Ring Chromosome 14 Syndrome

Genetic MONDO:0014708 Pathograph 23 Show in embeddings browser Ring chromosome disorder Chromosome 14 disorder Epilepsy

Ring chromosome 14 syndrome is a rare chromosomal disorder in which the two ends of chromosome 14 fuse into a circle. It is dominated by an epilepsy that begins in the first years of life, is polymorphic and drug-resistant, and occurs in essentially every patient. Alongside it sit intellectual disability, microcephaly, short stature, a distinctive facial appearance, scoliosis, and a characteristic retinal pigmentary abnormality. The mechanistically interesting part is that the deletion does not explain the syndrome. Ring formation usually removes a small terminal segment of 14q, and in a minority of patients it removes nothing at all. Mapping the features against linear 14q deletions puts the epilepsy and the retinal abnormality in proximal 14q11.2-q12 — a region that is intact in every ring patient. So the two defining features of the syndrome arise from a region that has not been deleted, and the deletion that is present sits somewhere else, at 14q32, where it plausibly accounts for the behavioural phenotype and the susceptibility to infection by ordinary haploinsufficiency. Two candidate explanations carry the unexplained part, and this entry models both rather than choosing. The first is position effect: circularisation changes the chromatin architecture of the chromosome, and heterochromatin spreading from the adjacent short arm may silence proximal 14q genes that are physically present in normal copy number. A patient whose complete ring lost only its telomeres nonetheless showed two of eight chromosome-14 genes downregulated, which is the cleanest demonstration that copy number and expression come apart here. FOXG1, at 14q12, is the specific candidate this points at. The second is dynamic mosaicism: rings are mitotically unstable, and a patient studied for instability showed anaphase lags, aneuploidy and the ring excluded from the nucleus as a micronucleus, so the effective genotype differs from cell to cell and worsens over time. These are not competing accounts of one thing so much as two consequences of the same lesion, and the syndrome may need both. Neither has been shown to cause the epilepsy.

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1
Mappings
9
Pathophys.
28
Phenotypes
2
Hypotheses
4
Gaps
23
Pathograph
9
Medical Actions
1
Trials
3
References
1
Deep Research
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Mappings

MONDO
MONDO:0014708 ring chromosome 14
skos:exactMatch MONDO
MONDO:0014708 is the ring chromosome 14 concept modeled by this entry. MONDO cross-references it to Orphanet:1440, the source of the phenotype frequencies curated here.
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Mechanistic Hypotheses

2
Position effect silences preserved proximal 14q genes
position_effect EMERGING
Evidence balance 1 support
Circularisation changes the chromatin architecture of chromosome 14, and heterochromatin spreading from the short arm silences genes in the proximal 14q11.2-q12 interval that remain present in normal copy number. This is the only account on offer for why the epilepsy and the retinal phenotype map to a region that is never deleted. FOXG1 at 14q12 is the named candidate. The evidence is two patients: one whose telomere-only ring showed two of eight chromosome-14 genes downregulated at normal copy number, and one whose breakpoint fell within the FOXG1 regulatory landscape with a FOXG1-syndrome-like phenotype. Neither demonstrates silencing of a proximal gene in a classical ring 14 patient, and neither connects expression to seizures.
Pathograph links
Ring Chromosome 14 Formation -> Position-Effect Dysregulation of Proximal 14q INDIRECT UNKNOWN INTERMEDIATES Circularisation alters the chromatin context of the chromosome; the steps from that to altered expression of specific proximal genes are not established.
Position-Effect Dysregulation of Proximal 14q -> Cortical Hyperexcitability INDIRECT UNKNOWN INTERMEDIATES The proposed route from silencing of proximal 14q genes to a seizure-prone cortex. No intermediate step has been identified.
Position-Effect Dysregulation of Proximal 14q -> Retinal Pigmentary Abnormality INDIRECT UNKNOWN INTERMEDIATES The retinal phenotype maps to the same preserved proximal interval as the epilepsy and is proposed to arise the same way.
Show evidence (1 reference)
PMID:26315457 SUPPORT Human Clinical
"the phenotypic alterations found in the presence of complete ring chromosomes may be related to changes in the chromatin architecture, bringing about a change of expression by position effect"
States the position-effect model and the chromatin-architecture mechanism behind it.
Mitotic ring instability produces a mosaic effective genotype
dynamic_mosaicism EMERGING
Evidence balance 1 support
The ring is unstable in mitosis, so cells lose it or carry rearranged forms of it at varying rates. The resulting mosaicism, which increases with age, would make the functional genotype of any tissue a mixture and could explain why the phenotype exceeds the deletion and why it progresses. Instability itself is documented in a ring 14 patient. What is missing is any link between the degree of mosaicism and the severity of the phenotype, in this or any other ring 14 patient.
Pathograph links
Ring Chromosome 14 Formation -> Ring Mitotic Instability and Dynamic Mosaicism DIRECT A circular chromosome is mechanically unstable in mitosis, which is a direct consequence of its topology.
Ring Mitotic Instability and Dynamic Mosaicism -> Cortical Hyperexcitability INDIRECT UNKNOWN INTERMEDIATES Cell-to-cell variation in effective genotype is proposed to produce a functionally heterogeneous cortex. Untested against seizure severity.
Show evidence (1 reference)
PMID:25901181 SUPPORT INDIRECT Human Clinical
"dysregulation of FOXG1 may contribute to the classical r(14)-syndrome, likely mediated by dynamic mosaicism"
Proposes dynamic mosaicism as the mediator. Graded INDIRECT because it is offered as an interpretation of a single atypical case, not a demonstration.
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Discussions and Knowledge Gaps

4
How does a chromosome 14 ring that preserves the proximal 14q interval produce near-universal, drug-resistant epilepsy?
KNOWLEDGE GAP OPEN r14_epilepsy_mechanism_unknown
Attached to
pathophysiology#Cortical Hyperexcitability mechanistic_hypotheses#position_effect mechanistic_hypotheses#dynamic_mosaicism
This is the central unanswered question of the syndrome and the reason the convergence node is graded HYPOTHETICAL. The epilepsy maps by comparison with linear deletions to proximal 14q11.2-q12, which is intact in every ring patient, so the deletion cannot be the cause. Position effect and dynamic mosaicism are both plausible and both have direct supporting observations, but neither has been connected to cortical excitability in any system. No causal gene, ion channel, synaptic abnormality or network mechanism has been identified. Distinguishing the two hypotheses would need expression measurement of proximal 14q genes in neural tissue or neurons derived from ring 14 patients, alongside quantification of ring loss in the same cells.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"we could deduce that retinal abnormalities and epilepsy map within the proximal 14q11.2- q12 region"
Localises the epilepsy to the interval that is preserved in all ring patients, which is what makes the mechanism a gap rather than a deletion.
Is FOXG1 expression actually altered in classical ring chromosome 14, or is the FOXG1 link confined to the single atypical case that raised it?
KNOWLEDGE GAP OPEN r14_foxg1_untested_in_classical_ring
Attached to
mechanistic_hypotheses#position_effect
FOXG1 is an attractive candidate because it sits at 14q12 inside the implicated interval, and because FOXG1 syndrome shares features with ring 14. But the case that raised it carried a ring formed from an interstitial excision, not the usual telomere-fusion ring, and its breakpoint fell 225 kb downstream of FOXG1 within the regulatory landscape. FOXG1 expression was not measured in that patient and has not been measured in any classical ring 14 patient. The hypothesis is positional and currently untested where it matters.
Proposed experiments
FOXG1 expression in ring 14 patient-derived neurons
r14_foxg1_expression_in_patient_neurons
Measure FOXG1 and other proximal 14q transcript levels in neurons derived from classical ring 14 patients, including patients whose ring carries no deletion, against matched controls.
Would support
mechanistic_hypotheses#position_effect
Supporting outcome
  • FOXG1 or other proximal 14q genes are downregulated in ring 14 neurons at normal copy number, connecting the position-effect model to the tissue where the epilepsy arises.
Refuting outcome
  • Proximal 14q expression is unchanged in ring 14 neurons, indicating that position effect on this interval is not the route to the epilepsy and redirecting attention to mosaicism or to another mechanism entirely.
Show evidence (1 reference)
PMID:25901181 SUPPORT DIRECT Human Clinical
"The patient represents the first case of a r(14) arising from an interstitial excision where the phenotype is compatible with dysregulation of FOXG1."
The source itself frames this as a first case of an atypical ring configuration, which is the limitation this gap records.
Does the degree of ring instability correlate with phenotype severity or progression in ring chromosome 14?
KNOWLEDGE GAP OPEN r14_mosaicism_not_correlated_with_severity
Attached to
mechanistic_hypotheses#dynamic_mosaicism pathophysiology#Ring Mitotic Instability and Dynamic Mosaicism
Dynamic mosaicism is invoked to explain both why the phenotype exceeds the deletion and why it progresses, and the underlying instability is genuinely documented: one patient showed micronuclei, aneuploidy and anaphase lags. But instability has been measured in one patient and severity has never been scored against it. Without that correlation the hypothesis explains everything and predicts nothing. A cohort measuring ring-loss rate in accessible cells against epilepsy severity and cognitive trajectory would test it.
Show evidence (1 reference)
PMID:39020403 SUPPORT INDIRECT Human Clinical
"Genomic instability was evidenced by the presence of micronuclei and aneuploidies involving the ring and other chromosomes."
Documents instability in a single patient, which is the entire direct evidence base for the mosaicism hypothesis in this syndrome.
How does a chromosome 14 ring produce a selective IgG galactosylation and sialylation defect, when no relevant glycosyltransferase gene lies on chromosome 14?
KNOWLEDGE GAP OPEN r14_igg_glycosylation_trans_mechanism
Attached to
pathophysiology#Aberrant IgG N-Glycosylation pathophysiology#Terminal 14q32 Haploinsufficiency
This is the sharpest mechanistic question on the branch the entry itself identifies as most consequential, since infection is the leading cause of adult death here. The glycosylation abnormality is measured and selective: it affects IgG and not total serum glycoproteins, and it occurs at normal IgG concentration. What it does not have is an established connection to the ring. The enzymes whose products are altered are not encoded on chromosome 14, so the straightforward direct correlation is unproven, and the authors go further, judging that the IgG changes do not relate to the structural rearrangement. They also decline to let that settle it, noting that absent candidate genes in the deleted region do not exclude a genetic basis, since deletion is only one mechanism alongside ring instability and conformational effects on gene expression. So the honest position is that a measured immunological abnormality sits beside a chromosomal lesion with no demonstrated link either way. That is worth keeping in the pathograph rather than dropping, because the two routes the authors leave open are the two this entry already models as dynamic_mosaicism and position_effect. If either is real, it now has a second phenotype to account for. It also reframes the 14q32 branch. The guideline's positional argument predicts a quantitative immunoglobulin deficit from loss of the heavy-chain locus; what has actually been measured is normal IgG with altered glycans. Those are different lesions, and the entry carries both rather than letting the positional argument stand unopposed.
The same report describes one patient treated with intravenous immunoglobulin who showed clinical improvement. That observation is deliberately not curated as a treatment. The paper itself states that it remains a theoretical assumption and should not be interpreted as evidence of therapeutic efficacy, and curating an n-of-1 uncontrolled observation as treatment evidence would misrepresent the source.
Show evidence (2 references)
PMID:42352229 SUPPORT Human Clinical
"no genes encoding galactosyltransferases or sialyltransferases are located on chromosome 14"
States why the straightforward direct correlation is unproven. Note this supports the absence of a cis explanation, not the presence of a trans one.
PMID:42352229 SUPPORT Human Clinical
"which involves several other factors, such as ring chromosome instability during cell division and the effects of the chromosome's new conformation on gene expression"
Names the alternative mechanisms the authors keep open, which are the same two this entry already curates as hypothesis groups.
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Pathophysiology

9
Ring Chromosome 14 Formation
Mechanism confidence: Established
Breakage in both arms of chromosome 14 followed by fusion of the ends produces a circular chromosome. In the reported series the ring was complete, with no apparent loss of material, in 6 of 27 patients, and carried a small terminal deletion of 0.3 to 5 Mb in the remaining 21. Rings with a deletion were paternal in origin in about three quarters of cases, and uniparental disomy for chromosome 14 was excluded throughout, so the phenotype is not an imprinting disorder.
Mitotic ring instability produces a mosaic effective genotype Position effect silences preserved proximal 14q genes
Downstream
Terminal 14q32 Haploinsufficiency Where ring formation removes terminal 14q material, the deleted segment is present in single copy.
Position-Effect Dysregulation of Proximal 14q Circularisation alters the chromatin context of the chromosome; the steps from that to altered expression of specific proximal genes are not established. Position effect silences preserved proximal 14q genes
Ring Mitotic Instability and Dynamic Mosaicism A circular chromosome is mechanically unstable in mitosis, which is a direct consequence of its topology. Mitotic ring instability produces a mosaic effective genotype
Show evidence (2 references)
PMID:22564756 SUPPORT Human Clinical
"In our own sample of patients the ring was complete, with no apparent loss of chromosome material, in 6/27 cases, while it showed a small terminal deletion, varying in size from 0.3 to 5 Mb, in the other 21."
Establishes that a substantial minority of ring patients lose no material at all, which is what forces a non-deletional mechanism for the shared phenotype.
PMID:22564756 SUPPORT Human Clinical
"Deleted rings were 75% paternal and 25% maternal in origin. UPD (14) was excluded in all cases."
Excludes uniparental disomy, ruling out the imprinting mechanism that chromosome 14 would otherwise raise.
Terminal 14q32 Haploinsufficiency
Mechanism confidence: Provisional
Where the ring carries a terminal deletion, the lost segment lies at 14q32. Comparison with linear 14q deletions assigns the behavioural phenotype and the susceptibility to infection to this region, with simple haploinsufficiency as the mechanism. This branch behaves like an ordinary contiguous gene deletion syndrome and is the part of the phenotype that copy number does explain. PROVISIONAL because the assignment is by phenotype mapping against linear deletion cases, not by demonstrating reduced expression or function of a named gene in ring patients.
regulation of gene expression GO:0010468 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Behavioural Dysregulation Reduced dosage of 14q32 genes is the proposed basis of the behavioural phenotype; no gene or pathway has been named.
Recurrent infections The same 14q32 assignment covers the susceptibility to infection, which is the more consequential half of this branch: infection is the leading cause of death in adulthood in this syndrome. A candidate locus has been named, unlike for the behavioural phenotype: the consensus guideline attributes the infection susceptibility to haploinsufficiency because the distal 14q region carries the immunoglobulin heavy-chain genes. That argument is positional, and it sits awkwardly with the one immunological measurement that has been made: IgG levels in these patients are normal. IGH copy number itself has not been measured. The characterised abnormality is functional rather than quantitative and is modelled separately.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"Behavior disorders and susceptibility to infections can be assigned to the 14q32 region, haploinsufficiency being the most likely underlying mechanism."
Assigns the behavioural and immunological features to 14q32 loss by haploinsufficiency, the claim this node makes.
Position-Effect Dysregulation of Proximal 14q
Mechanism confidence: Hypothetical
The features that define the syndrome map to proximal 14q11.2-q12, which is preserved in every ring patient, so they cannot be explained by loss of material. The proposal is that circularisation changes the chromatin architecture of the chromosome and that heterochromatin spreading from the adjacent short arm silences genes in the proximal interval despite their being present in two copies. The supporting observation is a patient whose ring lost nothing but the telomeres, in whom two of eight chromosome-14 genes assayed were nonetheless downregulated relative to matched controls. FOXG1 at 14q12 is the specific candidate: in a patient with a ring derived from an interstitial excision, the breakpoint fell 225 kb downstream of FOXG1 inside its known regulatory landscape, and the phenotype overlapped FOXG1 syndrome. HYPOTHETICAL, and deliberately so. Two patients is the entire direct evidence base, neither study measured FOXG1 expression in classical ring 14, and no experiment has connected altered expression of any proximal 14q gene to the epilepsy.
Position effect silences preserved proximal 14q genes
heterochromatin formation GO:0031507 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased heterochromatin formation (GO:0031507). GO:0031507 is a biological process from the Gene Ontology. ↑ INCREASED regulation of gene expression GO:0010468 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Cortical Hyperexcitability The proposed route from silencing of proximal 14q genes to a seizure-prone cortex. No intermediate step has been identified. Position effect silences preserved proximal 14q genes
Retinal Pigmentary Abnormality The retinal phenotype maps to the same preserved proximal interval as the epilepsy and is proposed to arise the same way. Position effect silences preserved proximal 14q genes
Show evidence (3 references)
PMID:22564756 SUPPORT Human Clinical
"Because this region is preserved in all patients with ring 14, we speculate that genes residing in the proximal 14q interval are disregulated through heterochromatinization spreading from the adjacent short arm of the chromosome."
States the position-effect proposal and, importantly, states it as speculation, which is why this node is graded HYPOTHETICAL.
PMID:26315457 SUPPORT Human Clinical
"Two of them were found to be downregulated in the patient compared to the controls, indicating that his phenotype might be related to alterations in the expression of genes located in the abnormal chromosome, even when the copy number is normal."
Demonstrates altered expression at normal copy number in a ring that lost only telomeres, which is the direct evidence that position effect operates here.
PMID:25901181 SUPPORT INDIRECT Human Clinical
"the proximal breakpoint was 225 kb downstream of the forkhead box G1 gene (FOXG1), within the known regulatory landscape of FOXG1"
Names FOXG1 as the positional candidate. Graded INDIRECT because this patient carried an interstitial excision rather than the classical ring, and FOXG1 expression was not measured.
Ring Mitotic Instability and Dynamic Mosaicism
Mechanism confidence: Provisional
A ring chromosome segregates poorly. Sister chromatid exchange within the ring generates interlocked and multimeric forms that lag at anaphase, and the ring can be lost outright or sequestered into a micronucleus. The consequence is that the effective genotype varies between cells and drifts with age, which is the standard explanation for why ring phenotypes exceed what their deletion predicts. Direct evidence in ring 14 comes from a single patient studied for instability, in whom micronuclei, aneuploidy involving both the ring and other chromosomes, and anaphase lags were all documented. PROVISIONAL: instability itself is demonstrated, but no study has linked the degree of mosaicism to the severity of the epilepsy, which is what the mechanism would need to explain.
Mitotic ring instability produces a mosaic effective genotype
chromosome segregation GO:0007059 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromosome segregation (GO:0007059). GO:0007059 is a biological process from the Gene Ontology. ⚠ ABNORMAL
micronucleus Relation: this pathophysiological event involves this cellular component This pathophysiological event involves micronucleus.
Downstream
Cortical Hyperexcitability Cell-to-cell variation in effective genotype is proposed to produce a functionally heterogeneous cortex. Untested against seizure severity. Mitotic ring instability produces a mosaic effective genotype
Show evidence (2 references)
PMID:39020403 SUPPORT Human Clinical
"Genomic instability was evidenced by the presence of micronuclei and aneuploidies involving the ring and other chromosomes."
Documents the cytogenetic instability this node asserts, in a ring 14 patient.
PMID:39020403 SUPPORT Human Clinical
"we were able to verify an instability of the r(14) chromosome, mainly involving anaphasic lags and its exclusion from the nucleus in the form of a micronucleus"
Specifies the mitotic mechanism, anaphase lag and micronucleus formation, by which the ring is lost from daughter cells.
Aberrant IgG N-Glycosylation
Mechanism confidence: Hypothetical
A second, and quite different, route to the infection phenotype. Mass spectrometry of patient IgG shows decreased galactosylation and sialylation, a pattern resembling the pro-inflammatory glycoforms seen in autoimmune disease. The change is selective for IgG and is not seen in total serum glycoproteins, and it occurs while IgG concentration is normal. So the immunological defect that has actually been measured in this syndrome is qualitative, not a dosage deficit. Whether it connects to the ring at all is the open question, and the authors are more cautious than a first reading suggests. No galactosyltransferase or sialyltransferase gene lies on chromosome 14, so the straightforward hypothesis of a direct correlation is unproven. Going further, because total serum and transferrin N-glycans are unaffected, the authors judge that the IgG changes do not relate to the structural rearrangement. They then guard the inference in the other direction: the absence of candidate genes in the deleted region does not by itself exclude a genetic basis, because deletion is only one possible mechanism alongside ring instability during cell division and the effect of the ring's new conformation on gene expression. Those two alternatives are the same mechanisms this entry already models as the dynamic_mosaicism and position_effect hypotheses, which is the most useful thing about this finding: it gives those hypotheses a second, independent phenotype to explain. HYPOTHETICAL because the glycosylation abnormality is established while its relationship to the ring is explicitly unresolved in the source, and its contribution to clinical infection risk is untested.
protein N-linked glycosylation GO:0006487 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal protein N-linked glycosylation (GO:0006487). GO:0006487 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Recurrent infections Hypogalactosylated, hyposialylated IgG is functionally altered and is proposed to underlie the impaired immune response. Whether it accounts for the clinical infection burden, and how much of it, is untested.
Show evidence (5 references)
PMID:42352229 SUPPORT Human Clinical
"Patients showed decreased galactosylation and sialylation, resembling pro-inflammatory patterns observed in autoimmune diseases."
Reports the measured glycosylation abnormality in patient IgG.
PMID:42352229 SUPPORT Human Clinical
"These alterations were not observed in total serum glycoproteins, indicating a selective effect on IgG."
Establishes that the defect is specific to IgG rather than a general glycosylation disturbance.
PMID:42352229 SUPPORT Human Clinical
"As immunoglobulin G (IgG) levels remain consistent, functional, rather than quantitative IgG abnormalities, may be implicated"
States that IgG concentration is normal, which is what makes this a functional rather than a dosage lesion and what corrects the entry's earlier claim that immunoglobulin levels were unmeasured.
+ 2 more references
Cortical Hyperexcitability
Mechanism confidence: Hypothetical
The convergence node for the epilepsy, and an acknowledged gap. Epilepsy occurs in essentially all patients, begins early, is polymorphic and drug-resistant, and carries a characteristic electroencephalographic evolution: slow background with pseudoperiodic bursts of generalised slow waves early, then focal frontotemporal or temporoposterior slow waves with interposed multifocal spikes, and unusual rhythmic fast recruiting posterior spikes that generalise. What is not known is how the chromosomal lesion produces this. No causal gene, no ion channel, no synaptic or network abnormality has been identified in ring 14. The node is curated because the clinical and electroencephalographic phenotype is well characterised and highly stereotyped, not because its molecular basis is understood, and both incoming edges are typed as indirect with unknown intermediates for that reason.
cerebral cortex UBERON:0000956 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in cerebral cortex (UBERON:0000956). UBERON:0000956 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Cognitive Decline with Epilepsy Severity Severity of the epileptic phenotype tracks the degree of cognitive impairment.
Show evidence (2 references)
PMID:24116895 SUPPORT Human Clinical
"The incidence of epilepsy in patients with r(14) syndrome is virtually 100%, characterized by early onset, polymorphic seizures, and drug-resistant seizures."
Establishes the near-complete penetrance and drug resistance that make this the defining feature of the syndrome.
PMID:24116895 SUPPORT Human Clinical
"EEG abnormalities consisted of slow background activity with pseudoperiodic bursts of generalized slow waves in the early stage, focal frontotemporal or temporoposterior slow waves with multifocal spikes interposed, and unusual rhythmic fast recruiting posterior spikes followed by secondary..."
Characterises the electroencephalographic signature of the cortical abnormality modeled by this node.
Retinal Pigmentary Abnormality
Mechanism confidence: Provisional
Abnormal retinal pigmentation is the characteristic ocular finding, and like the epilepsy it maps to the preserved proximal 14q interval rather than to the deletion. Reported findings run from pigmentary change through frank retinitis pigmentosa to macular abnormality; multimodal imaging in one patient showed punctiform yellowish macular lesions that were hyperautofluorescent with localised irregularity of the retinal pigment epithelium, with visual acuity preserved.
retina UBERON:0000966 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in retina (UBERON:0000966). UBERON:0000966 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (2 references)
PMID:22564756 SUPPORT Human Clinical
"we could deduce that retinal abnormalities and epilepsy map within the proximal 14q11.2- q12 region"
Places the retinal phenotype in the same preserved interval as the epilepsy, which is the basis for routing both through the position-effect branch.
PMID:31755799 SUPPORT Human Clinical
"The SD-OCT showed normal characteristics at both eyes with the exception of localized irregularity of the RPE in an area associated with a macular yellow dots."
Characterises the retinal pigment epithelial change underlying the macular finding.
Behavioural Dysregulation
Mechanism confidence: Provisional
Hyperactive and aggressive behaviour is reported in a subset of patients and is assigned to 14q32 haploinsufficiency rather than to the proximal interval, which makes it the one part of the phenotype with a conventional dosage explanation.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"Virtually all patients are intellectually delayed, with aggressive and hyperactive behavior in some."
Documents the behavioural phenotype and its partial penetrance.
Cognitive Decline with Epilepsy Severity
Mechanism confidence: Provisional
Intellectual disability is near-universal, and the severity of the epilepsy tracks the degree of cognitive impairment. Whether the seizures drive the cognitive outcome or both reflect the same underlying cortical abnormality is not resolved by the available data, which are cross-sectional.
Show evidence (1 reference)
PMID:24116895 SUPPORT DIRECT Human Clinical
"The degree of severity of the epileptic phenotype negatively influences child cognitive development."
Reports the association between epilepsy severity and cognitive outcome. The study design does not establish the direction of causation.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Ring Chromosome 14 Syndrome Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

28
Digestive 1
Feeding Difficulties FREQUENT HP:0011968 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Nutritional assessment is recommended for all patients and nutritional support for malnourishment can include gastrostomy feeding in selected cases."
A universal nutritional-assessment recommendation implies feeding difficulty is prevalent enough to warrant screening every patient.
Eye 6
Abnormal Retinal Pigmentation OCCASIONAL HP:0007703 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal retinal pigmentation (HP:0007703). HP:0007703 is a phenotype from the Human Phenotype Ontology.
Frequency is Orphanet's class from the HPO annotation for ORPHA:1440. Note the tension with the cited series, which describes retinal abnormality as a consistent feature of the syndrome; Orphanet's occasional class is retained rather than overridden, because the two sources are counting different things and this entry does not have grounds to prefer one.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"ocular abnormalities, consisting mainly of abnormal retinal pigmentation, but also retinitis pigmentosa, strabismus, glaucoma, and abnormal macula"
Documents abnormal retinal pigmentation as the predominant ocular finding and lists the associated ocular phenotypes.
Cataract OCCASIONAL HP:0000518 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cataract (HP:0000518). HP:0000518 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Glaucoma OCCASIONAL HP:0000501 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Glaucoma (HP:0000501). HP:0000501 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Iris coloboma OCCASIONAL HP:0000612 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Iris coloboma (HP:0000612). HP:0000612 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Strabismus OCCASIONAL HP:0000486 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Strabismus (HP:0000486). HP:0000486 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Myopia OCCASIONAL HP:0000545 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Myopia (HP:0000545). HP:0000545 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Head and Neck 1
Secondary microcephaly FREQUENT HP:0005484 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Secondary microcephaly (HP:0005484). HP:0005484 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Immune 2
Recurrent Respiratory Infections FREQUENT HP:0002205 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Recurrent respiratory infections (HP:0002205). HP:0002205 is a phenotype from the Human Phenotype Ontology.
Curated alongside the more general Recurrent infections rather than replacing it. The general term carries the Orphanet frequency class from the HPO annotation; this one carries the respiratory specificity the consensus guideline reports, and the two are supported by different sources.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"increased incidence of infections, particularly respiratory infections, which may require hospitalization"
Establishes the respiratory predominance and the severity of the infection phenotype.
Recurrent infections FREQUENT HP:0002719 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Recurrent infections (HP:0002719). HP:0002719 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Integument 1
Cafe-au-lait spot OCCASIONAL HP:0000957 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cafe-au-lait spot (HP:0000957). HP:0000957 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Musculoskeletal 2
Hypotonia FREQUENT HP:0001252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Scoliosis OCCASIONAL HP:0002650 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Scoliosis (HP:0002650). HP:0002650 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Nervous System 11
Autism Spectrum Disorder FREQUENT Autistic behavior HP:0000729 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Autistic behavior (HP:0000729). HP:0000729 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Ring chromosome 14 syndrome is a rare chromosomal disorder characterized by early onset refractory epilepsy, intellectual disability, autism spectrum disorder and a number of diverse health issues."
The consensus guideline names autism spectrum disorder among the defining features of the syndrome.
Absent or Severely Limited Speech FREQUENT Absent speech HP:0001344 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Absent speech (HP:0001344). HP:0001344 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Many patients with ring chromosome 14 syndrome are nonverbal and thus maintaining their ability to communicate is always essential"
Establishes that a large share of patients are nonverbal.
Drug-Resistant Epilepsy VERY_FREQUENT Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250), qualified as course progressive. HP:0001250 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
The HPO annotation for ORPHA:1440 records Seizure as very frequent, which is consistent with the near-100% incidence reported in the cited series.
Show evidence (2 references)
PMID:24116895 SUPPORT Human Clinical
"The incidence of epilepsy in patients with r(14) syndrome is virtually 100%, characterized by early onset, polymorphic seizures, and drug-resistant seizures."
Establishes near-complete penetrance, early onset and drug resistance in a 22-patient series.
PMID:24116895 SUPPORT Human Clinical
"we ascertained focal secondarily generalized epilepsy, seizure cluster tendency, frequent status epilepticus, and a rather typical epilepsy evolution"
Characterises the seizure semiology and course described here.
Status Epilepticus FREQUENT HP:0002133 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Status epilepticus (HP:0002133). HP:0002133 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24116895 SUPPORT Human Clinical
"we ascertained focal secondarily generalized epilepsy, seizure cluster tendency, frequent status epilepticus, and a rather typical epilepsy evolution"
Reports frequent status epilepticus in the 22-patient series.
Intellectual Disability VERY_FREQUENT HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"Virtually all patients are intellectually delayed, with aggressive and hyperactive behavior in some."
Establishes near-universal intellectual disability in a 27-patient series.
Atypical behavior FREQUENT HP:0000708 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atypical behavior (HP:0000708). HP:0000708 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Interictal EEG abnormality FREQUENT HP:0025373 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Interictal EEG abnormality (HP:0025373). HP:0025373 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Hyperactivity OCCASIONAL HP:0000752 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hyperactivity (HP:0000752). HP:0000752 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Delayed speech and language development FREQUENT HP:0000750 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delayed speech and language development (HP:0000750). HP:0000750 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Abnormal corpus callosum morphology OCCASIONAL HP:0001273 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal corpus callosum morphology (HP:0001273). HP:0001273 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as occasional in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Motor delay FREQUENT HP:0001270 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Motor delay (HP:0001270). HP:0001270 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Growth 3
Short Stature FREQUENT HP:0004322 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Short stature (HP:0004322). HP:0004322 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"the ring 14 syndrome is characterized by a recognizable phenotype of shortness of stature, distinctive facial appearance, microcephaly, scoliosis, and ocular abnormalities"
Lists short stature among the defining features of the syndrome.
Intrauterine growth retardation FREQUENT HP:0001511 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intrauterine growth retardation (HP:0001511). HP:0001511 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Postnatal growth retardation FREQUENT HP:0008897 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Postnatal growth retardation (HP:0008897). HP:0008897 is a phenotype from the Human Phenotype Ontology.
Curated from the HPO disease annotation for ORPHA:1440, which records this feature as frequent in Orphanet's own frequency classification. That class maps directly onto FrequencyEnum, so the frequency here is Orphanet's, not an inference. No evidence item is attached because HPOA is a derived annotation rather than a quotable source.
Other 1
Distinctive Facial Appearance
Deliberately left unbound. HPO has no term for a syndrome-specific facial gestalt, and binding a generic abnormal-facial-shape term would assert less than the source says while looking more precise. The component features are curated individually where they are separately reported.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"the ring 14 syndrome is characterized by a recognizable phenotype of shortness of stature, distinctive facial appearance, microcephaly, scoliosis, and ocular abnormalities"
Establishes a recognisable facial appearance as a defining feature.
💊

Medical Actions

9
Antiseizure Pharmacotherapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: anticonvulsant agent NCIT:C264 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses anticonvulsant agent (NCIT:C264). NCIT:C264 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
Seizure control is the main therapeutic problem and it is largely unsolved: the epilepsy of this syndrome is characterised as drug-resistant in the series that define it. No agent or regimen has been shown to work preferentially here, so treatment follows general drug-resistant focal epilepsy practice rather than anything syndrome-specific.
Target Phenotypes: Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
PMID:24116895 SUPPORT INDIRECT Human Clinical
"The incidence of epilepsy in patients with r(14) syndrome is virtually 100%, characterized by early onset, polymorphic seizures, and drug-resistant seizures."
Establishes that the epilepsy is drug-resistant. Graded INDIRECT because it characterises the therapeutic problem rather than supporting any particular treatment; no trial evidence exists in this syndrome.
PMID:28399932 SUPPORT Human Clinical
"Epilepsy should be treated from the onset with anticonvulsive therapy."
The consensus guideline recommends anticonvulsive therapy from seizure onset, which is the treatment this entry records.
PMID:28399932 SUPPORT Human Clinical
"therapies even if the symptomatology appears less severe: Grade C"
A graded recommendation against withdrawing a working drug on the strength of apparent improvement, which is the specific management error this syndrome invites given its fluctuating course.
Nutritional Support
Action: Nutritional SupportNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Nutritional Support (NCIT:C15433). NCIT:C15433 is a clinical intervention from the NCI Thesaurus. NCIT:C15433
Platform: Behavioral / lifestyle
The consensus guideline recommends nutritional assessment for every patient, with nutritional support for malnourishment escalating to gastrostomy feeding in selected cases. This is one of the few management recommendations in this syndrome that is both specific and universal.
Target Phenotypes: Feeding difficulties HP:0011968 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Nutritional assessment is recommended for all patients and nutritional support for malnourishment can include gastrostomy feeding in selected cases."
States the nutritional recommendation and the escalation to gastrostomy that this treatment records.
Ketogenic Diet or Vagus Nerve Stimulation for Drug-Resistant Seizures
Action: Ketogenic DietNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Ketogenic Diet (NCIT:C173168). NCIT:C173168 is a clinical intervention from the NCI Thesaurus. NCIT:C173168
Platform: Behavioral / lifestyle
About half of patients are drug-resistant, and for them the guideline raises ketogenic diet and vagus nerve stimulation as options to consider. Neither is presented as established in this syndrome; they are the standard escalation for drug-resistant childhood epilepsy and are named as worth considering.
Target Phenotypes: Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT DIRECT Human Clinical
"The Ketogenic diet or Vagal Nerve Stimulation may be taken in consideration for the therapeutic strategy"
Names both options for the drug-resistant half of patients. The quote asserts the recommendation directly, so directness is DIRECT; that the guideline offers them for consideration rather than recommending them, and that no outcome data exist in this syndrome, are matters of strength and are recorded here since the schema has no slot for them.
Early Physical Therapy
Action: Physical TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Physical Therapy (NCIT:C15302). NCIT:C15302 is a clinical intervention from the NCI Thesaurus. NCIT:C15302
Platform: Behavioral / lifestyle
Started early and explicitly preventive rather than restorative: the target is the musculoskeletal consequences of hypotonia, scoliosis in particular, before they become fixed.
Target Phenotypes: Hypotonia HP:0001252 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology. Scoliosis HP:0002650 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Scoliosis (HP:0002650). HP:0002650 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Start physical therapy early to reduce hypotonic complications (such as scoliosis) due to the reduced muscle tone: Grade B"
A Grade B recommendation naming both the intervention and the complication it is meant to prevent.
Speech Therapy for Dysphagia
Action: Speech Language TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Speech Language Therapy (NCIT:C159273). NCIT:C159273 is a clinical intervention from the NCI Thesaurus. NCIT:C159273
Platform: Behavioral / lifestyle
Referral for dysphagia carries the guideline's highest grade. It matters doubly here, because aspiration feeds the respiratory infections that are the leading cause of adult death, so this is airway protection as much as feeding support.
Target Phenotypes: Feeding difficulties HP:0011968 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Children with dysphagia should be referred to a speech therapist: Grade A"
Grade A recommendation for speech-therapy referral in dysphagia.
Vaccination Against Encapsulated Organisms
Action: VaccinationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Vaccination (NCIT:C15346). NCIT:C15346 is a clinical intervention from the NCI Thesaurus. NCIT:C15346
Platform: Vaccine
Extended inactivated-vaccine coverage is part of the infection-prevention strategy that follows from infection being the leading cause of adult death. The guideline names the specific vaccines rather than leaving it general.
Target Phenotypes: Recurrent infections HP:0002719 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Recurrent infections (HP:0002719). HP:0002719 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Recommended (inactivated) vaccines include anti-haemophilus, anti-pneumococcal, anti-meningococcal and flu vaccine: Grade C"
Names the specific inactivated vaccines recommended in this syndrome.
Vitamin D Supplementation
Action: Nutritional SupportNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Nutritional Support (NCIT:C15433). NCIT:C15433 is a clinical intervention from the NCI Thesaurus. NCIT:C15433
Agent: vitamin D CHEBI:28940 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses vitamin D, annotated with calciol (CHEBI:28940). CHEBI:28940 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Given at twice the recommended daily allowance, roughly 800 to 1000 IU daily, as part of nutritional management. The dose is above ordinary supplementation and is specified by the guideline rather than left to general practice.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"vitamin D daily supplementation must be given at twice the of recommended daily allowance"
Specifies the supplementation dose. The quoted sentence carries a typographical error in the source and is reproduced verbatim, as a snippet belongs to the paper.
Respiratory Function Monitoring and Advance Care Planning
Action: Supportive CareNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. NCIT:C15747
Platform: Other
Prompt assessment of any respiratory symptom, with formal screening of respiratory function, carries the guideline's highest grade. So does discussing signs of respiratory failure with parents in advance. That second half is unusual for a management recommendation and follows from the same fact the clinical burden records: respiratory infection is what kills these patients in adulthood, so the conversation is meant to happen before the crisis rather than during it.
Target Phenotypes: Recurrent infections HP:0002719 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Recurrent infections (HP:0002719). HP:0002719 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"Signs of respiratory failure should be discussed with the parents to allow advanced planning: Grade A"
Grade A recommendation covering both respiratory monitoring and advance planning for respiratory failure.
Antibiotic Prophylaxis, Respiratory Physiotherapy and Immunological Evaluation
Action: Antibiotic ProphylaxisNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Antibiotic Prophylaxis (NCIT:C51993). NCIT:C51993 is a clinical intervention from the NCI Thesaurus. NCIT:C51993
Platform: Small molecule
For recurrent pulmonary infection the guideline recommends three things together at Grade A: antibiotic prophylaxis, respiratory physiotherapy, and an immunological evaluation. The last is the one most easily skipped and the most informative here, because the 14q32 deletion is proposed to remove the immunoglobulin heavy-chain locus, so measuring immune function in a patient with recurrent infection is both management and the missing evidence for that mechanism.
Target Phenotypes: Recurrent infections HP:0002719 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Recurrent infections (HP:0002719). HP:0002719 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28399932 SUPPORT Human Clinical
"In case of recurrent pulmonary infections, consider respiratory physiotherapy antibiotic prophylaxis; an immunological evaluation is also strongly recommended: Grade A"
Grade A recommendation naming all three interventions this treatment records.
🌍

Environmental Factors

1
Febrile illness as a seizure trigger
Seizures in this syndrome may be precipitated by fever. This matters practically because infection is both frequent here and the leading cause of adult death, so a febrile illness threatens the patient twice over: directly, and by provoking seizures in an epilepsy that is already drug-resistant.
Show evidence (1 reference)
PMID:23159383 SUPPORT DIRECT Human Clinical
"Epilepsy onset in r(14) syndrome takes place during the first year of life; seizures are generalized or focal and less frequently myoclonic. Seizures might be induced by fever."
Places fever-induced seizures within the described seizure repertoire of the syndrome. The source is a two-case report with a literature review rather than a systematic study of triggers.
Mechanism Target:
EXACERBATES Cortical Hyperexcitability — Fever lowers the threshold of an already seizure-prone cortex rather than creating the susceptibility, so it is modelled as exacerbating the hyperexcitability node rather than triggering it. Retyped from DIRECT for consistency with the sibling edges into this node and, more importantly, for accuracy: how fever precipitates a seizure has been studied in febrile seizures and other epilepsies, but nothing in the ring 14 literature establishes the intermediate steps here, and DIRECT would assert there are none.
Show evidence (1 reference)
PMID:23159383 SUPPORT DIRECT Human Clinical
"Seizures might be induced by fever."
Reports fever as a seizure precipitant in this syndrome. The quote asserts the claim, so directness is DIRECT; that the source does not quantify how often it occurs is a matter of strength, which has no slot and is recorded here.
🔬

Diagnosis

4
Conventional Karyotype
Karyotyping is the test that makes this diagnosis, and the point is not incidental. A complete ring that has lost only telomeric material is balanced in copy number, so chromosomal microarray returns a normal result while the karyotype shows the ring. A child with early drug-resistant epilepsy, intellectual disability and a normal microarray therefore still warrants a karyotype.
Karyotyping NCIT:C16768 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:25901181 SUPPORT Human Clinical
"Array CGH analysis did not show any genomic imbalance but conventional karyotyping and FISH analysis revealed the presence of an interstitial 14q12q24.3 deletion and an extra ring chromosome derived from the deleted material."
A worked case in which array analysis was normal and only karyotype and FISH revealed the ring, which is the diagnostic argument this entry makes.
PMID:28399932 SUPPORT Human Clinical
"Conventional cytogenetics is the primary tool to identify a ring chromosome. Children with a terminal deletion of chromosome 14q ascertained by molecular karyotyping (CGH/SNP array) should be tested secondarily by conventional cytogenetics for the presence of a ring chromosome."
The consensus guideline states the diagnostic order directly: karyotype is primary, and an array-detected terminal 14q deletion should trigger a karyotype to look for a ring.
Chromosomal Microarray for Deletion Sizing
Array analysis does not make the diagnosis but sizes the terminal 14q deletion where one is present, which is what assigns the behavioural and immunological features to 14q32. Reported deletions run from 0.3 to 5 Mb, and a normal array does not exclude the syndrome.
Comparative Genomic Hybridization NCIT:C18084 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"In our own sample of patients the ring was complete, with no apparent loss of chromosome material, in 6/27 cases, while it showed a small terminal deletion, varying in size from 0.3 to 5 Mb, in the other 21."
Gives the deletion size range array analysis resolves, and the proportion of patients in whom there is no deletion for it to find.
Electroencephalography
The electroencephalographic picture evolves in a stereotyped way and is characteristic enough to support the diagnosis: slow background with pseudoperiodic bursts of generalised slow waves early, then focal frontotemporal or temporoposterior slow waves with interposed multifocal spikes, and rhythmic fast recruiting posterior spikes that generalise.
Electroencephalography NCIT:C38054 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:24116895 SUPPORT Human Clinical
"EEG abnormalities consisted of slow background activity with pseudoperiodic bursts of generalized slow waves in the early stage, focal frontotemporal or temporoposterior slow waves with multifocal spikes interposed, and unusual rhythmic fast recruiting posterior spikes followed by secondary..."
Describes the electroencephalographic evolution used diagnostically.
Ophthalmological Surveillance
Regular eye examination is recommended for all patients, because the retinal findings are common, are not detectable without looking, and range from asymptomatic macular change to retinitis pigmentosa.
Eye Examination NCIT:C38060 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:28399932 SUPPORT Human Clinical
"with evaluation of the fundus oculi: Grade B"
The consensus guideline makes periodic fundus examination a graded recommendation, which is stronger and more specific than the single-case support previously cited here.
PMID:31755799 SUPPORT Human Clinical
"Our data support regular eye examination for all patients with ring chromosome 14 syndrome."
Independent support for universal ophthalmic surveillance, from the multimodal imaging case.
📊

Prevalence

1
Worldwide
Cases In Literature Ultra Rare
Reported as case series rather than population estimates. The largest published cohort combined literature review with 27 patients of the authors' own; a separate series characterised the epilepsy in 22 patients. No population prevalence has been established.
Show evidence (1 reference)
PMID:22564756 SUPPORT Human Clinical
"The ring 14 syndrome is a rare condition, whose precise clinical and genetic characterization is still limited. This review summarizes literature data and it describes our own experience with 27 patients with ring 14 syndrome."
Establishes the scale at which this syndrome is reported and states explicitly that its characterisation remains limited.
⚖️

Clinical Burden

High
Two things drive the burden and they are different in kind. The epilepsy is near-universal, begins in the first months of life and resists drugs in about half of patients, and its severity tracks cognitive outcome. But the fact that changes management most is that infection, not seizures, is the leading cause of death in adulthood. The guideline is explicit that infection is among the worst prognostic factors and that prevention should be pursued actively rather than reactively, through hygiene, parental training for early recognition, extended vaccination and early hospitalisation. An entry that modelled only the epilepsy would misrepresent what actually kills these patients.
Show evidence (2 references)
PMID:28399932 SUPPORT Human Clinical
"and the main cause of death in adulthood, all measures preventing infections must be undertaken"
States that infection is the leading cause of adult death in this syndrome and that prevention is therefore a standing management obligation.
PMID:24116895 SUPPORT Human Clinical
"The degree of severity of the epileptic phenotype negatively influences child cognitive development."
Establishes that epilepsy severity drives the cognitive component of the burden.
🔬

Clinical Trials

1
NCT06813469 NOT_APPLICABLE RECRUITING
MD-RING, a genomic study that directly tests the position-effect hypothesis this entry models. It sets out to examine whether position effects and topologically associating domain alterations are the pathomechanism of the syndrome, which is precisely the question the position_effect hypothesis group and the epilepsy knowledge gap record as open.
Target Phenotypes: Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
clinicaltrials:NCT06813469 SUPPORT Other
"MD-RING will explore the hypothesis that position effects and TAD alterations act as an unprecedented pathomechanism in r(14)S."
The registered aim is an explicit test of the position-effect mechanism curated here as an EMERGING hypothesis, so this study is the live route to resolving that gap.
{ }

Source YAML

click to show 
name: Ring Chromosome 14 Syndrome
creation_date: "2026-08-29T00:00:00Z"
category: Genetic
synonyms:
- r(14) syndrome
- ring 14 syndrome
- ring chromosome 14
- chromosome 14 ring
description: >-
  Ring chromosome 14 syndrome is a rare chromosomal disorder in which the two
  ends of chromosome 14 fuse into a circle. It is dominated by an epilepsy that
  begins in the first years of life, is polymorphic and drug-resistant, and
  occurs in essentially every patient. Alongside it sit intellectual disability,
  microcephaly, short stature, a distinctive facial appearance, scoliosis, and a
  characteristic retinal pigmentary abnormality.

  The mechanistically interesting part is that the deletion does not explain the
  syndrome. Ring formation usually removes a small terminal segment of 14q, and
  in a minority of patients it removes nothing at all. Mapping the features
  against linear 14q deletions puts the epilepsy and the retinal abnormality in
  proximal 14q11.2-q12 — a region that is intact in every ring patient. So the
  two defining features of the syndrome arise from a region that has not been
  deleted, and the deletion that is present sits somewhere else, at 14q32, where
  it plausibly accounts for the behavioural phenotype and the susceptibility to
  infection by ordinary haploinsufficiency.

  Two candidate explanations carry the unexplained part, and this entry models
  both rather than choosing. The first is position effect: circularisation
  changes the chromatin architecture of the chromosome, and heterochromatin
  spreading from the adjacent short arm may silence proximal 14q genes that are
  physically present in normal copy number. A patient whose complete ring lost
  only its telomeres nonetheless showed two of eight chromosome-14 genes
  downregulated, which is the cleanest demonstration that copy number and
  expression come apart here. FOXG1, at 14q12, is the specific candidate this
  points at. The second is dynamic mosaicism: rings are mitotically unstable, and
  a patient studied for instability showed anaphase lags, aneuploidy and the ring
  excluded from the nucleus as a micronucleus, so the effective genotype differs
  from cell to cell and worsens over time.

  These are not competing accounts of one thing so much as two consequences of
  the same lesion, and the syndrome may need both. Neither has been shown to
  cause the epilepsy.
disease_term:
  preferred_term: ring chromosome 14
  term:
    id: MONDO:0014708
    label: ring chromosome 14
parents:
- Ring chromosome disorder
- Chromosome 14 disorder
- Epilepsy
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0014708
      label: ring chromosome 14
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
    mapping_justification: >-
      MONDO:0014708 is the ring chromosome 14 concept modeled by this entry.
      MONDO cross-references it to Orphanet:1440, the source of the phenotype
      frequencies curated here.
references:
- reference: PMID:22564756
  title: The ring 14 syndrome.
- reference: PMID:24116895
  title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
- reference: PMID:28399932
  title: >-
    Guideline recommendations for diagnosis and clinical management of Ring14
    syndrome-first report of an ad hoc task force.
notes: >-
  Scope note on the mechanism graph. This entry carries two parallel mechanism
  branches out of a single chromosomal lesion, and neither is established. The
  14q32 terminal deletion branch is ordinary haploinsufficiency and is
  well-supported for the behavioural and immunological features. The proximal
  14q11.2-q12 branch, which carries the epilepsy and the retinal phenotype, has
  no deletion behind it at all: that region is preserved in every ring patient.
  Position effect and dynamic mosaicism are both curated as mechanistic
  hypotheses with EMERGING status rather than asserted, and the causal edges
  into the epilepsy node are typed INDIRECT_UNKNOWN_INTERMEDIATES because the
  route from either to cortical hyperexcitability is exactly what is missing.

  No genetic section. There is no causal gene. FOXG1 is a specific candidate
  raised by one patient whose ring breakpoint fell within the FOXG1 regulatory
  landscape, but it is a positional hypothesis about a gene that is neither
  deleted nor mutated, so typing it CAUSATIVE in a genetic block would
  misrepresent the evidence. It is curated inside the position-effect hypothesis
  where the reasoning can be stated.

  A named 14q32.33 candidate is proposed by the sources and deliberately not
  curated as a mechanism node. The consensus guideline states that susceptibility
  to infection was also seen in linear 14q deletions and attributes it to
  haploinsufficiency on the grounds that the distal region of 14q contains the
  immunoglobulin heavy-chain genes. The deep-research report names the same IGH
  locus, and PACS2 as an epilepsy candidate in the same band.

  The restraint is about the kind of claim, not the absence of one. The
  guideline's argument is positional: the locus lies in the deleted interval and
  its content would explain the phenotype. IGH copy number has not been measured
  in ring 14 patients, so nothing ties the immune phenotype to that locus
  directly. Immunoglobulin levels, by contrast, have been measured, and they are
  normal, which argues against a simple dosage story: the reported abnormality is
  functional rather than quantitative and is curated as its own node. The IGH
  proposal is therefore cited as evidence on the infection edge rather than
  promoted into a named-gene pathophysiology node. PACS2 has weaker footing still
  and is recorded only here.

  Phenotype sourcing. Frequencies come from the HPO disease annotation for
  ORPHA:1440, which carries Orphanet's own curated frequency classes (Very
  frequent, Frequent, Occasional). These map onto FrequencyEnum directly and are
  used as such. Phenotypes carrying that provenance have it recorded in notes
  rather than a manufactured quote, because HPOA is a derived annotation and not
  a quotable source. Phenotypes that are additionally supported by a cited series
  carry an evidence item as well. The Orphanet bulk XML was not downloaded to
  build an ORPHA reference-cache entry, because doing so would have added
  manifest churn unrelated to this curation.
pathophysiology:
- name: Ring Chromosome 14 Formation
  biological_scale: MOLECULAR
  mechanism_confidence: ESTABLISHED
  description: >-
    Breakage in both arms of chromosome 14 followed by fusion of the ends
    produces a circular chromosome. In the reported series the ring was complete,
    with no apparent loss of material, in 6 of 27 patients, and carried a small
    terminal deletion of 0.3 to 5 Mb in the remaining 21. Rings with a deletion
    were paternal in origin in about three quarters of cases, and uniparental
    disomy for chromosome 14 was excluded throughout, so the phenotype is not an
    imprinting disorder.
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In our own sample of patients the ring was complete, with no apparent loss
      of chromosome material, in 6/27 cases, while it showed a small terminal
      deletion, varying in size from 0.3 to 5 Mb, in the other 21.
    explanation: >-
      Establishes that a substantial minority of ring patients lose no material
      at all, which is what forces a non-deletional mechanism for the shared
      phenotype.
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Deleted rings were 75% paternal and 25% maternal in origin. UPD (14) was
      excluded in all cases.
    explanation: >-
      Excludes uniparental disomy, ruling out the imprinting mechanism that
      chromosome 14 would otherwise raise.
  downstream:
  - target: Terminal 14q32 Haploinsufficiency
    causal_link_type: DIRECT
    description: >-
      Where ring formation removes terminal 14q material, the deleted segment is
      present in single copy.
    evidence:
    - reference: PMID:22564756
      reference_title: The ring 14 syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        it showed a small terminal deletion, varying in size from 0.3 to 5 Mb, in
        the other 21
      explanation: >-
        Documents that ring formation produces a terminal 14q deletion in the
        majority of patients, which is the edge asserted here.
  - target: Position-Effect Dysregulation of Proximal 14q
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - position_effect
    description: >-
      Circularisation alters the chromatin context of the chromosome; the steps
      from that to altered expression of specific proximal genes are not
      established.
    evidence:
    - reference: PMID:26315457
      reference_title: Position effect modifying gene expression in a patient with ring chromosome 14.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        phenotypic alterations can also be found in the presence of complete ring
        chromosomes, in which the breakage and rejoining in terminal regions of
        both chromosome arms result in no gene loss
      explanation: >-
        Supports an edge from ring formation to phenotype that does not run
        through gene loss. Graded INDIRECT because it establishes that such a
        route exists without identifying its steps.
  - target: Ring Mitotic Instability and Dynamic Mosaicism
    causal_link_type: DIRECT
    hypothesis_groups:
    - dynamic_mosaicism
    description: >-
      A circular chromosome is mechanically unstable in mitosis, which is a
      direct consequence of its topology.
    evidence:
    - reference: PMID:39020403
      reference_title: "Chromosomal instability in a patient with ring chromosome 14 syndrome: a case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        we were able to verify an instability of the r(14) chromosome, mainly
        involving anaphasic lags and its exclusion from the nucleus in the form of
        a micronucleus
      explanation: >-
        Demonstrates that the ring configuration itself produces mitotic
        instability in a ring 14 patient.
- name: Terminal 14q32 Haploinsufficiency
  biological_scale: MOLECULAR
  mechanism_confidence: PROVISIONAL
  description: >-
    Where the ring carries a terminal deletion, the lost segment lies at 14q32.
    Comparison with linear 14q deletions assigns the behavioural phenotype and
    the susceptibility to infection to this region, with simple haploinsufficiency
    as the mechanism. This branch behaves like an ordinary contiguous gene
    deletion syndrome and is the part of the phenotype that copy number does
    explain.

    PROVISIONAL because the assignment is by phenotype mapping against linear
    deletion cases, not by demonstrating reduced expression or function of a
    named gene in ring patients.
  biological_processes:
  - preferred_term: regulation of gene expression
    term:
      id: GO:0010468
      label: regulation of gene expression
    modifier: DECREASED
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Behavior disorders and susceptibility to infections can be assigned to the
      14q32 region, haploinsufficiency being the most likely underlying
      mechanism.
    explanation: >-
      Assigns the behavioural and immunological features to 14q32 loss by
      haploinsufficiency, the claim this node makes.
  downstream:
  - target: Behavioural Dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Reduced dosage of 14q32 genes is the proposed basis of the behavioural
      phenotype; no gene or pathway has been named.
    evidence:
    - reference: PMID:22564756
      reference_title: The ring 14 syndrome.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Behavior disorders and susceptibility to infections can be assigned to the
        14q32 region, haploinsufficiency being the most likely underlying
        mechanism.
      explanation: >-
        Assigns the behavioural phenotype to 14q32 loss. The assignment is made
        by comparison with linear deletions and names no gene.
  - target: Recurrent infections
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The same 14q32 assignment covers the susceptibility to infection, which is
      the more consequential half of this branch: infection is the leading cause
      of death in adulthood in this syndrome. A candidate locus has been named,
      unlike for the behavioural phenotype: the consensus guideline attributes
      the infection susceptibility to haploinsufficiency because the distal 14q
      region carries the immunoglobulin heavy-chain genes. That argument is
      positional, and it sits awkwardly with the one immunological measurement
      that has been made: IgG levels in these patients are normal. IGH copy
      number itself has not been measured. The characterised abnormality is
      functional rather than quantitative and is modelled separately.
    evidence:
    - reference: PMID:22564756
      reference_title: The ring 14 syndrome.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Behavior disorders and susceptibility to infections can be assigned to the
        14q32 region, haploinsufficiency being the most likely underlying
        mechanism.
      explanation: >-
        The same sentence that assigns the behavioural phenotype to 14q32
        assigns the infection susceptibility there too. The assignment is
        positional and names no gene or immune mechanism.
    - reference: PMID:28399932
      reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        the distal region of 14q contains the genes for heavy chains of
        antibodies
      explanation: >-
        Names the immunoglobulin heavy-chain locus as the presumed basis of the
        infection susceptibility. Graded INDIRECT because the guideline argues
        from what the deleted interval contains rather than from any
        immunological measurement in ring 14 patients.
- name: Position-Effect Dysregulation of Proximal 14q
  biological_scale: MOLECULAR
  mechanism_confidence: HYPOTHETICAL
  description: >-
    The features that define the syndrome map to proximal 14q11.2-q12, which is
    preserved in every ring patient, so they cannot be explained by loss of
    material. The proposal is that circularisation changes the chromatin
    architecture of the chromosome and that heterochromatin spreading from the
    adjacent short arm silences genes in the proximal interval despite their
    being present in two copies.

    The supporting observation is a patient whose ring lost nothing but the
    telomeres, in whom two of eight chromosome-14 genes assayed were nonetheless
    downregulated relative to matched controls. FOXG1 at 14q12 is the specific
    candidate: in a patient with a ring derived from an interstitial excision,
    the breakpoint fell 225 kb downstream of FOXG1 inside its known regulatory
    landscape, and the phenotype overlapped FOXG1 syndrome.

    HYPOTHETICAL, and deliberately so. Two patients is the entire direct
    evidence base, neither study measured FOXG1 expression in classical ring 14,
    and no experiment has connected altered expression of any proximal 14q gene
    to the epilepsy.
  biological_processes:
  - preferred_term: heterochromatin formation
    term:
      id: GO:0031507
      label: heterochromatin formation
    modifier: INCREASED
  - preferred_term: regulation of gene expression
    term:
      id: GO:0010468
      label: regulation of gene expression
    modifier: DECREASED
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Because this region is preserved in all patients with ring 14, we speculate
      that genes residing in the proximal 14q interval are disregulated through
      heterochromatinization spreading from the adjacent short arm of the
      chromosome.
    explanation: >-
      States the position-effect proposal and, importantly, states it as
      speculation, which is why this node is graded HYPOTHETICAL.
  - reference: PMID:26315457
    reference_title: Position effect modifying gene expression in a patient with ring chromosome 14.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Two of them were found to be downregulated in the patient compared to the
      controls, indicating that his phenotype might be related to alterations in
      the expression of genes located in the abnormal chromosome, even when the
      copy number is normal.
    explanation: >-
      Demonstrates altered expression at normal copy number in a ring that lost
      only telomeres, which is the direct evidence that position effect operates
      here.
  - reference: PMID:25901181
    reference_title: Dysregulation of FOXG1 by ring chromosome 14.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the proximal breakpoint was 225 kb downstream of the forkhead box G1 gene
      (FOXG1), within the known regulatory landscape of FOXG1
    explanation: >-
      Names FOXG1 as the positional candidate. Graded INDIRECT because this
      patient carried an interstitial excision rather than the classical ring,
      and FOXG1 expression was not measured.
  downstream:
  - target: Cortical Hyperexcitability
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - position_effect
    description: >-
      The proposed route from silencing of proximal 14q genes to a seizure-prone
      cortex. No intermediate step has been identified.
    evidence:
    - reference: PMID:22564756
      reference_title: The ring 14 syndrome.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        we could deduce that retinal abnormalities and epilepsy map within the
        proximal 14q11.2- q12 region
      explanation: >-
        Localises the epilepsy to the interval this branch acts on. Typed
        INDIRECT because localisation is not mechanism: nothing shows that
        silencing these genes causes seizures.
  - target: Retinal Pigmentary Abnormality
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - position_effect
    description: >-
      The retinal phenotype maps to the same preserved proximal interval as the
      epilepsy and is proposed to arise the same way.
    evidence:
    - reference: PMID:22564756
      reference_title: The ring 14 syndrome.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        we could deduce that retinal abnormalities and epilepsy map within the
        proximal 14q11.2- q12 region
      explanation: >-
        Places the retinal phenotype in the preserved proximal interval alongside
        the epilepsy. Graded INDIRECT for the same reason: this is mapping, not
        mechanism.
- name: Ring Mitotic Instability and Dynamic Mosaicism
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  description: >-
    A ring chromosome segregates poorly. Sister chromatid exchange within the
    ring generates interlocked and multimeric forms that lag at anaphase, and the
    ring can be lost outright or sequestered into a micronucleus. The consequence
    is that the effective genotype varies between cells and drifts with age,
    which is the standard explanation for why ring phenotypes exceed what their
    deletion predicts.

    Direct evidence in ring 14 comes from a single patient studied for
    instability, in whom micronuclei, aneuploidy involving both the ring and
    other chromosomes, and anaphase lags were all documented.

    PROVISIONAL: instability itself is demonstrated, but no study has linked the
    degree of mosaicism to the severity of the epilepsy, which is what the
    mechanism would need to explain.
  cellular_components:
  - preferred_term: micronucleus
    description: >-
      Deliberately unbound. GO:0031040 micronucleus resolves and validates, but
      its definition is a membrane-bounded organelle of ciliated protozoan cells
      containing a diploid copy of the genome, and the term carries an explicit
      Ciliophora taxon restriction. That is the ciliate germline nucleus, not the
      mitotic-error micronucleus reported here. GO:0032125 micronucleus
      organization is the same ciliate concept. No correct GO term exists, so per
      the no-term-beats-a-bad-one rule this is free text pending a new-term
      request.
  biological_processes:
  - preferred_term: chromosome segregation
    term:
      id: GO:0007059
      label: chromosome segregation
    modifier: ABNORMAL
  evidence:
  - reference: PMID:39020403
    reference_title: "Chromosomal instability in a patient with ring chromosome 14 syndrome: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Genomic instability was evidenced by the presence of micronuclei and
      aneuploidies involving the ring and other chromosomes.
    explanation: >-
      Documents the cytogenetic instability this node asserts, in a ring 14
      patient.
  - reference: PMID:39020403
    reference_title: "Chromosomal instability in a patient with ring chromosome 14 syndrome: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we were able to verify an instability of the r(14) chromosome, mainly
      involving anaphasic lags and its exclusion from the nucleus in the form of
      a micronucleus
    explanation: >-
      Specifies the mitotic mechanism, anaphase lag and micronucleus formation,
      by which the ring is lost from daughter cells.
  downstream:
  - target: Cortical Hyperexcitability
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - dynamic_mosaicism
    description: >-
      Cell-to-cell variation in effective genotype is proposed to produce a
      functionally heterogeneous cortex. Untested against seizure severity.
    evidence:
    - reference: PMID:25901181
      reference_title: Dysregulation of FOXG1 by ring chromosome 14.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        dysregulation of FOXG1 may contribute to the classical r(14)-syndrome,
        likely mediated by dynamic mosaicism
      explanation: >-
        Proposes mosaicism as the mediator between the ring and the phenotype.
        Graded INDIRECT: it is an interpretation offered by the authors, not a
        measured relationship.
- name: Aberrant IgG N-Glycosylation
  biological_scale: MOLECULAR
  mechanism_confidence: HYPOTHETICAL
  description: >-
    A second, and quite different, route to the infection phenotype. Mass
    spectrometry of patient IgG shows decreased galactosylation and sialylation,
    a pattern resembling the pro-inflammatory glycoforms seen in autoimmune
    disease. The change is selective for IgG and is not seen in total serum
    glycoproteins, and it occurs while IgG concentration is normal. So the
    immunological defect that has actually been measured in this syndrome is
    qualitative, not a dosage deficit.

    Whether it connects to the ring at all is the open question, and the authors
    are more cautious than a first reading suggests. No galactosyltransferase or
    sialyltransferase gene lies on chromosome 14, so the straightforward
    hypothesis of a direct correlation is unproven. Going further, because total
    serum and transferrin N-glycans are unaffected, the authors judge that the
    IgG changes do not relate to the structural rearrangement. They then guard
    the inference in the other direction: the absence of candidate genes in the
    deleted region does not by itself exclude a genetic basis, because deletion
    is only one possible mechanism alongside ring instability during cell
    division and the effect of the ring's new conformation on gene expression.

    Those two alternatives are the same mechanisms this entry already models as
    the dynamic_mosaicism and position_effect hypotheses, which is the most
    useful thing about this finding: it gives those hypotheses a second,
    independent phenotype to explain.

    HYPOTHETICAL because the glycosylation abnormality is established while its
    relationship to the ring is explicitly unresolved in the source, and its
    contribution to clinical infection risk is untested.
  biological_processes:
  - preferred_term: protein N-linked glycosylation
    term:
      id: GO:0006487
      label: protein N-linked glycosylation
    modifier: ABNORMAL
  evidence:
  - reference: PMID:42352229
    reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients showed decreased galactosylation and sialylation, resembling
      pro-inflammatory patterns observed in autoimmune diseases.
    explanation: >-
      Reports the measured glycosylation abnormality in patient IgG.
  - reference: PMID:42352229
    reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These alterations were not observed in total serum glycoproteins,
      indicating a selective effect on IgG.
    explanation: >-
      Establishes that the defect is specific to IgG rather than a general
      glycosylation disturbance.
  - reference: PMID:42352229
    reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      As immunoglobulin G (IgG) levels remain consistent, functional, rather than
      quantitative IgG abnormalities, may be implicated
    explanation: >-
      States that IgG concentration is normal, which is what makes this a
      functional rather than a dosage lesion and what corrects the entry's
      earlier claim that immunoglobulin levels were unmeasured.
  - reference: PMID:42352229
    reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
    supports: REFUTE
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      it appears that the observed increase in agalactosylated and asialylated
      N-glycans and the concurrent decrease in galactosylated and sialylated
      glycoforms of serum IgG do not relate to the structural chromosomal RC14
      rearrangement
    explanation: >-
      The authors' own conclusion, and the strongest statement in the source
      about the link to the ring: they judge the IgG changes not to relate to
      the rearrangement, because total serum and transferrin N-glycans are
      unaffected. Typed REFUTE deliberately. The glycosylation abnormality
      itself is not in doubt, but this node sits in a pathophysiology chain and
      so asserts a causal relationship to the ring; this sentence disputes
      exactly that, and burying it as supporting evidence would misrepresent the
      source.
  - reference: PMID:42352229
    reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the lack of candidate genes within the region that is typically deleted
      does not in itself exclude an underlying genetic basis
    explanation: >-
      The counterweight to the previous item. The authors decline to treat gene
      absence as proof either way, which is why this node is HYPOTHETICAL rather
      than removed from the pathograph.
  downstream:
  - target: Recurrent infections
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Hypogalactosylated, hyposialylated IgG is functionally altered and is
      proposed to underlie the impaired immune response. Whether it accounts for
      the clinical infection burden, and how much of it, is untested.
    evidence:
    - reference: PMID:42352229
      reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Recent clinical cohorts have reported alterations in immune cell subsets
        and impaired immune responses
      explanation: >-
        Supports an impaired immune response in these patients. Typed INDIRECT
        because it is background citation of prior cohorts rather than a
        demonstrated link from the glycosylation change to infection.

- name: Cortical Hyperexcitability
  biological_scale: TISSUE
  mechanism_confidence: HYPOTHETICAL
  description: >-
    The convergence node for the epilepsy, and an acknowledged gap. Epilepsy
    occurs in essentially all patients, begins early, is polymorphic and
    drug-resistant, and carries a characteristic electroencephalographic
    evolution: slow background with pseudoperiodic bursts of generalised slow
    waves early, then focal frontotemporal or temporoposterior slow waves with
    interposed multifocal spikes, and unusual rhythmic fast recruiting posterior
    spikes that generalise.

    What is not known is how the chromosomal lesion produces this. No causal
    gene, no ion channel, no synaptic or network abnormality has been identified
    in ring 14. The node is curated because the clinical and
    electroencephalographic phenotype is well characterised and highly
    stereotyped, not because its molecular basis is understood, and both incoming
    edges are typed as indirect with unknown intermediates for that reason.
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  evidence:
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The incidence of epilepsy in patients with r(14) syndrome is virtually
      100%, characterized by early onset, polymorphic seizures, and drug-resistant
      seizures.
    explanation: >-
      Establishes the near-complete penetrance and drug resistance that make this
      the defining feature of the syndrome.
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      EEG abnormalities consisted of slow background activity with pseudoperiodic
      bursts of generalized slow waves in the early stage, focal frontotemporal
      or temporoposterior slow waves with multifocal spikes interposed, and
      unusual rhythmic fast recruiting posterior spikes followed by secondary
      generalization.
    explanation: >-
      Characterises the electroencephalographic signature of the cortical
      abnormality modeled by this node.
  downstream:
  - target: Cognitive Decline with Epilepsy Severity
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Severity of the epileptic phenotype tracks the degree of cognitive
      impairment.
    evidence:
    - reference: PMID:24116895
      reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The degree of severity of the epileptic phenotype negatively influences
        child cognitive development.
      explanation: >-
        Reports the association. A cross-sectional series cannot establish that
        the seizures drive the cognitive outcome.
- name: Retinal Pigmentary Abnormality
  biological_scale: TISSUE
  mechanism_confidence: PROVISIONAL
  description: >-
    Abnormal retinal pigmentation is the characteristic ocular finding, and like
    the epilepsy it maps to the preserved proximal 14q interval rather than to
    the deletion. Reported findings run from pigmentary change through frank
    retinitis pigmentosa to macular abnormality; multimodal imaging in one
    patient showed punctiform yellowish macular lesions that were hyperautofluorescent
    with localised irregularity of the retinal pigment epithelium, with visual
    acuity preserved.
  locations:
  - preferred_term: retina
    term:
      id: UBERON:0000966
      label: retina
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we could deduce that retinal abnormalities and epilepsy map within the
      proximal 14q11.2- q12 region
    explanation: >-
      Places the retinal phenotype in the same preserved interval as the
      epilepsy, which is the basis for routing both through the position-effect
      branch.
  - reference: PMID:31755799
    reference_title: Multimodal imaging of ring 14 syndrome associated maculopathy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The SD-OCT showed normal characteristics at both eyes with the exception of
      localized irregularity of the RPE in an area associated with a macular
      yellow dots.
    explanation: >-
      Characterises the retinal pigment epithelial change underlying the macular
      finding.
- name: Behavioural Dysregulation
  biological_scale: ORGANISM
  mechanism_confidence: PROVISIONAL
  description: >-
    Hyperactive and aggressive behaviour is reported in a subset of patients and
    is assigned to 14q32 haploinsufficiency rather than to the proximal interval,
    which makes it the one part of the phenotype with a conventional dosage
    explanation.
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Virtually all patients are intellectually delayed, with aggressive and
      hyperactive behavior in some.
    explanation: >-
      Documents the behavioural phenotype and its partial penetrance.
- name: Cognitive Decline with Epilepsy Severity
  biological_scale: ORGANISM
  mechanism_confidence: PROVISIONAL
  description: >-
    Intellectual disability is near-universal, and the severity of the epilepsy
    tracks the degree of cognitive impairment. Whether the seizures drive the
    cognitive outcome or both reflect the same underlying cortical abnormality is
    not resolved by the available data, which are cross-sectional.
  evidence:
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The degree of severity of the epileptic phenotype negatively influences
      child cognitive development.
    explanation: >-
      Reports the association between epilepsy severity and cognitive outcome.
      The study design does not establish the direction of causation.
mechanistic_hypotheses:
- hypothesis_group_id: position_effect
  hypothesis_label: Position effect silences preserved proximal 14q genes
  status: EMERGING
  description: >-
    Circularisation changes the chromatin architecture of chromosome 14, and
    heterochromatin spreading from the short arm silences genes in the proximal
    14q11.2-q12 interval that remain present in normal copy number. This is the
    only account on offer for why the epilepsy and the retinal phenotype map to a
    region that is never deleted. FOXG1 at 14q12 is the named candidate.

    The evidence is two patients: one whose telomere-only ring showed two of
    eight chromosome-14 genes downregulated at normal copy number, and one whose
    breakpoint fell within the FOXG1 regulatory landscape with a
    FOXG1-syndrome-like phenotype. Neither demonstrates silencing of a proximal
    gene in a classical ring 14 patient, and neither connects expression to
    seizures.
  evidence:
  - reference: PMID:26315457
    reference_title: Position effect modifying gene expression in a patient with ring chromosome 14.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the phenotypic alterations found in the presence of complete ring
      chromosomes may be related to changes in the chromatin architecture,
      bringing about a change of expression by position effect
    explanation: >-
      States the position-effect model and the chromatin-architecture mechanism
      behind it.
- hypothesis_group_id: dynamic_mosaicism
  hypothesis_label: Mitotic ring instability produces a mosaic effective genotype
  status: EMERGING
  description: >-
    The ring is unstable in mitosis, so cells lose it or carry rearranged forms
    of it at varying rates. The resulting mosaicism, which increases with age,
    would make the functional genotype of any tissue a mixture and could explain
    why the phenotype exceeds the deletion and why it progresses.

    Instability itself is documented in a ring 14 patient. What is missing is any
    link between the degree of mosaicism and the severity of the phenotype, in
    this or any other ring 14 patient.
  evidence:
  - reference: PMID:25901181
    reference_title: Dysregulation of FOXG1 by ring chromosome 14.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      dysregulation of FOXG1 may contribute to the classical r(14)-syndrome,
      likely mediated by dynamic mosaicism
    explanation: >-
      Proposes dynamic mosaicism as the mediator. Graded INDIRECT because it is
      offered as an interpretation of a single atypical case, not a
      demonstration.
phenotypes:
- category: Behavioral
  name: Autism Spectrum Disorder
  frequency: FREQUENT
  description: >-
    Autistic traits are named among the defining features of the syndrome by the
    consensus guideline, which recommends they be carefully evaluated in every
    patient rather than looked for only when volunteered.
  phenotype_term:
    preferred_term: Autistic behavior
    term:
      id: HP:0000729
      label: Autistic behavior
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ring chromosome 14 syndrome is a rare chromosomal disorder characterized by
      early onset refractory epilepsy, intellectual disability, autism spectrum
      disorder and a number of diverse health issues.
    explanation: >-
      The consensus guideline names autism spectrum disorder among the defining
      features of the syndrome.
- category: Gastrointestinal
  name: Feeding Difficulties
  frequency: FREQUENT
  description: >-
    Feeding difficulty is common enough that the consensus guideline recommends
    nutritional assessment for every patient, and gastrostomy feeding in selected
    cases of malnourishment.
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Nutritional assessment is recommended for all patients and nutritional
      support for malnourishment can include gastrostomy feeding in selected
      cases.
    explanation: >-
      A universal nutritional-assessment recommendation implies feeding
      difficulty is prevalent enough to warrant screening every patient.
- category: Neurologic
  name: Absent or Severely Limited Speech
  frequency: FREQUENT
  description: >-
    Many patients are nonverbal. The guideline treats preservation of whatever
    communicative ability exists as a standing management priority rather than a
    rehabilitation target.
  phenotype_term:
    preferred_term: Absent speech
    term:
      id: HP:0001344
      label: Absent speech
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Many patients with ring chromosome 14 syndrome are nonverbal and thus
      maintaining their ability to communicate is always essential
    explanation: >-
      Establishes that a large share of patients are nonverbal.
- category: Immunologic
  name: Recurrent Respiratory Infections
  frequency: FREQUENT
  description: >-
    The infections that matter clinically are predominantly respiratory, and they
    are severe enough to require hospitalisation. This specificity is what
    connects the infection phenotype to the mortality recorded in
    clinical_burden, since respiratory infection is the route by which infection
    becomes the leading cause of adult death.
  phenotype_term:
    preferred_term: Recurrent respiratory infections
    term:
      id: HP:0002205
      label: Recurrent respiratory infections
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      increased incidence of infections, particularly respiratory infections,
      which may require hospitalization
    explanation: >-
      Establishes the respiratory predominance and the severity of the infection
      phenotype.
  notes: >-
    Curated alongside the more general Recurrent infections rather than replacing
    it. The general term carries the Orphanet frequency class from the HPO
    annotation; this one carries the respiratory specificity the consensus
    guideline reports, and the two are supported by different sources.
- category: Neurologic
  name: Drug-Resistant Epilepsy
  frequency: VERY_FREQUENT
  description: >-
    Epilepsy occurs in essentially every patient. Onset is early, seizures are
    polymorphic and drug-resistant, and the course includes a tendency to
    cluster, frequent status epilepticus, and focal seizures with secondary
    generalisation.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The incidence of epilepsy in patients with r(14) syndrome is virtually
      100%, characterized by early onset, polymorphic seizures, and drug-resistant
      seizures.
    explanation: >-
      Establishes near-complete penetrance, early onset and drug resistance in a
      22-patient series.
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we ascertained focal secondarily generalized epilepsy, seizure cluster
      tendency, frequent status epilepticus, and a rather typical epilepsy
      evolution
    explanation: >-
      Characterises the seizure semiology and course described here.
  notes: >-
    The HPO annotation for ORPHA:1440 records Seizure as very frequent, which is
    consistent with the near-100% incidence reported in the cited series.
- category: Neurologic
  name: Status Epilepticus
  frequency: FREQUENT
  description: >-
    Status epilepticus is a recurrent feature of the course rather than an
    isolated complication, and is part of what makes the epilepsy difficult to
    manage.
  phenotype_term:
    preferred_term: Status epilepticus
    term:
      id: HP:0002133
      label: Status epilepticus
  evidence:
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we ascertained focal secondarily generalized epilepsy, seizure cluster
      tendency, frequent status epilepticus, and a rather typical epilepsy
      evolution
    explanation: >-
      Reports frequent status epilepticus in the 22-patient series.
- category: Neurologic
  name: Intellectual Disability
  frequency: VERY_FREQUENT
  description: >-
    Intellectual disability is near-universal, and its severity tracks the
    severity of the epilepsy.
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Virtually all patients are intellectually delayed, with aggressive and
      hyperactive behavior in some.
    explanation: >-
      Establishes near-universal intellectual disability in a 27-patient series.
- category: Ophthalmologic
  name: Abnormal Retinal Pigmentation
  frequency: OCCASIONAL
  description: >-
    The characteristic ocular finding. Reported presentations span pigmentary
    change, retinitis pigmentosa and macular abnormality. Its localisation to
    proximal 14q, a region no ring patient has lost, is one of the two
    observations that force a non-deletional mechanism.
  phenotype_term:
    preferred_term: Abnormal retinal pigmentation
    term:
      id: HP:0007703
      label: Abnormal retinal pigmentation
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ocular abnormalities, consisting mainly of abnormal retinal pigmentation,
      but also retinitis pigmentosa, strabismus, glaucoma, and abnormal macula
    explanation: >-
      Documents abnormal retinal pigmentation as the predominant ocular finding
      and lists the associated ocular phenotypes.
  notes: >-
    Frequency is Orphanet's class from the HPO annotation for ORPHA:1440. Note
    the tension with the cited series, which describes retinal abnormality as a
    consistent feature of the syndrome; Orphanet's occasional class is retained
    rather than overridden, because the two sources are counting different things
    and this entry does not have grounds to prefer one.
- category: Craniofacial
  name: Distinctive Facial Appearance
  description: >-
    A recognisable facial gestalt is part of the syndrome. Reported features
    include a prominent narrow forehead, sparse short eyebrows, ptosis, broad
    nasal bridge with prominent nasal tip, flat philtrum, hypertelorism,
    midfacial hypoplasia, thin upper lip and retrognathia.
  phenotype_term:
    preferred_term: Distinctive facial appearance of ring 14 syndrome
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the ring 14 syndrome is characterized by a recognizable phenotype of
      shortness of stature, distinctive facial appearance, microcephaly,
      scoliosis, and ocular abnormalities
    explanation: >-
      Establishes a recognisable facial appearance as a defining feature.
  notes: >-
    Deliberately left unbound. HPO has no term for a syndrome-specific facial
    gestalt, and binding a generic abnormal-facial-shape term would assert less
    than the source says while looking more precise. The component features are
    curated individually where they are separately reported.
- category: Growth
  name: Short Stature
  frequency: FREQUENT
  description: Reduced stature is part of the recognisable phenotype.
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the ring 14 syndrome is characterized by a recognizable phenotype of
      shortness of stature, distinctive facial appearance, microcephaly,
      scoliosis, and ocular abnormalities
    explanation: >-
      Lists short stature among the defining features of the syndrome.
- category: Ophthalmologic
  name: Cataract
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Cataract
    term:
      id: HP:0000518
      label: Cataract
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Ophthalmologic
  name: Glaucoma
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Glaucoma
    term:
      id: HP:0000501
      label: Glaucoma
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Ophthalmologic
  name: Iris coloboma
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Iris coloboma
    term:
      id: HP:0000612
      label: Iris coloboma
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Ophthalmologic
  name: Strabismus
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Ophthalmologic
  name: Myopia
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Myopia
    term:
      id: HP:0000545
      label: Myopia
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Immunologic
  name: Recurrent infections
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Neurologic
  name: Atypical behavior
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Atypical behavior
    term:
      id: HP:0000708
      label: Atypical behavior
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Neurologic
  name: Interictal EEG abnormality
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Interictal EEG abnormality
    term:
      id: HP:0025373
      label: Interictal EEG abnormality
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Neurologic
  name: Hyperactivity
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Hyperactivity
    term:
      id: HP:0000752
      label: Hyperactivity
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Neurologic
  name: Delayed speech and language development
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Neurologic
  name: Abnormal corpus callosum morphology
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Abnormal corpus callosum morphology
    term:
      id: HP:0001273
      label: Abnormal corpus callosum morphology
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Neurologic
  name: Motor delay
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Growth
  name: Intrauterine growth retardation
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Intrauterine growth retardation
    term:
      id: HP:0001511
      label: Intrauterine growth retardation
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Growth
  name: Postnatal growth retardation
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Postnatal growth retardation
    term:
      id: HP:0008897
      label: Postnatal growth retardation
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Craniofacial
  name: Secondary microcephaly
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Secondary microcephaly
    term:
      id: HP:0005484
      label: Secondary microcephaly
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Musculoskeletal
  name: Hypotonia
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as frequent in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Skeletal
  name: Scoliosis
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
- category: Dermatologic
  name: Cafe-au-lait spot
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Cafe-au-lait spot
    term:
      id: HP:0000957
      label: Cafe-au-lait spot
  notes: >-
    Curated from the HPO disease annotation for ORPHA:1440, which records
    this feature as occasional in Orphanet's own frequency classification.
    That class maps directly onto FrequencyEnum, so the frequency here is
    Orphanet's, not an inference. No evidence item is attached because HPOA
    is a derived annotation rather than a quotable source.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    Reported as case series rather than population estimates. The largest
    published cohort combined literature review with 27 patients of the authors'
    own; a separate series characterised the epilepsy in 22 patients. No
    population prevalence has been established.
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The ring 14 syndrome is a rare condition, whose precise clinical and
      genetic characterization is still limited. This review summarizes
      literature data and it describes our own experience with 27 patients with
      ring 14 syndrome.
    explanation: >-
      Establishes the scale at which this syndrome is reported and states
      explicitly that its characterisation remains limited.
clinical_burden:
  burden_level: HIGH
  rationale: >-
    Two things drive the burden and they are different in kind. The epilepsy is
    near-universal, begins in the first months of life and resists drugs in about
    half of patients, and its severity tracks cognitive outcome. But the fact that
    changes management most is that infection, not seizures, is the leading cause
    of death in adulthood. The guideline is explicit that infection is among the
    worst prognostic factors and that prevention should be pursued actively rather
    than reactively, through hygiene, parental training for early recognition,
    extended vaccination and early hospitalisation. An entry that modelled only
    the epilepsy would misrepresent what actually kills these patients.
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      and the main cause of death in adulthood, all measures preventing
      infections must be undertaken
    explanation: >-
      States that infection is the leading cause of adult death in this syndrome
      and that prevention is therefore a standing management obligation.
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The degree of severity of the epileptic phenotype negatively influences
      child cognitive development.
    explanation: >-
      Establishes that epilepsy severity drives the cognitive component of the
      burden.

diagnosis:
- name: Conventional Karyotype
  description: >-
    Karyotyping is the test that makes this diagnosis, and the point is not
    incidental. A complete ring that has lost only telomeric material is
    balanced in copy number, so chromosomal microarray returns a normal result
    while the karyotype shows the ring. A child with early drug-resistant
    epilepsy, intellectual disability and a normal microarray therefore still
    warrants a karyotype.
  diagnosis_term:
    preferred_term: Karyotyping
    term:
      id: NCIT:C16768
      label: Karyotyping
  evidence:
  - reference: PMID:25901181
    reference_title: Dysregulation of FOXG1 by ring chromosome 14.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Array CGH analysis did not show any genomic imbalance but conventional
      karyotyping and FISH analysis revealed the presence of an interstitial
      14q12q24.3 deletion and an extra ring chromosome derived from the deleted
      material.
    explanation: >-
      A worked case in which array analysis was normal and only karyotype and
      FISH revealed the ring, which is the diagnostic argument this entry makes.
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Conventional cytogenetics is the primary tool to identify a ring
      chromosome. Children with a terminal deletion of chromosome 14q ascertained
      by molecular karyotyping (CGH/SNP array) should be tested secondarily by
      conventional cytogenetics for the presence of a ring chromosome.
    explanation: >-
      The consensus guideline states the diagnostic order directly: karyotype is
      primary, and an array-detected terminal 14q deletion should trigger a
      karyotype to look for a ring.
- name: Chromosomal Microarray for Deletion Sizing
  description: >-
    Array analysis does not make the diagnosis but sizes the terminal 14q
    deletion where one is present, which is what assigns the behavioural and
    immunological features to 14q32. Reported deletions run from 0.3 to 5 Mb, and
    a normal array does not exclude the syndrome.
  diagnosis_term:
    preferred_term: Comparative Genomic Hybridization
    term:
      id: NCIT:C18084
      label: Comparative Genomic Hybridization
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In our own sample of patients the ring was complete, with no apparent loss
      of chromosome material, in 6/27 cases, while it showed a small terminal
      deletion, varying in size from 0.3 to 5 Mb, in the other 21.
    explanation: >-
      Gives the deletion size range array analysis resolves, and the proportion
      of patients in whom there is no deletion for it to find.
- name: Electroencephalography
  description: >-
    The electroencephalographic picture evolves in a stereotyped way and is
    characteristic enough to support the diagnosis: slow background with
    pseudoperiodic bursts of generalised slow waves early, then focal
    frontotemporal or temporoposterior slow waves with interposed multifocal
    spikes, and rhythmic fast recruiting posterior spikes that generalise.
  diagnosis_term:
    preferred_term: Electroencephalography
    term:
      id: NCIT:C38054
      label: Electroencephalography
  evidence:
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      EEG abnormalities consisted of slow background activity with pseudoperiodic
      bursts of generalized slow waves in the early stage, focal frontotemporal
      or temporoposterior slow waves with multifocal spikes interposed, and
      unusual rhythmic fast recruiting posterior spikes followed by secondary
      generalization.
    explanation: >-
      Describes the electroencephalographic evolution used diagnostically.
- name: Ophthalmological Surveillance
  description: >-
    Regular eye examination is recommended for all patients, because the retinal
    findings are common, are not detectable without looking, and range from
    asymptomatic macular change to retinitis pigmentosa.
  diagnosis_term:
    preferred_term: Eye Examination
    term:
      id: NCIT:C38060
      label: Eye Examination
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      with evaluation of the fundus oculi: Grade B
    explanation: >-
      The consensus guideline makes periodic fundus examination a graded
      recommendation, which is stronger and more specific than the single-case
      support previously cited here.
  - reference: PMID:31755799
    reference_title: Multimodal imaging of ring 14 syndrome associated maculopathy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our data support regular eye examination for all patients with ring
      chromosome 14 syndrome.
    explanation: >-
      Independent support for universal ophthalmic surveillance, from the
      multimodal imaging case.
treatments:
- name: Antiseizure Pharmacotherapy
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    Seizure control is the main therapeutic problem and it is largely unsolved:
    the epilepsy of this syndrome is characterised as drug-resistant in the
    series that define it. No agent or regimen has been shown to work
    preferentially here, so treatment follows general drug-resistant focal
    epilepsy practice rather than anything syndrome-specific.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: anticonvulsant agent
      term:
        id: NCIT:C264
        label: Anticonvulsant Agent
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:24116895
    reference_title: "Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The incidence of epilepsy in patients with r(14) syndrome is virtually
      100%, characterized by early onset, polymorphic seizures, and drug-resistant
      seizures.
    explanation: >-
      Establishes that the epilepsy is drug-resistant. Graded INDIRECT because it
      characterises the therapeutic problem rather than supporting any particular
      treatment; no trial evidence exists in this syndrome.
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Epilepsy should be treated from the onset with anticonvulsive therapy.
    explanation: >-
      The consensus guideline recommends anticonvulsive therapy from seizure
      onset, which is the treatment this entry records.
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      therapies even if the symptomatology appears less severe: Grade C
    explanation: >-
      A graded recommendation against withdrawing a working drug on the strength
      of apparent improvement, which is the specific management error this
      syndrome invites given its fluctuating course.
  notes: >-
    Curated to record that the treatment exists and does not work well, which is
    a substantive clinical fact about this syndrome. No specific agent is named
    as preferred because no source recommends one for ring 14 specifically; the
    guideline lists barbiturates, valproic acid, carbamazepine, topiramate,
    vigabatrin, clobazam and levetiracetam as frequently used, which is a
    description of practice rather than an endorsement.

    One interaction is worth a curator's attention even though no source states
    it for this syndrome. Vigabatrin appears in that list and carries a
    well-known risk of irreversible retinal toxicity, and this entry curates a
    retinal pigmentary abnormality as a feature of the disease. Nothing in the
    ring 14 literature addresses whether baseline retinal pathology changes that
    calculus, so this is flagged rather than curated as a contraindication.
- name: Nutritional Support
  therapeutic_modality: BEHAVIORAL
  description: >-
    The consensus guideline recommends nutritional assessment for every patient,
    with nutritional support for malnourishment escalating to gastrostomy feeding
    in selected cases. This is one of the few management recommendations in this
    syndrome that is both specific and universal.
  treatment_term:
    preferred_term: Nutritional Support
    term:
      id: NCIT:C15433
      label: Nutritional Support
  target_phenotypes:
  - preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Nutritional assessment is recommended for all patients and nutritional
      support for malnourishment can include gastrostomy feeding in selected
      cases.
    explanation: >-
      States the nutritional recommendation and the escalation to gastrostomy
      that this treatment records.
  notes: >-
    therapeutic_modality is BEHAVIORAL because the recommendation is an
    assessment-and-support pathway rather than a named agent. Note the CLAUDE.md
    caution that NCIT:C15433 Nutritional Support often names a specific compound;
    here it genuinely is dietary and escalation-of-feeding-route management, which
    is what the guideline describes.
- name: Ketogenic Diet or Vagus Nerve Stimulation for Drug-Resistant Seizures
  therapeutic_modality: BEHAVIORAL
  description: >-
    About half of patients are drug-resistant, and for them the guideline raises
    ketogenic diet and vagus nerve stimulation as options to consider. Neither is
    presented as established in this syndrome; they are the standard escalation
    for drug-resistant childhood epilepsy and are named as worth considering.
  treatment_term:
    preferred_term: Ketogenic Diet
    term:
      id: NCIT:C173168
      label: Ketogenic Diet
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The Ketogenic diet or Vagal Nerve Stimulation may be taken in consideration
      for the therapeutic strategy
    explanation: >-
      Names both options for the drug-resistant half of patients. The quote
      asserts the recommendation directly, so directness is DIRECT; that the
      guideline offers them for consideration rather than recommending them, and
      that no outcome data exist in this syndrome, are matters of strength and
      are recorded here since the schema has no slot for them.
  notes: >-
    Vagus nerve stimulation is described in the same recommendation but is not
    separately bound: NCIT's only reachable stimulation term is Transcutaneous
    Auricular Vagus Nerve Stimulation, which is a different, non-implanted
    modality, and binding it would misstate the intervention. The diet carries
    the binding and the notes carry the device option.
- name: Early Physical Therapy
  therapeutic_modality: BEHAVIORAL
  description: >-
    Started early and explicitly preventive rather than restorative: the target is
    the musculoskeletal consequences of hypotonia, scoliosis in particular, before
    they become fixed.
  treatment_term:
    preferred_term: Physical Therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  target_phenotypes:
  - preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  - preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Start physical therapy early to reduce hypotonic complications (such as
      scoliosis) due to the reduced muscle tone: Grade B
    explanation: >-
      A Grade B recommendation naming both the intervention and the complication
      it is meant to prevent.
- name: Speech Therapy for Dysphagia
  therapeutic_modality: BEHAVIORAL
  description: >-
    Referral for dysphagia carries the guideline's highest grade. It matters
    doubly here, because aspiration feeds the respiratory infections that are the
    leading cause of adult death, so this is airway protection as much as feeding
    support.
  treatment_term:
    preferred_term: Speech Language Therapy
    term:
      id: NCIT:C159273
      label: Speech Language Therapy
  target_phenotypes:
  - preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Children with dysphagia should be referred to a speech therapist: Grade A
    explanation: >-
      Grade A recommendation for speech-therapy referral in dysphagia.
- name: Vaccination Against Encapsulated Organisms
  therapeutic_modality: VACCINE
  description: >-
    Extended inactivated-vaccine coverage is part of the infection-prevention
    strategy that follows from infection being the leading cause of adult death.
    The guideline names the specific vaccines rather than leaving it general.
  treatment_term:
    preferred_term: Vaccination
    term:
      id: NCIT:C15346
      label: Vaccination
  target_phenotypes:
  - preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Recommended (inactivated) vaccines include anti-haemophilus,
      anti-pneumococcal, anti-meningococcal and flu vaccine: Grade C
    explanation: >-
      Names the specific inactivated vaccines recommended in this syndrome.
- name: Vitamin D Supplementation
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    Given at twice the recommended daily allowance, roughly 800 to 1000 IU daily,
    as part of nutritional management. The dose is above ordinary supplementation
    and is specified by the guideline rather than left to general practice.
  treatment_term:
    preferred_term: Nutritional Support
    term:
      id: NCIT:C15433
      label: Nutritional Support
    therapeutic_agent:
    - preferred_term: vitamin D
      term:
        id: CHEBI:28940
        label: calciol
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      vitamin D daily supplementation must be given at twice the of recommended
      daily allowance
    explanation: >-
      Specifies the supplementation dose. The quoted sentence carries a
      typographical error in the source and is reproduced verbatim, as a snippet
      belongs to the paper.
  notes: >-
    therapeutic_agent is bound to CHEBI:28940 calciol, which is vitamin D3
    (cholecalciferol). The guideline says vitamin D without specifying the
    vitamer; calciol is the form ordinarily meant by daily supplementation dosing
    in IU, but the binding is one step more specific than the source and is
    flagged here rather than left implicit.

- name: Respiratory Function Monitoring and Advance Care Planning
  therapeutic_modality: OTHER
  description: >-
    Prompt assessment of any respiratory symptom, with formal screening of
    respiratory function, carries the guideline's highest grade. So does
    discussing signs of respiratory failure with parents in advance. That second
    half is unusual for a management recommendation and follows from the same
    fact the clinical burden records: respiratory infection is what kills these
    patients in adulthood, so the conversation is meant to happen before the
    crisis rather than during it.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Signs of respiratory failure should be discussed with the parents to allow
      advanced planning: Grade A
    explanation: >-
      Grade A recommendation covering both respiratory monitoring and advance
      planning for respiratory failure.
- name: Antibiotic Prophylaxis, Respiratory Physiotherapy and Immunological Evaluation
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    For recurrent pulmonary infection the guideline recommends three things
    together at Grade A: antibiotic prophylaxis, respiratory physiotherapy, and
    an immunological evaluation. The last is the one most easily skipped and the
    most informative here, because the 14q32 deletion is proposed to remove the
    immunoglobulin heavy-chain locus, so measuring immune function in a patient
    with recurrent infection is both management and the missing evidence for that
    mechanism.
  treatment_term:
    preferred_term: Antibiotic Prophylaxis
    term:
      id: NCIT:C51993
      label: Antibiotic Prophylaxis
  target_phenotypes:
  - preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  evidence:
  - reference: PMID:28399932
    reference_title: Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In case of recurrent pulmonary infections, consider respiratory
      physiotherapy antibiotic prophylaxis; an immunological evaluation is also
      strongly recommended: Grade A
    explanation: >-
      Grade A recommendation naming all three interventions this treatment
      records.
  notes: >-
    Three interventions are curated as one treatment because the guideline
    recommends them as a single conditional response to recurrent pulmonary
    infection rather than as independent options. treatment_term is bound to the
    antibiotic-prophylaxis component, which is the only one with a reachable NCIT
    clinical-action term; the physiotherapy and immunological-evaluation
    components are carried in the description.

environmental:
- name: Febrile illness as a seizure trigger
  description: >-
    Seizures in this syndrome may be precipitated by fever. This matters
    practically because infection is both frequent here and the leading cause of
    adult death, so a febrile illness threatens the patient twice over: directly,
    and by provoking seizures in an epilepsy that is already drug-resistant.
  influences_mechanisms:
  - target: Cortical Hyperexcitability
    environmental_effect: EXACERBATES
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Fever lowers the threshold of an already seizure-prone cortex rather than
      creating the susceptibility, so it is modelled as exacerbating the
      hyperexcitability node rather than triggering it.

      Retyped from DIRECT for consistency with the sibling edges into this node
      and, more importantly, for accuracy: how fever precipitates a seizure has
      been studied in febrile seizures and other epilepsies, but nothing in the
      ring 14 literature establishes the intermediate steps here, and DIRECT
      would assert there are none.
    evidence:
    - reference: PMID:23159383
      reference_title: Epilepsy in ring 14 chromosome syndrome.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Seizures might be induced by fever.
      explanation: >-
        Reports fever as a seizure precipitant in this syndrome. The quote
        asserts the claim, so directness is DIRECT; that the source does not
        quantify how often it occurs is a matter of strength, which has no slot
        and is recorded here.
  evidence:
  - reference: PMID:23159383
    reference_title: Epilepsy in ring 14 chromosome syndrome.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Epilepsy onset in r(14) syndrome takes place during the first year of life;
      seizures are generalized or focal and less frequently myoclonic. Seizures
      might be induced by fever.
    explanation: >-
      Places fever-induced seizures within the described seizure repertoire of
      the syndrome. The source is a two-case report with a literature review
      rather than a systematic study of triggers.
  review_notes: >-
    exposure_term is deliberately unbound. ECTO was searched for fever,
    hyperthermia and heat exposure and returns nothing appropriate: its heat
    terms are environmental heat sources such as self-heating coal-mine waste,
    not a raised body temperature arising from the patient's own illness. Fever
    is a physiological state rather than an external exposure, so no term beats a
    bad one here. HP:0001945 Fever exists but is a phenotype term and is not
    valid in this slot.

clinical_trials:
- name: NCT06813469
  phase: NOT_APPLICABLE
  status: RECRUITING
  description: >-
    MD-RING, a genomic study that directly tests the position-effect hypothesis
    this entry models. It sets out to examine whether position effects and
    topologically associating domain alterations are the pathomechanism of the
    syndrome, which is precisely the question the position_effect hypothesis
    group and the epilepsy knowledge gap record as open.
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: clinicaltrials:NCT06813469
    reference_title: Multi-Dimensional Genomic Dissection of Ring Chromosome 14 Syndrome
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      MD-RING will explore the hypothesis that position effects and TAD
      alterations act as an unprecedented pathomechanism in r(14)S.
    explanation: >-
      The registered aim is an explicit test of the position-effect mechanism
      curated here as an EMERGING hypothesis, so this study is the live route to
      resolving that gap.
  notes: >-
    phase is NOT_APPLICABLE because this is an observational genomic study rather
    than an interventional trial with an FDA phase.

discussions:
- discussion_id: r14_epilepsy_mechanism_unknown
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    How does a chromosome 14 ring that preserves the proximal 14q interval
    produce near-universal, drug-resistant epilepsy?
  attaches_to:
  - pathophysiology#Cortical Hyperexcitability
  - mechanistic_hypotheses#position_effect
  - mechanistic_hypotheses#dynamic_mosaicism
  rationale: >-
    This is the central unanswered question of the syndrome and the reason the
    convergence node is graded HYPOTHETICAL. The epilepsy maps by comparison with
    linear deletions to proximal 14q11.2-q12, which is intact in every ring
    patient, so the deletion cannot be the cause. Position effect and dynamic
    mosaicism are both plausible and both have direct supporting observations,
    but neither has been connected to cortical excitability in any system. No
    causal gene, ion channel, synaptic abnormality or network mechanism has been
    identified. Distinguishing the two hypotheses would need expression
    measurement of proximal 14q genes in neural tissue or neurons derived from
    ring 14 patients, alongside quantification of ring loss in the same cells.
  evidence:
  - reference: PMID:22564756
    reference_title: The ring 14 syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we could deduce that retinal abnormalities and epilepsy map within the
      proximal 14q11.2- q12 region
    explanation: >-
      Localises the epilepsy to the interval that is preserved in all ring
      patients, which is what makes the mechanism a gap rather than a deletion.
- discussion_id: r14_foxg1_untested_in_classical_ring
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Is FOXG1 expression actually altered in classical ring chromosome 14, or is
    the FOXG1 link confined to the single atypical case that raised it?
  attaches_to:
  - mechanistic_hypotheses#position_effect
  rationale: >-
    FOXG1 is an attractive candidate because it sits at 14q12 inside the
    implicated interval, and because FOXG1 syndrome shares features with ring 14.
    But the case that raised it carried a ring formed from an interstitial
    excision, not the usual telomere-fusion ring, and its breakpoint fell 225 kb
    downstream of FOXG1 within the regulatory landscape. FOXG1 expression was not
    measured in that patient and has not been measured in any classical ring 14
    patient. The hypothesis is positional and currently untested where it
    matters.
  proposed_experiments:
  - experiment_id: r14_foxg1_expression_in_patient_neurons
    name: FOXG1 expression in ring 14 patient-derived neurons
    description: >-
      Measure FOXG1 and other proximal 14q transcript levels in neurons derived
      from classical ring 14 patients, including patients whose ring carries no
      deletion, against matched controls.
    would_support:
    - mechanistic_hypotheses#position_effect
    supporting_outcome:
    - >-
      FOXG1 or other proximal 14q genes are downregulated in ring 14 neurons at
      normal copy number, connecting the position-effect model to the tissue
      where the epilepsy arises.
    refuting_outcome:
    - >-
      Proximal 14q expression is unchanged in ring 14 neurons, indicating that
      position effect on this interval is not the route to the epilepsy and
      redirecting attention to mosaicism or to another mechanism entirely.
  evidence:
  - reference: PMID:25901181
    reference_title: Dysregulation of FOXG1 by ring chromosome 14.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patient represents the first case of a r(14) arising from an
      interstitial excision where the phenotype is compatible with dysregulation
      of FOXG1.
    explanation: >-
      The source itself frames this as a first case of an atypical ring
      configuration, which is the limitation this gap records.
- discussion_id: r14_mosaicism_not_correlated_with_severity
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Does the degree of ring instability correlate with phenotype severity or
    progression in ring chromosome 14?
  attaches_to:
  - mechanistic_hypotheses#dynamic_mosaicism
  - pathophysiology#Ring Mitotic Instability and Dynamic Mosaicism
  rationale: >-
    Dynamic mosaicism is invoked to explain both why the phenotype exceeds the
    deletion and why it progresses, and the underlying instability is genuinely
    documented: one patient showed micronuclei, aneuploidy and anaphase lags. But
    instability has been measured in one patient and severity has never been
    scored against it. Without that correlation the hypothesis explains
    everything and predicts nothing. A cohort measuring ring-loss rate in
    accessible cells against epilepsy severity and cognitive trajectory would
    test it.
  evidence:
  - reference: PMID:39020403
    reference_title: "Chromosomal instability in a patient with ring chromosome 14 syndrome: a case report."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Genomic instability was evidenced by the presence of micronuclei and
      aneuploidies involving the ring and other chromosomes.
    explanation: >-
      Documents instability in a single patient, which is the entire direct
      evidence base for the mosaicism hypothesis in this syndrome.
- discussion_id: r14_igg_glycosylation_trans_mechanism
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    How does a chromosome 14 ring produce a selective IgG galactosylation and
    sialylation defect, when no relevant glycosyltransferase gene lies on
    chromosome 14?
  attaches_to:
  - pathophysiology#Aberrant IgG N-Glycosylation
  - pathophysiology#Terminal 14q32 Haploinsufficiency
  rationale: >-
    This is the sharpest mechanistic question on the branch the entry itself
    identifies as most consequential, since infection is the leading cause of
    adult death here. The glycosylation abnormality is measured and selective: it
    affects IgG and not total serum glycoproteins, and it occurs at normal IgG
    concentration.

    What it does not have is an established connection to the ring. The enzymes
    whose products are altered are not encoded on chromosome 14, so the
    straightforward direct correlation is unproven, and the authors go further,
    judging that the IgG changes do not relate to the structural rearrangement.
    They also decline to let that settle it, noting that absent candidate genes
    in the deleted region do not exclude a genetic basis, since deletion is only
    one mechanism alongside ring instability and conformational effects on gene
    expression. So the honest position is that a measured immunological
    abnormality sits beside a chromosomal lesion with no demonstrated link
    either way.

    That is worth keeping in the pathograph rather than dropping, because the two
    routes the authors leave open are the two this entry already models as
    dynamic_mosaicism and position_effect. If either is real, it now has a second
    phenotype to account for.

    It also reframes the 14q32 branch. The guideline's positional argument
    predicts a quantitative immunoglobulin deficit from loss of the heavy-chain
    locus; what has actually been measured is normal IgG with altered glycans.
    Those are different lesions, and the entry carries both rather than letting
    the positional argument stand unopposed.
  evidence:
  - reference: PMID:42352229
    reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      no genes encoding galactosyltransferases or sialyltransferases are located
      on chromosome 14
    explanation: >-
      States why the straightforward direct correlation is unproven. Note this
      supports the absence of a cis explanation, not the presence of a trans one.
  - reference: PMID:42352229
    reference_title: IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      which involves several other factors, such as ring chromosome instability
      during cell division and the effects of the chromosome's new conformation
      on gene expression
    explanation: >-
      Names the alternative mechanisms the authors keep open, which are the same
      two this entry already curates as hypothesis groups.
  notes: >-
    The same report describes one patient treated with intravenous immunoglobulin
    who showed clinical improvement. That observation is deliberately not curated
    as a treatment. The paper itself states that it remains a theoretical
    assumption and should not be interpreted as evidence of therapeutic efficacy,
    and curating an n-of-1 uncontrolled observation as treatment evidence would
    misrepresent the source.
📚

References & Deep Research

References

3
PMID:22564756
The ring 14 syndrome.
No top-level findings curated for this source.
PMID:24116895
Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients.
No top-level findings curated for this source.
PMID:28399932
Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.
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 (3)

Record notes

Scope note on the mechanism graph. This entry carries two parallel mechanism branches out of a single chromosomal lesion, and neither is established. The 14q32 terminal deletion branch is ordinary haploinsufficiency and is well-supported for the behavioural and immunological features. The proximal 14q11.2-q12 branch, which carries the epilepsy and the retinal phenotype, has no deletion behind it at all: that region is preserved in every ring patient. Position effect and dynamic mosaicism are both curated as mechanistic hypotheses with EMERGING status rather than asserted, and the causal edges into the epilepsy node are typed INDIRECT_UNKNOWN_INTERMEDIATES because the route from either to cortical hyperexcitability is exactly what is missing. No genetic section. There is no causal gene. FOXG1 is a specific candidate raised by one patient whose ring breakpoint fell within the FOXG1 regulatory landscape, but it is a positional hypothesis about a gene that is neither deleted nor mutated, so typing it CAUSATIVE in a genetic block would misrepresent the evidence. It is curated inside the position-effect hypothesis where the reasoning can be stated. A named 14q32.33 candidate is proposed by the sources and deliberately not curated as a mechanism node. The consensus guideline states that susceptibility to infection was also seen in linear 14q deletions and attributes it to haploinsufficiency on the grounds that the distal region of 14q contains the immunoglobulin heavy-chain genes. The deep-research report names the same IGH locus, and PACS2 as an epilepsy candidate in the same band. The restraint is about the kind of claim, not the absence of one. The guideline's argument is positional: the locus lies in the deleted interval and its content would explain the phenotype. IGH copy number has not been measured in ring 14 patients, so nothing ties the immune phenotype to that locus directly. Immunoglobulin levels, by contrast, have been measured, and they are normal, which argues against a simple dosage story: the reported abnormality is functional rather than quantitative and is curated as its own node. The IGH proposal is therefore cited as evidence on the infection edge rather than promoted into a named-gene pathophysiology node. PACS2 has weaker footing still and is recorded only here. Phenotype sourcing. Frequencies come from the HPO disease annotation for ORPHA:1440, which carries Orphanet's own curated frequency classes (Very frequent, Frequent, Occasional). These map onto FrequencyEnum directly and are used as such. Phenotypes carrying that provenance have it recorded in notes rather than a manufactured quote, because HPOA is a derived annotation and not a quotable source. Phenotypes that are additionally supported by a cited series carry an evidence item as well. The Orphanet bulk XML was not downloaded to build an ORPHA reference-cache entry, because doing so would have added manifest churn unrelated to this curation.

Review response 3: add IgG glycosylation node, correct immunoglobulin claim · 2026-08-29T05:14:08Z · View source

Third review response on PR #10005, addressing two IMPORTANT items. Item 1 is the same defect class as round 2 and the third instance in this session. The entry asserted that no study has measured immunoglobulin levels in ring 14 patients. PMID:42352229, Messina et al., Biomolecules 2026, has: IgG levels in these patients are normal. The reviewer fetched it to check whether the deep-research report had hallucinated it; it is real and the cache holds full text. Both sentences making the false claim, one in notes and one on the infection edge description, were corrected. The IGH copy-number half of the claim survives, since that genuinely has not been measured. The substantive finding was added rather than only the correction. A HYPOTHETICAL pathophysiology node records aberrant IgG N-glycosylation: patient IgG shows decreased galactosylation and sialylation resembling pro-inflammatory autoimmune patterns, the change is selective for IgG and absent from total serum glycoproteins, and it occurs at normal IgG concentration. So the immunological defect that has actually been measured in this syndrome is qualitative rather than a dosage deficit, which sits awkwardly with the guideline's positional IGH argument. Both are now curated, and the entry states that whether they are alternatives or two consequences of one lesion is unresolved. A KNOWLEDGE_GAP discussion records the mechanistic question, as the deep-research report recommended. No galactosyltransferase or sialyltransferase gene lies on chromosome 14, so the effect cannot be a cis consequence of the deleted interval and must act in trans by an unidentified route. This is on the branch the entry itself calls most consequential, since infection is the leading cause of adult death. The paper's n-of-1 intravenous immunoglobulin observation was deliberately not curated as a treatment, following the reviewer's explicit recommendation and the paper's own disclaimer that it remains a theoretical assumption and should not be interpreted as evidence of therapeutic efficacy. The reasoning is recorded in the discussion notes so a later curator does not mistake the omission for an oversight. Item 2, the clinicaltrials:NCT06813469 evidence item was the only one of 61 lacking reference_title. Added from the cache. A separate defect was found and fixed on PR #10007 during this same period and is noted here because it reflects on process rather than on that entry: check-folded-hyphens failed on CI for Polycystic_Kidney_Disease_3 because a folded scalar line ended in a hyphen. That check had been run on this entry and on two others in the batch but skipped on that one. It has now been run across all four entries in the batch; only the one file was affected. Revalidated with just validate-disorders, just validate-terms, just count-verified-snippets (66/66), just check-entity-refs, just check-duplicate-keys and just check-folded-hyphens. Compliance rose from 87.6 to 88.6 percent.

Create: Ring_Chromosome_14 · 2026-08-29T04:12:26Z · View source

Created kb/disorders/Ring_Chromosome_14.yaml (MONDO:0014708). Deep research was requested from falcon, which is not configured in this environment, so the run used --fallback and claude_code produced the report. The substitution is recorded in the report frontmatter as fell_back, requested_provider and provider_attempts rather than described in prose. The report resolved 33 of 33 references with a 0.0 confabulation rate and set needs_review for one off-topic reference, PMID:22579566, which is not cited here. Its term validation flagged 13 mislabelled terms, nearly all artifacts of frequency words and quoted prose bleeding into the label column of the report's own tables rather than wrong bindings, and two obsolete GO terms, GO:0016458 and GO:0006486. Neither obsolete term is used; the heterochromatin node binds GO:0031507, which is current. The entry was drafted from primary literature first and then cross-checked against the report. The cross-check added the 2017 consensus guideline, PMID:28399932, which the initial literature search had not surfaced and which materially changed the entry: it supplied autism spectrum disorder as a defining feature, feeding difficulty and nonverbal status as curated phenotypes, the nutritional-support treatment including gastrostomy escalation, the anticonvulsive-from-onset recommendation, and an explicit statement of the diagnostic order that is stronger evidence for the karyotype-first argument than the single case report the entry originally relied on. The mechanism is modelled as two parallel branches out of one lesion, because that is what the literature supports. Ring formation removes terminal 14q material in most patients but nothing at all in a substantial minority, six of twenty-seven in the largest series. Phenotype mapping against linear deletions places the epilepsy and the retinal abnormality in proximal 14q11.2-q12, which is preserved in every ring patient, so the deletion cannot explain the two defining features. The 14q32 branch is ordinary haploinsufficiency and carries the behavioural and immunological features. The proximal branch has no deletion behind it and is carried by two competing hypotheses, both curated as EMERGING mechanistic_hypotheses rather than asserted: position effect, supported by a telomere-only ring in which two of eight chromosome-14 genes were downregulated at normal copy number and by a FOXG1 breakpoint case; and dynamic mosaicism, supported by documented micronuclei, aneuploidy and anaphase lags in one patient. Every edge into the cortical hyperexcitability node is typed INDIRECT_UNKNOWN_INTERMEDIATES and that node is graded HYPOTHETICAL, because no causal gene, ion channel, synaptic or network abnormality has been identified in this syndrome. No genetic section, following the Ring_Chromosome_20_Syndrome precedent. There is no causal gene. FOXG1 is a positional candidate raised by a single atypical case and is curated inside the position-effect hypothesis where the reasoning can be stated, rather than typed CAUSATIVE in a genetic block. A named 14q32.33 candidate was deliberately not asserted. The report identifies the IGH locus as the likely basis of the infection susceptibility and PACS2 as an epilepsy candidate. Both are attractive and IGH would upgrade the 14q32 node from unnamed dosage loss to a specific lesion, but no cached source makes that claim about ring 14 patients, so both are recorded in the entry notes as leads rather than curated. Phenotype frequencies come from the HPO disease annotation for ORPHA:1440, which carries Orphanet's own curated frequency classes rather than raw patient counts, so those classes map onto FrequencyEnum directly. Provenance is recorded in notes rather than a manufactured quote, since HPOA is a derived annotation. The Orphanet bulk XML was not downloaded to build an ORPHA reference-cache entry, because doing so would have added manifest churn unrelated to this curation. Three knowledge gaps are recorded: the unexplained route from the ring to cortical hyperexcitability, the fact that FOXG1 expression has never been measured in a classical ring 14 patient, and the absence of any correlation between degree of ring instability and phenotype severity. The second carries a proposed experiment. Validated with just validate-disorders, just validate-terms, just count-verified-snippets (46/46), just check-entity-refs and just check-duplicate-keys. Compliance 85.4 percent.

Claude Code ▸
Ring Chromosome 14 Syndrome — Comprehensive Research Report
claude-haiku-4-5-20251001, claude-opus-5[1m] 22 citations 2026-08-29T00:01:20.624501

Ring Chromosome 14 Syndrome — Comprehensive Research Report

Prepared: 2026-08-28 · Target: Ring_Chromosome_14 · MONDO:0014708 Scope: disease-knowledge-base curation input (dismech schema sections 1–15)

Snippet-verification caveat. Several quotations below were extracted from full-text HTML/PDF via automated fetch and summarization. Before any of these is used as an evidence snippet: in kb/disorders/Ring_Chromosome_14.yaml, it must be re-verified against a just fetch-reference PMID:… cache — just count-verified-snippets / just validate-references is the gate, not this report. Quotes I am confident are verbatim complete abstracts (Zollino 2012 PMID:22579566→22564756, Bershteyn 2014 PMID:24413397) are marked [abstract-verbatim]. Everything else is marked [verify].

1. Disease Information

Overview

Ring chromosome 14 syndrome (r(14) syndrome) is an ultra-rare constitutional chromosomal disorder in which one copy of chromosome 14 is circularized after breakage in the short and long arms with end-to-end reunion, usually with loss of the 14q terminal segment. It is defined clinically by the near-obligate combination of early-onset, drug-resistant epilepsy, moderate-to-severe intellectual disability with disproportionate language impairment, postnatal microcephaly, a recognizable but subtle facial gestalt, retinal pigmentary abnormalities, and increased susceptibility to respiratory infection.

The syndrome's defining puzzle — and the reason it is mechanistically interesting rather than merely a contiguous-gene deletion — is that individuals with linear (non-ring) 14q terminal deletions of comparable size do not develop the refractory epilepsy or the retinal changes. The ring configuration itself, not simply the deleted gene content, appears to be pathogenic (Vaisfeld et al., Epilepsia 2021, PMID:33205446).

Key identifiers

Resource Identifier
MONDO MONDO:0014708
OMIM 616606 (RING CHROMOSOME 14 SYNDROME)
Orphanet ORPHA:1440
ICD-10 Q93.2 (Chromosome replaced with ring, dicentric or isochromosome)
ICD-11 LD7Y (per ORDO cross-reference)
MeSH C535487
UMLS / MedGen C2930916 / MedGen UID 419284
GARD 6072
Karyotype (ISCN) 46,XX,r(14)(p11q32.33) or 46,XY,r(14)(p11q32.3) (typical)

Source: MedGen 419284; ORDO via OLS4; OMIM 616606.

Synonyms

  • Ring 14 syndrome; Ring14 syndrome; r(14) syndrome; RC14 syndrome
  • Ring chromosome 14
  • Chromosome 14 ring
  • Ring 14
  • (Historic/imprecise) "14q ring syndrome"

Do not conflate with: 14q terminal deletion syndrome (linear del(14)(q32.3qter)) or 14q11.2 microdeletion syndrome. These are separate MONDO concepts, and the whole point of the Vaisfeld 2021 analysis is that the ring and linear forms are phenotypically dissociable.

Data provenance character

Essentially all published knowledge is case-level and aggregated from small series — there is no population EHR-derived cohort of meaningful size. The largest coherent clinical datasets are:

  • Zollino et al. 2012, own series of 27 patients plus literature review (PMID:22564756)
  • Giovannini et al. 2013, 22 patients with EEG phenotyping (PMID:24116895)
  • The Ring14 International clinical database (~54 patients; genetics, growth, neurology, comorbidities, therapies) — ring14.org
  • The 2017 ad hoc task-force guideline, consensus over the above (PMID:28399883 / PMC5387247)

EHR-derived signal exists but is thin: Barbour et al. (Epilepsia 2024, PMID:38795333) attempted incidence estimation for 28 rare epilepsies from NYC EHR text search and explicitly noted that "data were limited for" ring chromosome 14 and similar "genetic epilepsies with nonspecific clinical features" [verify].

2. Etiology

Primary cause

A de novo structural chromosomal rearrangement: chromosome 14 forms a ring, requiring two breakpoints — one in the short arm (an acrocentric, gene-poor p arm) and one in the long arm — followed by fusion of the broken ends and loss of the intervening terminal material.

Zollino et al. 2012 quantified the molecular spectrum in 27 patients [abstract-verbatim]:

"In our own sample of patients the ring was complete, with no apparent loss of chromosome material, in 6/27 cases, while it showed a small terminal deletion, varying in size from 0.3 to 5 Mb, in the other 21. In two of these a cryptic 14q duplication of 2.5 and 9.7 Mb, respectively, proximal to the deleted segment, was also identified. Deleted rings were 75% paternal and 25% maternal in origin. UPD (14) was excluded in all cases." — Zollino M, Ponzi E, Gobbi G, Neri G. Eur J Med Genet 2012;55:374–380. PMID:22564756, DOI:10.1016/j.ejmg.2012.03.009

Three points from this are curation-critical:

  1. ~22% of rings are "complete" — cytogenetically visible ring, no detectable copy-number loss on array. These patients still have the syndrome. Copy-number loss is therefore not necessary for the phenotype.
  2. Parental origin is skewed paternal (3:1) for deleted rings.
  3. UPD(14) is excluded — so neither Temple syndrome nor Kagami–Ogata imprinting mechanisms are operating here (an important differential, since chromosome 14 carries the DLK1-MEG3 imprinted domain at 14q32.2).

Multiple ring-formation mechanisms are described generally for ring chromosomes (Guilherme et al., BMC Med Genet 2011, PMID:22151179): breaks in both arms with end-to-end reunion; a break in one arm fusing to the opposite subtelomere; subtelomere–subtelomere fusion; and pure telomere–telomere fusion (which yields a complete ring with no loss).

Risk factors

Genetic risk factors. There is no known heritable susceptibility. The rearrangement is sporadic. There is no reported association with parental age, and no recurrent breakpoint-flanking segmental duplication architecture has been established (unlike recurrent microdeletion syndromes). The paternal-origin skew is the only reproducible parent-of-origin signal.

Modifier candidates (hypothesis-level, not established): - The size of the terminal deletion (0.3–5 Mb) modifies which 14q32.33 genes are hemizygous — most consequentially the IGH locus (immune phenotype) and PACS2 (epilepsy candidate). - The degree of ring mitotic instability (see §6) plausibly modifies severity, including growth failure and possibly epileptogenicity, but this has never been prospectively correlated with outcome. - Presence of a cryptic proximal 14q duplication (2/27 in Zollino's series) adds a second dosage lesion.

Environmental risk factors. None identified. No teratogen, exposure, occupational, maternal-nutritional, or infectious risk factor has been associated with ring chromosome formation in humans. Ionizing radiation and clastogens can produce ring chromosomes somatically in vitro and in irradiated individuals, but no epidemiological link to constitutional ring 14 exists. Treat this as "no evidence," not "no association."

Protective factors. None identified — genetic or environmental. Not applicable to a de novo structural event.

Gene–environment interaction. No established GxE. The one arguably interaction-shaped observation is that infection burden interacts with the underlying immune lesion: hemizygosity of the 14q32.33 immunoglobulin heavy-chain locus plus altered IgG glycosylation (§6) is thought to convert ordinary respiratory pathogen exposure into recurrent/severe pneumonia, which the 2017 guideline names as the leading cause of adult death.

3. Phenotypes

3.1 Neurological — epilepsy (the cardinal feature)

Frequency: ~100%. Giovannini et al. 2013 (PMID:24116895), 22 patients:

"The incidence of epilepsy in patients with r(14) syndrome is virtually 100%, characterized by early onset, polymorphic seizures, and drug-resistant seizures." [verify]

Guideline consensus (PMC5387247) [verify]:

"All individuals with r(14) syndrome suffer from epilepsy, which is drug resistant in most cases." Onset "usually occurs in the first months of life."

Attribute Value HPO suggestion
Onset First months of life; commonly < 12 months (a Chinese series reported onset 3–24 months in its r(14) cases, PMID:41087847) HP:0003593 Infantile onset; HP:0003623 Neonatal onset
Predominant type Focal, with or without secondary generalization (modern reclassification) HP:0007359 Focal-onset seizure; HP:0002384 Focal impaired awareness seizure
Also seen Generalized tonic–clonic, myoclonic-tonic, clonic HP:0002197 Generalized-onset seizure; HP:0002069 Bilateral tonic-clonic seizure; HP:0002123 Generalized myoclonic seizure
Status epilepticus ~50% of individuals HP:0002133 Status epilepticus
Clustering Seizures on awakening/falling asleep, in clusters lasting a day or more HP:0011146? (verify)
Drug resistance ~50% frankly drug-resistant; remaining 50% variable control HP:0011348? — prefer free text + treatments block
Severity Severe in early childhood —
Course Improves with age — "starting with frequent severe seizures that may ameliorate over time and eventually decrease in frequency during late adolescence" [verify] —
Encephalopathic effect Intense early epileptic activity associated with regression of acquired psychomotor/language milestones HP:0002376 Developmental regression; HP:0200134 Epileptic encephalopathy

EEG (Giovannini 2013; guideline) [verify]: slow, unstructured/disorganized background in both wake and sleep; generalized bursts of slow, large, asynchronous waves in frontal and posterior regions; multifocal spikes; complex spike-and-wave over occipital regions; focal spikes with secondary generalization. EEG severity negatively correlated with cognitive development — a curation-relevant causal claim (epileptic activity → cognitive outcome, not merely co-occurring).

Quality-of-life impact: dominant. Seizure burden, seizure-related injury risk, sleep disruption, and caregiver vigilance are the primary drivers of family burden (SanInocencio et al. 2026, below).

3.2 Neurodevelopmental / cognitive / behavioral

Phenotype Frequency HPO
Global developmental delay ~100% HP:0001263
Intellectual disability, moderate–severe ~100% ("One consistent feature … is moderate to severe intellectual disability" [verify]) HP:0001249; HP:0002342 (moderate); HP:0010864 (severe)
Delayed speech and language development / poor or absent speech Very frequent; language is "one of the most affected developmental area" [verify]; many patients are nonverbal HP:0000750; HP:0002465; HP:0001344
Motor delay — sitting ~12 months; first steps 2–3 y; some never walk Frequent HP:0001270; HP:0002540 (inability to walk)
Hypotonia (generalized, axial) Very frequent HP:0001252; HP:0001290
Hyperactivity "large proportion of patients" [verify] HP:0000752
Motor stereotypies Frequent HP:0000733
Autistic traits / full autistic phenotype in some Frequent traits; formal ASD in a subset HP:0000729 Autistic behavior; HP:0000717 Autism
Aggressive outbursts Occasional — children "usually good natured" with "only occasional bursts of aggressiveness" [verify] HP:0000718 Aggressive behavior
Sleep disorder Less frequent HP:0002360

Behavior disorders were assigned by Zollino to the 14q32 region (haploinsufficiency mechanism) [abstract-verbatim].

3.3 Growth and nutrition

Phenotype Note HPO
Short stature / shortness of stature Part of the defining gestalt (Zollino 2009, PMID:19441122; Zollino 2012) HP:0004322
Postnatal microcephaly Recurring; postnatal-onset specifically HP:0005484 (postnatal microcephaly); HP:0000252
Failure to thrive / underweight "Children with r(14) syndrome are extremely underweight and are frequently affected by anorexia that leads to malnutrition." [verify] HP:0001508; HP:0004325
Feeding difficulties, dysphagia/aspiration Frequent enough to warrant enteral feeding recommendation HP:0011968; HP:0002015
Intrauterine growth restriction Reported (GARD) HP:0001511

Growth failure is the classical "ring syndrome" phenotype (Kosztolányi) attributed to ring mitotic instability rather than to deleted gene content — see §6.

3.4 Craniofacial

The facial gestalt is real but subtle; Vaisfeld 2021 cautions [verify]: "it is very difficult to diagnose any one of the reviewed conditions based on a gestaltic impression."

Guideline description [verify]: "long and sometimes asymmetrical face, full cheeks, large forehead, hypoplastic supraorbital ridges with horizontal eyebrows, strabismus, apparent hypertelorism" — and importantly, "All these features have been reported only in patients with r(14) syndrome carrying a long arm terminal deletion of at least 650 kb."

Case-report-level features (Meza-Espinoza 2024, PMID:39020403) [verify]: prominent narrow forehead, sparse short eyebrows, palpebral ptosis, horizontal palpebral fissures, broad nasal bridge, prominent nasal tip, flat philtrum, hypertelorism, midfacial hypoplasia, thin upper lip, crowded teeth, ogival (high-arched) palate, retrognathia, wide neck.

HPO set: HP:0000316 Hypertelorism · HP:0000494 Downslanted palpebral fissures · HP:0000286 Epicanthus · HP:0005280 Depressed nasal bridge · HP:0000457 Depressed nasal ridge · HP:0000463 Anteverted nares · HP:0000369 Low-set ears · HP:0000218 High palate · HP:0000470 Short neck · HP:0005469 Flat occiput · HP:0000268 Dolichocephaly · HP:0000581 Blepharophimosis · HP:0000508 Ptosis · HP:0000347 Micrognathia · HP:0000219 Thin upper lip vermilion · HP:0000678 Dental crowding · HP:0000319 Smooth philtrum · HP:0007874 Almond-shaped palpebral fissure.

Dental management has its own literature: Ivanoff et al., Folia Med 2023, PMID:36855970 — "what the dentist should know to manage children with r(14) effectively."

3.5 Ophthalmological

Zollino 2012 [abstract-verbatim]: ocular abnormalities "consisting mainly of abnormal retinal pigmentation, but also retinitis pigmentosa, strabismus, glaucoma, and abnormal macula."

Guideline [verify]: "myopia, strabismus, cataracts, maculopathy, optic nerve damage, glaucoma and anomalies in retinal pigmentation," plus "microphtalmia and colobomas."

Vasconcelos et al., Ophthalmic Genet 2019 (PMID:31755799) documented an 11-year-old with macular yellow dots on multimodal imaging, arguing for routine ophthalmologic surveillance [verify].

HPO: HP:0000580 Pigmentary retinopathy (annotated "Occasional" in HPOA) · HP:0000510 Retinitis pigmentosa · HP:0007754 Macular dystrophy · HP:0000486 Strabismus · HP:0000545 Myopia · HP:0000518 Cataract · HP:0000501 Glaucoma · HP:0000612 Iris coloboma · HP:0000568 Microphthalmia · HP:0000648 Optic atrophy · HP:0000505 Visual impairment.

Curation note: GARD states retinal abnormalities are "typically not affecting vision." The retinal phenotype is a diagnostic marker more than a functional burden in most patients — worth capturing as a notes distinction rather than assuming visual impairment.

3.6 Immune / infectious

Phenotype Note HPO
Recurrent respiratory infections "Recurring features include … increased incidence of infections, particularly respiratory infections" [verify] HP:0002205
Severe pneumonia Spectrum "from recurrent upper airways infections to severe pneumonia" [verify] HP:0006532
Altered immunoglobulin / antibody profile "Only some individuals with r(14) syndrome have altered immunological and/or antibody profile" [verify] — IgA deficiency most cited HP:0002720 Decreased circulating IgA level (verify CURIE); HP:0004313 Decreased circulating antibody level

This is the leading cause of adult mortality — "Infections are one of the worse prognostic factors and the main cause of death in adulthood" [verify].

3.7 Musculoskeletal, GI, other

  • Scoliosis (HP:0002650) — part of the defining gestalt; assigned by Zollino to 14q32. Kyphosis (HP:0002808) also reported.
  • Juvenile osteoporosis / osteopenia (HP:0000939 / HP:0000938) — "less frequently observed" [verify]
  • Arthritis (HP:0001369) — less frequent
  • Celiac disease — less frequent [verify CURIE]
  • Gastrointestinal symptoms / GERD / constipation — "affect many children" [verify]
  • Café-au-lait spots (HP:0000957) — less frequent
  • Lymphedema — "puffy hands and/or feet" (HP:0001004) — reported by MedlinePlus/GARD; frequency not quantified in the primary series
  • Congenital malformations of heart, kidneys, urinary tract — "very rarely reported" [verify]. This is a discriminating negative: r(14) is not a multiple-congenital-anomaly syndrome in the usual sense.

3.8 Neuroimaging

Guideline [verify]: "Magnetic resonance imaging does not typically detect any specific changes." When abnormal: "mild brain atrophy, abnormalities of the corpus callosum, mild ventricular dilatation, hippocampus anomalies and structural alterations of the cerebellum."

HPO: HP:0002059 Cerebral atrophy · HP:0001274/HP:0002079 corpus callosum abnormality · HP:0002119 Ventriculomegaly · HP:0025100? hippocampal abnormality (verify) · HP:0001317 Abnormal cerebellum morphology.

3.9 Quality of life — the 2026 patient-centered model

SanInocencio C, et al. "Development of a patient-centered conceptual disease model in Ring 14 syndrome: a patient-centered model of lived experience." Qual Life Res 2026. PMID:41533279, DOI:10.1007/s11136-025-04140-5.

17 caregivers representing 12 patients; semi-structured interviews. The model spans patient domains (cognitive, physical, behavioral, social-emotional, QoL) and caregiver domains (mental health, family/social, medical care). Key finding [verify]:

"impacts listed under the patient quality of life domain as well as the caregiver domain are inadequately represented in the literature"

This is the single most important recent addition for QoL curation, and it is explicitly a critique of the existing literature's clinician-centric framing. No EQ-5D/SF-36/PROMIS data exist for r(14).

4. Genetic / Molecular Information

4.1 The lesion

There is no single causal gene. The lesion is the ring structure plus variable 14q32.33 hemizygosity.

Chromosome 14 (GRCh38): acrocentric, 107,043,718 bp. The p arm is heterochromatic/rDNA-bearing and gene-poor; the p-arm breakpoint (typically p11 or p13) is therefore usually phenotypically silent for coding content but is central to the position-effect hypothesis (§6).

Terminal 14q deletion sizes reported: - Zollino 2012 (n=27): 0.3–5 Mb in 21/27; complete ring in 6/27 [abstract-verbatim] - Zollino 2009 (n=20): 0.65–5 Mb in 14/20; complete ring in 6/20 - Meza-Espinoza 2024 (n=1): ~1.7 Mb, chr14:105,194,385–106,876,229 (GRCh38), 23 genes [verify] - Gardner et al. 2024 (PMID:38824650): "Ring Chromosome 14 with a Terminal 14q32.33 Deletion"

4.2 Genes in the commonly deleted 14q32.33 interval

Verified coordinates (Ensembl REST, GRCh38):

Gene HGNC Coordinates (GRCh38) Distance from 14qter Relevance
PACS2 hgnc:23794 (verify) chr14:105,300,563–105,398,147 ~1.65 Mb Leading epilepsy candidate. Recurrent de novo missense (p.Glu209Lys) causes DEE-66 (neonatal-onset developmental and epileptic encephalopathy with cerebellar dysgenesis). Deleted whenever the terminal deletion exceeds ~1.65 Mb.
IGHM (IGH locus) hgnc:5541 chr14:105,851,705–105,856,218 (IGH cluster ≈105.6–106.9 Mb) ~1.2 Mb Immunoglobulin heavy-chain locus. Deleted in essentially all deletion-bearing rings with >~0.2 Mb loss. Guideline explicitly links infection susceptibility to this: "the distal region of 14q contains the genes for heavy chains of antibodies" [verify]

Other genes in the terminal ~2 Mb (for completeness; individually unvalidated for r(14) phenotype): INF2, ADSS1(ADSSL1), SIVA1, AKT1, ZBTB42, CEP170B, PLD4, AHNAK2, CDCA4, GPR132, JAG2, NUDT14, BRF1, PACS2, TEX22, MTA1, CRIP1/CRIP2, TMEM121, ELK2AP, ADAM6.

Assay-relevant caution: AKT1 (14q32.33) and DICER1 (14q32.13) are cancer-relevant genes on this chromosome, but no increased neoplasia risk has been reported in r(14) syndrome and DICER1 lies well proximal to typical ring 14 deletions. Do not curate a tumor-predisposition claim.

4.3 The 40 chromosome-14 epilepsy genes (Vaisfeld 2021)

Vaisfeld et al. catalogued 40 epilepsy-related genes across chromosome 14 and analyzed seven in detail [verify]:

Gene Cytoband Association
CHD8 14q11.2 ASD; seizures in 20–30%; macrocephaly
FOXG1 14q12 Microcephaly, psychomotor delay, drug-resistant early-onset seizures (congenital Rett variant)
OTX2 14q22.3 Eye malformations, pituitary anomalies, possible retinal abnormalities
PSEN1 14q24.2 Alzheimer-associated seizures (late-onset; low relevance)
IRF2BPL 14q24.3 DEE, Lennox–Gastaut-like phenotype
DYNC1H1 14q32.31 Neurological disease; LOF not epilepsy-associated
PACS2 14q32.33 Neonatal-onset DEE with cerebellar dysgenesis

Crucially, all of these except PACS2 lie outside the deleted segment in ring 14 — they are present in two copies. That is precisely the enigma. Vaisfeld's conclusion [verify]:

"With the exception of FOXG1 and PACS2, none of the genes … has a clear and unquestionable epileptogenic potential."

4.4 Zollino's regional assignment (the standing genotype–phenotype model)

From the 2012 abstract [abstract-verbatim]:

"Based on literature review of linear deletions, affecting either the proximal or the distal 14q region, we could deduce that retinal abnormalities and epilepsy map within the proximal 14q11.2-q12 region. Because this region is preserved in all patients with ring 14, we speculate that genes residing in the proximal 14q interval are disregulated through heterochromatinization spreading from the adjacent short arm of the chromosome. Behavior disorders and susceptibility to infections can be assigned to the 14q32 region, haploinsufficiency being the most likely underlying mechanism."

This yields a two-mechanism model that should structure the dismech pathophysiology graph:

  • Proximal 14q11.2–q12 (present in 2 copies) → dysregulated by position effect / heterochromatin spreading → epilepsy + retinal abnormalities. Candidate effector: FOXG1.
  • Distal 14q32.33 (hemizygous) → classical haploinsufficiency → behavior disorders + infection susceptibility (IGH), possibly seizures via PACS2.

Note that Zollino 2009 (PMID:19441122) placed microcephaly and intellectual disability with the proximal group as well; scoliosis with 14q32.

4.5 Variant classification, allele frequency, origin

  • Classification: Not an ACMG sequence-variant question. Reported as a pathogenic structural/cytogenetic abnormality; ClinVar/DECIPHER/ECARUCA/dbVar carry the CNV component (terminal 14q32.33 loss) but not the ring topology.
  • Allele frequency: Not applicable. Terminal 14q32.33 deletions of this size are absent from gnomAD-SV control frequencies at any appreciable level.
  • Origin: Germline, de novo, in the overwhelming majority. Deleted rings 75% paternal / 25% maternal (Zollino 2012) [abstract-verbatim]. Somatic mosaicism for ring loss is universal (§6) but is a secondary somatic event on a germline lesion.
  • Functional consequence: Combined loss of function (hemizygosity, 14q32.33) and loss of normal regulation (position effect on 14q proximal — a qualitative, not quantitative, change).

dismech schema note. For the 14q32.33 genes, GeneticContext.functional_impact_category: LOSS_OF_FUNCTION with allele_type structural/CNV. For the proximal 14q dysregulation, the correct slot is Descriptor.modifier — and because the claim is that the locus is "no longer under normal regulatory control" rather than merely running low, LOSS_OF_FUNCTION (qualitative, unbound) is defensible over DECREASED. Make that trade explicitly per CLAUDE.md guidance.

4.6 Modifier genes

None validated. Candidate modifiers, all hypothesis-level: deletion size (determines PACS2 / IGH status); presence of cryptic proximal duplication; degree of somatic ring instability; parental origin (paternal skew — imprinting at DLK1-MEG3 14q32.2 is a theoretical but unproven contributor, and UPD(14) was excluded in all Zollino cases).

4.7 Epigenetics

This is where the modern mechanistic action is.

  • Heterochromatin spreading / telomere position effect (TPE): ring formation juxtaposes the acrocentric p-arm heterochromatin (rDNA, satellite) with proximal 14q euchromatin, and removes the native 14q telomere. Guideline [verify]: ring formation may cause "perturbation of the epigenetic state of specific genes along chromosome 14," with "heterochromatin spreading and possible repositioning" as proposed mechanisms.
  • Empirical support: Ferreira et al., J Appl Genet 2015 — "Position effect modifying gene expression in a patient with ring chromosome 14." Guideline notes recent studies "confirmed gene expression changes in patients with r(14) syndrome" [verify]. Analogous TPE evidence exists for ring 17 (PMC3892072) and transcriptome-level evidence for ring 20 (PMID:33207017).
  • Non-coding RNA gap (Vaisfeld 2021) [verify]: "there is essentially no literature concerning the possible role of untranslated RNAs in the r(14) syndrome," and the 14q32 region "contains the largest cluster of microRNAs in the entire human genome" — the imprinted DLK1-DIO3 miRNA mega-cluster at 14q32.2. This is a first-class KNOWLEDGE_GAP discussion for the entry.
  • TADs: the active NCT06813469 study (below) is testing whether ring formation disrupts topologically associating domains.

4.8 Chromosomal abnormality summary

  • Constitutional ring chromosome 14, replacing one normal chromosome 14
  • Typical ISCN: 46,XX,r(14)(p11q32.33) / 46,XY,r(14)(p13q32.33)
  • Frequently accompanied in vivo by a secondary somatic mosaic: 45,XX,-14 / 46,XX,r(14) / 46,XX,r(14)x2 / 47,XX,r(14),+r(14) etc.
  • Detected by karyotype (ring topology) + array CGH/SNP array (deletion extent). Array alone will miss a complete ring and will misclassify a deleted ring as a linear terminal deletion — a diagnostically consequential error.

5. Environmental Information

Environmental factors: None causally implicated. Ring chromosome formation is a de novo mitotic/meiotic accident; no toxin, radiation, pollutant, or occupational exposure has been linked to constitutional r(14).

Lifestyle factors: None causally implicated in disease occurrence. Post-diagnosis, nutrition is a major modifying exposure — anorexia/malnutrition is a named prognostic determinant, and vitamin D insufficiency is prevalent enough that the guideline recommends double-RDA supplementation (≈800–1,000 IU/day) prophylactically [verify].

Infectious agents: Not causal. But respiratory pathogens are a first-class disease-modifying exposure — they act on an established immune lesion and represent the main adult mortality mechanism. This is the one environmental entry that genuinely earns influences_mechanisms in the dismech pathograph:

environmental:
- name: Recurrent respiratory pathogen exposure
  influences_mechanisms:
  - target: Impaired humoral immunity
    environmental_effect: EXACERBATES
    causal_link_type: DIRECT

A second, iatrogenic exposure is documented: chronic aspiration of cannabis oil used for seizure control caused lipoid pneumonia in a 4-year-old with ring chromosome 14 (Hanzal et al., Chest 2025, PMID:40348517) [verify] — a real adverse-event signal given how commonly CBD oil is used in this population.

ECTO binding candidates (all require OAK verification against cache/ecto/; per the dismech-terms rule, no term beats a bad one): exposure to respiratory pathogens; oral exposure to cannabidiol. If ECTO has nothing precise, leave unbound with a review_notes: waiver recording the search.

6. Mechanism / Pathophysiology

This is the section that should carry the entry's mechanistic weight. The causal architecture has four partially independent arms, and the field explicitly does not know which dominates.

6.1 Upstream initiating event

Ring chromosome 14 formation — two breakpoints (14p + 14q), end-to-end fusion, telomere loss.

GO: GO:0032200 telomere organization · GO:0006281 DNA repair · GO:0000724 double-strand break repair via homologous recombination · GO:0051276 chromosome organization.

6.2 Arm A — Position effect / heterochromatin spreading (→ epilepsy, retinal phenotype)

Causal chain:

ring formation
  → loss of 14q telomere + juxtaposition of 14p acrocentric heterochromatin to proximal 14q
  → heterochromatin spreading / altered nuclear repositioning (telomere position effect)
  → transcriptional silencing/dysregulation of proximal 14q11.2–q12 genes (2 copies present)
  → reduced FOXG1 (and neighbors) function in developing forebrain
  → abnormal cortical neuron differentiation and excitation/inhibition imbalance
  → early-onset drug-resistant focal epilepsy; microcephaly; retinal pigmentary abnormality

This arm explains the central dissociation: linear 14q deletions of matched size cause neither refractory epilepsy nor retinal changes, because they leave the p-arm/telomere relationship intact.

GO: GO:0031507 heterochromatin formation · GO:0016458 gene silencing · GO:0006357 regulation of transcription by RNA Pol II · GO:0007399 nervous system development · GO:0021895 cerebral cortex neuron differentiation · GO:0060384? — prefer GO:0050767 regulation of neurogenesis. CL: CL:0000540 neuron · CL:0000598 pyramidal neuron · CL:0000617 GABAergic neuron · CL:0000679 glutamatergic neuron · CL:0011005? (verify) · CL:0002586 retinal pigment epithelial cell. UBERON: UBERON:0000955 brain · UBERON:0000956 cerebral cortex · UBERON:0002421 hippocampal formation · UBERON:0000966 retina.

biological_scale: — the heterochromatin/transcription nodes are MOLECULAR; neuron differentiation is CELLULAR; epilepsy is ORGANISM.

6.3 Arm B — Ring mitotic instability and dynamic mosaicism (→ growth failure, possible epileptogenic focus)

Rings are structurally unstable. Sister chromatid exchange within a ring generates dicentric and interlocked rings; anaphase bridging and lagging generate ring loss and micronuclei.

Vaisfeld 2021 [verify]:

"Sister chromatid exchanges occurring during mitosis can result in the generation of dicentric or interlocked rings, or lead to ring chromosome loss, creating a mosaic of cells with different functional properties."

And, critically for tissue-specificity:

the proportion of cells with complete ring loss "is known to be around 20% in peripheral blood cells" — but "it could be higher in areas of the brain contributing to a potential epileptogenic focus."

Directly measured instability (Meza-Espinoza et al., Mol Cytogenet 2024, PMID:39020403) [verify]: - 30/243 cells (12.3%) monosomic for 14 (ring lost) - 15/243 cells (6.2%) with three signals (duplicated/dicentric ring) - 27/305 (9%) interphase cells with micronuclei; FISH confirmed r(14) inside 21/21 micronuclei tested - Authors: "we were able to verify an instability of the r(14) chromosome, mainly involving anaphasic lags and its exclusion from the nucleus in the form of a micronucleus."

The guideline's counterpoint on the diagnostic side [verify]: in blood, "at least 85–90%" of cells harbor the ring, and aneuploid fractions are "usually below the sensitivity of a CGH-array."

Kosztolányi's "ring syndrome": growth failure as the near-universal, chromosome-independent consequence of ring instability ("dynamic mosaicism"), because mosaic monosomic cells have low viability and high death rate. Contemporary opinion has partly shifted toward hemizygous gene loss as the driver of malformations, with dynamic mosaicism retained principally for growth failure.

ring instability
  → anaphase lag / bridge → micronucleus formation → ring loss
  → mosaic monosomy 14 in a subset of somatic cells
  → cell-cycle arrest / apoptosis / reduced proliferative output
  → generalized growth failure, short stature, postnatal microcephaly
  → (hypothesized) locally high monosomic fraction in cortex → epileptogenic focus

GO: GO:0007059 chromosome segregation · GO:0140014 mitotic nuclear division · GO:0007094 mitotic spindle assembly checkpoint signaling · GO:0006915 apoptotic process · GO:0090398 cellular senescence · GO:0008283 cell population proliferation.

6.4 Arm C — 14q32.33 haploinsufficiency (→ immune, behavior, ?seizures)

terminal 14q32.33 deletion (0.3–5 Mb)
  → hemizygosity of IGH constant-region locus (chr14:~105.6–106.9 Mb)
  → reduced/skewed immunoglobulin heavy-chain repertoire
  → impaired humoral immunity (esp. IgA)
  → recurrent upper-airway infection → severe pneumonia → adult mortality

  → (when deletion >1.65 Mb) hemizygosity of PACS2
  → possible minimally penetrant epileptogenic effect, "enhanced by the formation of the ring"

Vaisfeld on PACS2 [verify]: "it may be worth exploring whether haploinsufficiency has a minimally penetrant epileptogenic effect, which is enhanced by the formation of the ring." This is an explicit two-hit / synergy hypothesis and should be curated as a mechanistic_hypotheses group with status: EMERGING, with the relevant downstream edges opting in via hypothesis_groups.

GO: GO:0002377 immunoglobulin production · GO:0006959 humoral immune response · GO:0016064 immunoglobulin mediated immune response · GO:0002250 adaptive immune response. CL: CL:0000236 B cell · CL:0000786 plasma cell · CL:0000084 T cell. UBERON: UBERON:0002405 immune system · UBERON:0001004 respiratory system · UBERON:0002048 lung.

6.5 Arm D — Aberrant IgG N-glycosylation (2026, newest)

Messina A, et al. "IgG Glycosylation Analysis in Patients with Ring14 Syndrome Unveils Novel Pathomechanisms and New Therapy Perspectives." Biomolecules 2026;16(6):760. PMID:42352229, DOI:10.3390/biom16060760 (preprint: doi:10.20944/preprints202604.0844.v1)

Six RC14 patients vs. age-matched controls; UHPLC-FLR + high-resolution ESI-MS [verify]: - Decreased galactosylation and sialylation, "resembling pro-inflammatory patterns observed in autoimmune diseases" - Increases in the afucosylated species A2G1 and the agalactosylated structures FA2 and FA2B; increases in bisected and afucosylated N-glycans - ANOVA identified seven N-glycans with significant intensity differences - Changes appeared selective to IgG - Interpretation: alterations "might enhance the pro-inflammatory IgG structures while decreasing the anti-inflammatory ones"

The mechanistic puzzle the authors themselves raise [verify]: "No genes encoding galactosyltransferases or sialyltransferases are located on chromosome 14." So the glycosylation phenotype cannot be explained by simple hemizygosity — it is either a trans consequence of ring-driven transcriptional dysregulation or a secondary inflammatory-state readout. Curate this explicitly as a KNOWLEDGE_GAP.

Therapeutic signal: Patient 1 on IVIG showed "a reduction in seizures from 5–6/week to one/week," causality uncertain [verify]. Authors propose IVIG and/or monoclonal antibodies to modulate the inflammatory response.

GO: GO:0006487 protein N-linked glycosylation · GO:0006486 protein glycosylation · GO:0006954 inflammatory response · GO:0002455? humoral immune response mediated by circulating immunoglobulin. CHEBI: N-glycan / oligosaccharide terms — verify before binding.

6.6 What is not known

  • No proteomics, metabolomics, or lipidomics studies of r(14) exist beyond the IgG glycan work.
  • No single-cell or spatial transcriptomics.
  • No CRISPR/RNAi functional screen.
  • Transcriptomics is limited to small position-effect studies (Ferreira 2015) and the ring 20 analogue (PMID:33207017).
  • The MD-RING study (NCT06813469) is the first systematic multi-omic/long-read effort — see §12/§15.

7. Anatomical Structures Affected

Organ level

Primary: - Brain / central nervous system — UBERON:0000955. Cerebral cortex (UBERON:0000956), hippocampal formation (UBERON:0002421), corpus callosum (UBERON:0002336), cerebellum (UBERON:0002037), lateral ventricles (UBERON:0002285). - Eye / retina — UBERON:0000970 eye; UBERON:0000966 retina; UBERON:0004864? macula lutea (verify); UBERON:0000941 optic nerve; UBERON:0001769 iris; UBERON:0000965 lens of camera-type eye.

Secondary / systemic: - Immune system — UBERON:0002405; respiratory system — UBERON:0001004; lung — UBERON:0002048 - Digestive system — UBERON:0001007 (feeding difficulty, dysphagia, GERD, celiac disease) - Musculoskeletal: vertebral column — UBERON:0001130 (scoliosis, kyphosis); skeleton — UBERON:0004288 (osteopenia/osteoporosis); musculature — UBERON:0001015 (hypotonia) - Craniofacial skeleton — UBERON:0010363? / UBERON:0001474 bone element; dentition — UBERON:0003672? (verify) - Lymphatic system — UBERON:0006558? / UBERON:0002465 lymphoid system (lymphedema of hands/feet)

Body systems: nervous, visual/sensory, immune, respiratory, digestive, musculoskeletal, lymphatic. Notably spared: cardiovascular and renal/urinary — congenital malformations of heart, kidney, and urinary tract are "very rarely reported."

Tissue and cell level

Tissue/cell CL/UBERON Basis
Cortical neurons (excitatory/inhibitory) CL:0000540, CL:0000679, CL:0000617, CL:0000598 epilepsy, E/I imbalance
Neural progenitor cells CL:0011020 neural progenitor cell microcephaly, FOXG1 biology
Astrocytes, microglia CL:0000127, CL:0000129 inferred; not directly demonstrated in r(14)
Retinal pigment epithelium CL:0002586 pigmentary retinopathy
Photoreceptors (rod/cone) CL:0000604 / CL:0000573 retinitis pigmentosa reports
B cells / plasma cells CL:0000236 / CL:0000786 IGH hemizygosity, IgA deficiency
Skeletal muscle CL:0000188 hypotonia (likely central, not myopathic — curate cautiously)
Dermal fibroblasts CL:0000057 the tissue in which ring instability and iPSC reprogramming are studied

Subcellular level

  • Nucleus — GO:0005634; chromosome / centromeric region — GO:0000775; heterochromatin — GO:0000792; nuclear periphery/lamina — GO:0005652? nuclear lamina (verify) — relevant to repositioning
  • Micronucleus — GO:0097604? (verify; may require free text) — the direct cytological readout of ring loss
  • Mitotic spindle — GO:0072686
  • Golgi apparatus — GO:0005794 (site of IgG N-glycan maturation)

Localization / lateralization

Brain involvement is bilateral and diffuse; EEG shows generalized slow background with multifocal spikes and a posterior/occipital predominance of complex spike-and-wave. Retinal involvement is bilateral. Facial asymmetry ("long and sometimes asymmetrical face") is a described but minor asymmetric feature. Scoliosis is by definition an asymmetric axial deformity.

8. Temporal Development

Onset

  • Lesion: congenital — de novo, arising in gametogenesis or very early embryogenesis.
  • Growth restriction: may begin prenatally (IUGR reported), but microcephaly is characteristically postnatal-onset — a useful discriminator.
  • Epilepsy: "usually … in the first months of life"; infantile onset is the annotated HPO onset (HP:0003593). One series reported r(14) seizure onset at 3–24 months, after developmental delay was already apparent (PMID:41087847) [verify].
  • Developmental delay: recognized in infancy, frequently before seizure onset.
  • Onset pattern: chronic/insidious for the developmental phenotype; the epilepsy onset can be abrupt.

Progression

The disease is non-progressive at the level of the underlying lesion (GARD explicitly: "Condition is non-progressive"), but the clinical course has three distinguishable phases:

Phase Age Character
Early / encephalopathic 0–5 y Highest seizure burden; status epilepticus; risk of developmental regression — "intense epileptic activity, more frequent in the early years of life, may be associated with regression of the stages of psychomotor development or previously acquired language" [verify]. This is the critical window.
Plateau childhood–adolescence Slow developmental gains; seizures persist but frequency often declines
Late / adult late adolescence onward Seizures "eventually decrease in frequency during late adolescence" [verify]; morbidity shifts to infection, malnutrition, scoliosis, osteopenia

Progression rate: variable, driven by seizure burden. Course pattern: episodic seizures (with clusters) on a stable, non-degenerative developmental baseline. Duration: chronic, lifelong.

Patterns

  • Remission: no spontaneous remission of the disorder. Seizure amelioration with age is real but partial. A critical caveat from the guideline [verify]: "Interrupting effective antiepileptic therapies when the symptomatology appears less severe could lead to the return of seizures that may even result no longer responsive to previously effective treatments." — i.e. apparent improvement is not a license to withdraw ASMs.
  • Critical periods / intervention windows:
  • First 5 years — aggressive seizure control to protect the developmental trajectory (the encephalopathic-effect claim)
  • Infancy onward — early physical therapy "to reduce hypotonic complications (such as scoliosis) due to the reduced muscle tone" [verify]
  • Throughout — nutritional support before malnutrition is established
  • Adulthood — infection prophylaxis/surveillance, the dominant mortality risk

9. Inheritance and Population

Epidemiology

Measure Value Source
Point prevalence <1 / 1,000,000 worldwide Orphanet ORPHA:1440 (ORDO annotation)
Cumulative reported cases ~80–100 since first report in 1971 Guideline PMC5387247: "Over 80 cases have been described since the first report in 1971"; MedlinePlus: "More than 80 affected individuals have been reported in the scientific literature"
Incidence Not established —
Registry cohort ~54 patients in the Ring14 International clinical database ring14.org

For dismech prevalence::

prevalence:
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: BELOW_1_IN_1000000
  rate_per_100000: 0.1        # upper bound; <1 per 1,000,000 = <0.1 per 100,000
  notes: >-
    Orphanet worldwide point-prevalence class <1/1,000,000. Approximately 80-100
    cases reported in the literature since 1971; exact prevalence unknown and
    almost certainly underascertained because array-only testing misses the ring.

Ascertainment caveat worth curating: because chromosomal microarray has largely displaced karyotyping as a first-tier test, a deleted ring 14 is now readily misreported as a linear 14q terminal deletion, and a complete ring 14 (no copy-number change, ~22% of cases) is invisible to array entirely. Reported prevalence is therefore a floor.

Inheritance

  • Pattern: Sporadic / de novo, not inherited (HP:0003745 Sporadic). ORDO annotates inheritance as "Not applicable; Unknown."
  • MedlinePlus: "Ring chromosome 14 syndrome is typically not inherited. A ring chromosome usually occurs as a random event during the formation of reproductive cells or during early embryonic development." Rare familial transmission has been documented but is exceptional.
  • Penetrance: complete for the ring carrier state (all reported ring 14 individuals are affected).
  • Expressivity: variable — driven by deletion size, ring instability, and cryptic duplications.
  • Anticipation: not applicable (no repeat expansion; transmission is essentially never observed).
  • Germline mosaicism: not reported; empiric recurrence risk to parents is very low but a de novo event cannot be formally excluded from a gonadal-mosaicism origin.
  • Somatic mosaicism: universal — for ring loss/duplication (see §6.3). Distinguish carefully from constitutional mosaicism for the ring itself, which is occasionally reported.
  • Founder effects: none. Consanguinity: no role. Carrier frequency: not applicable.

Population demographics

  • Ethnic/geographic: no predilection reported; cases described worldwide (Italy, USA, Mexico, Russia, China, Turkey, Bulgaria, Estonia in the recent literature).
  • Sex ratio: not established. A general ring-chromosome cohort (Murry et al., Genes 2025, PMID:40725393; 40 constitutional rings over 37 years) noted "a preponderance of pediatric-aged females at first ascertainment" [verify] — but this is an ascertainment observation across all rings, not an r(14)-specific sex ratio, and should not be curated as one. A 2025 Chinese series of 9 ring-chromosome children was 6F:3M overall (PMID:41087847), again too small and not r(14)-specific.
  • Age distribution: diagnosis typically in infancy/early childhood following seizure onset and developmental delay; GARD notes symptom recognition often ages 2–11 y. Adults are described but the adult natural history is poorly characterized.

10. Diagnostics

The diagnostic algorithm (2017 task-force consensus)

The guideline's central diagnostic recommendation has two halves, and the second is the one most often missed [verify]:

  1. Array-CGH as the first diagnostic step for a child with "neuro-psychological alterations and drug-resistant epilepsy."
  2. "All subject for whom a 14q terminal deletion is identified should be addressed to a standard karyotype to assess the presence of the ring."

Plus a sensitivity requirement: "The analysis of at least 30 metaphases is necessary for a >95% chance of detecting a r(14) chromosome that occurs in at least 80% of cells."

Genetic testing

Modality Utility for r(14)
Karyotype (≥30 metaphases) Essential and diagnostic. The only routine test that visualizes ring topology. Also quantifies mosaic ring loss/duplication.
Chromosomal microarray (CMA / aCGH / SNP array) Defines terminal deletion size and gene content; cannot detect a complete ring; will mislabel a deleted ring as linear. SNP arrays additionally exclude UPD(14).
FISH (subtelomeric 14q, centromere 14) Confirms ring, quantifies mosaic monosomy/duplicated rings, identifies r(14) within micronuclei (Meza-Espinoza 2024 method).
Long-read sequencing (LRS) Investigational — the intervention under study in NCT06813469 for breakpoint resolution and TAD analysis.
WES Low yield for the ring itself; useful to exclude phenocopies.
WGS Can call the terminal CNV and, with structural-variant calling, the fusion junction. Not yet standard.
Gene panels / single-gene testing Not diagnostic. Epilepsy panels covering FOXG1, PACS2, CHD8, IRF2BPL, CDKL5, STXBP1, SCN1A will be negative and can delay diagnosis — a real clinical trap.
mtDNA testing / repeat expansion testing Not applicable.
Parental karyotypes Recommended for counseling (rare familial ring).

Baseline clinical evaluation (guideline) [verify]

"cerebral MR, EEG, heart and abdomen US, oculistic and audiologic evaluation, neuropsychological assessment."

Clinical / laboratory / imaging tests

  • EEG (essential; also a severity marker correlating negatively with cognition) — LOINC/NCIT term needed
  • Brain MRI — usually normal or with nonspecific mild atrophy/callosal/ventricular/hippocampal/cerebellar changes
  • Ophthalmologic exam incl. dilated fundoscopy and multimodal imaging (OCT, fundus autofluorescence, near-infrared reflectance — Vasconcelos 2019 showed macular yellow dots only on multimodal imaging)
  • Immunological workup: quantitative immunoglobulins (IgG, IgA, IgM), IgG subclasses, specific antibody responses — annually per guideline
  • Nutritional/growth: anthropometrics, vitamin D, swallow study when aspiration suspected
  • Skeletal: spine radiographs for scoliosis; DXA for osteopenia
  • Cytogenetic instability assays (research/specialist): micronucleus assay + FISH (Meza-Espinoza 2024)
  • Emerging biomarker (research only): IgG N-glycan profile by UHPLC-FLR/ESI-MS — decreased galactosylation and sialylation (Messina 2026). Not validated; no PPV/NPV data.

No validated biochemical biomarker, no newborn-screening analyte, no FDA-listed biomarker exists.

Diagnostic criteria and differential

There are no formal consensus diagnostic criteria (no DSM/ICD-style rule set). Diagnosis is cytogenetic.

Differential diagnosis:

Condition Distinguishing feature
Linear 14q32.33 terminal deletion syndrome Same CNV, no ring → epilepsy reported in only ~2/11 published cases and no retinal abnormalities reported (Vaisfeld 2021) [verify]. The single most important distinction.
FOXG1 syndrome (congenital Rett variant) Point mutation/14q12 deletion; postnatal microcephaly + dyskinesia; no ring
PACS2-DEE (DEE-66) Neonatal seizures, cerebellar dysgenesis; recurrent p.Glu209Lys
Ring chromosome 20 syndrome Also epilepsy-dominant ring; characteristic prolonged nonconvulsive status with distinctive EEG; normal development early
Dravet syndrome (SCN1A) Fever-sensitive hemiclonic seizures; normal early development
Angelman syndrome Happy demeanour, ataxia, characteristic EEG; 15q11-13
Lennox–Gastaut syndrome Slow spike-wave, tonic seizures in sleep — a pattern, not an etiology; r(14) can present LGS-like
Temple syndrome / Kagami–Ogata (UPD14) Imprinting; excluded in r(14) series
Other DEEs (CDKL5, STXBP1, SCN2A) Gene-specific

Screening

  • Newborn screening: not applicable — no biochemical marker.
  • Carrier screening: not applicable — de novo.
  • Cascade screening: not indicated (parental karyotype is for counseling reassurance, not cascade testing).
  • Prenatal: karyotype ± CMA on CVS/amniocentesis will detect a ring 14; NIPT/cfDNA will not reliably detect it (small terminal CNV; no ring topology information). Prenatal detection is generally incidental or follows an abnormal ultrasound (IUGR).

11. Outcome / Prognosis

Survival and mortality

The honest curation answer is "not established." Guideline [verify]:

"A precise prognosis in terms of expected lifespan in individuals with r(14) syndrome has yet to be established." "Prognosis should be estimated individually and depends primarily on comorbidities and medical complications." "The epileptic burden, infectious complications and nutritional deficiencies should be considered as major determinants."

  • No 5-year or 10-year survival figures, no life-expectancy estimate, no mortality rate exists in the literature. Do not manufacture one.
  • Leading cause of adult death: infection. "Infections are one of the worse prognostic factors and the main cause of death in adulthood" [verify].
  • Survival into adulthood is clearly attainable — the Meza-Espinoza 2024 index case was 21 years old.
  • SUDEP risk is not quantified for r(14) but is a reasonable concern given lifelong drug-resistant epilepsy; do not curate a numeric estimate.

Morbidity and function

  • Intellectual disability, moderate to severe, in essentially all patients — the dominant long-term functional determinant alongside epilepsy.
  • Many patients are nonverbal; the guideline's management emphasis on preserving communication reflects this.
  • Ambulation: achieved late (2–3 years) in most; some never walk.
  • Lifelong dependence for activities of daily living is the norm.
  • No EQ-5D, SF-36, PROMIS, or disease-specific validated QoL instrument has been applied. The SanInocencio 2026 conceptual disease model (PMID:41533279) is the first systematic characterization of lived experience and is explicitly the foundation for a future COA/PRO instrument — cite it as the QoL source of record and note the absence of quantitative instruments as a gap.

Complications

Recurrent/severe respiratory infection · aspiration pneumonia (including iatrogenic lipoid pneumonia from oil-based CBD, PMID:40348517) · status epilepticus (~50%) · developmental regression during periods of intense epileptic activity · malnutrition requiring enteral feeding · scoliosis · juvenile osteoporosis/osteopenia with fracture risk · visual impairment in a minority · sleep disorder · celiac disease.

Recovery potential

None in the sense of cure. Meaningful, treatment-attributable improvement is possible in seizure frequency (with ASMs, ketogenic diet, VNS, CBD), nutritional status (enteral feeding), and motor complications (early physiotherapy). The developmental disability itself is not reversible with current therapy.

Prognostic factors

  1. Seizure burden and EEG severity in the first years — negatively correlated with cognitive development (Giovannini 2013)
  2. Infection frequency/severity — the adult mortality driver
  3. Nutritional status — named guideline determinant
  4. Deletion size — larger terminal deletions include PACS2 and more of IGH; the ≥650 kb threshold marks the recognizable facial gestalt
  5. Degree of ring instability — biologically plausible, clinically unvalidated

No prognostic biomarker is validated. The IgG glycan profile is the only candidate on the horizon.

12. Treatment

There is no disease-modifying or curative therapy. Management is symptomatic, multidisciplinary, and guideline-directed.

12.1 Antiseizure pharmacotherapy

Guideline [verify]: "Antiepileptic drugs are frequently used: barbiturates (in the first months of life), valproic acid, carbamazepine, topiramate, vigabatrin, clobazam and levetiracetam." And: "About half of patients with r(14) syndrome show drug resistance, while in the remaining half seizure control is variable."

Drug Class / MoA dismech annotation
Phenobarbital Barbiturate; GABA-A positive allosteric modulator. First months of life. High-dose oral phenobarbital was effective in 7/11 (63.6%) children with refractory seizures in a series that included r(14) (PMID:40129048) [verify] treatment_term: NCIT:C15986 Pharmacotherapy; therapeutic_agent: CHEBI phenobarbital (verify CURIE); therapeutic_modality: SMALL_MOLECULE
Valproic acid Broad-spectrum; HDAC inhibition, GABAergic, Na⁺ channel CHEBI:39867 (verify)
Carbamazepine Na⁺ channel blocker; appropriate given predominantly focal semiology CHEBI:3387 (verify)
Topiramate Multi-mechanism (verify CURIE)
Vigabatrin Irreversible GABA-transaminase inhibitor. Retinal toxicity risk — noteworthy in a syndrome with baseline retinal pathology; visual-field/ERG monitoring is doubly important here. (verify CURIE)
Clobazam Benzodiazepine (verify CURIE)
Levetiracetam SV2A ligand (verify CURIE)

Explicit management warning to curate [verify]: do not withdraw an effective ASM during a quiescent phase — "Interrupting effective antiepileptic therapies when the symptomatology appears less severe could lead to the return of seizures that may even result no longer responsive to previously effective treatments."

12.2 Cannabidiol

Guideline preliminary data [verify]: seizure frequency reduced with an "adequate safety profile," dosing "2–5 mg/Kg per day, up-titrated until intolerance or to a maximum of 20–25 mg/kg per day" — i.e. the Epidiolex regimen. Note that CBD has RCT-grade evidence and FDA/EMA approval in Dravet and Lennox–Gastaut, not in r(14); its use here is extrapolation plus small-series experience.

Safety signal: oil-based CBD aspiration caused lipoid pneumonia in a 4-year-old with ring chromosome 14 (PMID:40348517) — relevant given the high baseline aspiration risk in this population.

therapeutic_modality: SMALL_MOLECULE; therapeutic_agent: cannabidiol (verify CHEBI CURIE).

12.3 Non-pharmacological seizure therapy

  • Ketogenic diet — "may be taken in consideration for the therapeutic strategy" [verify]. treatment_term: NCIT:C15447 Dietary Intervention; therapeutic_modality: BEHAVIORAL.
  • Vagus nerve stimulation — same recommendation strength. therapeutic_modality: DEVICE; NCIT term for vagus nerve stimulation (verify).
  • Epilepsy surgery — not applicable; the epilepsy is multifocal/diffuse with no resectable focus.

12.4 Immunological / experimental

  • IVIG — one RC14 patient on IVIG showed seizure reduction from 5–6/week to ~1/week (Messina 2026) [verify]; causality explicitly uncertain, n=1. The authors propose IVIG and/or monoclonal antibodies to modulate inflammation. Curate as EMERGING hypothesis with supports: PARTIAL, not as an established treatment.
  • Antibiotic prophylaxis / immunization — implied by the annual immunology follow-up recommendation; specific regimens are not specified in the guideline.

12.5 Supportive, nutritional, rehabilitative

Intervention Guideline detail [verify] NCIT
Enteral tube feeding "recommended when anorexia is limiting caloric intake and/or when aspiration occurs during swallowing" NCIT:C15433 Nutritional Support (+ gastrostomy procedure term)
Vitamin D supplementation "must be given at twice the of recommended daily allowance (approximately 800-1.000 IU/day)" NCIT:C15433; therapeutic_agent: cholecalciferol (CHEBI, verify); therapeutic_modality: SMALL_MOLECULE
Physical therapy "Start physical therapy early to reduce hypotonic complications (such as scoliosis) due to the reduced muscle tone" NCIT:C15302 Physical Therapy; BEHAVIORAL
Speech / AAC "Many patients … are nonverbal and thus maintaining their ability to communicate is always essential" NCIT:C159273 Speech Therapy; BEHAVIORAL
Occupational therapy implied by multidisciplinary model NCIT:C121351
Scoliosis management (bracing/surgery) complication-driven NCIT:C16186 Orthopedic Surgical Procedure; SURGERY
Genetic counseling de novo, low recurrence risk NCIT:C15240
Multidisciplinary specialist care "Multidisciplinary care at a major clinical facility should be available for patients and their relatives to reduce medical complications and improve quality of life" NCIT:C15747 Supportive Care

Follow-up cadence (guideline) [verify]: "Immunologist, once per year; child Neurologist/Neurologist, as needed; Ophthalmologist, as needed; Gastroenterologist/Nutritionist, as needed."

12.6 Advanced therapeutics — none available

  • Gene therapy / gene editing: not applicable in current form — the lesion spans megabases and, per the position-effect model, involves chromosome architecture rather than a single gene.
  • RNA-based therapy (ASO/siRNA): no target established.
  • Cell therapy: none clinically. But see the "chromosome therapy" concept in §15 — reprogramming-mediated ring correction is the only conceptual disease-modifying route ever proposed for ring disorders, and it is preclinical.
  • Pharmacogenomics: no r(14)-specific PGx. Standard CPIC guidance applies (notably HLA-B*15:02/HLA-A*31:01 for carbamazepine, CYP2C9 for phenytoin/valproate considerations, POLG contraindication screening before valproate in unexplained epileptic encephalopathy). These are population-standard, not disease-specific.

12.7 Clinical trials

NCT Title Status Type
NCT06813469 Multi-Dimensional Genomic Dissection of Ring Chromosome 14 Syndrome (MD-RING) Active, not recruiting Interventional (registry-classified); intervention = LRS analysis (long-read sequencing)

Brief summary [verify]: "The MD-RING study investigates how position effects and TAD alterations may cause ring chromosome 14 syndrome. Researchers aim to clarify genetic-to-clinical relationships, establish resources for ring syndrome research, and ultimately enhance family counseling, patient management, and identify potential therapeutic approaches."

No interventional therapeutic trial specific to ring chromosome 14 has ever been conducted.

13. Prevention

Primary prevention: not possible. A de novo structural chromosomal event with no known modifiable risk factor. There is nothing to modify — no vaccination, no exposure reduction, no behavioral intervention that alters occurrence.

Secondary prevention (early detection): - No population screening program exists or is justifiable at this prevalence. - The actionable secondary-prevention message is diagnostic: karyotype every child in whom a 14q terminal deletion is found on array, and karyotype (≥30 metaphases) children with early-onset drug-resistant epilepsy + developmental delay + microcephaly + retinal changes whose gene panel is negative. Earlier diagnosis enables earlier immunological, ophthalmologic, and nutritional surveillance. - Prenatal/reproductive: karyotype ± CMA on CVS/amniocentesis detects a ring 14. PGT is theoretically available but essentially never indicated given the de novo origin and negligible recurrence risk. Prenatal testing in a subsequent pregnancy may be offered for reassurance.

Tertiary prevention (preventing complications) — this is where nearly all the actionable prevention lives:

Target complication Preventive action
Developmental regression Aggressive early seizure control; do not withdraw effective ASMs prematurely
Recurrent/severe infection → adult mortality Annual immunology review; routine + risk-based immunization; prompt treatment of respiratory infection
Malnutrition Early nutritional assessment; enteral feeding before failure to thrive is entrenched
Aspiration pneumonia Swallow assessment; caution with oil-based CBD preparations (PMID:40348517)
Scoliosis Early physiotherapy from infancy
Osteopenia/fracture Vitamin D at 2× RDA (800–1,000 IU/day); weight-bearing where possible; note valproate/ASM bone effects
Vision loss Regular ophthalmologic exam; special vigilance with vigabatrin
Dental disease Ivanoff 2023 (PMID:36855970) — dedicated dental management guidance

Genetic counseling: the core message is (1) sporadic, de novo origin; (2) recurrence risk to the parents is very low (empiric, with the caveat that germline mosaicism cannot be formally excluded); (3) parental karyotypes are appropriate to exclude the rare familial ring; (4) recurrence risk for the affected individual's own offspring is not a practical question given the severity of the phenotype. NCIT:C15240 Genetic Counseling.

Public health / environmental interventions: not applicable.

14. Other Species / Natural Disease

Direct orthologue disease

None. There is no naturally occurring "ring chromosome 14 syndrome" in any non-human species, and there cannot be a direct orthologue: human chromosome 14 is a synteny construct that maps onto multiple chromosomes in mouse (principally Mmu 12 and Mmu 14) and other mammals. The disease concept is human-chromosome-specific.

  • NCBI Taxonomy: NCBITaxon:9606 Homo sapiens — the only species in which this disease entity is defined.
  • VBO breed terms: not applicable.

Comparative biology that is relevant

  • Ring chromosomes as a class occur in other species. Constitutional and radiation-induced ring chromosomes are documented in mouse, dog, cattle, and horse cytogenetics, and ring-chromosome instability (anaphase bridging, sister-chromatid-exchange–driven ring loss) is a conserved mitotic phenomenon, not a human peculiarity. This makes the instability arm of the mechanism (§6.3) comparatively tractable even though the disease is not.
  • OMIA: no ring chromosome 14 entry. Searching OMIA for ring-chromosome entries is worthwhile for the general instability biology but will not yield a disease analogue.
  • Gene orthologues (for arm-specific modeling rather than for the syndrome): Foxg1 (mouse, NCBI Gene 15228), Pacs2 (mouse), Chd8 (mouse) — all have well-characterized mouse models with neurodevelopmental phenotypes.
  • Evolutionary conservation: telomere position effect and heterochromatin spreading are deeply conserved (classic Drosophila position-effect variegation, S. cerevisiae subtelomeric silencing), which is the strongest cross-species support for the position-effect hypothesis — though as an analogy, not as evidence about r(14) itself.

Transmission

Not applicable. Non-infectious, non-zoonotic, no cross-species susceptibility.

15. Model Organisms

The core problem

There is no animal model of ring chromosome 14 syndrome, and building one is not straightforward. A mouse cannot carry a ring human chromosome 14; engineering a ring from the syntenic mouse regions would not reproduce either the gene content or the p-arm heterochromatin juxtaposition that the position-effect model depends on. Vaisfeld et al. close by calling for work "especially addressing the expression and functional consequences of candidate pathogenic genes and the role of epigenetic mechanisms in simplified model systems" [verify] — an explicit acknowledgment that no faithful whole-organism model exists.

For dismech, this belongs in a HUMAN_MODEL_MISMATCH discussion, not a generic KNOWLEDGE_GAP: model-system evidence exists for the component genes, but its translational validity to the ring-specific mechanism is precisely the open question.

15.1 Patient-derived cellular models (the workhorse)

System Use Notes
Patient dermal fibroblasts (CL:0000057) Cytogenetic instability assays: metaphase FISH for mosaic monosomy/duplicated ring; micronucleus assay; SCE The substrate for Meza-Espinoza 2024's instability quantification. Directly MEASURES the ring-instability node.
Peripheral blood lymphocytes Standard karyotype (≥30 metaphases); mosaicism quantification Guideline-mandated diagnostic tissue
Patient-derived iPSCs (CL:0002248 verify) Position-effect / transcriptome studies; differentiation to neurons Major caveat below
iPSC-derived cortical neurons / cerebral organoids The only plausible route to modeling the epileptogenic mechanism in human cells Not yet published for r(14)
Lymphoblastoid cell lines Expression profiling (the Ferreira 2015 position-effect approach) Blood-derived; brain relevance limited

15.2 The iPSC caveat that must be curated

Bershteyn M, Hayashi Y, Desachy G, et al. "Cell-autonomous correction of ring chromosomes in human induced pluripotent stem cells." Nature 2014;507(7490):99–103. PMID:24413397, DOI:10.1038/nature12923 — studied ring 13 and ring 17, not ring 14. Abstract [abstract-verbatim]:

"Ring chromosomes are structural aberrations commonly associated with birth defects, mental disabilities and growth retardation. Rings form after fusion of the long and short arms of a chromosome, and are sometimes associated with large terminal deletions. Owing to the severity of these large aberrations that can affect multiple contiguous genes, no possible therapeutic strategies for ring chromosome disorders have been proposed. During cell division, ring chromosomes can exhibit unstable behaviour leading to continuous production of aneuploid progeny with low viability and high cellular death rate. The overall consequences of this chromosomal instability have been largely unexplored in experimental model systems. Here we generated human induced pluripotent stem cells (iPSCs) from patient fibroblasts containing ring chromosomes with large deletions and found that reprogrammed cells lost the abnormal chromosome and duplicated the wild-type homologue through the compensatory uniparental disomy (UPD) mechanism. The karyotypically normal iPSCs with isodisomy for the corrected chromosome outgrew co-existing aneuploid populations, enabling rapid and efficient isolation of patient-derived iPSCs devoid of the original chromosomal aberration. Our results suggest a fundamentally different function for cellular reprogramming as a means of 'chromosome therapy' to reverse combined loss-of-function across many genes in cells with large-scale aberrations involving ring structures. In addition, our work provides an experimentally tractable human cellular system for studying mechanisms of chromosomal number control, which is of critical relevance to human development and disease."

The two-edged implication for r(14) modeling:

  1. As therapy concept — "chromosome therapy": reprogramming purges the ring. Related work: Kim et al. (PMID:25482192), and PMID:27882407 on ring correction via iPSC reprogramming. Entirely preclinical; no route to correcting a whole organism.
  2. As a modeling hazard — this is the point that matters for curation. iPSC lines derived from ring-chromosome patients spontaneously lose the ring and become karyotypically normal via compensatory UPD, and the corrected cells then outcompete the ring-bearing ones. Any r(14) iPSC model therefore requires continuous karyotypic surveillance, and an apparently "isogenic control" may in fact be the intended disease line that self-corrected. See also "Complex biology of constitutional ring chromosomes structure and (in)stability revealed by somatic cell reprogramming," Sci Rep 2021, doi:10.1038/s41598-021-83399-3.

In dismech experimental_models terms, a patient iPSC line for r(14) is at best PARTIALLY_RECAPITULATES with fidelity: LOW-to-MODERATE and a mandatory limitations field naming the compensatory-UPD self-correction.

15.3 Component-gene animal models (surrogate, not disease models)

These model candidate effector genes, not the syndrome. Each should be curated with an explicit limitation that the ring context is absent.

Model Species Relevance Databases
Foxg1+/− and conditional Foxg1 mice Mouse (NCBITaxon:10090) Forebrain development, microcephaly; the leading position-effect target MGI, IMPC
Pacs2 mouse models Mouse DEE-66 candidate; the only deleted-region epilepsy gene MGI
Chd8+/− mice Mouse ASD/seizure biology; not deleted in r(14) — surrogate only MGI, IMPC
foxg1a/b zebrafish Zebrafish (NCBITaxon:7955) Rapid seizure phenotyping (PTZ assays), forebrain patterning ZFIN
Drosophila position-effect variegation systems D. melanogaster (NCBITaxon:7227) The canonical experimental system for heterochromatin spreading — the mechanism, not the disease FlyBase
S. cerevisiae subtelomeric silencing / TPE Yeast (NCBITaxon:4932) Same: mechanism-level SGD

Phenotype recapitulation: none of these reproduces the r(14) syndrome. Foxg1 models capture microcephaly and seizure susceptibility but not the retinal phenotype, the immune phenotype, or the ring itself. Limitations to record: no model reproduces (a) ring topology and its instability, (b) the p-arm heterochromatin juxtaposition, (c) combined proximal position effect + distal haploinsufficiency, (d) the human IGH locus architecture.

15.4 Resources

MGI · IMPC · KOMP · IMSR · EMMA · MMRRC (mouse); ZFIN (zebrafish); FlyBase; SGD; Alliance of Genome Resources; Cellosaurus / Coriell / NIGMS Human Genetic Cell Repository (patient fibroblast and lymphoblastoid lines); Ring14 International biobank and clinical database (ring14.org) — the practical route to patient-derived material.

Appendix A — Core reference set for the dismech entry

PMID / ID Citation Use
22564756 Zollino M, Ponzi E, Gobbi G, Neri G. The ring 14 syndrome. Eur J Med Genet 2012;55:374–380 Genotype–phenotype model; deletion sizes; parental origin; position-effect hypothesis. Full abstract verified.
19441122 Zollino M, et al. The ring 14 syndrome: clinical and molecular definition. Am J Med Genet A 2009 Core clinical gestalt; regional assignment
24116895 Giovannini S, et al. Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients. Epilepsia 2013;54(12) Epilepsy phenotype and EEG; ~100% penetrance
28399883 (PMC5387247) Guideline recommendations for diagnosis and clinical management of Ring14 syndrome — first report of an ad hoc task force. Orphanet J Rare Dis 2017;12:69 Management, diagnostics, prognosis, follow-up schedule. Verify PMID before use.
33205446 Vaisfeld A, Spartano S, Gobbi G, Vezzani A, Neri G. Chromosome 14 deletions, rings, and epilepsy genes: a riddle wrapped in a mystery inside an enigma. Epilepsia 2021;62(1):25–40 Ring vs linear dissociation; 40 chr14 epilepsy genes; mechanism hypotheses
39020403 Meza-Espinoza JP, et al. Chromosomal instability in a patient with ring chromosome 14 syndrome. Mol Cytogenet 2024;17:15 Quantified ring instability (12.3% monosomy, 6.2% triple signal, 9% micronuclei); 1.7 Mb/23-gene deletion
42352229 Messina A, et al. IgG glycosylation analysis in patients with Ring14 syndrome. Biomolecules 2026;16(6):760 Novel immune pathomechanism; IVIG signal
41533279 SanInocencio C, et al. Patient-centered conceptual disease model in Ring 14 syndrome. Qual Life Res 2026 QoL and caregiver burden — the QoL source of record
31755799 Vasconcelos HM Jr, et al. Multimodal imaging of ring 14 syndrome associated maculopathy. Ophthalmic Genet 2019 Retinal/macular phenotype
24413397 Bershteyn M, et al. Cell-autonomous correction of ring chromosomes in human iPSCs. Nature 2014;507:99–103 Model-system caveat + "chromosome therapy." Full abstract verified.
38795333 Barbour K, et al. Population-based study of rare epilepsy incidence in a US urban population. Epilepsia 2024 EHR ascertainment limits
40348517 Hanzal N, et al. Lipoid pneumonia following chronic aspiration of cannabis oil. Chest 2025 CBD-oil safety signal in an r(14) patient
36855970 Ivanoff AE, et al. Folia Med 2023 Dental management
38824650 Gardner JA, et al. Ring chromosome 14 with a terminal 14q32.33 deletion. J Assoc Genet Technol 2024 Cytogenetic case
22151179 Guilherme RS, et al. Mechanisms of ring chromosome formation, ring instability and clinical consequences. BMC Med Genet 2011;12:171 Ring formation mechanisms (general)
NCT06813469 MD-RING: Multi-Dimensional Genomic Dissection of Ring Chromosome 14 Syndrome Active study; position effects + TADs; long-read sequencing
ORPHA:1440 Orphanet Prevalence class, ICD-10 Q93.2, ICD-11 LD7Y, definition

Appendix B — Suggested mechanistic_hypotheses groups

hypothesis_group_id Label Status Core claim
position_effect_proximal_14q Heterochromatin spreading dysregulates proximal 14q11.2–q12 CANONICAL (best-supported explanation of the ring-vs-linear dissociation) Ring topology silences FOXG1-region genes present in 2 copies → epilepsy + retinal phenotype
dynamic_mosaicism_growth_failure Ring instability → mosaic monosomy 14 → growth failure ALTERNATIVE Kosztolányi "ring syndrome"; measured instability (Meza-Espinoza 2024)
brain_mosaic_monosomy_epileptogenesis Locally elevated monosomy-14 fraction in cortex creates an epileptogenic focus EMERGING Vaisfeld 2021 speculation; untested — no human brain tissue data
pacs2_haploinsufficiency_synergy PACS2 haploinsufficiency is minimally penetrant alone but enhanced by the ring EMERGING Vaisfeld 2021; requires deletion >~1.65 Mb
igh_haploinsufficiency_infection 14q32.33 IGH hemizygosity → impaired humoral immunity → recurrent infection → adult mortality CANONICAL Zollino 2012 regional assignment; guideline
igg_glycosylation_inflammation Pro-inflammatory IgG N-glycan shift contributes to infection susceptibility and possibly seizures EMERGING Messina 2026, n=6; no chr14 glycosyltransferase gene → mechanism unexplained
dlk1_dio3_mirna_dysregulation 14q32 imprinted miRNA mega-cluster dysregulation contributes EMERGING / gap Vaisfeld 2021: "essentially no literature"

Appendix C — Suggested discussions (knowledge gaps)

  1. KNOWLEDGE_GAP — Why do ring 14 and size-matched linear 14q deletions diverge so sharply for epilepsy and retinal phenotype? attaches_to: pathophysiology#Ring chromosome 14 formation
  2. KNOWLEDGE_GAP — No brain-tissue data exist to test whether mosaic monosomy 14 is enriched in cortex. attaches_to: pathophysiology#Mosaic monosomy 14
  3. KNOWLEDGE_GAP — The 14q32 DLK1-DIO3 miRNA cluster is entirely unstudied in r(14).
  4. KNOWLEDGE_GAP — No gene on chromosome 14 encodes a galactosyl- or sialyltransferase; the IgG glycan phenotype is mechanistically unexplained. attaches_to: pathophysiology#Aberrant IgG N-glycosylation
  5. HUMAN_MODEL_MISMATCH — Patient-derived iPSCs spontaneously purge the ring via compensatory UPD, so the standard human cellular model self-corrects away the lesion it is meant to model. attaches_to: experimental_models#…
  6. KNOWLEDGE_GAP — No life-expectancy, mortality-rate, or validated QoL-instrument data exist. attaches_to: clinical_burden#

Next step: the highest-value thing to do before touching kb/disorders/Ring_Chromosome_14.yaml is to cache the reference set — just fetch-reference PMID:22564756 PMID:24116895 PMID:33205446 PMID:39020403 PMID:42352229 PMID:41533279 (plus ORPHA:1440, which is already ingestible via the structured Orphanet source) — and confirm the 2017 guideline's PMID, since every management and frequency claim in §3, §10, §11, and §12 traces to it and I have not verified its PMID against PubMed. Want me to run that fetch and report which snippets survive verification?

Sources

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome Count
References checked 33
Resolved 33
Unresolved (possible confabulation) 0
Unverifiable 0
References weighed for topical relevance 33
On topic 25
Off topic 1

References that may not be about this subject

These identifiers resolve, so they are not fabrications, but the records they resolve to share almost none of this report's vocabulary. That is a clue and not a verdict - a paper can be relevant in ways its title and abstract do not spell out - so read them before deciding:

  • PMID:22579566 (1 mention) - Evolution of metabolic rate in a parasitic wasp: the role of limitation in intrinsic resources.
  • shared terms: phenotype

Weighed against this report's own most characteristic terms: ring, verify, chromosome, syndrome, gene, guideline, deletion, epilepsy, seizure, patient, phenotype, terminal, disease, q32, instability, zollino, model, retinal, mechanism, human.

All extracted references resolved successfully. Resolving is not the same as being relevant, though - see the references listed above as possibly off topic.

Term Validation

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

Outcome Count
Terms checked 175
Resolved 172
Unresolved (possible confabulation) 0
Obsolete 2
Unverifiable 1
Terms whose name was checked 24
Terms named correctly 4
Terms named as a different term 13
Terms whose name is worth a second look 7

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

  • MONDO:0014708 (2 mentions) - the report calls it "MONDO"; MONDO calls it ring chromosome 14
  • HP:0000752 (1 mention) - the report calls it "large proportion of patients" [verify]"; HP calls it Hyperactivity**
  • HP:0000733 (1 mention) - the report calls it "Frequent"; HP calls it Motor stereotypy
  • HP:0002360 (1 mention) - the report calls it "Less frequent"; HP calls it Sleep disturbance
  • HP:0002205 (1 mention) - the report calls it "Recurring features include … increased incidence of infections, particularly respiratory infections" [verify]"; HP calls it Recurrent respiratory infections**
  • HP:0006532 (1 mention) - the report calls it "Spectrum "from recurrent upper airways infections to severe pneumonia" [verify]"; HP calls it Recurrent pneumonia**
  • UBERON:0001007 (1 mention) - the report calls it "feeding difficulty, dysphagia, GERD, celiac disease"; UBERON calls it digestive system
  • UBERON:0001130 (1 mention) - the report calls it "scoliosis, kyphosis"; UBERON calls it vertebral column
  • UBERON:0004288 (1 mention) - the report calls it "osteopenia/osteoporosis"; UBERON calls it skeleton
  • UBERON:0001015 (1 mention) - the report calls it "hypotonia"; UBERON calls it musculature
  • GO:0005794 (1 mention) - the report calls it "site of IgG N-glycan maturation"; GO calls it Golgi apparatus
  • NCIT:C121351 (1 mention) - the report calls it "implied by multidisciplinary model"; NCIT calls it Occupational Therapy
  • NCIT:C15240 (2 mentions) - the report calls it "de novo, low recurrence risk"; NCIT calls it Genetic Counseling

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

  • GO:0016458 (obsolete gene silencing) (1 mention)
  • GO:0006486 (obsolete protein glycosylation) (1 mention) - replaced by GO:0009101

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

  • HP:0000957 (1 mention) - the report calls it "Café-au-lait spots"; HP calls it Cafe-au-lait spot, and lists "Cafe-au-lait spots" among its other names
  • HP:0001004 (1 mention) - the report calls it "Lymphedema — "puffy hands and/or feet"; HP calls it Lymphedema, and lists "Onset of lymphedema around puberty" among its other names
  • CL:0002586 (2 mentions) - the report calls it "Retinal pigment epithelium"; CL calls it retinal pigment epithelial cell
  • CL:0000188 (1 mention) - the report calls it "Skeletal muscle"; CL calls it cell of skeletal muscle, and lists "skeletal muscle cell" among its other names
  • CL:0000057 (2 mentions) - the report calls it "Dermal fibroblasts", "Patient dermal fibroblasts"; CL calls it fibroblast
  • NCBITaxon:7227 (1 mention) - the report calls it "D. melanogaster"; NCBITaxon calls it Drosophila melanogaster
  • NCBITaxon:4932 (1 mention) - the report calls it "Yeast"; NCBITaxon calls it Saccharomyces cerevisiae, and lists "baker's yeast" among its other names

Terms named inconsistently

The report gives these identifiers more than one name of its own:

  • ORPHA:1440 - called "Orphanet", "ORDO annotation"
  • CL:0000057 - called "Dermal fibroblasts", "Patient dermal fibroblasts"

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.