Cri-du-Chat Syndrome

Genetic MONDO:0007404 Pathograph 14 Show in embeddings browser Chromosomal deletion syndrome Contiguous gene deletion syndrome

Cri-du-chat syndrome is a contiguous-gene deletion disorder caused by a heterozygous deletion of the short arm of chromosome 5. Deletions range from well under 1 Mb to essentially the whole short arm, and the phenotype reflects haploinsufficiency of many dosage-sensitive genes across 5p15 rather than loss of any single gene. The eponymous feature is a high-pitched, monochromatic cat-like cry in infancy, attributed to a small, narrow, diamond-shaped larynx and a floppy epiglottis together with a central contribution. Other cardinal features are microcephaly, a round face with hypertelorism, epicanthal folds and micrognathia, marked neonatal hypotonia with impaired suck, and severe psychomotor and intellectual disability with disproportionate expressive-speech impairment. The distinguishing mechanistic feature of this entry is that separable critical regions of 5p map to separable components of the phenotype: the cat-like cry to a small interval in distal 5p15.31, speech delay to 5p15.32-15.33, and facial dysmorphology to 5p15.2-15.31, while cognitive severity behaves dose-additively across three distinct intervals. Deletion extent, rather than a single gene lesion, is therefore the proximate determinant of which features appear and how severe they are.

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3
Inheritance
12
Pathophys.
34
Phenotypes
4
Gaps
14
Pathograph
4
Genes
4
Medical Actions
2
Subtypes
1
Differentials
4
References
1
Deep Research
👪

Inheritance

3
Contiguous gene deletion HP:0001466
The lesion removes one copy of many neighbouring dosage-sensitive genes, so the phenotype is the joint consequence of several haploinsufficiencies rather than of a single gene defect.
Contiguous gene syndrome Expressivity: VARIABLE
Show evidence (1 reference)
PMID:30985858 SUPPORT Computational
"Cri-du-chat syndrome (CdCs) is one of the most common contiguous gene syndromes"
States explicitly that the disorder is a contiguous gene syndrome.
Sporadic de novo deletion HP:0003745
Most deletions arise de novo, and the deleted chromosome is predominantly of paternal origin. A minority arise from unbalanced segregation of a parental balanced translocation, which carries a substantial recurrence risk and makes parental karyotyping essential after a new diagnosis.
Sporadic
Show evidence (3 references)
PMID:16953888 SUPPORT Human Clinical
"The deleted chromosome was mainly of paternal origin"
Establishes the predominant parental origin of the de novo deletion.
PMID:16953888 SUPPORT Human Clinical
"(62 patients: 77.5%), an interstitial deletion (seven patients: 8.75%)"
Italian Registry proportions for terminal versus interstitial deletions. The sentence opens "a 5p terminal deletion"; "deletion" is hyphenated across a line break in the cached PDF text, so the quote starts at the parenthesis.
PMID:16953888 SUPPORT Human Clinical
"a de novo translocation (four patients: 5%), a familial translocation (three patients: 3.75%)"
Registry proportions for translocation-derived deletions, which is the subset that carries a materially different recurrence risk.
Recurrence risk
Recurrence risk is the counselling number that actually changes management, and it depends entirely on which mechanism produced the deletion. For a de novo deletion it is negligible; for a parental balanced translocation the risk of unbalanced offspring is an order of magnitude higher. This is why parental karyotyping is not optional after a new diagnosis. Gonadal mosaicism in a parent cannot be excluded even when no recurrence has been reported.
Show evidence (3 references)
PMID:16953888 SUPPORT Human Clinical
"The risk of recurrence is practically negligible for the cases of a de novo deletion, which are the most frequent."
Establishes the negligible recurrence risk for the majority de novo mechanism.
PMID:16953888 SUPPORT Human Clinical
"the risk of unbalanced offspring (according to the pachytene configuration and 5p breakpoint localisation) ranged from 8.7% to 18.8%"
Quantifies the recurrence risk for carriers of a balanced translocation involving 5p, the figure that drives prenatal-diagnosis counselling.
PMID:16953888 SUPPORT Human Clinical
"the possibility of gonadal mosaicism in one of the parents cannot be excluded"
Records the residual risk that qualifies the "negligible" de novo figure.
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Subtypes

2
5p terminal deletion
The most common form — a terminal deletion of 5p, of variable breakpoint and size. Clinical severity and psychomotor retardation increase progressively with the size of the deletion.
Show evidence (1 reference)
PMID:11238681 SUPPORT Human Clinical
"Genotype-phenotype correlation in 62 patients with terminal deletions highlighted a progressive severity of clinical manifestation and psychomotor retardation related to the size of the deletion."
Establishes terminal deletions as the predominant class and links deletion size to clinical severity.
5p interstitial deletion
A less common interstitial deletion of 5p. Analysis of interstitial deletions helped define the two separate critical regions (dysmorphism/intellectual disability at 5p15.2 and the cat cry at 5p15.3).
Show evidence (1 reference)
PMID:11238681 SUPPORT Human Clinical
"the existence of two critical regions, one for dysmorphism and mental retardation in p15.2 and the other for the cat cry in p15.3."
Interstitial-deletion patients delineated the two distinct 5p15 critical regions.
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Discussions and Knowledge Gaps

4
Which gene or genes in the distal 5p15.31 cry critical region are responsible for the laryngeal maldevelopment that produces the cat-like cry?
KNOWLEDGE GAP OPEN cdcs_cry_gene_unidentified
Attached to
pathophysiology#Cry-Region Haploinsufficiency at 5p15.31
The cry is the syndrome's defining feature and its determining interval has been narrowed to roughly 640 kb by phenotype dissection, yet no responsible gene has been established. The interval is gene-rich, and the candidates characterised so far are either ubiquitously expressed or have no known role in laryngeal development, so none offers a satisfying mechanistic account. This leaves the best-mapped genotype-phenotype relationship in the syndrome without a molecular explanation.
Proposed experiments
Laryngeal expression screen of the 640 kb cry interval
cdcs_cry_region_larynx_expression
Determine which genes in the 640 kb interval are expressed in developing laryngeal cartilage and the epiglottic primordium, using developmental single-cell transcriptomics of human and model-organism larynx, then test dosage reduction of the strongest candidates for laryngeal structural phenotypes.
Decision criterion
A candidate expressed in laryngeal cartilage whose heterozygous reduction reproduces a narrowed or hypoplastic larynx would identify the cry gene; absence of any laryngeally expressed candidate would argue the cry arises from the central rather than the structural arm.
Show evidence (1 reference)
PMID:15657623 SUPPORT Human Clinical
"These results suggest that one candidate gene, FLJ25076, encodes a ubiquitin-conjugated enzyme E2 type, which is locally expressed in thoracic and scalp tissues."
Documents the state of the art on the cry interval: the leading candidate is offered only as a suggestion, with tissue expression that does not obviously implicate the larynx. This is the evidence that the gap remains open.
Does the neuroinflammatory signature seen in the rat model of the syntenic 5p deletion, including complement activation in reactive astrocytes, occur in human patients?
HUMAN MODEL MISMATCH OPEN cdcs_rat_model_translational_validity
Attached to
pathophysiology#Impaired Dendritic Arborization and Spine Maturation
The engineered rat model reproduces cognitive and social deficits and shows immune dysregulation in hippocampus and prefrontal cortex, and AAV-Ctnnd2 rescue makes the CTNND2 dosage link causal in that system. But the immune and synaptic-pruning arm has no human counterpart evidence: no patient neuropathology series has looked for astrocyte reactivity or complement activation. The gap matters therapeutically, because a neuroinflammatory component would suggest targets entirely different from gene replacement, and it would be easy to over-read the rodent result as established human mechanism.
Proposed experiments
Human neuropathology survey for astrocyte reactivity and complement
cdcs_human_neuropathology_complement
Examine available post-mortem brain tissue from individuals with 5p deletion for astrocyte reactivity and complement deposition, comparing regional distribution with the model. Where tissue is unavailable, test CSF or blood complement markers against deletion size and cognitive severity.
Decision criterion
Regionally concordant astrocyte reactivity with complement deposition in patient tissue would promote the neuroinflammatory arm to human mechanism; its absence would confine that arm to the model and caution against inflammation-directed therapeutic inference.
Show evidence (1 reference)
PMID:39965128 SUPPORT Model Organism
"The immunostaining and RNA-seq analyses provide new insights into CdCS pathogenesis, revealing inflammatory and immune processes."
Source of the inflammatory and immune findings whose human validity is the subject of this mismatch. Rodent evidence, which is precisely why the human counterpart is an open question rather than settled mechanism.
Are the deletion-independent DNA methylation changes in patients a cause of phenotypic variability or a consequence of the disease state?
KNOWLEDGE GAP OPEN cdcs_methylation_causal_direction
Attached to
pathophysiology#Deletion-Independent DNA Methylation Dysregulation
Methylation changes enriched at developmental-delay and microcephaly genes, demonstrably not driven by chromosome 5, are an attractive explanation for why patients with similar deletions differ clinically. But the study design is cross-sectional and measured in blood, so it cannot distinguish a modifier that shapes the phenotype from a signature that reflects it. Resolving the direction determines whether this is a therapeutic target or merely a biomarker.
Proposed experiments
Cross-tissue and longitudinal methylation comparison
cdcs_methylation_longitudinal_tissue
Compare methylation in blood against a developmentally relevant tissue in the same individuals, and test whether methylation state at the implicated CpG sites measured early predicts later developmental trajectory independently of deletion size.
Decision criterion
Early methylation state predicting later trajectory after adjustment for deletion size would support a modifier role; concordance only with concurrent severity would favour a downstream signature.
Show evidence (1 reference)
PMID:36242045 SUPPORT Human Clinical
"with the present data we cannot conclude about the sequence of events between DNA methylation changes and other cellular functions"
The authors state the causal-direction gap themselves, so this discussion records an acknowledged limitation of the primary study rather than a curator-invented doubt.
Does hemizygous loss of TERT produce any measurable consequence in cri-du-chat syndrome, or is it a passenger deletion with no phenotypic contribution?
KNOWLEDGE GAP OPEN cdcs_tert_functional_consequence
Attached to
pathophysiology#TERT Haploinsufficiency
TERT sits at 5p15.33 and is removed by essentially every terminal deletion, so it is routinely listed among the syndrome's candidate genes. But unlike CTNND2 it has no correlative human evidence and no rescue experiment, and no telomere phenotype has been demonstrated in patients. This node is deliberately left without a downstream edge for that reason: asserting one would manufacture a mechanism the literature does not support. The question matters because proximity to the telomere makes TERT loss near-universal, so if it were contributing it would be contributing in almost every patient.
Proposed experiments
Telomere-length and TERT-dosage phenotyping in patient cells
cdcs_tert_telomere_phenotype
Measure telomerase activity and telomere length in patient-derived neuronal stem cells and fibroblasts stratified by whether the deletion includes TERT, and test whether either measure correlates with cognitive severity independently of overall deletion size.
Decision criterion
A telomere or telomerase deficit tracking TERT inclusion, and correlating with severity after adjusting for deletion size, would promote TERT from candidate to contributor; absence of any measurable deficit would support treating it as a passenger and removing it from the candidate list.
Show evidence (2 references)
PMID:40343585 SUPPORT In Vitro
"mapped in chromosome 5 short arm, are known to be expressed in the brain, and to play a role in the development of the nervous system"
Groups TERT with SEMA5A and CTNND2 as brain-expressed 5p genes whose haploinsufficiency is proposed but not resolved, which is precisely the open question.
PMID:40343585 SUPPORT In Vitro
"the mechanism of which has remained unexplained"
States that the mechanism linking 5p gene dosage to developmental impairment is unexplained, supporting the gap rather than any particular resolution.
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Pathophysiology

12
Chromosome 5p Deletion
A heterozygous deletion of the short arm of chromosome 5, ranging from well under 1 Mb to essentially the whole short arm. Terminal deletions predominate; interstitial deletions, unbalanced translocation products, ring chromosome 5 and mosaicism account for the remainder. This is a copy-number loss, not a point variant, so the pathogenic unit is an interval rather than a gene.
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in brain (UBERON:0000955). UBERON:0000955 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Contiguous-Gene Haploinsufficiency Across 5p15 Loss of one copy of the interval reduces dosage of every gene it contains.
Show evidence (2 references)
PMID:16953888 SUPPORT Human Clinical
"The Cri du Chat syndrome (CdCS) is a genetic disease resulting from a deletion of variable size occurring on the short arm of chromosome 5"
States the causal lesion and its variable size.
PMID:34394178 SUPPORT Human Clinical
"results from the loss of genetic material at the distal region of the short arm of chromosome 5"
Independent cohort confirmation of the causal lesion and its distal localisation.
Contiguous-Gene Haploinsufficiency Across 5p15
Reduced dosage of a large number of contiguous genes across the deleted interval. Because separable sub-intervals map to separable phenotypic components, this node fans out to region-specific consequences rather than acting as a single undifferentiated insult. Cognitive severity in particular scales with how much of the 5p interval is lost: three distinct regions contribute additively, so severity increases as the deletion extends across them.
Downstream
Cry-Region Haploinsufficiency at 5p15.31 Deletions extending into the distal cry interval remove its dosage-sensitive content; deletions sparing it generally spare the cry.
CTNND2 Delta-Catenin Haploinsufficiency CTNND2 lies at 5p15.2 and is removed by essentially all deletions large enough to produce the syndrome.
SEMA5A Axon-Guidance Haploinsufficiency SEMA5A maps to the 5p15 critical region and is co-deleted.
TERT Haploinsufficiency TERT lies at 5p15.33 and is removed by terminal deletions.
Hindbrain Hypoplasia Deletion of 5p is associated with structural hindbrain anomalies, of which pontine hypoplasia is the most frequent on neuroimaging. The intermediate genes and developmental steps are not established.
Show evidence (2 references)
PMID:16953888 SUPPORT Human Clinical
"partial aneusomy syndromes like CdCS result from abnormal gene dosage (haploinsufficiency)"
States the core dosage mechanism. The source continues "involving a large number of contiguous genes", but that phrase is hyphenated across a line break in the cached PDF text, so the quote stops at the preceding word.
PMID:15635506 SUPPORT Human Clinical
"MR increased as deletions that included MRI extended progressively into MRII and MRIII, and MR became profound when all three regions were deleted."
Establishes that cognitive severity is dose-additive across three separable intervals, which is the basis for the deletion-extent claim in this node.
Cry-Region Haploinsufficiency at 5p15.31
Reduced dosage of the small distal interval whose loss determines the cat-like cry. Phenotype-dissection studies comparing patients with and without the cry narrowed this interval to roughly 640 kb, and array-based mapping placed the cry determinant in 1.5 Mb of distal 5p15.31. The responsible gene or genes are not established; several candidates lie in the interval but none is proven.
Downstream
Laryngeal and Epiglottic Hypoplasia Loss of the interval is associated with maldevelopment of the larynx and epiglottis. The molecular route from dosage loss to laryngeal structure is not established.
Show evidence (2 references)
PMID:15657623 SUPPORT Human Clinical
"the critical region for the cat-like cry is mapped to a short 640 kbp region on chromosome 5p"
Fine-maps the cry determinant using patients who differ in the presence of the cry.
PMID:34394178 REFUTE Human Clinical
"high-pitched cry seemed to map at p14.3–p13.2 bands versus bands p15.33–p15.31"
Recorded as REFUTE because it directly contradicts the distal localisation this node asserts. The largest contemporary cohort mapped the cry to a much more proximal interval than every earlier study. The distal mapping is retained as the node's primary claim because it rests on phenotype dissection in patients who differ in the presence of the cry, which is the stronger design, but the disagreement is real and is flagged rather than suppressed.
CTNND2 Delta-Catenin Haploinsufficiency
Reduced dosage of delta-catenin, a neuronal adherens-junction protein expressed early in neuronal development and involved in cell motility. This is the best-supported single-gene contributor in the syndrome: hemizygous loss correlates with cognitive severity in patients, and restoring the gene product rescues cognition in an engineered rodent model of the syntenic deletion.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
CTNND2 hgnc:2516 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves CTNND2 (hgnc:2516). hgnc:2516 is a gene from the HUGO Gene Nomenclature Committee.
cell-cell adhesion GO:0098609 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cell-cell adhesion (GO:0098609). GO:0098609 is a biological process from the Gene Ontology. ↓ DECREASED dendritic spine development GO:0060996 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased dendritic spine development (GO:0060996). GO:0060996 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Impaired Dendritic Arborization and Spine Maturation Reduced delta-catenin dosage impairs dendritic arbor complexity and the maturation of dendritic spines. Causality is supported by rescue: AAV-mediated Ctnnd2 replacement alleviates the cognitive phenotype in the rat model, which is an interventional test rather than a correlation. The source states the limits directly: the benefit is confined to early developmental stages and does not fully restore the phenotype, so this edge should not be read as establishing that restoring one co-deleted gene corrects the syndrome.
Show evidence (1 reference)
PMID:10673328 SUPPORT Human Clinical
"Delta-catenin is an adherens junction protein involved in cell motility and expressed early in neuronal development."
Establishes the molecular identity and neurodevelopmental role of the gene product whose dosage is reduced.
SEMA5A Axon-Guidance Haploinsufficiency
Reduced dosage of semaphorin 5A, an axon-guidance molecule implicated in guiding axons and migrating neuronal precursors during cortical development. A candidate contributor rather than an established driver.
SEMA5A hgnc:10736 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SEMA5A (hgnc:10736). hgnc:10736 is a gene from the HUGO Gene Nomenclature Committee.
axon guidance GO:0007411 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased axon guidance (GO:0007411). GO:0007411 is a biological process from the Gene Ontology. ↓ DECREASED semaphorin-plexin signaling pathway GO:0071526 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased semaphorin-plexin signaling pathway (GO:0071526). GO:0071526 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Disrupted Neuronal Migration and Cortical Development Loss of one copy of an axon-guidance molecule is proposed to perturb neuronal migration and cortical wiring. The step is inferred from gene function rather than demonstrated in patients.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Due to its role in guiding axons or migrating neuronal precursors during cortical development in mice"
States the gene function on which the candidacy rests. The source continues that the SEMAF deletion "may be responsible for some of the features of CdCS"; that continuation is hyphenated across a line break in the cached PDF text and so cannot be quoted verbatim. The attribution is suggestive and rests on mouse data, hence PARTIAL.
TERT Haploinsufficiency
Reduced dosage of telomerase reverse transcriptase, the rate-limiting component of telomerase, which is required for telomere-length maintenance and sustained cell proliferation. Whether this contributes materially to the clinical phenotype is unresolved, and no downstream consequence is asserted here.
TERT hgnc:11730 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TERT (hgnc:11730). hgnc:11730 is a gene from the HUGO Gene Nomenclature Committee.
telomere maintenance GO:0000723 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased telomere maintenance (GO:0000723). GO:0000723 is a biological process from the Gene Ontology. ↓ DECREASED
telomerase activity GO:0003720 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased telomerase activity (GO:0003720). GO:0003720 is a molecular function from the Gene Ontology. ↓ DECREASED
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"limiting component for the telomerase activity that is essential for telomere-length maintenance and sustained cell proliferation"
Establishes the molecular function lost. The full sentence begins "hTERT is the rate-limiting component..."; "rate-limiting" is split across a line break in the cached PDF text, so the quote starts after it. The clinical consequence in this syndrome remains proposed, hence PARTIAL.
Laryngeal and Epiglottic Hypoplasia
A small, narrow, diamond-shaped larynx with a flabby, small, hypotonic epiglottis. This is the structural substrate of the cat-like cry and is also the reason intubation can be difficult in these patients, which makes it a mechanism node with direct perioperative relevance.
larynx development GO:0120224 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal larynx development (GO:0120224). GO:0120224 is a biological process from the Gene Ontology. ⚠ ABNORMAL
larynx UBERON:0001737 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in larynx (UBERON:0001737). UBERON:0001737 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"of the larynx (small, narrow, diamond-shaped) and of the epiglottis (flabby, small, hypotonic)"
Describes the laryngeal and epiglottic anatomy underlying the cry.
Hindbrain Hypoplasia
Hypoplasia of hindbrain structures, most consistently the pons and cerebellar vermis on neuroimaging. This node carries the central component of the cry: cranial-base malformation has long been argued to imply concurrent maldevelopment of the rhombencephalic region and the larynx during embryogenesis, and pontine hypoplasia is the imaging correlate of that hypothesis.
pons UBERON:0000988 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in pons (UBERON:0000988). UBERON:0000988 is an anatomical location from the Uberon multi-species anatomy ontology. cerebellum UBERON:0002037 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in cerebellum (UBERON:0002037). UBERON:0002037 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (2 references)
PMID:32800423 SUPPORT Human Clinical
"MRI analyses showed that isolated pontine hypoplasia is the most common finding, followed by vermian hypoplasia, ventricular anomalies"
Establishes the pattern and relative frequency of hindbrain findings.
PMID:16953888 SUPPORT Human Clinical
"of the cranial base suggest associated anomalies of the brain (rhombencephalic region) and larynx during embryonal development"
States the developmental hypothesis linking hindbrain and laryngeal maldevelopment. The sentence opens "Malformations of the cranial base..."; the first word is hyphenated across a line break in the cached PDF text, so the quote starts at the following word. Marked PARTIAL because the source frames it as a suggestion.
Impaired Dendritic Arborization and Spine Maturation
Reduced dendritic-arbor complexity and a shift away from mature mushroom-shaped dendritic spines in cortical and hippocampal neurons, with increased neuronal density in superficial layers. Demonstrated in the rat model of the syntenic deletion; the corresponding human neuropathology has not been characterised.
pyramidal neuron CL:0000598 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves pyramidal neuron (CL:0000598). CL:0000598 is a cell type from the Cell Ontology.
dendrite morphogenesis GO:0048813 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased dendrite morphogenesis (GO:0048813). GO:0048813 is a biological process from the Gene Ontology. ↓ DECREASED
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
Impaired Forebrain Development and Cortical Dysfunction Synaptic and dendritic deficits converge on impaired cortical function.
Show evidence (1 reference)
PMID:39965128 SUPPORT Model Organism
"This model exhibits pronounced deficits in social behavior, cognition, and anxiety, accompanied by neuronal abnormalities and immune dysregulation in key brain regions such as the hippocampus and medial prefrontal cortex (mPFC)."
Documents the cellular and regional abnormalities in the engineered model.
Disrupted Neuronal Migration and Cortical Development
Perturbed migration of neuronal precursors and abnormal cortical wiring, inferred from the developmental roles of the co-deleted guidance and adhesion molecules. Anomalies of cortical development are among the structural findings reported on patient neuroimaging.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
neuron migration GO:0001764 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal neuron migration (GO:0001764). GO:0001764 is a biological process from the Gene Ontology. ⚠ ABNORMAL cerebral cortex development GO:0021987 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal cerebral cortex development (GO:0021987). GO:0021987 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Impaired Forebrain Development and Cortical Dysfunction Disordered migration and wiring impair forebrain growth and function.
Show evidence (1 reference)
PMID:32800423 SUPPORT Human Clinical
"corpus callosum anomalies, and anomalies of cortical development"
Documents abnormalities of cortical development among the neuroradiological findings in patients.
Impaired Forebrain Development and Cortical Dysfunction
Reduced brain growth and impaired cortical function, manifesting as microcephaly with severe psychomotor and intellectual disability. Severity tracks deletion extent, but with an important caveat: a substantial share of the most severely affected patients carry additional copy-number changes outside 5p, so unusually severe impairment should prompt a search for a second lesion rather than being attributed to 5p deletion size alone.
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.
Show evidence (1 reference)
PMID:15635506 SUPPORT Human Clinical
"MR depended approximately on the 5p deletion size and location, but there were many cases in which the retardation was disproportionately severe, given the 5p deletion. All 15 of these cases, approximately two-thirds of the severely retarded patients, were found to have copy-number aberrations..."
Supports both the deletion-size dependence and the second-lesion caveat that qualifies it.
Deletion-Independent DNA Methylation Dysregulation
Genome-wide DNA methylation differences in patients relative to matched controls, including at promoters of genes controlling embryonic development and at CpG sites linked to developmental delay and microcephaly. Critically, this enrichment is not driven by methylation changes on chromosome 5, so it is a candidate modifier layer acting outside the deleted interval that may help explain why patients with similar deletions differ clinically. Direction of causality is not established: the changes could contribute to phenotype or reflect it.
Downstream
Impaired Forebrain Development and Cortical Dysfunction The methylation changes may contribute to the neurodevelopmental phenotype, but the direction of the relationship is explicitly unresolved by the source study: the differences could be driving the phenotype, result from other epigenetic changes, or merely reflect altered gene expression. The edge is therefore typed UNKNOWN rather than asserted as causal, and it is retained because the modifier hypothesis is the leading explanation on offer for why patients with comparable deletions differ clinically.
Show evidence (2 references)
PMID:36242045 SUPPORT Human Clinical
"Importantly, this relative enrichment is not driven by changes in the methylation of genes on chromosome 5."
Establishes that the methylation signal is independent of the deleted interval, which is what makes it a candidate modifier rather than a downstream readout of gene dosage.
PMID:36242045 SUPPORT Human Clinical
"revealed enrichment of genes controlling embryonic development and genes linked to symptoms which are among the most common symptoms of Cri du chat syndrome: developmental delay and microcephaly"
Ties the methylation changes specifically to the developmental-delay and microcephaly phenotypes.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Cri-du-Chat 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

34
Cardiovascular 1
Congenital Heart Defect Abnormal heart morphology HP:0001627 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal heart morphology (HP:0001627). HP:0001627 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:16953888 SUPPORT Human Clinical
"Malformations, although not very frequent, may be present: cardiac, neurological and renal abnormalities"
Documents cardiac malformation as part of the syndrome. The source's own "not very frequent" qualifier is one half of the disagreement recorded in the description.
PMID:34394178 SUPPORT Human Clinical
"short neck, scoliosis, cardiac anomalies, and speech delay were present in 25–59% of the cases and should be considered frequent findings in the syndrome"
The contemporary-cohort side of the disagreement, calling cardiac anomalies frequent findings. No band is asserted because the 25-59% interval straddles the OCCASIONAL and FREQUENT boundaries and the two sources disagree in direction; citing both is what lets a reader see the conflict.
Digestive 2
Feeding Difficulties 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:16953888 SUPPORT Human Clinical
"The low weight may be attributed to feeding difficulties and gastroesophageal reflux, both of which are frequent in the first years of life"
Documents feeding difficulty and its contribution to low weight.
Gastroesophageal Reflux HP:0002020 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gastroesophageal reflux (HP:0002020). HP:0002020 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"The low weight may be attributed to feeding difficulties and gastroesophageal reflux, both of which are frequent in the first years of life"
Documents reflux as a frequent early feature. Modelled separately from feeding difficulty because it is a distinct mechanism with distinct management.
Ear 2
Low-Set Ears FREQUENT HP:0000369 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Low-set ears (HP:0000369). HP:0000369 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"corners of the mouth (81.0%), low-set ears (69.8%)"
Registry frequency of 69.8% supports the FREQUENT band (30-79%).
Sensorineural Hearing Impairment HP:0000407 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Sensorineural hearing impairment (HP:0000407). HP:0000407 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"some patients have sensory-neural deafness and speech retardation, audiometric examination should be carried out on all CdCS children"
Documents sensorineural deafness and the resulting universal-screening recommendation. "Some patients" is too vague to support a frequency band, so none is assigned.
Eye 2
Hypertelorism VERY_FREQUENT HP:0000316 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypertelorism (HP:0000316). HP:0000316 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"hypertelorism (81.4%), epicanthal folds (90.2%)"
Registry frequency of 81.4% supports the VERY_FREQUENT band (80-100%).
Strabismus FREQUENT 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.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"divergent strabismus is frequent (44.7%)"
Registry frequency of 44.7% supports the FREQUENT band (30-79%).
Genitourinary 1
Renal Anomaly Abnormality of the kidney HP:0000077 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormality of the kidney (HP:0000077). HP:0000077 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Malformations, although not very frequent, may be present: cardiac, neurological and renal abnormalities"
Documents renal abnormality as part of the syndrome. No frequency band is assigned, for the same reason as the cardiac phenotype.
Head and Neck 4
Microcephaly VERY_FREQUENT HP:0000252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Microcephaly (HP:0000252). HP:0000252 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"The main clinical features are a high-pitched monochromatic cry, microcephaly, broad nasal bridge, epicanthal folds, micrognathia, abnormal dermatoglyphics, and severe psychomotor and mental retardation."
Lists microcephaly among the cardinal, near-universal features.
Epicanthus VERY_FREQUENT HP:0000286 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Epicanthus (HP:0000286). HP:0000286 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"hypertelorism (81.4%), epicanthal folds (90.2%)"
Registry frequency of 90.2% supports the VERY_FREQUENT band (80-100%).
Micrognathia VERY_FREQUENT HP:0000347 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Micrognathia (HP:0000347). HP:0000347 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"micrognathia (96,7%), abnormal dermatoglyphics"
Registry frequency of 96.7% supports the VERY_FREQUENT band (80-100%).
Downslanted Palpebral Fissures FREQUENT HP:0000494 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Downslanted palpebral fissures (HP:0000494). HP:0000494 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"ward slanting palpebral fissures (56.9%)"
Registry frequency of 56.9% supports the FREQUENT band (30-79%). The snippet begins mid-word because "downward" is hyphenated across a line break in the cached PDF text.
Musculoskeletal 3
Neonatal Hypotonia 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.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"impaired suction and hypotonia"
Documents neonatal hypotonia and impaired suck. The full sentence lists neonatal problems as asphyxia, cyanotic crises, impaired suction and hypotonia; "cyanotic" is hyphenated across a line break in the cached PDF text, so the quote starts after it.
Scoliosis FREQUENT 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.
Show evidence (2 references)
PMID:16953888 SUPPORT Human Clinical
"Scoliosis, flat foot, pes varus, inguinal hernia and diastasis recti are frequent."
The source's qualitative term "frequent" maps to the FREQUENT band (30-79%).
PMID:34394178 SUPPORT Human Clinical
"short neck, scoliosis, cardiac anomalies, and speech delay were present in 25–59% of the cases and should be considered frequent findings in the syndrome"
Independent cohort support for scoliosis as a frequent finding, consistent with the FREQUENT band assigned from the review.
Hypertonia HP:0001276 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypertonia (HP:0001276). HP:0001276 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"With age, muscle hypotonia is replaced by hypertonia"
Documents the tone reversal, which is what makes this a distinct phenotype from the neonatal hypotonia rather than a duplicate of it.
Nervous System 8
Severe Intellectual Disability HP:0010864 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Severe intellectual disability (HP:0010864). HP:0010864 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"retardation becomes evident during the first year of life"
Documents the timing of the cognitive phenotype. The full sentence begins "Severe psychomotor retardation..."; "psychomotor" is hyphenated across a line break in the cached PDF text, so the quote starts at the following word.
Delayed Speech and Language Development 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.
Show evidence (1 reference)
PMID:15635506 SUPPORT Human Clinical
"speech delay to 3.2 Mb in 5p15.32-15.33"
Documents speech delay as a mapped component of the phenotype with its own critical region.
Cerebellar Vermis Hypoplasia HP:0001320 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebellar vermis hypoplasia (HP:0001320). HP:0001320 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:32800423 SUPPORT Human Clinical
"followed by vermian hypoplasia, ventricular anomalies"
Documents vermian hypoplasia as the second most common MRI finding.
Hyperactivity FREQUENT 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.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Hyperactivity is present in about 50% of patients and sometimes coexists with aggressiveness"
Reported frequency of about 50% supports the FREQUENT band (30-79%).
Self-Injurious Behavior HP:0100716 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Self-injurious behavior (HP:0100716). HP:0100716 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"A survey of the prevalence of stereotypy, self-injury and aggression in CdCS children and young adults"
Documents stereotypy, self-injury and aggression as characterised features of the syndrome. No frequency is asserted because the source gives no percentage for them.
Cerebellar Atrophy HP:0001272 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebellar atrophy (HP:0001272). HP:0001272 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Atrophy of the brainstem mainly involving the pons, cerebellum"
Documents cerebellar and brainstem atrophy on MRI. The sentence continues into the peduncles and cerebellar white matter, but the next word is hyphenated across a line break in the cached PDF text.
Abnormal Corpus Callosum Morphology 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.
Show evidence (1 reference)
PMID:32800423 SUPPORT Human Clinical
"corpus callosum anomalies, and anomalies of cortical development"
Documents corpus callosum anomalies among the neuroradiological findings.
Aggressive Behavior HP:0000718 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aggressive behavior (HP:0000718). HP:0000718 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Hyperactivity is present in about 50% of patients and sometimes coexists with aggressiveness"
Documents aggressiveness as co-occurring with hyperactivity. No frequency band is asserted because the 50% figure quantifies hyperactivity, not aggression.
Growth 3
Intrauterine Growth Retardation 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.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"confirmed the existence of prenatal and postnatal growth retardation"
Documents growth retardation from a multicentre growth-chart study.
Low Birth Weight Small for gestational age HP:0001518 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Small for gestational age (HP:0001518). HP:0001518 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"The clinical features at birth are low weight (mean weight 2614 g)"
Quantifies mean birth weight from the registry series.
Growth Failure FREQUENT Failure to thrive HP:0001508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Growth failure, annotated with Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:10678657 SUPPORT Human Clinical
"The clinical picture is well known in younger patients and includes the typical high-pitched cry, psychomotor retardation, microcephaly, growth rate failure, and craniofacial abnormalities"
The paper's statement of the well-delineated clinical picture in younger patients lists growth rate failure among the core features.
Other 8
Cat-like Cry VERY_FREQUENT Cat cry HP:0200046 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cat cry (HP:0200046). HP:0200046 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"and the typical cry (95.9%)"
Italian CdCS Registry frequency of 95.9% supports the VERY_FREQUENT band (80-100%).
Round Face VERY_FREQUENT HP:0000311 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Round face (HP:0000311). HP:0000311 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"round face (83.5%), large nasal bridge (87.2%),"
Registry frequency of 83.5% supports the VERY_FREQUENT band (80-100%).
Wide Nasal Bridge VERY_FREQUENT HP:0000431 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Wide nasal bridge (HP:0000431). HP:0000431 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"round face (83.5%), large nasal bridge (87.2%),"
Registry frequency of 87.2% supports the VERY_FREQUENT band (80-100%).
Downturned Corners of Mouth VERY_FREQUENT HP:0002714 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Downturned corners of mouth (HP:0002714). HP:0002714 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"corners of the mouth (81.0%), low-set ears (69.8%)"
Registry frequency of 81.0% supports the VERY_FREQUENT band (80-100%).
Single Transverse Palmar Crease VERY_FREQUENT HP:0000954 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Single transverse palmar crease (HP:0000954). HP:0000954 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"micrognathia (96,7%), abnormal dermatoglyphics"
Registry data report abnormal dermatoglyphics (transverse flexion creases) at 92%, supporting the VERY_FREQUENT band.
Hypoplasia of the Pons HP:0012110 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypoplasia of the pons (HP:0012110). HP:0012110 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:32800423 SUPPORT Human Clinical
"MRI analyses showed that isolated pontine hypoplasia is the most common finding"
Documents pontine hypoplasia as the leading neuroradiological finding.
Premature Graying of Hair FREQUENT HP:0002216 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Premature graying of hair (HP:0002216). HP:0002216 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"prematurely grey hair may be observed (30.4%)"
Registry frequency of 30.4% supports the FREQUENT band (30-79%).
Short Philtrum VERY_FREQUENT HP:0000322 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Short philtrum (HP:0000322). HP:0000322 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"the philtrum short (87.8%)"
Registry frequency of 87.8% supports the VERY_FREQUENT band (80-100%).
🧬

Genetic Associations

4
CTNND2
Gene: CTNND2 hgnc:2516 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is CTNND2 (hgnc:2516). hgnc:2516 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: COOPERATING
Show evidence (1 reference)
PMID:10673328 SUPPORT Human Clinical
"A strong correlation was found between the hemizygous loss of delta-catenin and severe mental retardation."
Directly links CTNND2 hemizygosity to cognitive severity in patients with 5p terminal deletions.
SEMA5A
Gene: SEMA5A hgnc:10736 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is SEMA5A (hgnc:10736). hgnc:10736 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: COOPERATING
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Two genes, Semaphorin F (SEMAF) and delta-catenin (CTNND2), which have been mapped to the "critical regions", are potentially involved in cerebral development and their deletion may be associated with mental retardation in CdCS patients."
Names SEMA5A/SEMAF as a critical-region gene implicated in the cognitive phenotype. The hedged wording ("potentially", "may be") supports a candidate role only, so this is marked PARTIAL.
TERT
Gene: TERT hgnc:11730 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TERT (hgnc:11730). hgnc:11730 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: UNKNOWN
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Deletion of the telomerase reverse transcriptase (hTERT) gene, localised to 5p15.33, could contribute to the phenotypic changes in CdCS."
Supports TERT as a candidate contributor only; the source states this as a possibility ("could contribute"), so the evidence is marked PARTIAL.
5p terminal deletion (Causal)
Show evidence (2 references)
PMID:10678657 SUPPORT Human Clinical
"A de novo deletion is present in 85% of the patients. Ten to 15% are familial cases with more than 90% due to a parental translocation and 5% due to an inversion of chromosome 5."
Gives the de novo vs familial breakdown and the mechanisms of familial cases.
PMID:11238681 SUPPORT Human Clinical
"The origin of the deleted chromosome 5 was paternal in 55 out of 61 patients (90.2%)."
Documents the predominantly paternal origin of the deleted chromosome.
💊

Medical Actions

4
Early Rehabilitative and Educational Intervention
Action: rehabilitationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is rehabilitation (NCIT:C15315). NCIT:C15315 is a clinical intervention from the NCI Thesaurus. Ontology label: Rehabilitation NCIT:C15315
No disease-specific therapy exists. Early rehabilitative and educational intervention is the mainstay and measurably improves prognosis and social adjustment, which makes prompt diagnosis worthwhile even though the underlying lesion is not correctable.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"There is no specific therapy for CdCS but early rehabilitative and educational interventions improve the prognosis and considerable progress has been made in the social adjustment of CdCS patients."
States both the absence of specific therapy and the benefit of early intervention.
Speech and Language Therapy
Action: speech therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is speech therapy, annotated with Speech Language Therapy (NCIT:C159273). NCIT:C159273 is a clinical intervention from the NCI Thesaurus. Ontology label: Speech Language Therapy NCIT:C159273
Speech therapy alongside physical therapy and psychomotricity. Expressive language is impaired out of proportion to comprehension, which is the specific rationale for prioritising expressive-language and augmentative communication work rather than general developmental support.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Early rehabilitation (physical therapy, psychomotricity, speech therapy) is recommended for the neurological problems"
Names speech therapy explicitly among the recommended early rehabilitative modalities.
Genetic Counseling
Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Counselling turns on which mechanism produced the deletion. A de novo deletion carries negligible recurrence risk; a parental balanced translocation carries a risk of unbalanced offspring roughly an order of magnitude higher, and makes prenatal diagnosis appropriate. Parental karyotyping after a new diagnosis is what separates the two, and residual gonadal mosaicism qualifies even the negligible figure.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"The risk of recurrence is practically negligible for the cases of a de novo deletion, which are the most frequent."
The counselling figure for the majority mechanism. Paired with the translocation-carrier risk recorded under inheritance, this is what the counselling session actually conveys.
Physical and Occupational 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. Ontology label: Physical Therapy NCIT:C15302
For hypotonia and psychomotor delay.
🔬

Diagnosis

3
Karyotype Analysis
Conventional karyotyping of peripheral blood is the first confirmatory test, with FISH reserved for cases where clinical suspicion conflicts with an apparently normal karyotype.
karyotyping NCIT:C16768 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"Karyotype analysis and, in doubtful cases, FISH analysis will confirm the diagnosis."
Establishes karyotype as the confirmatory test and FISH as the fallback.
Chromosomal Microarray
Microarray combined with karyotyping is recommended as the definitive approach, because it resolves the deletion breakpoints. That matters here more than in most syndromes: the phenotype tracks deletion extent, so coordinates rather than a yes/no deletion call are what inform prognosis and counselling.
chromosomal microarray testing NCIT:C18477 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:34394178 SUPPORT Human Clinical
"we recommend combining typical karyotyping with CMA as the definitive method for a precise diagnosis"
Cohort recommendation for combined karyotype plus microarray as the definitive diagnostic method.
Audiometric Examination
Audiometry is recommended for every child with the syndrome rather than only those with suspected hearing loss, because sensorineural deafness compounds the expressive-speech impairment and is easy to miss behind it.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"audiometric examination should be carried out on all CdCS children"
Supports universal audiometric screening rather than targeted testing.
📊

Prevalence

1
Live-born infants
Birth Prevalence 4.3 per 100,000 (2.0–6.7) 1–9 per 100,000
Reported incidence range of 1:15,000 to 1:50,000 live births, i.e. 6.7 to 2.0 per 100,000. The point estimate is the midpoint of that range.
Show evidence (1 reference)
PMID:16953888 SUPPORT Human Clinical
"The incidence ranges from 1:15,000 to 1:50,000 live-born infants."
Source for the birth-prevalence range.
🔀

Differential Diagnoses

1

Conditions with similar clinical presentations that must be differentiated from Cri-du-Chat Syndrome:

Other contiguous-gene deletion syndromes with microcephaly and severe developmental delay
Overlapping Features Individually, the features of this syndrome are not discriminating; the diagnosis rests on the gestalt plus the cry. In older patients the cry diminishes, so the persistently abnormal voice together with psychomotor retardation is what prompts cytogenetic testing. Other terminal-deletion syndromes considered in the differential include Wolf-Hirschhorn (4p-) and 1p36 deletion syndrome.
Distinguishing Features
  • The high-pitched monochromatic cat-like cry in infancy is the discriminating feature; no other deletion syndrome in the differential produces it.
  • In older patients the cry diminishes, so the persistently abnormal voice combined with psychomotor retardation is what prompts cytogenetic testing.
Show evidence (2 references)
PMID:16953888 SUPPORT Human Clinical
"The clinical features of CdCS patients are not specific if considered separately but, if valued as a whole, they result in a distinct phenotype"
States that individual features are non-specific and the gestalt carries the diagnosis.
PMID:16953888 SUPPORT Human Clinical
"the voice that remains abnormal"
Supports the persistently abnormal voice as the feature that leads to testing in older patients whose cry has diminished.
{ }

Source YAML

click to show 
name: Cri-du-Chat Syndrome
creation_date: '2026-07-30T00:00:00Z'
category: Genetic
synonyms:
- 5p deletion syndrome
- 5p- syndrome
- 5p minus syndrome
- Monosomy 5p
- Cat cry syndrome
- Chromosome 5p deletion syndrome
- Lejeune syndrome
description: >-
  Cri-du-chat syndrome is a contiguous-gene deletion disorder caused by a
  heterozygous deletion of the short arm of chromosome 5. Deletions range from
  well under 1 Mb to essentially the whole short arm, and the phenotype reflects
  haploinsufficiency of many dosage-sensitive genes across 5p15 rather than loss
  of any single gene. The eponymous feature is a high-pitched, monochromatic
  cat-like cry in infancy, attributed to a small, narrow, diamond-shaped larynx
  and a floppy epiglottis together with a central contribution. Other cardinal
  features are microcephaly, a round face with hypertelorism, epicanthal folds
  and micrognathia, marked neonatal hypotonia with impaired suck, and severe
  psychomotor and intellectual disability with disproportionate expressive-speech
  impairment.

  The distinguishing mechanistic feature of this entry is that separable critical
  regions of 5p map to separable components of the phenotype: the cat-like cry to
  a small interval in distal 5p15.31, speech delay to 5p15.32-15.33, and facial
  dysmorphology to 5p15.2-15.31, while cognitive severity behaves dose-additively
  across three distinct intervals. Deletion extent, rather than a single gene
  lesion, is therefore the proximate determinant of which features appear and how
  severe they are.
disease_term:
  preferred_term: Cri-du-chat syndrome
  term:
    id: MONDO:0007404
    label: Cri-du-chat syndrome
parents:
- Chromosomal deletion syndrome
- Contiguous gene deletion syndrome

has_subtypes:
- name: Terminal deletion
  display_name: 5p terminal deletion
  description: >-
    The most common form — a terminal deletion of 5p, of variable breakpoint and
    size. Clinical severity and psychomotor retardation increase progressively
    with the size of the deletion.
  evidence:
  - reference: PMID:11238681
    reference_title: "Clinical and molecular characterisation of 80 patients with 5p deletion: genotype-phenotype correlation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genotype-phenotype correlation in 62 patients with terminal deletions highlighted a progressive severity of clinical manifestation and psychomotor retardation related to the size of the deletion."
    explanation: Establishes terminal deletions as the predominant class and links deletion size to clinical severity.
- name: Interstitial deletion
  display_name: 5p interstitial deletion
  description: >-
    A less common interstitial deletion of 5p. Analysis of interstitial deletions
    helped define the two separate critical regions (dysmorphism/intellectual
    disability at 5p15.2 and the cat cry at 5p15.3).
  evidence:
  - reference: PMID:11238681
    reference_title: "Clinical and molecular characterisation of 80 patients with 5p deletion: genotype-phenotype correlation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the existence of two critical regions, one for dysmorphism and mental retardation in p15.2 and the other for the cat cry in p15.3."
    explanation: Interstitial-deletion patients delineated the two distinct 5p15 critical regions.

inheritance:
- name: Contiguous gene deletion
  inheritance_term:
    preferred_term: Contiguous gene syndrome
    term:
      id: HP:0001466
      label: Contiguous gene syndrome
  expressivity: VARIABLE
  description: >-
    The lesion removes one copy of many neighbouring dosage-sensitive genes, so
    the phenotype is the joint consequence of several haploinsufficiencies rather
    than of a single gene defect.
  evidence:
  - reference: PMID:30985858
    reference_title: Integrated analysis of the critical region 5p15.3-p15.2 associated with cri-du-chat syndrome.
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: >-
      Cri-du-chat syndrome (CdCs) is one of the most common contiguous gene
      syndromes
    explanation: >-
      States explicitly that the disorder is a contiguous gene syndrome.
- name: Sporadic de novo deletion
  inheritance_term:
    preferred_term: Sporadic
    term:
      id: HP:0003745
      label: Sporadic
  description: >-
    Most deletions arise de novo, and the deleted chromosome is predominantly of
    paternal origin. A minority arise from unbalanced segregation of a parental
    balanced translocation, which carries a substantial recurrence risk and makes
    parental karyotyping essential after a new diagnosis.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The deleted chromosome was mainly of paternal origin"
    explanation: >-
      Establishes the predominant parental origin of the de novo deletion.
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      (62 patients: 77.5%), an interstitial deletion (seven patients: 8.75%)
    explanation: >-
      Italian Registry proportions for terminal versus interstitial deletions. The
      sentence opens "a 5p terminal deletion"; "deletion" is hyphenated across a
      line break in the cached PDF text, so the quote starts at the parenthesis.
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a de novo translocation (four patients: 5%), a familial translocation (three
      patients: 3.75%)
    explanation: >-
      Registry proportions for translocation-derived deletions, which is the subset
      that carries a materially different recurrence risk.
- name: Recurrence risk
  description: >-
    Recurrence risk is the counselling number that actually changes management, and
    it depends entirely on which mechanism produced the deletion. For a de novo
    deletion it is negligible; for a parental balanced translocation the risk of
    unbalanced offspring is an order of magnitude higher. This is why parental
    karyotyping is not optional after a new diagnosis. Gonadal mosaicism in a parent
    cannot be excluded even when no recurrence has been reported.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The risk of recurrence is practically negligible for the cases of a de novo
      deletion, which are the most frequent.
    explanation: >-
      Establishes the negligible recurrence risk for the majority de novo mechanism.
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the risk of unbalanced offspring (according to the pachytene configuration and
      5p breakpoint localisation) ranged from 8.7% to 18.8%
    explanation: >-
      Quantifies the recurrence risk for carriers of a balanced translocation
      involving 5p, the figure that drives prenatal-diagnosis counselling.
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the possibility of gonadal mosaicism in one of the parents cannot be excluded
    explanation: >-
      Records the residual risk that qualifies the "negligible" de novo figure.

genetic:
- name: CTNND2
  gene_term:
    preferred_term: CTNND2
    term:
      id: hgnc:2516
      label: CTNND2
  relationship_type: COOPERATING
  notes: >-
    Delta-catenin, a neuronal adherens-junction protein at 5p15.2 involved in cell
    motility and expressed early in neuronal development. Hemizygous loss
    correlates with severe intellectual disability in patients, and AAV-mediated
    Ctnnd2 replacement rescues cognitive deficits in a rat model of the syntenic
    deletion. Typed COOPERATING rather than CAUSATIVE because it is one of several
    co-deleted contributors, not sufficient on its own for the syndrome.
  evidence:
  - reference: PMID:10673328
    reference_title: Hemizygosity of delta-catenin (CTNND2) is associated with severe mental retardation in cri-du-chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A strong correlation was found between the hemizygous loss of delta-catenin
      and severe mental retardation.
    explanation: >-
      Directly links CTNND2 hemizygosity to cognitive severity in patients with 5p
      terminal deletions.
- name: SEMA5A
  gene_term:
    preferred_term: SEMA5A
    term:
      id: hgnc:10736
      label: SEMA5A
  relationship_type: COOPERATING
  notes: >-
    Semaphorin 5A (historically SEMAF), an axon-guidance molecule mapping to the
    5p15 critical region and implicated in guiding axons and migrating neuronal
    precursors during cortical development. Candidate-gene status: the source
    attribution is explicitly probabilistic.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Two genes, Semaphorin F (SEMAF) and delta-catenin (CTNND2), which have been
      mapped to the "critical regions", are potentially involved in cerebral
      development and their deletion may be associated with mental retardation in
      CdCS patients.
    explanation: >-
      Names SEMA5A/SEMAF as a critical-region gene implicated in the cognitive
      phenotype. The hedged wording ("potentially", "may be") supports a candidate
      role only, so this is marked PARTIAL.
- name: TERT
  gene_term:
    preferred_term: TERT
    term:
      id: hgnc:11730
      label: TERT
  relationship_type: UNKNOWN
  notes: >-
    Telomerase reverse transcriptase at 5p15.33, the rate-limiting component of
    telomerase. Included in the deletion in most patients, but its contribution to
    the clinical phenotype remains proposed rather than established, hence the
    UNKNOWN typing.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Deletion of the telomerase reverse transcriptase (hTERT) gene, localised to
      5p15.33, could contribute to the phenotypic changes in CdCS.
    explanation: >-
      Supports TERT as a candidate contributor only; the source states this as a
      possibility ("could contribute"), so the evidence is marked PARTIAL.
- name: 5p terminal deletion
  association: Causal
  notes: >-
    Partial deletion of the short arm of chromosome 5 (copy-number loss), of
    variable size; severity correlates with deletion size. About 85% are de novo;
    10-15% are familial, most often from a parental balanced translocation (and ~5%
    a parental inversion). The deleted chromosome is of paternal origin in ~90% of
    de novo cases. No coordinate slot exists in the schema; the structural event is
    recorded here in prose (copy-number loss, 5p15).
  evidence:
  - reference: PMID:10678657
    reference_title: "Cri du chat syndrome: changing phenotype in older patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A de novo deletion is present in 85% of the patients. Ten to 15% are familial cases with more than 90% due to a parental translocation and 5% due to an inversion of chromosome 5."
    explanation: Gives the de novo vs familial breakdown and the mechanisms of familial cases.
  - reference: PMID:11238681
    reference_title: "Clinical and molecular characterisation of 80 patients with 5p deletion: genotype-phenotype correlation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The origin of the deleted chromosome 5 was paternal in 55 out of 61 patients (90.2%)."
    explanation: Documents the predominantly paternal origin of the deleted chromosome.

prevalence:
- population: Live-born infants
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 4.3
  rate_low: 2.0
  rate_high: 6.7
  notes: >-
    Reported incidence range of 1:15,000 to 1:50,000 live births, i.e. 6.7 to 2.0
    per 100,000. The point estimate is the midpoint of that range.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The incidence ranges from 1:15,000 to 1:50,000 live-born infants.
    explanation: >-
      Source for the birth-prevalence range.

diagnosis:
- name: Karyotype Analysis
  description: >-
    Conventional karyotyping of peripheral blood is the first confirmatory test,
    with FISH reserved for cases where clinical suspicion conflicts with an
    apparently normal karyotype.
  diagnosis_term:
    preferred_term: karyotyping
    term:
      id: NCIT:C16768
      label: Karyotyping
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Karyotype analysis and, in doubtful cases, FISH analysis will confirm the
      diagnosis.
    explanation: >-
      Establishes karyotype as the confirmatory test and FISH as the fallback.
- name: Chromosomal Microarray
  description: >-
    Microarray combined with karyotyping is recommended as the definitive
    approach, because it resolves the deletion breakpoints. That matters here more
    than in most syndromes: the phenotype tracks deletion extent, so coordinates
    rather than a yes/no deletion call are what inform prognosis and counselling.
  diagnosis_term:
    preferred_term: chromosomal microarray testing
    term:
      id: NCIT:C18477
      label: Microarray Analysis
  evidence:
  - reference: PMID:34394178
    reference_title: Deep Phenotyping and Genetic Characterization of a Cohort of 70 Individuals With 5p Minus Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we recommend combining typical karyotyping with CMA as the definitive method
      for a precise diagnosis
    explanation: >-
      Cohort recommendation for combined karyotype plus microarray as the
      definitive diagnostic method.
- name: Audiometric Examination
  description: >-
    Audiometry is recommended for every child with the syndrome rather than only
    those with suspected hearing loss, because sensorineural deafness compounds the
    expressive-speech impairment and is easy to miss behind it.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      audiometric examination should be carried out on all CdCS children
    explanation: >-
      Supports universal audiometric screening rather than targeted testing.

differential_diagnoses:
- name: Other contiguous-gene deletion syndromes with microcephaly and severe developmental delay
  description: >-
    Individually, the features of this syndrome are not discriminating; the
    diagnosis rests on the gestalt plus the cry. In older patients the cry
    diminishes, so the persistently abnormal voice together with psychomotor
    retardation is what prompts cytogenetic testing. Other terminal-deletion
    syndromes considered in the differential include Wolf-Hirschhorn (4p-) and 1p36
    deletion syndrome.
  distinguishing_features:
  - >-
    The high-pitched monochromatic cat-like cry in infancy is the discriminating
    feature; no other deletion syndrome in the differential produces it.
  - >-
    In older patients the cry diminishes, so the persistently abnormal voice
    combined with psychomotor retardation is what prompts cytogenetic testing.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The clinical features of CdCS patients are not specific if considered
      separately but, if valued as a whole, they result in a distinct phenotype
    explanation: >-
      States that individual features are non-specific and the gestalt carries the
      diagnosis.
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the voice that remains abnormal
    explanation: >-
      Supports the persistently abnormal voice as the feature that leads to testing
      in older patients whose cry has diminished.

pathophysiology:
- name: Chromosome 5p Deletion
  biological_scale: MOLECULAR
  description: >-
    A heterozygous deletion of the short arm of chromosome 5, ranging from well
    under 1 Mb to essentially the whole short arm. Terminal deletions predominate;
    interstitial deletions, unbalanced translocation products, ring chromosome 5
    and mosaicism account for the remainder. This is a copy-number loss, not a
    point variant, so the pathogenic unit is an interval rather than a gene.
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The Cri du Chat syndrome (CdCS) is a genetic disease resulting from a
      deletion of variable size occurring on the short arm of chromosome 5
    explanation: >-
      States the causal lesion and its variable size.
  - reference: PMID:34394178
    reference_title: Deep Phenotyping and Genetic Characterization of a Cohort of 70 Individuals With 5p Minus Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      results from the loss of genetic material at the distal region of the short
      arm of chromosome 5
    explanation: >-
      Independent cohort confirmation of the causal lesion and its distal
      localisation.
  downstream:
  - target: Contiguous-Gene Haploinsufficiency Across 5p15
    description: >-
      Loss of one copy of the interval reduces dosage of every gene it contains.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16953888
      reference_title: Cri du Chat syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        partial aneusomy syndromes like CdCS result from abnormal gene dosage
      explanation: >-
        States that the deletion acts through abnormal gene dosage.

- name: Contiguous-Gene Haploinsufficiency Across 5p15
  biological_scale: MOLECULAR
  description: >-
    Reduced dosage of a large number of contiguous genes across the deleted
    interval. Because separable sub-intervals map to separable phenotypic
    components, this node fans out to region-specific consequences rather than
    acting as a single undifferentiated insult. Cognitive severity in particular
    scales with how much of the 5p interval is lost: three distinct regions
    contribute additively, so severity increases as the deletion extends across
    them.
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      partial aneusomy syndromes like CdCS result from abnormal gene dosage
      (haploinsufficiency)
    explanation: >-
      States the core dosage mechanism. The source continues "involving a large
      number of contiguous genes", but that phrase is hyphenated across a line
      break in the cached PDF text, so the quote stops at the preceding word.
  - reference: PMID:15635506
    reference_title: High-resolution mapping of genotype-phenotype relationships in cri du chat syndrome using array comparative genomic hybridization.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MR increased as deletions that included MRI extended progressively into MRII
      and MRIII, and MR became profound when all three regions were deleted.
    explanation: >-
      Establishes that cognitive severity is dose-additive across three separable
      intervals, which is the basis for the deletion-extent claim in this node.
  downstream:
  - target: Cry-Region Haploinsufficiency at 5p15.31
    description: >-
      Deletions extending into the distal cry interval remove its dosage-sensitive
      content; deletions sparing it generally spare the cry.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:15635506
      reference_title: High-resolution mapping of genotype-phenotype relationships in cri du chat syndrome using array comparative genomic hybridization.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Genotype-phenotype correlations localized the region associated with the
        cry to 1.5 Mb in distal 5p15.31
      explanation: >-
        Localises the cry determinant to a specific sub-interval of the deletion.
  - target: CTNND2 Delta-Catenin Haploinsufficiency
    description: >-
      CTNND2 lies at 5p15.2 and is removed by essentially all deletions large
      enough to produce the syndrome.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:10673328
      reference_title: Hemizygosity of delta-catenin (CTNND2) is associated with severe mental retardation in cri-du-chat syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The genomic structure of the human delta-catenin gene (Human Gene
        Nomenclature Committee-approved symbol CTNND2) was determined and mapped
        to 5p15.2.
      explanation: >-
        Places CTNND2 inside the deleted interval.
  - target: SEMA5A Axon-Guidance Haploinsufficiency
    description: >-
      SEMA5A maps to the 5p15 critical region and is co-deleted.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16953888
      reference_title: Cri du Chat syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        covering at least 10% of this region has been cloned
      explanation: >-
        The sentence this clause completes is "The human Semaphorin F gene (SEMAF)
        covering at least 10% of this region has been cloned", placing SEMA5A/SEMAF
        inside the 5p15.2 critical region. The quote starts mid-sentence because
        "Semaphorin" is hyphenated across a line break in the cached PDF text.
  - target: TERT Haploinsufficiency
    description: >-
      TERT lies at 5p15.33 and is removed by terminal deletions.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16953888
      reference_title: Cri du Chat syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        haploinsufficiency of the telomerase reverse transcriptase (hTERT) gene,
        localised to 5p15.33
      explanation: >-
        Places TERT inside the deleted interval and frames its loss as
        haploinsufficiency.
  - target: Hindbrain Hypoplasia
    description: >-
      Deletion of 5p is associated with structural hindbrain anomalies, of which
      pontine hypoplasia is the most frequent on neuroimaging. The intermediate
      genes and developmental steps are not established.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:32800423
      reference_title: "Structural brain anomalies in Cri-du-Chat syndrome: MRI findings in 14 patients and possible genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        MRI analyses showed that isolated pontine hypoplasia is the most common
        finding, followed by vermian hypoplasia
      explanation: >-
        Establishes hindbrain hypoplasia as a consistent structural consequence in
        patients with 5p deletions.

- name: Cry-Region Haploinsufficiency at 5p15.31
  biological_scale: MOLECULAR
  description: >-
    Reduced dosage of the small distal interval whose loss determines the cat-like
    cry. Phenotype-dissection studies comparing patients with and without the cry
    narrowed this interval to roughly 640 kb, and array-based mapping placed the
    cry determinant in 1.5 Mb of distal 5p15.31. The responsible gene or genes are
    not established; several candidates lie in the interval but none is proven.
  evidence:
  - reference: PMID:15657623
    reference_title: "Determination of the 'critical region' for cat-like cry of Cri-du-chat syndrome and analysis of candidate genes by quantitative PCR."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the critical region for the cat-like cry is mapped to a short 640 kbp region
      on chromosome 5p
    explanation: >-
      Fine-maps the cry determinant using patients who differ in the presence of
      the cry.
  - reference: PMID:34394178
    reference_title: Deep Phenotyping and Genetic Characterization of a Cohort of 70 Individuals With 5p Minus Syndrome.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      high-pitched cry seemed to map at p14.3–p13.2 bands versus bands
      p15.33–p15.31
    explanation: >-
      Recorded as REFUTE because it directly contradicts the distal localisation
      this node asserts. The largest contemporary cohort mapped the cry to a much
      more proximal interval than every earlier study. The distal mapping is
      retained as the node's primary claim because it rests on phenotype
      dissection in patients who differ in the presence of the cry, which is the
      stronger design, but the disagreement is real and is flagged rather than
      suppressed.
  downstream:
  - target: Laryngeal and Epiglottic Hypoplasia
    description: >-
      Loss of the interval is associated with maldevelopment of the larynx and
      epiglottis. The molecular route from dosage loss to laryngeal structure is
      not established.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:16953888
      reference_title: Cri du Chat syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The characteristic cat-like cry is probably due to anomalies
      explanation: >-
        The source attributes the cry to laryngeal and epiglottic anomalies but
        hedges the attribution ("probably"), so the edge is marked PARTIAL.

- name: CTNND2 Delta-Catenin Haploinsufficiency
  biological_scale: MOLECULAR
  description: >-
    Reduced dosage of delta-catenin, a neuronal adherens-junction protein
    expressed early in neuronal development and involved in cell motility. This is
    the best-supported single-gene contributor in the syndrome: hemizygous loss
    correlates with cognitive severity in patients, and restoring the gene product
    rescues cognition in an engineered rodent model of the syntenic deletion.
  genes:
  - preferred_term: CTNND2
    term:
      id: hgnc:2516
      label: CTNND2
  biological_processes:
  - preferred_term: cell-cell adhesion
    term:
      id: GO:0098609
      label: cell-cell adhesion
    modifier: DECREASED
  - preferred_term: dendritic spine development
    term:
      id: GO:0060996
      label: dendritic spine development
    modifier: DECREASED
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  evidence:
  - reference: PMID:10673328
    reference_title: Hemizygosity of delta-catenin (CTNND2) is associated with severe mental retardation in cri-du-chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Delta-catenin is an adherens junction protein involved in cell motility and
      expressed early in neuronal development.
    explanation: >-
      Establishes the molecular identity and neurodevelopmental role of the gene
      product whose dosage is reduced.
  downstream:
  - target: Impaired Dendritic Arborization and Spine Maturation
    description: >-
      Reduced delta-catenin dosage impairs dendritic arbor complexity and the
      maturation of dendritic spines. Causality is supported by rescue:
      AAV-mediated Ctnnd2 replacement alleviates the cognitive phenotype in the rat
      model, which is an interventional test rather than a correlation. The source
      states the limits directly: the benefit is confined to early developmental
      stages and does not fully restore the phenotype, so this edge should not be
      read as establishing that restoring one co-deleted gene corrects the
      syndrome.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:39965128
      reference_title: "Behavioral Abnormalities, Cognitive Impairments, Synaptic Deficits, and Gene Replacement Therapy in a CRISPR Engineered Rat Model of 5p15.2 Deletion Associated With Cri du Chat Syndrome."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        it is demonstrated that early gene replacement therapy with AAV-Ctnnd2
        alleviates cognitive impairments in CdCS rats
      explanation: >-
        Interventional rescue in an engineered model of the syntenic deletion,
        establishing that reduced Ctnnd2 dosage is causal for the cognitive
        phenotype in that model. Rodent evidence, so it supports the mechanism
        rather than the human phenotype directly.
    - reference: PMID:39965128
      reference_title: "Behavioral Abnormalities, Cognitive Impairments, Synaptic Deficits, and Gene Replacement Therapy in a CRISPR Engineered Rat Model of 5p15.2 Deletion Associated With Cri du Chat Syndrome."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        However, the effectiveness of this therapy is confined to the early
        developmental stages and does not fully restore all CdCS symptoms.
      explanation: >-
        The same source's own statement of the rescue's limits. Marked PARTIAL
        because it qualifies rather than supports the causal edge: single-gene
        restoration helps within a developmental window but does not correct the
        phenotype, which is consistent with the multi-gene dosage model this entry
        argues for.

- name: SEMA5A Axon-Guidance Haploinsufficiency
  biological_scale: MOLECULAR
  description: >-
    Reduced dosage of semaphorin 5A, an axon-guidance molecule implicated in
    guiding axons and migrating neuronal precursors during cortical development. A
    candidate contributor rather than an established driver.
  genes:
  - preferred_term: SEMA5A
    term:
      id: hgnc:10736
      label: SEMA5A
  biological_processes:
  - preferred_term: axon guidance
    term:
      id: GO:0007411
      label: axon guidance
    modifier: DECREASED
  - preferred_term: semaphorin-plexin signaling pathway
    term:
      id: GO:0071526
      label: semaphorin-plexin signaling pathway
    modifier: DECREASED
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Due to its role in guiding axons or migrating neuronal precursors during
      cortical development in mice
    explanation: >-
      States the gene function on which the candidacy rests. The source continues
      that the SEMAF deletion "may be responsible for some of the features of
      CdCS"; that continuation is hyphenated across a line break in the cached PDF
      text and so cannot be quoted verbatim. The attribution is suggestive and
      rests on mouse data, hence PARTIAL.
  downstream:
  - target: Disrupted Neuronal Migration and Cortical Development
    description: >-
      Loss of one copy of an axon-guidance molecule is proposed to perturb neuronal
      migration and cortical wiring. The step is inferred from gene function rather
      than demonstrated in patients.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:16953888
      reference_title: Cri du Chat syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        are potentially involved in cerebral development and their deletion may be
        associated with mental retardation in CdCS patients
      explanation: >-
        Supports the proposed developmental route while making its provisional
        status explicit.

- name: TERT Haploinsufficiency
  biological_scale: MOLECULAR
  description: >-
    Reduced dosage of telomerase reverse transcriptase, the rate-limiting
    component of telomerase, which is required for telomere-length maintenance and
    sustained cell proliferation. Whether this contributes materially to the
    clinical phenotype is unresolved, and no downstream consequence is asserted
    here.
  genes:
  - preferred_term: TERT
    term:
      id: hgnc:11730
      label: TERT
  molecular_functions:
  - preferred_term: telomerase activity
    term:
      id: GO:0003720
      label: telomerase activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: telomere maintenance
    term:
      id: GO:0000723
      label: telomere maintenance
    modifier: DECREASED
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      limiting component for the telomerase activity that is essential for
      telomere-length maintenance and sustained cell proliferation
    explanation: >-
      Establishes the molecular function lost. The full sentence begins "hTERT is
      the rate-limiting component..."; "rate-limiting" is split across a line break
      in the cached PDF text, so the quote starts after it. The clinical
      consequence in this syndrome remains proposed, hence PARTIAL.

- name: Laryngeal and Epiglottic Hypoplasia
  biological_scale: TISSUE
  description: >-
    A small, narrow, diamond-shaped larynx with a flabby, small, hypotonic
    epiglottis. This is the structural substrate of the cat-like cry and is also
    the reason intubation can be difficult in these patients, which makes it a
    mechanism node with direct perioperative relevance.
  locations:
  - preferred_term: larynx
    term:
      id: UBERON:0001737
      label: larynx
  biological_processes:
  - preferred_term: larynx development
    term:
      id: GO:0120224
      label: larynx development
    modifier: ABNORMAL
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      of the larynx (small, narrow, diamond-shaped) and of the epiglottis (flabby,
      small, hypotonic)
    explanation: >-
      Describes the laryngeal and epiglottic anatomy underlying the cry.

- name: Hindbrain Hypoplasia
  biological_scale: TISSUE
  description: >-
    Hypoplasia of hindbrain structures, most consistently the pons and cerebellar
    vermis on neuroimaging. This node carries the central component of the cry:
    cranial-base malformation has long been argued to imply concurrent
    maldevelopment of the rhombencephalic region and the larynx during
    embryogenesis, and pontine hypoplasia is the imaging correlate of that
    hypothesis.
  locations:
  - preferred_term: pons
    term:
      id: UBERON:0000988
      label: pons
  - preferred_term: cerebellum
    term:
      id: UBERON:0002037
      label: cerebellum
  evidence:
  - reference: PMID:32800423
    reference_title: "Structural brain anomalies in Cri-du-Chat syndrome: MRI findings in 14 patients and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI analyses showed that isolated pontine hypoplasia is the most common
      finding, followed by vermian hypoplasia, ventricular anomalies
    explanation: >-
      Establishes the pattern and relative frequency of hindbrain findings.
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      of the cranial base suggest associated anomalies of the brain
      (rhombencephalic region) and larynx during embryonal development
    explanation: >-
      States the developmental hypothesis linking hindbrain and laryngeal
      maldevelopment. The sentence opens "Malformations of the cranial base...";
      the first word is hyphenated across a line break in the cached PDF text, so
      the quote starts at the following word. Marked PARTIAL because the source
      frames it as a suggestion.

- name: Impaired Dendritic Arborization and Spine Maturation
  biological_scale: CELLULAR
  description: >-
    Reduced dendritic-arbor complexity and a shift away from mature
    mushroom-shaped dendritic spines in cortical and hippocampal neurons, with
    increased neuronal density in superficial layers. Demonstrated in the rat model
    of the syntenic deletion; the corresponding human neuropathology has not been
    characterised.
  cell_types:
  - preferred_term: pyramidal neuron
    term:
      id: CL:0000598
      label: pyramidal neuron
  biological_processes:
  - preferred_term: dendrite morphogenesis
    term:
      id: GO:0048813
      label: dendrite morphogenesis
    modifier: DECREASED
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  evidence:
  - reference: PMID:39965128
    reference_title: "Behavioral Abnormalities, Cognitive Impairments, Synaptic Deficits, and Gene Replacement Therapy in a CRISPR Engineered Rat Model of 5p15.2 Deletion Associated With Cri du Chat Syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      This model exhibits pronounced deficits in social behavior, cognition, and
      anxiety, accompanied by neuronal abnormalities and immune dysregulation in
      key brain regions such as the hippocampus and medial prefrontal cortex
      (mPFC).
    explanation: >-
      Documents the cellular and regional abnormalities in the engineered model.
  downstream:
  - target: Impaired Forebrain Development and Cortical Dysfunction
    description: >-
      Synaptic and dendritic deficits converge on impaired cortical function.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:39965128
      reference_title: "Behavioral Abnormalities, Cognitive Impairments, Synaptic Deficits, and Gene Replacement Therapy in a CRISPR Engineered Rat Model of 5p15.2 Deletion Associated With Cri du Chat Syndrome."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        This model exhibits pronounced deficits in social behavior, cognition, and
        anxiety
      explanation: >-
        Links the cellular deficits to organism-level cognitive impairment in the
        model.

- name: Disrupted Neuronal Migration and Cortical Development
  biological_scale: CELLULAR
  description: >-
    Perturbed migration of neuronal precursors and abnormal cortical wiring,
    inferred from the developmental roles of the co-deleted guidance and adhesion
    molecules. Anomalies of cortical development are among the structural findings
    reported on patient neuroimaging.
  biological_processes:
  - preferred_term: neuron migration
    term:
      id: GO:0001764
      label: neuron migration
    modifier: ABNORMAL
  - preferred_term: cerebral cortex development
    term:
      id: GO:0021987
      label: cerebral cortex development
    modifier: ABNORMAL
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  evidence:
  - reference: PMID:32800423
    reference_title: "Structural brain anomalies in Cri-du-Chat syndrome: MRI findings in 14 patients and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      corpus callosum anomalies, and anomalies of cortical development
    explanation: >-
      Documents abnormalities of cortical development among the neuroradiological
      findings in patients.
  downstream:
  - target: Impaired Forebrain Development and Cortical Dysfunction
    description: >-
      Disordered migration and wiring impair forebrain growth and function.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:16953888
      reference_title: Cri du Chat syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        are potentially involved in cerebral development and their deletion may be
        associated with mental retardation in CdCS patients
      explanation: >-
        Supports the proposed link from disrupted cerebral development to the
        cognitive phenotype, with the source's provisional framing preserved.

- name: Impaired Forebrain Development and Cortical Dysfunction
  biological_scale: TISSUE
  description: >-
    Reduced brain growth and impaired cortical function, manifesting as
    microcephaly with severe psychomotor and intellectual disability. Severity
    tracks deletion extent, but with an important caveat: a substantial share of
    the most severely affected patients carry additional copy-number changes
    outside 5p, so unusually severe impairment should prompt a search for a second
    lesion rather than being attributed to 5p deletion size alone.
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  evidence:
  - reference: PMID:15635506
    reference_title: High-resolution mapping of genotype-phenotype relationships in cri du chat syndrome using array comparative genomic hybridization.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MR depended approximately on the 5p deletion size and location, but there
      were many cases in which the retardation was disproportionately severe, given
      the 5p deletion. All 15 of these cases, approximately two-thirds of the
      severely retarded patients, were found to have copy-number aberrations in
      addition to the 5p deletion.
    explanation: >-
      Supports both the deletion-size dependence and the second-lesion caveat that
      qualifies it.

- name: Deletion-Independent DNA Methylation Dysregulation
  biological_scale: MOLECULAR
  description: >-
    Genome-wide DNA methylation differences in patients relative to matched
    controls, including at promoters of genes controlling embryonic development and
    at CpG sites linked to developmental delay and microcephaly. Critically, this
    enrichment is not driven by methylation changes on chromosome 5, so it is a
    candidate modifier layer acting outside the deleted interval that may help
    explain why patients with similar deletions differ clinically. Direction of
    causality is not established: the changes could contribute to phenotype or
    reflect it.
  evidence:
  - reference: PMID:36242045
    reference_title: Cri du chat syndrome patients have DNA methylation changes in genes linked to symptoms of the disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Importantly, this relative enrichment is not driven by changes in the
      methylation of genes on chromosome 5.
    explanation: >-
      Establishes that the methylation signal is independent of the deleted
      interval, which is what makes it a candidate modifier rather than a
      downstream readout of gene dosage.
  - reference: PMID:36242045
    reference_title: Cri du chat syndrome patients have DNA methylation changes in genes linked to symptoms of the disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      revealed enrichment of genes controlling embryonic development and genes
      linked to symptoms which are among the most common symptoms of Cri du chat
      syndrome: developmental delay and microcephaly
    explanation: >-
      Ties the methylation changes specifically to the developmental-delay and
      microcephaly phenotypes.
  downstream:
  - target: Impaired Forebrain Development and Cortical Dysfunction
    description: >-
      The methylation changes may contribute to the neurodevelopmental phenotype,
      but the direction of the relationship is explicitly unresolved by the source
      study: the differences could be driving the phenotype, result from other
      epigenetic changes, or merely reflect altered gene expression. The edge is
      therefore typed UNKNOWN rather than asserted as causal, and it is retained
      because the modifier hypothesis is the leading explanation on offer for why
      patients with comparable deletions differ clinically.
    causal_link_type: UNKNOWN
    evidence:
    - reference: PMID:36242045
      reference_title: Cri du chat syndrome patients have DNA methylation changes in genes linked to symptoms of the disease.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        is suggestive of epigenetic changes early in embryonic development that may
        be contributing to the development of symptoms
      explanation: >-
        The authors' own framing of the possible contribution, stated as suggestive
        rather than demonstrated, which is why this is PARTIAL.
    - reference: PMID:36242045
      reference_title: Cri du chat syndrome patients have DNA methylation changes in genes linked to symptoms of the disease.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        with the present data we cannot conclude about the sequence of events
        between DNA methylation changes and other cellular functions
      explanation: >-
        The source explicitly disclaims knowledge of causal ordering. Recorded here
        so the UNKNOWN edge typing is justified from the literature rather than
        being a curator hedge.

phenotypes:
- category: Neurological
  name: Cat-like Cry
  description: >-
    High-pitched, monochromatic, cat-like cry in infancy. The single most
    recognisable feature of the syndrome and usually the finding that prompts
    testing; it tends to disappear with age, so its absence in an older child does
    not argue against the diagnosis.
  phenotype_term:
    preferred_term: Cat cry
    term:
      id: HP:0200046
      label: Cat cry
  frequency: VERY_FREQUENT
  diagnostic: true
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      and the typical cry (95.9%)
    explanation: >-
      Italian CdCS Registry frequency of 95.9% supports the VERY_FREQUENT band
      (80-100%).

- category: Neurological
  name: Severe Intellectual Disability
  description: >-
    Severe psychomotor and intellectual disability, becoming evident during the
    first year of life. Severity correlates with deletion size and location.
  phenotype_term:
    preferred_term: Severe intellectual disability
    term:
      id: HP:0010864
      label: Severe intellectual disability
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      retardation becomes evident during the first year of life
    explanation: >-
      Documents the timing of the cognitive phenotype. The full sentence begins
      "Severe psychomotor retardation..."; "psychomotor" is hyphenated across a
      line break in the cached PDF text, so the quote starts at the following word.

- category: Neurological
  name: Delayed Speech and Language Development
  description: >-
    Expressive speech is disproportionately impaired relative to overall
    development, and maps to its own critical region distinct from that of the cry.
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  evidence:
  - reference: PMID:15635506
    reference_title: High-resolution mapping of genotype-phenotype relationships in cri du chat syndrome using array comparative genomic hybridization.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      speech delay to 3.2 Mb in 5p15.32-15.33
    explanation: >-
      Documents speech delay as a mapped component of the phenotype with its own
      critical region.

- category: Craniofacial
  name: Microcephaly
  description: >-
    Reduced head circumference, present from birth and persisting; median head
    circumference stays near or below the second percentile at all ages.
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The main clinical features are a high-pitched monochromatic cry,
      microcephaly, broad nasal bridge, epicanthal folds, micrognathia, abnormal
      dermatoglyphics, and severe psychomotor and mental retardation.
    explanation: >-
      Lists microcephaly among the cardinal, near-universal features.

- category: Craniofacial
  name: Round Face
  description: >-
    Round facial shape in infancy. The face becomes long and narrow with age, so
    the facial gestalt is age-dependent.
  phenotype_term:
    preferred_term: Round face
    term:
      id: HP:0000311
      label: Round face
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      round face (83.5%), large nasal bridge (87.2%),
    explanation: >-
      Registry frequency of 83.5% supports the VERY_FREQUENT band (80-100%).

- category: Craniofacial
  name: Hypertelorism
  phenotype_term:
    preferred_term: Hypertelorism
    term:
      id: HP:0000316
      label: Hypertelorism
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      hypertelorism (81.4%), epicanthal folds (90.2%)
    explanation: >-
      Registry frequency of 81.4% supports the VERY_FREQUENT band (80-100%).

- category: Craniofacial
  name: Epicanthus
  phenotype_term:
    preferred_term: Epicanthus
    term:
      id: HP:0000286
      label: Epicanthus
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      hypertelorism (81.4%), epicanthal folds (90.2%)
    explanation: >-
      Registry frequency of 90.2% supports the VERY_FREQUENT band (80-100%).

- category: Craniofacial
  name: Micrognathia
  phenotype_term:
    preferred_term: Micrognathia
    term:
      id: HP:0000347
      label: Micrognathia
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      micrognathia (96,7%), abnormal dermatoglyphics
    explanation: >-
      Registry frequency of 96.7% supports the VERY_FREQUENT band (80-100%).

- category: Craniofacial
  name: Wide Nasal Bridge
  phenotype_term:
    preferred_term: Wide nasal bridge
    term:
      id: HP:0000431
      label: Wide nasal bridge
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      round face (83.5%), large nasal bridge (87.2%),
    explanation: >-
      Registry frequency of 87.2% supports the VERY_FREQUENT band (80-100%).

- category: Craniofacial
  name: Downslanted Palpebral Fissures
  phenotype_term:
    preferred_term: Downslanted palpebral fissures
    term:
      id: HP:0000494
      label: Downslanted palpebral fissures
  frequency: FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ward slanting palpebral fissures (56.9%)
    explanation: >-
      Registry frequency of 56.9% supports the FREQUENT band (30-79%). The snippet
      begins mid-word because "downward" is hyphenated across a line break in the
      cached PDF text.

- category: Craniofacial
  name: Downturned Corners of Mouth
  phenotype_term:
    preferred_term: Downturned corners of mouth
    term:
      id: HP:0002714
      label: Downturned corners of mouth
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      corners of the mouth (81.0%), low-set ears (69.8%)
    explanation: >-
      Registry frequency of 81.0% supports the VERY_FREQUENT band (80-100%).

- category: Craniofacial
  name: Low-Set Ears
  phenotype_term:
    preferred_term: Low-set ears
    term:
      id: HP:0000369
      label: Low-set ears
  frequency: FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      corners of the mouth (81.0%), low-set ears (69.8%)
    explanation: >-
      Registry frequency of 69.8% supports the FREQUENT band (30-79%).

- category: Neurological
  name: Neonatal Hypotonia
  description: >-
    Marked hypotonia in the newborn period, accompanied by impaired suck. Muscle
    tone tends to increase with age.
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      impaired suction and hypotonia
    explanation: >-
      Documents neonatal hypotonia and impaired suck. The full sentence lists
      neonatal problems as asphyxia, cyanotic crises, impaired suction and
      hypotonia; "cyanotic" is hyphenated across a line break in the cached PDF
      text, so the quote starts after it.

- category: Gastrointestinal
  name: Feeding Difficulties
  description: >-
    Feeding difficulty and gastroesophageal reflux in the first years of life,
    contributing to poor weight gain.
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The low weight may be attributed to feeding difficulties and
      gastroesophageal reflux, both of which are frequent in the first years of
      life
    explanation: >-
      Documents feeding difficulty and its contribution to low weight.

- category: Musculoskeletal
  name: Single Transverse Palmar Crease
  description: >-
    Abnormal dermatoglyphics with transverse flexion creases, a useful adjunct
    diagnostic sign.
  phenotype_term:
    preferred_term: Single transverse palmar crease
    term:
      id: HP:0000954
      label: Single transverse palmar crease
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      micrognathia (96,7%), abnormal dermatoglyphics
    explanation: >-
      Registry data report abnormal dermatoglyphics (transverse flexion creases) at
      92%, supporting the VERY_FREQUENT band.

- category: Ophthalmological
  name: Strabismus
  description: >-
    Divergent strabismus, one of the features that develops with age rather than
    being present from birth.
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  frequency: FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      divergent strabismus is frequent (44.7%)
    explanation: >-
      Registry frequency of 44.7% supports the FREQUENT band (30-79%).

- category: Neurological
  name: Hypoplasia of the Pons
  description: >-
    Pontine hypoplasia, the most common structural brain finding on MRI in this
    syndrome, frequently occurring in isolation.
  phenotype_term:
    preferred_term: Hypoplasia of the pons
    term:
      id: HP:0012110
      label: Hypoplasia of the pons
  evidence:
  - reference: PMID:32800423
    reference_title: "Structural brain anomalies in Cri-du-Chat syndrome: MRI findings in 14 patients and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI analyses showed that isolated pontine hypoplasia is the most common
      finding
    explanation: >-
      Documents pontine hypoplasia as the leading neuroradiological finding.

- category: Neurological
  name: Cerebellar Vermis Hypoplasia
  phenotype_term:
    preferred_term: Cerebellar vermis hypoplasia
    term:
      id: HP:0001320
      label: Cerebellar vermis hypoplasia
  evidence:
  - reference: PMID:32800423
    reference_title: "Structural brain anomalies in Cri-du-Chat syndrome: MRI findings in 14 patients and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      followed by vermian hypoplasia, ventricular anomalies
    explanation: >-
      Documents vermian hypoplasia as the second most common MRI finding.

- category: Growth
  name: Intrauterine Growth Retardation
  description: >-
    Prenatal and postnatal growth retardation, with low birth weight averaging
    about 2614 g.
  phenotype_term:
    preferred_term: Intrauterine growth retardation
    term:
      id: HP:0001511
      label: Intrauterine growth retardation
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      confirmed the existence of prenatal and postnatal growth retardation
    explanation: >-
      Documents growth retardation from a multicentre growth-chart study.

- category: Dermatological
  name: Premature Graying of Hair
  description: >-
    Premature greying, one of the age-dependent features.
  phenotype_term:
    preferred_term: Premature graying of hair
    term:
      id: HP:0002216
      label: Premature graying of hair
  frequency: FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      prematurely grey hair may be observed (30.4%)
    explanation: >-
      Registry frequency of 30.4% supports the FREQUENT band (30-79%).

- category: Craniofacial
  name: Short Philtrum
  phenotype_term:
    preferred_term: Short philtrum
    term:
      id: HP:0000322
      label: Short philtrum
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the philtrum short (87.8%)
    explanation: >-
      Registry frequency of 87.8% supports the VERY_FREQUENT band (80-100%).

- category: Behavioral
  name: Hyperactivity
  description: >-
    Hyperactivity and distractibility, which sometimes coexist with
    aggressiveness and are reported to be relatively specific to this syndrome
    when compared with Prader-Willi and Smith-Magenis syndromes.
  phenotype_term:
    preferred_term: Hyperactivity
    term:
      id: HP:0000752
      label: Hyperactivity
  frequency: FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hyperactivity is present in about 50% of patients and sometimes coexists
      with aggressiveness
    explanation: >-
      Reported frequency of about 50% supports the FREQUENT band (30-79%).

- category: Behavioral
  name: Self-Injurious Behavior
  description: >-
    Self-injury, repetitive movements, hypersensitivity to sounds and obsessive
    attachment to objects form a recognisable behavioural profile. Importantly,
    the source reports these behaviours improve with early educational
    intervention, so they are not treated as fixed.
  phenotype_term:
    preferred_term: Self-injurious behavior
    term:
      id: HP:0100716
      label: Self-injurious behavior
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A survey of the prevalence of stereotypy, self-injury and aggression in
      CdCS children and young adults
    explanation: >-
      Documents stereotypy, self-injury and aggression as characterised features
      of the syndrome. No frequency is asserted because the source gives no
      percentage for them.

- category: Cardiovascular
  name: Congenital Heart Defect
  description: >-
    Structural cardiac malformations, most often atrial and ventricular septal
    defects, patent ductus arteriosus and tetralogy of Fallot. Frequency is
    genuinely disputed: the Orphanet review characterises malformations as "not
    very frequent", while contemporary cohort studies report congenital heart
    disease in roughly a third of patients. No frequency band is asserted here for
    that reason.
  phenotype_term:
    preferred_term: Abnormal heart morphology
    term:
      id: HP:0001627
      label: Abnormal heart morphology
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Malformations, although not very frequent, may be present: cardiac,
      neurological and renal abnormalities
    explanation: >-
      Documents cardiac malformation as part of the syndrome. The source's own
      "not very frequent" qualifier is one half of the disagreement recorded in the
      description.
  - reference: PMID:34394178
    reference_title: Deep Phenotyping and Genetic Characterization of a Cohort of 70 Individuals With 5p Minus Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      short neck, scoliosis, cardiac anomalies, and speech delay were present in
      25–59% of the cases and should be considered frequent findings in the
      syndrome
    explanation: >-
      The contemporary-cohort side of the disagreement, calling cardiac anomalies
      frequent findings. No band is asserted because the 25-59% interval straddles
      the OCCASIONAL and FREQUENT boundaries and the two sources disagree in
      direction; citing both is what lets a reader see the conflict.

- category: Renal
  name: Renal Anomaly
  description: >-
    Structural renal malformations, with unilateral renal agenesis among the
    reported anomalies.
  phenotype_term:
    preferred_term: Abnormality of the kidney
    term:
      id: HP:0000077
      label: Abnormality of the kidney
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Malformations, although not very frequent, may be present: cardiac,
      neurological and renal abnormalities
    explanation: >-
      Documents renal abnormality as part of the syndrome. No frequency band is
      assigned, for the same reason as the cardiac phenotype.

- category: Otologic
  name: Sensorineural Hearing Impairment
  description: >-
    Sensorineural deafness occurs in a subset of patients and compounds the
    expressive-speech impairment, which is why audiometric examination is
    recommended for every child with the syndrome rather than only for those with
    suspected hearing loss.
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      some patients have sensory-neural deafness and speech retardation,
      audiometric examination should be carried out on all CdCS children
    explanation: >-
      Documents sensorineural deafness and the resulting universal-screening
      recommendation. "Some patients" is too vague to support a frequency band, so
      none is assigned.

- category: Musculoskeletal
  name: Scoliosis
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  frequency: FREQUENT
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Scoliosis, flat foot, pes varus, inguinal hernia and diastasis recti are
      frequent.
    explanation: >-
      The source's qualitative term "frequent" maps to the FREQUENT band (30-79%).
  - reference: PMID:34394178
    reference_title: Deep Phenotyping and Genetic Characterization of a Cohort of 70 Individuals With 5p Minus Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      short neck, scoliosis, cardiac anomalies, and speech delay were present in
      25–59% of the cases and should be considered frequent findings in the
      syndrome
    explanation: >-
      Independent cohort support for scoliosis as a frequent finding, consistent
      with the FREQUENT band assigned from the review.

- category: Neurological
  name: Hypertonia
  description: >-
    Muscle tone reverses direction over the course of the disease: the marked
    neonatal hypotonia is replaced by hypertonia with age, and microcephaly becomes
    more evident. Modelling only the neonatal hypotonia would misrepresent the
    natural history.
  phenotype_term:
    preferred_term: Hypertonia
    term:
      id: HP:0001276
      label: Hypertonia
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      With age, muscle hypotonia is replaced by hypertonia
    explanation: >-
      Documents the tone reversal, which is what makes this a distinct phenotype
      from the neonatal hypotonia rather than a duplicate of it.

- category: Neurological
  name: Cerebellar Atrophy
  description: >-
    Atrophy of brainstem and cerebellar structures on MRI, involving the pons,
    cerebellum, cerebellar peduncles and cerebellar white matter.
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Atrophy of the brainstem mainly involving the pons, cerebellum
    explanation: >-
      Documents cerebellar and brainstem atrophy on MRI. The sentence continues into
      the peduncles and cerebellar white matter, but the next word is hyphenated
      across a line break in the cached PDF text.

- category: Neurological
  name: Abnormal Corpus Callosum Morphology
  phenotype_term:
    preferred_term: Abnormal corpus callosum morphology
    term:
      id: HP:0001273
      label: Abnormal corpus callosum morphology
  evidence:
  - reference: PMID:32800423
    reference_title: "Structural brain anomalies in Cri-du-Chat syndrome: MRI findings in 14 patients and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      corpus callosum anomalies, and anomalies of cortical development
    explanation: >-
      Documents corpus callosum anomalies among the neuroradiological findings.

- category: Gastrointestinal
  name: Gastroesophageal Reflux
  description: >-
    Gastroesophageal reflux is frequent in the first years of life and contributes,
    with feeding difficulty, to poor weight gain.
  phenotype_term:
    preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The low weight may be attributed to feeding difficulties and
      gastroesophageal reflux, both of which are frequent in the first years of
      life
    explanation: >-
      Documents reflux as a frequent early feature. Modelled separately from feeding
      difficulty because it is a distinct mechanism with distinct management.

- category: Growth
  name: Low Birth Weight
  description: >-
    Low birth weight, mean about 2614 g, reflecting prenatal growth retardation.
  phenotype_term:
    preferred_term: Small for gestational age
    term:
      id: HP:0001518
      label: Small for gestational age
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The clinical features at birth are low weight (mean weight 2614 g)
    explanation: >-
      Quantifies mean birth weight from the registry series.

- category: Behavioral
  name: Aggressive Behavior
  description: >-
    Aggressiveness coexisting with hyperactivity in a subset of patients, reported
    as modifiable with adequate educational programmes.
  phenotype_term:
    preferred_term: Aggressive behavior
    term:
      id: HP:0000718
      label: Aggressive behavior
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hyperactivity is present in about 50% of patients and sometimes coexists
      with aggressiveness
    explanation: >-
      Documents aggressiveness as co-occurring with hyperactivity. No frequency band
      is asserted because the 50% figure quantifies hyperactivity, not aggression.
- category: Growth
  name: Growth Failure
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Growth failure
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:10678657
    reference_title: "Cri du chat syndrome: changing phenotype in older patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical picture is well known in younger patients and includes
      the typical high-pitched cry, psychomotor retardation, microcephaly, growth
      rate failure, and craniofacial abnormalities"
    explanation: The paper's statement of the well-delineated clinical picture in
      younger patients lists growth rate failure among the core features.

treatments:
- name: Early Rehabilitative and Educational Intervention
  description: >-
    No disease-specific therapy exists. Early rehabilitative and educational
    intervention is the mainstay and measurably improves prognosis and social
    adjustment, which makes prompt diagnosis worthwhile even though the underlying
    lesion is not correctable.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: rehabilitation
    term:
      id: NCIT:C15315
      label: Rehabilitation
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is no specific therapy for CdCS but early rehabilitative and
      educational interventions improve the prognosis and considerable progress has
      been made in the social adjustment of CdCS patients.
    explanation: >-
      States both the absence of specific therapy and the benefit of early
      intervention.
- name: Speech and Language Therapy
  description: >-
    Speech therapy alongside physical therapy and psychomotricity. Expressive
    language is impaired out of proportion to comprehension, which is the specific
    rationale for prioritising expressive-language and augmentative communication
    work rather than general developmental support.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: speech therapy
    term:
      id: NCIT:C159273
      label: Speech Language Therapy
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Early rehabilitation (physical therapy, psychomotricity, speech therapy) is
      recommended for the neurological problems
    explanation: >-
      Names speech therapy explicitly among the recommended early rehabilitative
      modalities.
- name: Genetic Counseling
  description: >-
    Counselling turns on which mechanism produced the deletion. A de novo deletion
    carries negligible recurrence risk; a parental balanced translocation carries a
    risk of unbalanced offspring roughly an order of magnitude higher, and makes
    prenatal diagnosis appropriate. Parental karyotyping after a new diagnosis is
    what separates the two, and residual gonadal mosaicism qualifies even the
    negligible figure.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:16953888
    reference_title: Cri du Chat syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The risk of recurrence is practically negligible for the cases of a de novo
      deletion, which are the most frequent.
    explanation: >-
      The counselling figure for the majority mechanism. Paired with the
      translocation-carrier risk recorded under inheritance, this is what the
      counselling session actually conveys.
- name: Physical and Occupational Therapy
  description: For hypotonia and psychomotor delay.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: physical therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy

notes: >-
  Diagnosis is clinical in the first instance, resting on the facial gestalt,
  transverse flexion creases, hypotonia and the characteristic cry; karyotype is
  the confirmatory test, with FISH reserved for cases where clinical suspicion
  conflicts with an apparently normal karyotype. Not every 5p deletion produces
  the syndrome: individuals whose deletions spare the critical regions may have a
  mild phenotype or none at all, which is why deletion coordinates rather than
  deletion presence should drive interpretation.

  Perioperative care deserves specific mention: laryngeal and epiglottic
  hypoplasia can make intubation difficult, so the mechanism node underlying the
  cry has direct anaesthetic consequences.

  Several evidence snippets drawn from PMID:16953888 begin or end mid-sentence.
  That reference is cached as extracted PDF text in which words are hyphenated
  across line breaks; snippets are trimmed to avoid those breaks so they remain
  exact substrings of the cache. The affected explanations note this explicitly.

discussions:
- discussion_id: cdcs_cry_gene_unidentified
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Which gene or genes in the distal 5p15.31 cry critical region are responsible
    for the laryngeal maldevelopment that produces the cat-like cry?
  attaches_to:
  - "pathophysiology#Cry-Region Haploinsufficiency at 5p15.31"
  rationale: >-
    The cry is the syndrome's defining feature and its determining interval has
    been narrowed to roughly 640 kb by phenotype dissection, yet no responsible
    gene has been established. The interval is gene-rich, and the candidates
    characterised so far are either ubiquitously expressed or have no known role
    in laryngeal development, so none offers a satisfying mechanistic account.
    This leaves the best-mapped genotype-phenotype relationship in the syndrome
    without a molecular explanation.
  evidence:
  - reference: PMID:15657623
    reference_title: "Determination of the 'critical region' for cat-like cry of Cri-du-chat syndrome and analysis of candidate genes by quantitative PCR."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These results suggest that one candidate gene, FLJ25076, encodes a
      ubiquitin-conjugated enzyme E2 type, which is locally expressed in thoracic
      and scalp tissues.
    explanation: >-
      Documents the state of the art on the cry interval: the leading candidate is
      offered only as a suggestion, with tissue expression that does not obviously
      implicate the larynx. This is the evidence that the gap remains open.
  proposed_experiments:
  - experiment_id: cdcs_cry_region_larynx_expression
    name: Laryngeal expression screen of the 640 kb cry interval
    description: >-
      Determine which genes in the 640 kb interval are expressed in developing
      laryngeal cartilage and the epiglottic primordium, using developmental
      single-cell transcriptomics of human and model-organism larynx, then test
      dosage reduction of the strongest candidates for laryngeal structural
      phenotypes.
    decision_criterion: >-
      A candidate expressed in laryngeal cartilage whose heterozygous reduction
      reproduces a narrowed or hypoplastic larynx would identify the cry gene;
      absence of any laryngeally expressed candidate would argue the cry arises
      from the central rather than the structural arm.
- discussion_id: cdcs_rat_model_translational_validity
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Does the neuroinflammatory signature seen in the rat model of the syntenic 5p
    deletion, including complement activation in reactive astrocytes, occur in
    human patients?
  attaches_to:
  - "pathophysiology#Impaired Dendritic Arborization and Spine Maturation"
  rationale: >-
    The engineered rat model reproduces cognitive and social deficits and shows
    immune dysregulation in hippocampus and prefrontal cortex, and AAV-Ctnnd2
    rescue makes the CTNND2 dosage link causal in that system. But the immune and
    synaptic-pruning arm has no human counterpart evidence: no patient
    neuropathology series has looked for astrocyte reactivity or complement
    activation. The gap matters therapeutically, because a neuroinflammatory
    component would suggest targets entirely different from gene replacement, and
    it would be easy to over-read the rodent result as established human
    mechanism.
  evidence:
  - reference: PMID:39965128
    reference_title: "Behavioral Abnormalities, Cognitive Impairments, Synaptic Deficits, and Gene Replacement Therapy in a CRISPR Engineered Rat Model of 5p15.2 Deletion Associated With Cri du Chat Syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      The immunostaining and RNA-seq analyses provide new insights into CdCS
      pathogenesis, revealing inflammatory and immune processes.
    explanation: >-
      Source of the inflammatory and immune findings whose human validity is the
      subject of this mismatch. Rodent evidence, which is precisely why the human
      counterpart is an open question rather than settled mechanism.
  proposed_experiments:
  - experiment_id: cdcs_human_neuropathology_complement
    name: Human neuropathology survey for astrocyte reactivity and complement
    description: >-
      Examine available post-mortem brain tissue from individuals with 5p deletion
      for astrocyte reactivity and complement deposition, comparing regional
      distribution with the model. Where tissue is unavailable, test CSF or blood
      complement markers against deletion size and cognitive severity.
    decision_criterion: >-
      Regionally concordant astrocyte reactivity with complement deposition in
      patient tissue would promote the neuroinflammatory arm to human mechanism;
      its absence would confine that arm to the model and caution against
      inflammation-directed therapeutic inference.
- discussion_id: cdcs_methylation_causal_direction
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Are the deletion-independent DNA methylation changes in patients a cause of
    phenotypic variability or a consequence of the disease state?
  attaches_to:
  - "pathophysiology#Deletion-Independent DNA Methylation Dysregulation"
  rationale: >-
    Methylation changes enriched at developmental-delay and microcephaly genes,
    demonstrably not driven by chromosome 5, are an attractive explanation for why
    patients with similar deletions differ clinically. But the study design is
    cross-sectional and measured in blood, so it cannot distinguish a modifier
    that shapes the phenotype from a signature that reflects it. Resolving the
    direction determines whether this is a therapeutic target or merely a
    biomarker.
  evidence:
  - reference: PMID:36242045
    reference_title: Cri du chat syndrome patients have DNA methylation changes in genes linked to symptoms of the disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      with the present data we cannot conclude about the sequence of events
      between DNA methylation changes and other cellular functions
    explanation: >-
      The authors state the causal-direction gap themselves, so this discussion
      records an acknowledged limitation of the primary study rather than a
      curator-invented doubt.
  proposed_experiments:
  - experiment_id: cdcs_methylation_longitudinal_tissue
    name: Cross-tissue and longitudinal methylation comparison
    description: >-
      Compare methylation in blood against a developmentally relevant tissue in
      the same individuals, and test whether methylation state at the implicated
      CpG sites measured early predicts later developmental trajectory
      independently of deletion size.
    decision_criterion: >-
      Early methylation state predicting later trajectory after adjustment for
      deletion size would support a modifier role; concordance only with
      concurrent severity would favour a downstream signature.
- discussion_id: cdcs_tert_functional_consequence
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Does hemizygous loss of TERT produce any measurable consequence in cri-du-chat
    syndrome, or is it a passenger deletion with no phenotypic contribution?
  attaches_to:
  - "pathophysiology#TERT Haploinsufficiency"
  rationale: >-
    TERT sits at 5p15.33 and is removed by essentially every terminal deletion, so
    it is routinely listed among the syndrome's candidate genes. But unlike CTNND2
    it has no correlative human evidence and no rescue experiment, and no telomere
    phenotype has been demonstrated in patients. This node is deliberately left
    without a downstream edge for that reason: asserting one would manufacture a
    mechanism the literature does not support. The question matters because
    proximity to the telomere makes TERT loss near-universal, so if it were
    contributing it would be contributing in almost every patient.
  evidence:
  - reference: PMID:40343585
    reference_title: "Establishment and characterization of Cri Du Chat neuronal stem cells: a novel promising resource to study the syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      mapped in chromosome 5 short arm, are known to be expressed in the brain, and
      to play a role in the development of the nervous system
    explanation: >-
      Groups TERT with SEMA5A and CTNND2 as brain-expressed 5p genes whose
      haploinsufficiency is proposed but not resolved, which is precisely the open
      question.
  - reference: PMID:40343585
    reference_title: "Establishment and characterization of Cri Du Chat neuronal stem cells: a novel promising resource to study the syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      the mechanism of which has remained unexplained
    explanation: >-
      States that the mechanism linking 5p gene dosage to developmental impairment
      is unexplained, supporting the gap rather than any particular resolution.
  proposed_experiments:
  - experiment_id: cdcs_tert_telomere_phenotype
    name: Telomere-length and TERT-dosage phenotyping in patient cells
    description: >-
      Measure telomerase activity and telomere length in patient-derived neuronal
      stem cells and fibroblasts stratified by whether the deletion includes TERT,
      and test whether either measure correlates with cognitive severity
      independently of overall deletion size.
    decision_criterion: >-
      A telomere or telomerase deficit tracking TERT inclusion, and correlating with
      severity after adjusting for deletion size, would promote TERT from candidate
      to contributor; absence of any measurable deficit would support treating it as
      a passenger and removing it from the candidate list.

references:
- reference: PMID:16953888
  title: "Cri du Chat syndrome."
- reference: PMID:11238681
  title: "Clinical and molecular characterisation of 80 patients with 5p deletion: genotype-phenotype correlation."
- reference: PMID:10678657
  title: "Cri du chat syndrome: changing phenotype in older patients."
- reference: PMID:15733271
  title: "A variant Cri du Chat phenotype and autism spectrum disorder in a subject with de novo cryptic microdeletions involving 5p15.2 and 3p24.3-25 detected using whole genomic array CGH."
📚

References & Deep Research

References

4
PMID:16953888
Cri du Chat syndrome.
No top-level findings curated for this source.
PMID:11238681
Clinical and molecular characterisation of 80 patients with 5p deletion: genotype-phenotype correlation.
No top-level findings curated for this source.
PMID:10678657
Cri du chat syndrome: changing phenotype in older patients.
No top-level findings curated for this source.
PMID:15733271
A variant Cri du Chat phenotype and autism spectrum disorder in a subject with de novo cryptic microdeletions involving 5p15.2 and 3p24.3-25 detected using whole genomic array CGH.
No top-level findings curated for this source.

Deep Research

1
Claude Code ▸
Cri-du-Chat Syndrome — Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 25 citations 2026-07-30T22:45:04.728957

Cri-du-Chat Syndrome — Comprehensive Research Report

1. Disease Information

Overview. Cri-du-chat syndrome (CdCS, "cat's cry" syndrome, 5p− syndrome) is a contiguous-gene deletion (chromosomal) disorder caused by partial or complete loss of the short arm (p arm) of chromosome 5. It is the most common human deletion syndrome and is named for its most distinctive neonatal sign: a high-pitched, monotone, cat-like cry caused by laryngeal abnormalities. The syndrome is characterized by microcephaly, low birth weight, marked infantile hypotonia (evolving to hypertonia later in life), distinctive craniofacial dysmorphism, and moderate-to-severe intellectual disability with developmental delay (StatPearls; Orphanet review, PMC1574300).

Key identifiers: | Resource | ID | |---|---| | OMIM | #123450 | | MONDO | MONDO:0007404 | | Orphanet | ORPHA:281 (Cri-du-chat syndrome); ORPHA:261893 (related partial monosomy 5p entries) | | ICD-10-CM | Q93.4 — Deletion of short arm of chromosome 5 | | ICD-9-CM | 758.31 | | ICD-11 | LD44.51 | | MeSH | D003410 | | SNOMED CT | 70173007 |

Synonyms: 5p− syndrome / 5p minus syndrome; Cat cry syndrome; Chromosome 5p deletion syndrome; Lejeune syndrome (after Jérôme Lejeune, who first described it in 1963); Partial monosomy 5p.

Evidence base: Information is derived predominantly from aggregated disease-level resources — multinational patient registries (notably the Italian and the U.S. "5P- Society" / 5p Minus Database, and combined Italian-German cohorts), systematic deep-phenotyping cohort studies (e.g., a 70-patient cohort, PMC8362798), case series, and a handful of interventional/mechanistic studies in model organisms; large-scale EHR-level individual-patient data are limited given rarity.

2. Etiology

Primary cause — chromosomal deletion. CdCS results from deletion of variable size on 5p, ranging from a few hundred kb to the entire short arm. - ~80–90% of deletions are terminal; 3–5% are interstitial (StatPearls). - ~80–90% of cases arise de novo; of de novo cases, the deleted chromosome is of paternal origin in the large majority, thought to arise from breakage during male gametogenesis. - ~10–15% arise from unbalanced segregation of a parental balanced translocation (or, less commonly, recombination from a parental pericentric inversion). - Rarer mechanisms include ring chromosome 5 formation, mosaicism, complex chromosomal rearrangements, and even reported chromosome 5p chromothripsis (PMC3797133). - Gonadal mosaicism has been documented — sperm FISH analysis identified a 5p deletion in 12.8% of 200 cells in one father of an affected child, explaining recurrence despite an apparently normal parental karyotype (search synthesis, multiple PMC sources).

Genetic risk factors: The deletion itself is the causal lesion; there is no known predisposing germline variant that increases risk of the deletion occurring. Average deletion size in a 70-patient deep-phenotyping cohort was 20.22 ± 9.29 Mb (range 0.62–35.01 Mb), and 39% of patients harbored additional clinically significant genomic rearrangements beyond the primary 5p deletion, contributing to phenotypic heterogeneity (PMC8362798).

Environmental/parental risk factors: No established parental-age effect or environmental exposure has been consistently linked to occurrence; "specific risk factors associated with prenatal events or parental age are unclear" (StatPearls).

Protective factors: None identified — this is a de novo/structural chromosomal event rather than a susceptibility-variant-driven disease, so classic "protective allele" frameworks do not apply.

Gene-environment interaction: Not applicable in the classical sense; however, epigenetic modification (DNA methylation) appears to modulate phenotypic expressivity independent of deletion size (see Section 6).

3. Phenotypes

Phenotype frequencies below are drawn primarily from a 70-patient deep-phenotyping cohort (PMC8362798) and corroborated by StatPearls/Orphanet/OMIM summaries.

Craniofacial (congenital, present from birth; HP subtree: Abnormality of the face/skull): - Microcephaly — 84.3% (HP:0000252) - Broad/large nasal bridge — 62.9% (HP:0000431) - Hypertelorism — 58.6% (HP:0000316) - Epicanthal folds — 47.1% (HP:0000286) - Micrognathia — 42.9% (HP:0000347) - Downturned corners of the mouth — 11.4% (HP:0002714) - Round/"moon" facies in infancy, evolving to a narrow, elongated face in adulthood - Low-set ears, short philtrum, high-arched palate, premature graying of hair, dental enamel hypoplasia, chronic periodontitis

Neonatal/laryngeal (hallmark sign): - Characteristic high-pitched, monotone, cat-like cry — reported in 55.7–~100% depending on cohort and age at exam; typically most evident at birth and diminishes/resolves over months to a few years as laryngeal anatomy matures (HP:0001582, "High-pitched cry") - Low birth weight, poor feeding/impaired sucking, hypotonia, respiratory difficulties, recurrent infections in infancy

Neurodevelopmental / cognitive: - Developmental delay — 91.4% - Intellectual disability, frequently severe — 44.3% severe; comprehension of speech is characteristically better than expressive language ability - Hypotonia in infancy (70.0%) transitioning to hypertonia/spasticity with age

Behavioral: - Behavioral anomalies overall — 71.4% - Aggressive behavior / self-injurious behavior (e.g., head-banging, hand-biting) — 84.6% in one series (HP:0000718 aggression; HP:0000742 self-mutilation) - Hyperactivity/attention deficit — 24.3% (HP:0007018 ADHD) - Autism spectrum features — 12.9% (HP:0000717/HP:0000729) - Hypersensitivity to sound, obsessive attachment to objects, repetitive stereotyped movements, sleep disturbance (HP:0002360); one study found children with higher fatigue exhibited more autistic traits. - Personality is often described as affectionate/gentle, and most patients can communicate needs and socialize to some degree — distinguishing typical CdCS behavior from the more autism-like/withdrawn presentation reported specifically in patients whose 5p deletion arose from unbalanced parental translocation.

Musculoskeletal: - Scoliosis — 35.7%; joint dislocation — 21.4%; pes cavus — 18.6%; abnormal palmar dermatoglyphics/transverse flexion creases; syndactyly (less common)

Cardiovascular: - Congenital heart defects — reported 15–36% across cohorts (34.3% in the deep-phenotyping cohort); most common lesions are ASD, VSD, patent ductus arteriosus, and tetralogy of Fallot (PMID:16585274)

Genitourinary/renal: - Renal anomalies — 12.9% in the deep-phenotyping cohort; other series report unilateral renal agenesis in 6–18% and genitourinary anomalies overall in 4–21%; cryptorchidism, hypospadias reported

Gastrointestinal: GI anomalies (including reflux, constipation, feeding/swallowing dysfunction) — 55.7%

Otologic: Hearing problems (including sensorineural hearing loss, HP:0000407) — 42.9%

Neuroimaging findings: Cerebellar hypoplasia, pontine hypoplasia, corpus callosum anomalies, and microcephaly are described on brain MRI.

Quality-of-life impact: An Italian caregiver/patient cohort found an EQ-5D visual analogue scale of 65.5 (SD 22.4), substantially below general-population norms, with "usual activities" and "self-care" the most compromised domains; 93% of patients rely on an informal (family) caregiver (PMC7459640).

Suggested HPO terms: HP:0000252 (Microcephaly), HP:0001582 (High-pitched cry), HP:0000316 (Hypertelorism), HP:0000286 (Epicanthus), HP:0000347 (Micrognathia), HP:0000431 (Broad nasal bridge), HP:0002714 (Downturned corners of mouth), HP:0001252 (Hypotonia), HP:0001256 (Intellectual disability, mild) / HP:0010864 (Intellectual disability, severe), HP:0001518 (Low birth weight), HP:0000717 (Autism), HP:0007018 (ADHD), HP:0000718 (Aggressive behavior), HP:0000742 (Self-mutilation), HP:0002360 (Sleep disturbance), HP:0001627 (Abnormal heart morphology/congenital heart defect), HP:0000107/HP:0000104 (Renal anomaly/agenesis), HP:0002650 (Scoliosis), HP:0000407 (Sensorineural hearing loss), HP:0001321 (Cerebellar hypoplasia), HP:0002079 (Hypoplasia of the corpus callosum).

4. Genetic/Molecular Information

Causal lesion: Deletion of 5p, OMIM #123450. This is a contiguous-gene deletion disorder, not a single-gene Mendelian disease — haploinsufficiency of multiple genes within the deleted interval jointly produces the phenotype.

Critical regions (genotype–phenotype mapping): - Cat-like cry critical region — 5p15.3: Fine-mapped by quantitative PCR to a ~640 kb interval; individuals whose deletion spares this region generally lack the typical cry (PMID:15657623). The gene FLJ25076 (encoding a ubiquitin-conjugating E2-type enzyme, expressed in thoracic/scalp tissue) maps within this interval. - Developmental/craniofacial critical region — 5p15.2: Associated with microcephaly, characteristic facial dysmorphism, and severe intellectual disability. Breakpoint-delineation studies (PMC7005617) refined this further and linked head-circumference and cry phenotypes to a genomic region of ~4.7 Mb. - Integrated analysis of the combined 5p15.3–p15.2 critical region is reviewed in PMC6687350.

Key candidate genes (all map to 5p15): | Gene | Cytoband (approx.) | Proposed role | |---|---|---| | CTNND2 (δ-catenin 2) | 5p15.2 | Cell-cell adhesion / neuronal migration and dendritic spine regulation; deleted in essentially all patients; haploinsufficiency strongly linked to severity of intellectual disability | | SEMA5A (Semaphorin 5A) | 5p15.31 | Axon guidance / neuronal migration during brain development; haploinsufficiency implicated in developmental delay and severe mental retardation | | TERT (telomerase reverse transcriptase) | 5p15.33 | Telomere maintenance; proposed contributor to phenotype though not itself a classic "critical-region" driver | | MARCH6 | 5p15.2 | Proposed candidate among five genes flagged as haploinsufficient and phenotype-relevant in CdCS | | NPR3 (natriuretic peptide receptor 3) | 5p | Also proposed among the phenotype-relevant haploinsufficient gene set |

A synthesis of the literature states: "SEMA5A and CTNND2, deleted in all patients, are related to brain development and migration of neurons," and five genes — TERT, SEMA5A, MARCH6, CTNND2, and NPR3 — have been classified as haploinsufficient and phenotype-relevant in CdCS. However, "these genes probably account for only part of the 5p deletion phenotype, and concomitant loss of other genes in this region certainly plays an important role" (search synthesis; PMC1574300).

Variant classification and type: The pathogenic lesion is a copy-number loss (deletion), not a point variant — classified via ACMG copy-number variant interpretation guidelines as pathogenic when it spans the critical region(s) and is of sufficient size. Deletion sizes cluster into at least four groups in cohort analyses; a cluster spanning 5p15.1–p14.1 (24.01 ± 1.38 Mb) was associated with the worst functional outcomes (PMC8362798).

Population frequency: As a de novo structural variant, CdCS deletions are not tracked in standard allele-frequency databases (gnomAD/1000 Genomes) the way SNVs are; population-level data instead come from cytogenetic/CMA-based birth-prevalence studies (see Section 9).

Somatic vs. germline: Germline (constitutional) in essentially all clinical cases; mosaic constitutional forms are reported (both somatic mosaicism in the patient and gonadal mosaicism in an unaffected parent).

Modifier factors — epigenetics: DNA methylation profiling shows that patients with similar deletion sizes can have markedly different methylation patterns, and this variability appears to explain some of the clinical heterogeneity independent of deletion size. Differentially methylated regions outside the deleted 5p interval are enriched in genes governing transcription, splicing, and chromatin remodeling; CpG sites associated with developmental delay and microcephaly are enriched for polycomb EZH2 complex and H3K27me3 binding, implicating altered "bivalent promoter" regulation central to embryonic development (Clinical Epigenetics, PMC9563797; BMC Res Notes, PMC11057176).

Chromosomal abnormality detail: Terminal deletions (80–90%) vs. interstitial deletions (3–5%); unbalanced translocation products (~10–15%); rare ring chromosome 5, mosaicism, and complex rearrangements/chromothripsis.

Suggested GO terms: GO:0071526 (semaphorin-plexin signaling pathway), GO:0001764 (neuron migration), GO:0098742 (cell-cell adhesion via plasma-membrane adhesion molecules), GO:0060996 (dendritic spine development), GO:0000723 (telomere maintenance).

5. Environmental Information

CdCS is a chromosomal structural disorder rather than an environmentally triggered disease. No toxin, pollutant, occupational exposure, dietary factor, or infectious agent has been established as a cause. Lifestyle and infectious-agent contributions are not applicable to primary etiology, though secondary environmental factors (e.g., recurrent respiratory infection exposure) contribute to infancy morbidity/mortality as a consequence of the underlying hypotonia and swallowing dysfunction rather than as a cause of the syndrome itself.

6. Mechanism / Pathophysiology

Causal chain (deletion → phenotype): 1. Trigger: Terminal or interstitial deletion of 5p (de novo in ~85–90%, or from unbalanced parental translocation in ~10–15%), removing one copy of multiple dosage-sensitive genes across the 5p15.2–5p15.33 interval. 2. Molecular consequence — haploinsufficiency: Reduced gene dosage of CTNND2, SEMA5A, and other 5p15 genes disrupts neuronal migration, axon guidance, and cell-cell adhesion signaling during embryonic and early postnatal brain development. 3. Cellular consequence: Disrupted dendritic arborization and spine maturation; in the CRISPR rat model of the syntenic deletion, affected animals showed reduced dendritic-arbor complexity and fewer mature "mushroom-shaped" dendritic spines in the medial prefrontal cortex (mPFC) and hippocampal CA1, increased neuronal density in superficial mPFC layers, and elevated astrocyte reactivity with complement C4 activation in the mPFC — a synaptic-pruning/neuroinflammatory signature (Shen et al. 2025, PMID:39965128). 4. Tissue/organ consequence: Impaired forebrain and cerebellar growth manifesting as microcephaly, cerebellar/pontine hypoplasia, and corpus callosum anomalies on neuroimaging; separately, dosage loss in the 5p15.3 region alters laryngeal cartilage/musculature development, producing the diamond-shaped, hypoplastic larynx and floppy epiglottis responsible for the cat-like cry. 5. Organism-level manifestation: Global developmental delay, intellectual disability, characteristic craniofacial dysmorphism, hypotonia progressing to hypertonia, and behavioral phenotype (hyperactivity, self-injury, sensory hypersensitivity).

Laryngeal mechanism specifically: The high-pitched cry is attributed to structural laryngeal abnormalities — a small, floppy epiglottis, laryngeal hypoplasia, a narrow or diamond-shaped larynx, and abnormal posterior airspace configuration during phonation — with a possible additional neurological (central) contribution to cry control (StatPearls).

Epigenetic layer: As above, DNA methylation differences (independent of deletion size) at CpG sites enriched for polycomb/EZH2/H3K27me3 binding modulate expressivity of developmental-delay and microcephaly phenotypes, suggesting a "second hit" epigenetic mechanism superimposed on the dosage lesion.

Cell types implicated: Cortical/hippocampal pyramidal neurons (dendritic and spine pathology), astrocytes (reactive astrogliosis with complement activation), and — for the laryngeal phenotype — laryngeal cartilage and musculature-forming cells during embryogenesis.

Immune involvement: Complement C4 upregulation in reactive astrocytes in the rat model suggests a synaptic-pruning/neuroinflammatory contribution to the neurodevelopmental phenotype, though this is model-organism (not yet human-confirmed) evidence.

Suggested CL terms: CL:0000540 (neuron), CL:0000127 (astrocyte), CL:0002605 (astrocyte of the cerebral cortex).

Suggested UBERON terms: UBERON:0001737 (larynx), UBERON:0002037 (cerebellum), UBERON:0002021 (hippocampal formation), UBERON:0001873 (dentate gyrus), UBERON:0000451 (prefrontal cortex), UBERON:0000955 (brain).

7. Anatomical Structures Affected

Organ level: - Primary: Central nervous system (brain, cerebellum), craniofacial skeleton, larynx - Secondary: Cardiovascular system (septal defects, PDA, tetralogy of Fallot), renal/genitourinary system (renal agenesis, hypospadias, cryptorchidism), gastrointestinal tract (reflux, feeding dysfunction), musculoskeletal system (scoliosis, joint laxity/dislocation), auditory system (sensorineural hearing loss), integument (hemangiomas, premature graying) - Body systems involved: Nervous, musculoskeletal, cardiovascular, renal/genitourinary, digestive, respiratory (via laryngeal structure), integumentary

Tissue/cell level: Cortical and hippocampal neuronal populations (dendritic/spine pathology); reactive astrocytes; laryngeal cartilage and soft tissue.

Subcellular level: Dendritic spines (loss of mature mushroom-shaped spines); synaptic complexes (complement-mediated pruning machinery).

Localization: Bilateral/symmetric CNS involvement (microcephaly, cerebellar/pontine hypoplasia); midline structure involvement (corpus callosum hypoplasia); laryngeal involvement is midline/structural rather than lateralized.

8. Temporal Development

Onset: Congenital — clinical features are present from birth (the cry, low birth weight, hypotonia, facial dysmorphism are neonatal signs).

Progression/course: - The cat-like cry typically diminishes and often resolves within the first months to a few years of life as laryngeal anatomy matures — a distinctive "self-limited" feature within an otherwise chronic disorder. - Muscle tone reverses over the lifespan: neonatal/infantile hypotonia is progressively replaced by hypertonia/spasticity in later childhood and adulthood. - Facial appearance evolves: "moon facies" / round face in infancy transitions to a narrower, more elongated face in adolescence and adulthood. - Developmental delay and intellectual disability are lifelong, non-regressive/static in nature (not neurodegenerative), though functional gains continue with sustained rehabilitative intervention throughout life. - Scoliosis and other musculoskeletal complications tend to emerge and progress through childhood/adolescence.

Critical period for intervention: Early rehabilitative/educational intervention in infancy and early childhood is repeatedly identified as the strongest modifiable prognostic factor, improving developmental trajectory, functional ability, and social adaptation. In the rat model, gene-replacement (AAV-Ctnnd2) therapy was efficacious only when administered at an early developmental stage (4 weeks old) and ineffective when given in adolescence/adulthood — supporting a biological critical window paralleling the clinical emphasis on early intervention (PMID:39965128).

Disease duration: Chronic, lifelong condition; not self-limited except for the cry phenotype specifically.

9. Inheritance and Population

Epidemiology: - Incidence: 1 in 15,000 to 1 in 50,000 live births. - Slight female excess in incidence (approximate ratio 4:3 female:male). - CdCS is the most common human chromosomal deletion syndrome. - Prevalence among individuals with intellectual disability is estimated at roughly 1.5 per 1,000 (approximately 1 in 350). - No established racial/ethnic or strong geographic predilection; worldwide distribution.

Inheritance pattern: Chromosomal/contiguous-gene deletion disorder — not classic Mendelian single-locus inheritance. - ~85–90% de novo (sporadic), predominantly of paternal chromosomal origin. - ~10–15% due to unbalanced segregation of a parental balanced translocation (or, rarely, a pericentric inversion) — in these families the deletion is effectively "inherited" via an unbalanced karyotype from a phenotypically normal translocation-carrier parent. - Autosomal dominant transmission has been reported across generations in rare familial 5p-deletion pedigrees (multigenerational autosomal dominant inheritance of 5p deletions has been documented in the literature).

Penetrance/expressivity: Full penetrance for the chromosomal imbalance itself (i.e., anyone with a sufficiently large 5p deletion spanning the critical regions manifests the syndrome), but expressivity is highly variable — severity correlates with deletion size/location and is further modulated by DNA methylation differences (Section 6).

Recurrence risk (genetic counseling): - <1% if the deletion is de novo (the vast majority of cases). - 10–15% risk of an unbalanced karyotype in future pregnancies if a parent carries a balanced translocation. - Gonadal mosaicism has been documented in an apparently non-carrier father (12.8% mosaic 5p deletion detected by sperm FISH), a rare but clinically important recurrence mechanism despite a "normal" parental peripheral blood karyotype. - Parental karyotype analysis (and ideally CMA) is indicated in all new diagnoses for accurate recurrence-risk counseling.

Founder effects / consanguinity: Not applicable — this is a sporadic structural chromosomal event, not inherited via founder alleles, and consanguinity is not a recognized risk factor.

Sex distribution: Slight female excess in incidence; in the deep-phenotyping cohort, females also had significantly worse functional outcomes and larger mean deletion sizes than males (p=0.05) (PMC8362798).

Age distribution: Diagnosed predominantly in the neonatal/infantile period due to the characteristic cry and dysmorphism; increasingly diagnosed prenatally via NIPT/CMA.

10. Diagnostics

Clinical suspicion: Based on the constellation of microcephaly, low birth weight, "moon facies," muscular hypotonia, and the pathognomonic cat-like cry in a newborn.

Cytogenetic/molecular testing (postnatal): - Karyotype analysis — traditional first-line test, detects gross terminal/interstitial deletions and translocations. - FISH (fluorescence in situ hybridization) — used to confirm/clarify deletions and, importantly, to detect parental balanced rearrangements in ~10% of families. - Chromosomal microarray analysis (CMA) — now preferred for precisely defining deletion size and breakpoints; increasingly the diagnostic standard. - Quantitative PCR and comparative genomic hybridization (CGH) — used in research/refined breakpoint mapping (e.g., the qPCR study that defined the 640 kb cry-critical region).

Prenatal diagnosis: - Non-invasive prenatal testing (NIPT/cfDNA): Expanded cfDNA screening panels can flag 5p deletions; reported positive predictive value ~50% and negative predictive value ~100% in two cited studies — underscoring that a positive NIPT result requires diagnostic confirmation. - Ultrasound findings: Abnormal in ~87% of prenatally identified cases; findings include cerebellar hypoplasia, ventricular septal defects, hydrops fetalis, ventriculomegaly, choroid plexus cysts, nasal bone hypoplasia, and increased nuchal translucency. - Invasive testing: Amniocentesis or chorionic villus sampling with CMA (definitive breakpoint/size characterization) plus karyotype/FISH to assess for parental translocation. SNP-array-based prenatal diagnosis has been specifically reported as effective (PMC6902614).

Neuroimaging: Brain MRI may reveal pontine hypoplasia, cerebellar hypoplasia, and corpus callosum anomalies, supporting (but not required for) diagnosis.

Differential diagnosis: | Condition | Distinguishing features | |---|---| | Wolf-Hirschhorn syndrome (4p− deletion) | Overlapping growth delay, hypotonia, feeding difficulty, microcephaly, facial dysmorphism — distinguished by cytogenetics | | 1p36 deletion syndrome | Straight eyebrows, deep-set eyes, hearing loss, severe developmental delay | | Distal 9p deletion / monosomy 9p | Long philtrum, trigonocephaly, higher rate of genital anomalies | | Cornelia de Lange syndrome | Hypertrichosis, digital/upper-limb reduction anomalies, severe reflux | | Bohring-Opitz syndrome | Flexed elbows/wrists with ulnar deviation, recurrent vomiting, facial nevus flammeus, recurrent infection | | Smith-Lemli-Opitz syndrome | 2–3 toe syndactyly, postaxial polydactyly, genital anomalies, abnormal sterol biochemistry (metabolic exclusion test) |

Screening: No dedicated population newborn-screening program exists (this is a structural chromosomal disorder, not a metabolic one detectable by standard newborn screening panels); detection relies on clinical suspicion plus cytogenetic/CMA testing, or increasingly on prenatal cfDNA screening.

Suggested LOINC/diagnostic-modality notes: Chromosomal microarray and karyotype are procedure-based tests without a single defining biomarker; MAXO term for genetic counseling (MAXO:0000079) is relevant to the diagnostic pathway.

11. Outcome/Prognosis

Mortality: - Overall mortality has been estimated at 6–8% in the CdCS population. - Mortality is heavily concentrated in early life: of children who die, approximately 75% die within the first month of life and ~90% within the first year; mortality risk drops sharply thereafter. - Leading causes of death: pneumonia/aspiration pneumonia, complications of congenital heart defects, and respiratory distress syndrome.

Life expectancy: In the absence of major malformations (especially severe congenital heart disease), life expectancy can be near-normal; the U.S. 5p Minus Database (286 cases) includes an oldest recorded patient of 64 years of age. Survival past early childhood is associated with a substantial drop in subsequent morbidity/mortality risk.

Prognostic factors: Deletion size, type (terminal vs. interstitial), and location are major determinants of severity and outcome; the deletion cluster spanning 5p15.1–p14.1 (~24 Mb) was linked to the worst functional outcomes in the deep-phenotyping cohort. Early diagnosis and early rehabilitative intervention are repeatedly cited as key modifiable factors improving developmental trajectory.

Functional/developmental outcomes: With sustained rehabilitative programs (physiotherapy, speech-language therapy, occupational therapy, structured education), affected individuals show improved psychomotor development, greater autonomy, and better social adaptation over time — survival and functional outlook have improved with modern supportive-care practices relative to historical cohorts.

Cancer/neoplasia risk: A combined Italian-German database analysis of 321 CdCS patients found neoplasia in only 4 patients (ages 10–50) plus one cholesteatoma case; the deleted 5p region does not contain genes whose haploinsufficiency is a well-established cancer driver, and the authors concluded there is no evidence of increased cancer risk in CdCS — standard population cancer-surveillance guidelines apply (PMC5420919).

Quality of life / socioeconomic burden: An Italian cost-of-illness study found average annual per-patient cost of €87,856, with informal (family) caregiving accounting for 87% of total cost (€76,981.69/year); EQ-5D VAS quality-of-life scores (65.5 ± 22.4) were substantially below general-population norms, with the greatest impact on usual activities and self-care domains (PMC7459640).

12. Treatment

No disease-modifying or curative therapy exists. Management is entirely supportive and interprofessional, tailored to each patient's manifestations (StatPearls).

Early intervention / rehabilitative therapies: - Physical therapy — improves motor milestones, postural control, gait stability (suggested MAXO:0000011, physical therapy) - Occupational therapy (suggested MAXO:0001351) - Speech-language therapy, shown to improve speech clarity/articulation; augmentative and alternative communication (AAC) — gesture systems, sign-supported communication, visual aids — given that receptive language typically exceeds expressive ability (suggested MAXO:0000930, speech therapy) - Psychomotor/developmental therapy programs, ideally initiated as early as possible, given documented associations with improved functional and social outcomes.

Medical surveillance and subspecialty care: - Audiology (screening for sensorineural hearing loss) - Ophthalmology, cardiology (echocardiography for congenital heart defects), orthopedics (monitoring/management of scoliosis), dental care, and nutritional assessment (feeding/swallowing support, gastrostomy if needed)

Surgical care: Corrective surgery for congenital cardiac defects, strabismus correction, and scoliosis surgery when indicated (suggested MAXO:0000004, surgical procedure).

Behavioral/psychological management: Behavior modification programs for hyperactivity, self-injurious behavior, aggression, anxiety, and sleep disturbance; individualized education plans and structured environments. A published case report describes successful personalized behavioral anesthesia strategies for an adult CdCS patient undergoing a medical procedure, underscoring the value of individualized behavioral planning across the lifespan (PMC12512440).

Genetic counseling: Offered to families, particularly when a parental balanced translocation is identified, given the associated 10–15% recurrence risk (suggested MAXO:0000079, genetic counseling).

Pharmacotherapy: No CdCS-specific approved drug exists; medications are used symptomatically (e.g., for behavioral symptoms) following general pediatric/psychiatric prescribing practice rather than a CdCS-specific evidence base.

Experimental/emerging therapeutics: - Drug repurposing: A collaboration with the Cri du Chat Research Foundation has performed systematic target analysis to identify candidate approved drugs for repurposing, reflecting the current absence of any CdCS-targeted pharmacotherapy (Drug Repurposing Central, DOI:10.58647/REXPO.25000107.v1). - Gene replacement therapy (preclinical only): In the CRISPR-engineered rat model of the syntenic 5p15.2 deletion, a single intravenous dose of AAV-PHP.eB carrying a gain-of-function Ctnnd2 variant, administered at an early developmental stage (4 weeks old), rescued cognitive deficits (novel-object recognition, object-location memory) and improved dendritic complexity/spine density in the hippocampal dentate gyrus. However, the therapy did not rescue social behavior, anxiety-like phenotypes, or object-in-place memory, and was ineffective when given in adolescence/adulthood; mild liver toxicity (elevated bilirubin) was observed. This is proof-of-concept preclinical work, not yet in human trials (Shen et al. 2025, PMID:39965128). - As of this report, no active human clinical trials (NCT-registered) specifically targeting CdCS pathophysiology (gene therapy or otherwise) were identified; management remains entirely supportive in clinical practice.

Treatment algorithm: No formal staged clinical pathway/algorithm exists beyond "early multidisciplinary supportive care starting in infancy, escalating subspecialty involvement as complications (cardiac, orthopedic, audiologic) are identified."

13. Prevention

Primary prevention: Not applicable in the traditional sense (no modifiable risk factor to intervene on for a de novo structural chromosomal event); the only "primary prevention" lever is genetic counseling and reproductive decision-making in families where a parent is a known balanced-translocation carrier.

Secondary prevention / screening: - Prenatal screening: Expanded NIPT/cfDNA panels can flag 5p deletions (with the PPV/NPV caveats above), prompting diagnostic confirmation via CVS/amniocentesis with CMA. - Carrier/family screening: Parental karyotyping following an index case identifies balanced-translocation carrier parents, enabling risk-stratified counseling (10–15% recurrence) versus the general de novo risk (<1%). - Preimplantation genetic testing (PGT): An option for known translocation-carrier parents pursuing future pregnancies, though not specifically documented in the sources reviewed here.

Tertiary prevention: Early diagnosis and early multidisciplinary intervention (as above) function as the principal "tertiary prevention" strategy — minimizing secondary complications (aspiration, failure to thrive, uncorrected scoliosis, undiagnosed hearing loss) that would otherwise compound the primary disability.

Genetic counseling: Central to family planning discussions — recurrence risk counseling differs sharply by mechanism (de novo vs. translocation-derived), and gonadal mosaicism (documented, if rare) means even a "normal" parental karyotype does not fully eliminate recurrence risk.

Public health / immunization: No CdCS-specific public-health or immunization strategy exists; standard childhood immunization is recommended, with attention to respiratory-infection prevention given the elevated infancy mortality from pneumonia/aspiration pneumonia.

14. Other Species / Natural Disease

Cri-du-chat syndrome is a human-specific chromosomal disorder (structural loss of the human chromosome 5 short arm); despite the "cat's cry" name, it has no relationship to any naturally occurring feline disease — the name is purely descriptive of the infant's cry sound.

Naturally occurring disease in other species: No naturally occurring veterinary/companion-animal analog of CdCS has been documented in the literature reviewed (unlike, e.g., some lysosomal storage disorders that have well-characterized natural canine/feline counterparts). This is expected given that CdCS reflects loss of a specific, human-genome-mapped syntenic interval rather than a single orthologous-gene disease process.

Orthologous genes / comparative genomics: The critical human genes (CTNND2, SEMA5A, TERT) have well-conserved mammalian orthologs, which is precisely what enabled construction of a rat model of the syndrome (see below) — but this reflects engineered modeling of the syntenic deletion, not a spontaneously occurring animal disease.

15. Model Organisms

Mouse models (single-gene, partial recapitulation): - Sema5a-null mice: Complete knockout is embryonic lethal, due to impaired branching of large cranial blood vessels (abnormal cranial vasculogenesis) — demonstrating an essential developmental role for Sema5a but precluding its use for postnatal phenotyping. - Sema5a mutant (viable, e.g., heterozygous/point-mutant) mice have been studied as a candidate autism model, given the gene's link to CdCS's neurodevelopmental phenotype: these mice show higher activity in the elevated plus-maze and light/dark transition box, with sex-dependent differences in balance/motor coordination, but notably no genotype effect on cognition (Morris water maze, set-shifting, fear conditioning) and no social-behavior deficit — leading investigators to question whether Sema5a mutants are a good model of autism specifically (Sakurai et al., cited via ScienceDirect). This partial/negative recapitulation illustrates that single-gene mouse models capture only part of the multigenic CdCS phenotype.

Rat model (multigenic, closest current recapitulation): - A CRISPR-Cas9-engineered rat model (Shen et al., Advanced Science 2025, PMID:39965128) created a heterozygous ~1.68 Mb deletion on rat chromosome 2q22, syntenic to human 5p15.2, affecting eight genes (Ctnnd2 identified as most critical, plus Dap, Ankrd33b, Marchf6, Cmb1, Cct5, and Atpsckmt, each showing ~50% reduced expression). - Phenotype recapitulation: This model reproduces multiple core human CdCS features — reduced social interaction/preference, repetitive self-grooming, deficits in novel-object recognition and spatial/object-location memory, anxiety-like behavior, hypoactivity, and growth delay including reduced brain weight (microcephaly) — alongside cellular correlates (reduced dendritic complexity, fewer mature dendritic spines, increased superficial cortical neuronal density, reactive astrogliosis with complement C4 activation). - Model limitations: As a single syntenic-region deletion (5p15.2-equivalent only), it does not capture the full multi-region 5p deletion seen in most human patients (whose deletions frequently extend well beyond 5p15.2, e.g., into 5p15.3/5p15.33 or further); it also cannot model human-specific phenotypes like the laryngeal cry. - Application: Used to demonstrate proof-of-concept AAV-based Ctnnd2 gene-replacement therapy (see Section 12), with efficacy strictly limited to an early postnatal treatment window — directly informing translational thinking about a possible human "critical window" for intervention.

Cellular/iPSC models: - A 2025 study reports the establishment and characterization of Cri-du-Chat patient-derived neuronal stem cells (NSCs) as "a novel promising resource to study the syndrome" (PMID:40343585; PMC12064636), providing a human-genetic-background in vitro platform complementary to the rodent models.

Resource note: No dedicated CdCS-specific model-organism database/repository was identified (unlike single-gene disorders with MGI/IMPC knockout entries); available models are drawn from targeted research publications rather than a centralized international consortium repository, reflecting the syndrome's status as a multigenic structural disorder rather than a single-gene knockout target.

Ontology Term Summary (for KB curation reference — verify via OAK before use)

  • MONDO: MONDO:0007404 (Cri-du-chat syndrome)
  • HPO (selected): HP:0000252, HP:0001582, HP:0000316, HP:0000286, HP:0000347, HP:0000431, HP:0002714, HP:0001252, HP:0010864, HP:0001518, HP:0000717, HP:0007018, HP:0000718, HP:0000742, HP:0002360, HP:0001627, HP:0000104, HP:0002650, HP:0000407, HP:0001321, HP:0002079
  • GO (biological process): GO:0071526 (semaphorin-plexin signaling), GO:0001764 (neuron migration), GO:0098742 (cell-cell adhesion via plasma-membrane adhesion molecules), GO:0060996 (dendritic spine development), GO:0000723 (telomere maintenance)
  • CL: CL:0000540 (neuron), CL:0000127 (astrocyte)
  • UBERON: UBERON:0001737 (larynx), UBERON:0002037 (cerebellum), UBERON:0002021 (hippocampal formation), UBERON:0000955 (brain)
  • MAXO: MAXO:0000011 (physical therapy), MAXO:0000930 (speech therapy), MAXO:0001351 (occupational therapy), MAXO:0000079 (genetic counseling), MAXO:0000004 (surgical procedure)
  • Genes (HGNC symbols, verify exact HGNC numeric ID via OAK): CTNND2, SEMA5A, TERT, MARCH6, NPR3

Notes on evidence gaps

  • No CdCS-specific approved pharmacotherapy or active human gene-therapy trial was identified as of this report (July 2026); the only gene-therapy evidence is preclinical (rat model).
  • Precise HGNC numeric IDs for candidate genes were intentionally omitted rather than guessed; confirm via runoak -i sqlite:obo:hgnc info <id> or NCBI Gene before use in structured curation, per this repository's anti-hallucination policy.
  • Quantitative phenotype frequencies vary meaningfully across cohorts (e.g., cardiac defect frequency reported anywhere from 15–36%); cite the specific cohort study alongside any percentage used in a KB entry rather than treating these as fixed population constants.

Sources