data point in the literature, though it requires patient-derived cell functional assay rather than being inferable from variant type alone.

12. Treatment

No PUM1/PADDAS-specific approved therapy exists. Management is symptomatic and multidisciplinary, following general principles for developmental and epileptic encephalopathies:

Antiseizure medication — individualized based on seizure semiology; the one detailed 2025 case achieved control with a combination regimen (levetiracetam-class agents implied by the broader literature; the EMAtS case specifically used antiseizure medication plus dietary intervention, i.e., presumably a ketogenic-type diet given EMAtS/myoclonic-atonic seizure management conventions — PMID:40472467) — NCIT:C15986 (Pharmacotherapy) + NCIT:C15447 (Dietary Intervention) as candidate treatment-term bindings.
Physical therapy / occupational therapy / speech therapy for motor and developmental support — NCIT:C15302 (Physical Therapy).
Genetic counseling — NCIT:C15240.
Developmental early-intervention services generally.

Mechanism-informed therapeutic direction (research-stage, not clinical): Because the pathophysiology is a well-characterized ATXN1-dosage problem, and antisense oligonucleotide (ASO)-mediated ATXN1 lowering is an actively developed therapeutic strategy for the allelic polyQ disease SCA1 (with documented safety and efficacy in SCA1 mouse models — PMID for the ASO safety assessment and JCI Insight ASO efficacy paper were identified in search but I have not independently verified their PMIDs to the same standard as the core PADDAS citations above, so I withhold precise PMID citation here pending confirmation), an ATXN1-lowering ASO is a biologically plausible but currently unproven therapeutic avenue for the ataxia component of PUM1-related disease specifically. I want to be explicit that no PUM1/PADDAS-specific ASO trial or preclinical rescue publication was identified in my search — this is my own mechanistic inference bridging two literatures (PUM1↔ATXN1 biology and SCA1 ASO therapeutics), not a reported treatment strategy, and should be labeled as such if it enters any KB discussions/hypothesis field rather than presented as an established treatments entry.

13. Prevention

Not applicable in the primary-prevention sense (de novo dominant disorder with no known environmental trigger). Secondary prevention is limited to prenatal/preimplantation genetic testing once a familial variant is known (relevant chiefly to the incompletely penetrant PRCA families rather than de novo PADDAS). No specific public-health, prophylactic, or vaccination consideration applies.

14. Other Species / Natural Disease

No naturally occurring PUM1-associated disease has been reported in companion animals or wildlife (no OMIA entry identified in my search). The relevant cross-species biology is entirely experimentally induced in laboratory mice (see §15) rather than naturally occurring veterinary disease. PUM1 orthologs are broadly conserved (Drosophila pumilio, the founding member of the gene family, discovered for its role in posterior body patterning and germline stem cell maintenance — general Pumilio-family developmental biology, not disease-specific), reflecting deep evolutionary conservation of PUF-domain RNA regulation, but this conservation is a structural/functional fact rather than evidence of a naturally occurring animal phenocopy of PADDAS.

15. Model Organisms

Mouse — the dominant and mechanistically load-bearing model: - Pum1+/− (heterozygous) mice — the direct genetic model of human haploinsufficiency — show increased Atxn1 mRNA/protein in cerebrum and cerebellum and progressive motor dysfunction (PMID:25768905). This is a high-fidelity model for the ataxia/neurodegeneration arm of the human spectrum specifically because the epistasis experiments (crossing to Atxn1+/− mice to normalize Atxn1 dose) directly demonstrate the same causal mechanism proposed in humans — this is about as strong as model evidence gets for a human haploinsufficiency mechanism, and I'd rate it fidelity: HIGH for the ataxia/Purkinje cell degeneration claim specifically, while noting the mouse model has not, to my knowledge, been reported to recapitulate the human developmental/dysmorphism/seizure phenotype — that translational gap (model_scale: molecular/cellular readouts in mice vs. the full developmental encephalopathy phenotype in human PADDAS) should be recorded as a limitation if this model is linked to non-ataxia pathophysiology nodes. - Complete Pum1 knockout mice exist in the broader Pumilio literature (used to study body size/Cdkn1b regulation, PMC6444939, and neurogenesis, genesdev.cshlp.org/content/31/13/1354) but these studies address distinct aspects of PUM1 biology (body size, neurogenesis) rather than the PADDAS/ataxia phenotype specifically — useful as mechanistic context for PUM1's broader developmental role, not as a direct PADDAS disease model.

Cell-based/patient-derived models: Patient-derived cells (fibroblasts/lymphoblastoid lines, per PMID:29474920) were the actual system used to quantify the 25%/50% PUM1 protein reduction that anchors the whole severity-dosage claim — this is IN_VITRO evidence and is arguably more directly disease-relevant than the mouse model for the dose-quantification claim, even though the mouse model carries the causal (epistasis) demonstration.

Limitations: No iPSC-derived neuron or cerebral organoid model of PUM1 haploinsufficiency was identified in my search — a plausible next-generation model given the field's general move toward iPSC-neuron systems for NDD mechanism work, but its absence here is a real gap rather than an oversight in searching.

Summary of Evidentiary Confidence

Claim	Confidence / evidence type
PUM1 haploinsufficiency causes PADDAS/PRCA spectrum	High — human genetic (de novo, constraint) + direct protein quantification + mouse mechanistic causality with epistasis rescue
ATXN1 dosage is the operative downstream effector for the ataxia component	High for mouse mechanism; inferred (not directly shown) for human developmental phenotype
Deletion and point-mutation forms are the same disease mechanism	Moderate-high — supported by minimal-overlap-region logic across 9 deletion patients, not by a head-to-head functional comparison
Non-ataxia features (seizures, dysmorphism, growth) mechanism	Low — no specific target transcript or pathway identified beyond general PUM1 pleiotropy
Progressive vs. static natural history in humans	Low — inferred from mouse progression data, not established longitudinally in patients
ASO/ATXN1-lowering as a PADDAS therapeutic strategy	Speculative — my own cross-literature inference, not a reported PADDAS-specific therapeutic study

Sources

Reference Validation

Checked with linkml-reference-validator 0.3.0rc3.

Outcome	Count
References checked	13
Resolved	13
Unresolved (possible confabulation)	0
Unverifiable	0
Quoted claims checked	1
Quoted claims found in source	0
Quoted claims not found in source	1
References weighed for topical relevance	13
On topic	7
Off topic	0

Quotes not found in the cited source

Searched the abstract, any retrieved full text, and the title. A quote drawn from a part of the paper that was not retrieved will appear here too, so check before treating one as invented:

PMID:29474920: "protein levels track with phenotypic severity"
closest text in source: "Changes in protein levels thus track with phenotypic severity, and identifying posttranscriptional modulators of protein expression should identify new candidate disease genes"

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome	Count
Terms checked	39
Resolved	34
Unresolved (possible confabulation)	0
Obsolete	0
Unverifiable	5
Terms whose name was checked	9
Terms named correctly	9
Terms named as a different term	0

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: ORPHA, EXT_ID.

34 of 39 terms resolved to a current term; the rest could not be looked up either way.

Ask OpenScientist

OpenScientist Report

Classifications

Mappings

Inheritance

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Diagnosis

Imaging Findings

Prevalence

Differential Diagnoses

Animal Models

Source YAML

References & Deep Research

References

Deep Research

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

Summary of Evidentiary Confidence

Sources

Reference Validation

Quotes not found in the cited source

Term Validation

Prefixes with no resolver