Cornelia de Lange Syndrome 1

Genetic MONDO:0007387 Pathograph 27 Show in embeddings browser Cornelia de Lange syndrome Cohesinopathy

Cornelia de Lange syndrome 1 (CdLS1; OMIM #122470) is the NIPBL-related form of the cohesinopathy, and the classic and most severe one. Heterozygous loss-of-function variants in NIPBL, which encodes the principal cohesin-loading factor, account for more than 60% of molecularly diagnosed CdLS. Nearly all cases are de novo and sporadic. The clinical picture is a recognizable craniofacial gestalt, pre- and postnatal growth restriction, upper-limb reduction defects, hirsutism, intellectual disability, and a neurobehavioural profile dominated by repetitive and self-injurious behaviour. The mechanism is transcriptional rather than mitotic, and that distinction is the substance of the entry rather than a nuance. NIPBL loads cohesin onto chromatin; halving its dosage reduces cohesin binding genome-wide, collapses cohesin-mediated chromatin loops, and impairs RNA polymerase II initiation and elongation. What results is not one broken pathway but thousands of individually modest expression changes, usually under 1.5-fold, whose collective action disrupts developmental programmes across limb, cardiac, diaphragmatic, craniofacial and central nervous system primordia. Sister-chromatid cohesion is largely spared, which is why CdLS is a developmental disorder rather than a chromosome-instability syndrome. This entry is scoped to the NIPBL form. The umbrella entry Cornelia_de_Lange_Syndrome (MONDO:0016033) curates the shared pan-cohesin mechanism, and Cornelia_de_Lange_Syndrome_4 (RAD21) is the precedent for splitting the per-gene forms into their own records. What belongs here rather than in the umbrella is what is specific to NIPBL: the dosage argument, the mosaicism that is selected against in blood, and the genotype comparison against SMC1A.

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1
Inheritance
6
Pathophys.
16
Phenotypes
2
Gaps
27
Pathograph
1
Genes
2
Medical Actions
1
Differentials
2
Models
1
References
1
Deep Research
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Classifications

Harrison's Part
GENETICS ENVIRONMENT DISEASE
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Inheritance

1
Autosomal dominant, almost always de novo HP:0000006
Heterozygous NIPBL variants act dominantly. Nearly every constitutional case is de novo and sporadic, and neither maternal nor paternal age is a risk factor. Recurrence risk is low but not zero: parental germline mosaicism is the reason counselling cannot quote zero.
Autosomal dominant inheritance
Show evidence (3 references)
PMID:18074387 SUPPORT Human Clinical
"All patients were sporadic. Maternal and paternal age did not seem to be risk factors for CdLS."
Registry-level confirmation that the disorder does not recur in families, and that neither parental age is a risk factor. Both halves matter: the first makes de novo origin the default assumption, and the second rules out the paternal-age effect that de novo dominant disorders usually show.
PMID:20301283 SUPPORT Other
"While most familial recurrences of CdLS are the result of gonadal mosaicism in a phenotypically normal parent"
GeneReviews names gonadal mosaicism as the mechanism behind the recurrences that do happen, which is what makes the counselled risk low rather than zero.
PMID:20301283 SUPPORT Other
"Each child of an affected individual has a 50% chance of inheriting the CdLS-related pathogenic variant."
The transmission risk for an affected individual's own children, which the de novo framing above does not cover.
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Discussions and Knowledge Gaps

2
Is the collective-perturbation model actually established, or is it the most plausible remaining account once no single dominant target has been found?
KNOWLEDGE GAP cdls1_collective_perturbation_untested
Attached to
pathophysiology#Collective Small Gene-Expression Perturbations
The observation is solid: hundreds of genes change and nearly all the changes are under 1.5-fold. The inference that severe developmental defects result from their collective action is stated by its own authors as an intriguing possibility raised by the data, and no experiment has since shown that summing subthreshold perturbations produces the phenotype. The alternative that has not been excluded is that a small number of the changes are the pathogenic ones and the rest are downstream noise. This matters therapeutically: under the collective model there is nothing to target, and under the alternative there is.
Proposed experiments
Combinatorial subthreshold perturbation in zebrafish
cdls1_combinatorial_perturbation_zebrafish
Reproduce the individual expression changes seen in nipbl morphants, singly and in defined combinations, in wild-type embryos, and test whether organ defects appear only above some number of simultaneous perturbations. The zebrafish model was developed for exactly this quantitative question.
Readouts
Heart and gut defect incidence by number of simultaneous perturbations
pathophysiology#Collective Small Gene-Expression Perturbations
Direction: INCREASED
Interpretation: A dose-of-perturbations relationship would support the collective model; a step change on one perturbation would identify a dominant driver instead.
Why does the congenital heart defect frequency differ between an echocardiographic cohort (33.3%) and population registry data (45.6%), and what is the NIPBL-specific figure?
KNOWLEDGE GAP cdls1_chd_frequency_discrepancy
Attached to
phenotypes#Congenital heart defect
Both numbers are curated here rather than one being chosen, because the difference is informative. Registries ascertain through malformation and so over-represent severely affected cases; the echocardiographic cohort was consecutive and so should be closer to the true rate among diagnosed patients, but is smaller and single-centre. Neither is stratified by gene, so the NIPBL-specific cardiac frequency, which is what this entry would want, is unpublished. A curator reading either figure alone would be over-reading it.
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Pathophysiology

6
NIPBL Haploinsufficiency
A heterozygous loss-of-function variant halves functional NIPBL, the cohesin loading factor. In humans and in the mouse models alike the transcript and protein deficit is modest, under about 30% below normal, so the disorder is a dosage disorder rather than a null-allele one: there is no second hit and no threshold below which the phenotype appears.
NIPBL hgnc:28862 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves NIPBL (hgnc:28862). hgnc:28862 is a gene from the HUGO Gene Nomenclature Committee.
Genetic context variant_origin: GERMLINE zygosity: HETEROZYGOUS functional_impact_category: LOSS_OF_FUNCTION
Downstream
Genome-Wide Reduction in Cohesin Binding
Show evidence (2 references)
PMID:29995837 SUPPORT Human Clinical
"It is caused by variants in any one of seven genes, all of which have a structural or regulatory function in the cohesin complex."
The consensus statement's framing of CdLS as a cohesin-complex disorder, which is the class this node's lesion sits in.
PMID:22039349 SUPPORT Other
"in both man and mouse, Nipbl heterozygotes show only a ,30% reduction in Nipbl mRNA and protein"
The quantitative basis for calling this a dosage disorder: a transcript and protein deficit of under about 30%, in humans as well as mice, is enough to produce the syndrome. Graded OTHER because this is the paper's background summary of the three studies it cites rather than a result of its own zebrafish work. The comma is a PDF-extraction artifact for the less-than sign.
Genome-Wide Reduction in Cohesin Binding
Less loader means less chromatin-bound cohesin, at CTCF boundary sites and at repeats. Cohesin-bound genes are enriched for H3K4me3 at their promoters and are disproportionately downregulated, which points at gene activation rather than cohesion as the sensitive function.
cohesin loading onto chromatin GO:0006325 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cohesin loading onto chromatin, annotated with chromatin organization (GO:0006325). GO:0006325 is a biological process from the Gene Ontology. ↓ DECREASED
cohesin binding to chromatin GO:0003682 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased cohesin binding to chromatin, annotated with chromatin binding (GO:0003682). GO:0003682 is a molecular function from the Gene Ontology. ↓ DECREASED
Animal models
Nipbl+/- mouse Mouse recapitulates The measurement this node asserts was made in this model: reduced chromatin cohesin with gene activation, not cohesion, as the sensitive function.
Downstream
Collapse of Cohesin-Mediated Chromatin Loops
Show evidence (1 reference)
PMID:28855971 SUPPORT Model Organism
"The results suggest that gene activation is the primary cohesin function sensitive to Nipbl reduction."
The paper's own conclusion that the sensitive cohesin function is transcriptional, which is the claim this whole chain rests on.
Collapse of Cohesin-Mediated Chromatin Loops
Reduced chromatin-bound cohesin weakens enhancer-promoter contacts and CTCF insulation. Acute NIPBL depletion in vivo diminishes chromatin loops rapidly, and the genes that depend most on NIPBL-supported conformation are cell-identity and developmental genes sitting near super-enhancers. That selectivity is what turns a globally acting chromatin factor into a developmental disorder.
chromatin looping GO:0140588 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased chromatin looping (GO:0140588). GO:0140588 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Impaired RNA Polymerase II Transcription
Show evidence (1 reference)
PMID:41699137 SUPPORT Model Organism
"NIPBL specifically regulates cell identity genes by supporting a unique local genome conformation defined by greater spatial proximity to nearby super-enhancers and weaker transcription start site insulation of genomic contacts"
Explains why loss of a general chromatin factor produces a developmental rather than a global phenotype.
Impaired RNA Polymerase II Transcription
Transcription itself is impaired at both ends: initiation at promoters and elongation through gene bodies. This is measured in CdLS patient cells, not only in models.
regulation of transcription by RNA polymerase II GO:0006357 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased regulation of transcription by RNA polymerase II (GO:0006357). GO:0006357 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Collective Small Gene-Expression Perturbations
Show evidence (1 reference)
PMID:26581180 SUPPORT In Vitro
"mutant cohesin impairs both RNA polymerase II (Pol II) transcription initiation at promoters and elongation in the gene body"
Locates the transcriptional lesion at two specific steps rather than asserting a general dysregulation.
Collective Small Gene-Expression Perturbations
The distinctive feature of this disease's mechanism, and the reason it resists the usual one-pathway account. Hundreds to thousands of genes change expression and nearly all the changes are modest, usually under 1.5-fold. No single perturbation is individually pathogenic; the phenotype is the sum. This is also why there is no obvious therapeutic target: there is no dominant node to correct.
Downstream
Disrupted Multi-Organ Developmental Programmes The step from a distributed expression signature to specific organ malformations is asserted by the sources as an integration of demonstrated components rather than demonstrated end to end, so the edge is typed indirect.
Show evidence (2 references)
PMID:22039349 SUPPORT Model Organism
"Nearly all such changes are modest, however--usually less than 1.5-fold--raising the intriguing possibility that, in CdLS, severe developmental defects result from the collective action of many otherwise innocuous perturbations."
States the collective-perturbation hypothesis in the terms this node curates it in, including that it remains a hypothesis.
PMID:29348408 SUPPORT In Vitro
"identified hundreds of mRNAs, pseudogenes, and non-coding RNAs with altered expression"
Reproduces the many-small-changes signature in human iPSC-derived cardiomyocytes, which is disease-relevant tissue rather than a fibroblast proxy.
Disrupted Multi-Organ Developmental Programmes
Developmental programmes fail across limb bud, cardiac and left-right patterning, foregut and diaphragm, craniofacial structures and the central nervous system. In the zebrafish model the deregulation is detectable from gastrulation onwards in endodermal differentiation and left-right patterning genes, which places the lesion early enough to explain heart and gut defects.
Animal models
nipbl-deficient zebrafish Zebrafish partially recapitulates Reproduces the heart, gut and craniofacial arms of the developmental failure.
Downstream
Upper-limb reduction defect
Congenital heart defect
Pulmonic stenosis Curated as its own edge rather than as a consequence of the congenital heart defect above, because it is a specific lesion within that category rather than something the category causes.
Congenital diaphragmatic hernia
Intellectual disability
Cleft palate
Synophrys The craniofacial programme this node names. Synophrys is the recognition sign of the syndrome and belongs to the same developmental failure as the cleft palate.
Abnormal brain morphology The central nervous system programme this node names, in its structural form.
Feeding difficulties The node names foregut development among the failing programmes, but no cited source traces a route from that to the feeding difficulty, which in practice is a mix of structural, oromotor and reflux contributions. Typed indirect for that reason.
Delayed speech and language development Attached to the developmental node rather than to the intellectual disability, because the two are parallel manifestations of the same programme failure rather than one causing the other. The specific route is not established.
Delayed gross motor development Same reasoning as the speech delay above.
Self-injurious behavior No cited source traces a route from the transcriptional lesion to this behavioural phenotype. The edge records that it belongs to the disease's central nervous system involvement, and its type records that the intermediates are unknown.
Motor stereotypy Same reasoning as the self-injurious behaviour above.
Hirsutism The integument is not among the programmes this node's evidence names, and no cited source traces a route from the transcriptional lesion to the hair phenotype. The edge records membership of the developmental syndrome; the type records that the mechanism is unknown.
Gastroesophageal reflux The node names foregut development, but reflux is a functional outcome and no cited source connects the two, so the intermediates are unknown.
Intrauterine growth retardation
Show evidence (1 reference)
PMID:27120001 SUPPORT Model Organism
"Studies of these vertebrate animal models have yielded novel insights into the developmental etiology and genes/gene pathways that contribute to CdLS-associated birth defects, particularly defects of the gut, heart, craniofacial structures, nervous system, and limbs."
Names the specific organ systems whose developmental programmes fail, which is what this node asserts.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Cornelia de Lange Syndrome 1 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

16
Cardiovascular 2
Congenital heart defect FREQUENT 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 (1 reference)
PMID:19449412 SUPPORT Human Clinical
"A cardiac anomaly was identified in 29/87 (33.3%) including 28 (32.2%) patients with a structural CHD, and an additional patient (1.2%) with isolated non-obstructive hypertrophic cardiomyopathy (HCM)."
The prospective echocardiographic frequency, from consecutive patients.
Pulmonic stenosis OCCASIONAL HP:0001642 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pulmonic stenosis (HP:0001642). HP:0001642 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19449412 SUPPORT Human Clinical
"Overall incidence of pulmonary stenosis was 39% (11/28)."
Gives the lesion distribution within the cardiac subgroup.
Digestive 2
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.
No frequency band. The cited sentence establishes that reflux is a feature requiring aggressive management, and says nothing about how many patients have it; neither GeneReviews nor the consensus statement gives a figure in the cached text. An absent band means nobody has assessed it, which is the honest state here.
Sequelae: Feeding difficulties
Show evidence (1 reference)
PMID:20301283 SUPPORT Other
"Aggressive management of gastroesophageal reflux disease (GERD)"
GeneReviews names GERD as requiring aggressive management, which presupposes it as a feature of the disease.
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.
No frequency band. The only figure any cited source gives is that about one in four children with CdLS receive a gastrostomy before age five, which counts an intervention rather than the phenotype; feeding difficulty short of gastrostomy is not counted anywhere in the cached references.
Show evidence (1 reference)
PMID:36053618 SUPPORT Human Clinical
"Around one in four children with Cornelia de Lange syndrome and Wolf-Hirschhorn syndrome had a gastrostomy"
A population-based measure of feeding failure severity, expressed as an intervention rate rather than a symptom report.
Head and Neck 2
Synophrys VERY_FREQUENT HP:0000664 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Synophrys (HP:0000664). HP:0000664 is a phenotype from the Human Phenotype Ontology.
The band rests on the counted eleven of eleven below rather than on the consensus statement's cardinal-feature phrasing, which carries no figure. Two caveats sit on that count and are recorded on the evidence item: it is for the composite craniofacial gestalt rather than for synophrys alone, and the cohort is selected for mosaicism.
Show evidence (2 references)
PMID:29995837 SUPPORT Human Clinical
"Cornelia de Lange syndrome (CdLS) is an archetypical genetic syndrome that is characterized by intellectual disability, well-defined facial features, upper limb anomalies and atypical growth, among numerous other signs and symptoms."
The consensus statement names well-defined facial features as one of the four cardinal characteristics, which is what makes the gestalt diagnostic rather than merely associated.
PMID:34326454 SUPPORT Human Clinical
"All of them presented the characteristic (classic) CdLS craniofacial features such as synophrys, thick arched eyebrows, thin upper lip vermilion and downturned corners of mouth (11/11)."
The only counted figure bearing on synophrys in any cited source: eleven of eleven. Two limits on what it counts. The eleven of eleven attaches to the composite craniofacial gestalt that synophrys is named within, not to synophrys measured on its own, so it is a ceiling for this phenotype rather than a measurement of it. And the cohort is individuals with postzygotic mosaic NIPBL variants, ten of the eleven scoring as classic CdLS, so it is a selected series rather than an unselected prevalence. It is quoted because it is a count, where the consensus statement above states a cardinal feature without one.
Cleft palate OCCASIONAL HP:0000175 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cleft palate (HP:0000175). HP:0000175 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:18074387 SUPPORT Human Clinical
"The most frequent associated congenital malformations were limb defects (73.1%), congenital heart defects (45.6%), central nervous system malformations (40.2%), and cleft palate (21.7%)."
Registry frequency for cleft palate.
Integument 1
Hirsutism FREQUENT HP:0001007 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hirsutism (HP:0001007). HP:0001007 is a phenotype from the Human Phenotype Ontology.
The only figure anybody reports for this is 76.9%, tabled in the deep-research report from a source not cached here, so it is not quoted. FREQUENT is the band that contains it. GeneReviews states hypertrichosis as a cardinal feature rather than as a percentage, so it cannot support a band on its own; using it that way put the band one tier above the number that had just been declined.
Show evidence (1 reference)
PMID:20301283 SUPPORT Other
"Severe (classic) CdLS is characterized by distinctive facial features, growth failure (often prenatal onset; height and weight <5th centile throughout life), hypertrichosis, and limb abnormalities"
GeneReviews lists hypertrichosis among the features that characterise severe classic CdLS, alongside the facial gestalt, growth failure and limb defects this entry already curates.
Limbs 1
Upper-limb reduction defect FREQUENT Abnormality of the upper limb HP:0002817 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Upper-limb reduction defect, annotated with Abnormality of the upper limb (HP:0002817). HP:0002817 is a phenotype from the Human Phenotype Ontology.
Bound to the general upper-limb term rather than a forearm-specific one: the quoted 73.1% covers limb defects as a class, and no cited source gives a forearm-specific figure.
Show evidence (1 reference)
PMID:18074387 SUPPORT Human Clinical
"The most frequent associated congenital malformations were limb defects (73.1%), congenital heart defects (45.6%), central nervous system malformations (40.2%), and cleft palate (21.7%)."
Registry frequencies for the four commonest malformations, used as the source for this and three other phenotype bands in this entry.
Musculoskeletal 1
Congenital diaphragmatic hernia HP:0000776 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Congenital diaphragmatic hernia (HP:0000776). HP:0000776 is a phenotype from the Human Phenotype Ontology.
No frequency band. No cited source reports how many patients have CDH. The two percentages in the cached references are cause-of-death attributions, 5-20% of CdLS deaths and 17% of infant deaths, whose denominator is deaths rather than patients; banding from either would restate a mortality figure as a prevalence.
Show evidence (1 reference)
PMID:32762940 SUPPORT Human Clinical
"Mortality was 76% for CdLS patients compared with 29% for non-CdLS patients"
The mortality comparison that makes CDH the principal prognostic lesion.
Nervous System 6
Intellectual disability VERY_FREQUENT HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
The band rests on the counted ten of eleven below, not on the milestone percentages, which measure the severity of the delay rather than how many patients have it.
Show evidence (2 references)
PMID:38462617 SUPPORT Human Clinical
"similarly delayed across motor and language milestones with about 70% not using phrase speech and 30-50% not walking by 5 years of age"
Quantifies the developmental delay through milestone attainment rather than through an IQ band.
PMID:34326454 SUPPORT Human Clinical
"Patients reported here had consistent global developmental delay and intellectual disability (10/11)."
Ten of eleven, which is the counted figure the band rests on. The same selected mosaic cohort as the synophrys count, so it supports the band without being an unselected prevalence.
Self-injurious behavior FREQUENT 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:32809170 SUPPORT Human Clinical
"All children had ≥ 1 type of RB; 44% had some form of SIB."
Gives both the self-injury frequency and the universality of repetitive behaviour in the same measured cohort.
Motor stereotypy VERY_FREQUENT HP:0000733 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Repetitive behaviour, annotated with Motor stereotypy (HP:0000733). HP:0000733 is a phenotype from the Human Phenotype Ontology.
VERY_FREQUENT rather than OBLIGATE because the 100% figure is for repetitive behaviour of any kind, which is broader than motor stereotypy specifically.
Show evidence (1 reference)
PMID:32809170 SUPPORT Human Clinical
"All children had ≥ 1 type of RB; 44% had some form of SIB."
The repetitive-behaviour half of the same sentence. HPO has no general repetitive-behaviour term at this level, so the binding is to Motor stereotypy and preferred_term carries the broader concept the cohort measured.
Delayed speech and language development FREQUENT HP:0000750 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delayed speech and language development (HP:0000750). HP:0000750 is a phenotype from the Human Phenotype Ontology.
Lowered from VERY_FREQUENT to the band containing the only quoted figure. The 70% is for a more severe endpoint than the phenotype names, so delay is plausibly commoner than that, but no cited source counts it and the band should not sit above the number that supports it.
Show evidence (1 reference)
PMID:38462617 SUPPORT Human Clinical
"about 70% not using phrase speech and 30-50% not walking by 5 years of age"
Milestone attainment for language.
Delayed gross motor development FREQUENT HP:0002194 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delayed gross motor development (HP:0002194). HP:0002194 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:38462617 SUPPORT Human Clinical
"about 70% not using phrase speech and 30-50% not walking by 5 years of age"
Milestone attainment for gross motor function.
Abnormal brain morphology FREQUENT HP:0012443 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal brain morphology (HP:0012443). HP:0012443 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:18074387 SUPPORT Human Clinical
"The most frequent associated congenital malformations were limb defects (73.1%), congenital heart defects (45.6%), central nervous system malformations (40.2%), and cleft palate (21.7%)."
Registry frequency for central nervous system malformation.
Growth 1
Intrauterine growth retardation FREQUENT HP:0001511 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intrauterine growth retardation (HP:0001511). HP:0001511 is a phenotype from the Human Phenotype Ontology.
Lowered from VERY_FREQUENT. The GeneReviews sentence quoted below states prenatal onset as a cardinal feature and carries no figure. The only counted figure in any cited source is the registry finding that almost 70% of patients born at term weighed 2,500 g or less, which is a proxy and a restricted denominator, and FREQUENT is the band containing it.
Show evidence (2 references)
PMID:20301283 SUPPORT Other
"growth failure (often prenatal onset; height and weight <5th centile throughout life)"
GeneReviews states both the prenatal onset and that the deficit persists lifelong, which is why this is curated as intrauterine growth retardation rather than as short stature alone.
PMID:18074387 SUPPORT Human Clinical
"Almost 70% of patients, born after the 37th week of gestation, weighed <or=2,500 g."
The registry's counted figure for growth restriction at birth. It is low birth weight rather than antenatally diagnosed growth restriction, and it counts only term births, so it is a floor for this phenotype rather than a measurement of it.
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Genetic Associations

1
NIPBL
Gene: NIPBL hgnc:28862 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is NIPBL (hgnc:28862). hgnc:28862 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Show evidence (3 references)
PMID:38735830 SUPPORT Human Clinical
"Pathogenic variants in NIPBL, which encodes a protein related to the cohesin complex, have been identified in more than 60% of patients, and pathogenic variants in other genes related to this complex in another 15%: SMC1A, SMC3, RAD21, and HDAC8."
Establishes NIPBL as the major causal gene and gives the share of cases that defines type 1.
PMID:16236812 SUPPORT Human Clinical
"Truncating mutations were generally found to cause a more severe phenotype but this correlation was not absolute."
States the genotype-phenotype trend together with the caveat that limits its predictive use. Both halves of the sentence matter here.
PMID:34326454 SUPPORT Human Clinical
"unusual high prevalence of mosaicism in CdLS, occurring in 13.1% of patients with a positive molecular diagnosis."
Quantifies postzygotic mosaicism among molecularly diagnosed patients.
💊

Medical Actions

2
Multidisciplinary Supportive Management
Action: Supportive CareNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. NCIT:C15747
No curative or disease-modifying therapy exists. Management is symptomatic: reflux control and gastrostomy for feeding failure, cardiac repair and ongoing echocardiographic surveillance, diaphragmatic hernia repair where the infant is a candidate, and speech, occupational and physical therapy alongside behavioural management of self-injury.
Target Phenotypes: Gastroesophageal reflux HP:0002020 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Gastroesophageal reflux (HP:0002020). HP:0002020 is a phenotype from the Human Phenotype Ontology. Abnormal heart morphology HP:0001627 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Abnormal heart morphology (HP:0001627). HP:0001627 is a phenotype from the Human Phenotype Ontology. Cleft palate HP:0000175 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Cleft palate (HP:0000175). HP:0000175 is a phenotype from the Human Phenotype Ontology. Delayed speech and language development HP:0000750 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Delayed speech and language development (HP:0000750). HP:0000750 is a phenotype from the Human Phenotype Ontology. Delayed gross motor development HP:0002194 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Delayed gross motor development (HP:0002194). HP:0002194 is a phenotype from the Human Phenotype Ontology. Self-injurious behavior HP:0100716 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Self-injurious behavior (HP:0100716). HP:0100716 is a phenotype from the Human Phenotype Ontology.
Show evidence (5 references)
PMID:29995837 SUPPORT Other
"Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria, both for classic CdLS and non-classic CdLS phenotypes, molecular investigations, long-term management and care planning."
Establishes that management is delivered as expert-consensus long-term care planning rather than as a disease-modifying therapy.
PMID:20301283 SUPPORT Other
"Aggressive management of gastroesophageal reflux disease (GERD)"
GeneReviews puts reflux control first among the management measures, which is what the entry's prose asserts.
PMID:20301283 SUPPORT Other
"Physical, occupational, and speech therapy to optimize psychomotor development and communication skills."
The therapy triad the entry's description names, stated by GeneReviews.
+ 2 more references
Gastrostomy
Action: gastrostomyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is gastrostomy (NCIT:C52006). NCIT:C52006 is a clinical intervention from the NCI Thesaurus. Ontology label: Gastrostomy NCIT:C52006
Platform: Surgery
Enteral access for feeding failure, required by roughly a quarter of children before age five.
Target Phenotypes: Feeding difficulties HP:0011968 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36053618 SUPPORT Human Clinical
"Around one in four children with Cornelia de Lange syndrome and Wolf-Hirschhorn syndrome had a gastrostomy"
Establishes gastrostomy as a routine rather than exceptional intervention in this population.
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Diagnosis

2
Clinical features with NIPBL sequencing (PRESENT)
The primary diagnostic route: the recognisable gestalt together with a heterozygous pathogenic variant in one of the cohesin-pathway genes. This entry is the NIPBL form; the alternative-tissue route below is what follows when blood sequencing is negative in a phenotypically classical patient.
Show evidence (1 reference)
PMID:20301283 SUPPORT Other
"The diagnosis of CdLS is established in a proband with suggestive clinical features and/or a heterozygous pathogenic variant in BRD4, MAU2, NIPBL, RAD21, or SMC3"
GeneReviews states the diagnostic criterion, naming NIPBL among the genes.
Alternative-tissue sequencing after negative blood testing (PRESENT)
The diagnostic consequence of mosaicism, and the practical point most likely to change what a clinician does. Somatic deleterious NIPBL variants are under negative selection in blood, so blood-based testing misses mosaic cases. In a phenotypically classical patient with negative blood testing, buccal swab or fibroblast sequencing should follow before NIPBL is excluded.
Show evidence (1 reference)
PMID:34326454 SUPPORT Human Clinical
"we demonstrate a negative selection against somatic deleterious NIPBL variants in blood."
The finding that makes blood a poor tissue for this test, which is what the recommendation follows from.
📊

Prevalence

1
Europe (EUROCAT registries, 1980-2002, 8,558,346 births)
Birth Prevalence 1.24 per 100,000 live births 1–9 per 100,000 (births)
Registry prevalence of the classical form, roughly 1 in 81,000 births, with an overall estimate of 1.6-2.2 per 100,000 once milder cases are included. This is a CdLS-wide figure, not a NIPBL-specific one; no registry stratifies by gene.
Show evidence (1 reference)
PMID:18074387 SUPPORT Human Clinical
"we found the prevalence of the classical form of CdLS to be 1.24/100,000 births or 1:81,000 births and estimated the overall CdLS prevalence at 1.6-2.2/100,000."
The population-registry prevalence estimate for the classical phenotype.
🔀

Differential Diagnoses

1

Conditions with similar clinical presentations that must be differentiated from Cornelia de Lange Syndrome 1:

Other cohesinopathy subtypes (SMC1A, SMC3, RAD21, HDAC8)
Overlapping Features The other CdLS genes account for roughly another 15% of cases. The distinction is not purely molecular: individuals with SMC1A variants have higher cognitive function and less self-injury than those with NIPBL variants, so the genotype carries prognostic information about the behavioural phenotype specifically.
Show evidence (1 reference)
PMID:30295920 SUPPORT Human Clinical
"Individuals with SMC1A variants show a higher cognitive level and less SIB than individuals with NIPBL variants"
A direct genotype comparison, which is what makes this a clinically meaningful differential rather than a nosological one.
🐁

Animal Models

2
Nipbl+/- mouse
The heterozygous mouse carries only a modest transcript deficit, which is what makes it a dosage model rather than a knockout model, and it is the system in which the genome-wide cohesin-binding and expression work was done.
Species
Mouse
Genotype
Nipbl heterozygous null
Publication
PMID:28855971
Pathograph links
Genome-Wide Reduction in Cohesin Binding recapitulates fidelity: high observes: molecular The measurement this node asserts was made in this model: reduced chromatin cohesin with gene activation, not cohesion, as the sensitive function.
Limitations: Mouse severity does not map onto the human spectrum, and the effect is strain dependent, so the model supports the molecular claim rather than the clinical one.
Show evidence (1 reference)
PMID:28855971 SUPPORT Model Organism
"The results suggest that gene activation is the primary cohesin function sensitive to Nipbl reduction."
The model's own conclusion, and the basis for this entry deliberately having no sister-chromatid-cohesion node.
nipbl-deficient zebrafish
The system in which the multi-organ developmental failure was traced back to gastrulation, which is what places the lesion early enough to account for heart and gut defects.
Species
Zebrafish
Genotype
nipbl morpholino knockdown
Publication
PMID:22039349
Pathograph links
Disrupted Multi-Organ Developmental Programmes partially recapitulates fidelity: moderate observes: organism Reproduces the heart, gut and craniofacial arms of the developmental failure.
Limitations: A morpholino knockdown is a transient and dose-controlled reduction rather than a germline heterozygous variant, and the zebrafish lacks counterparts for the limb and cognitive features that define much of the human phenotype.
Show evidence (1 reference)
PMID:27120001 SUPPORT Model Organism
"Studies of these vertebrate animal models have yielded novel insights into the developmental etiology and genes/gene pathways that contribute to CdLS-associated birth defects, particularly defects of the gut, heart, craniofacial structures, nervous system, and limbs."
Names the organ systems these models inform, which is the scope of the node they are linked to.
{ }

Source YAML

click to show 
name: Cornelia de Lange Syndrome 1
creation_date: "2026-09-05T00:00:00Z"
category: Genetic
synonyms:
- CDLS1
- NIPBL-related Cornelia de Lange syndrome
- Brachmann-de Lange syndrome
- typus degenerativus amstelodamensis
description: >
  Cornelia de Lange syndrome 1 (CdLS1; OMIM #122470) is the NIPBL-related form of
  the cohesinopathy, and the classic and most severe one. Heterozygous
  loss-of-function variants in NIPBL, which encodes the principal cohesin-loading
  factor, account for more than 60% of molecularly diagnosed CdLS. Nearly all cases
  are de novo and sporadic. The clinical picture is a recognizable craniofacial
  gestalt, pre- and postnatal growth restriction, upper-limb reduction defects,
  hirsutism, intellectual disability, and a neurobehavioural profile dominated by
  repetitive and self-injurious behaviour.

  The mechanism is transcriptional rather than mitotic, and that distinction is the
  substance of the entry rather than a nuance. NIPBL loads cohesin onto chromatin;
  halving its dosage reduces cohesin binding genome-wide, collapses cohesin-mediated
  chromatin loops, and impairs RNA polymerase II initiation and elongation. What
  results is not one broken pathway but thousands of individually modest expression
  changes, usually under 1.5-fold, whose collective action disrupts developmental
  programmes across limb, cardiac, diaphragmatic, craniofacial and central nervous
  system primordia. Sister-chromatid cohesion is largely spared, which is why CdLS
  is a developmental disorder rather than a chromosome-instability syndrome.

  This entry is scoped to the NIPBL form. The umbrella entry Cornelia_de_Lange_Syndrome
  (MONDO:0016033) curates the shared pan-cohesin mechanism, and
  Cornelia_de_Lange_Syndrome_4 (RAD21) is the precedent for splitting the per-gene
  forms into their own records. What belongs here rather than in the umbrella is
  what is specific to NIPBL: the dosage argument, the mosaicism that is selected
  against in blood, and the genotype comparison against SMC1A.
disease_term:
  preferred_term: Cornelia de Lange syndrome 1
  term:
    id: MONDO:0007387
    label: Cornelia de Lange syndrome 1
parents:
- Cornelia de Lange syndrome
- Cohesinopathy
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
references:
- reference: PMID:20301283
  title: "Cornelia de Lange Syndrome."
  tags:
  - GeneReviews
prevalence:
- population: Europe (EUROCAT registries, 1980-2002, 8,558,346 births)
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 1.24
  rate_denominator: LIVE_BIRTHS
  notes: >-
    Registry prevalence of the classical form, roughly 1 in 81,000 births, with an
    overall estimate of 1.6-2.2 per 100,000 once milder cases are included. This is
    a CdLS-wide figure, not a NIPBL-specific one; no registry stratifies by gene.
  evidence:
  - reference: PMID:18074387
    reference_title: "Descriptive epidemiology of Cornelia de Lange syndrome in Europe."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we found the prevalence of the classical form of CdLS to be 1.24/100,000 births or 1:81,000 births and estimated the overall CdLS prevalence at 1.6-2.2/100,000."
    explanation: The population-registry prevalence estimate for the classical phenotype.
inheritance:
- name: Autosomal dominant, almost always de novo
  description: >-
    Heterozygous NIPBL variants act dominantly. Nearly every constitutional case is
    de novo and sporadic, and neither maternal nor paternal age is a risk factor.
    Recurrence risk is low but not zero: parental germline mosaicism is the reason
    counselling cannot quote zero.
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:18074387
    reference_title: "Descriptive epidemiology of Cornelia de Lange syndrome in Europe."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients were sporadic. Maternal and paternal age did not seem to be risk factors for CdLS."
    explanation: >-
      Registry-level confirmation that the disorder does not recur in families, and
      that neither parental age is a risk factor. Both halves matter: the first
      makes de novo origin the default assumption, and the second rules out the
      paternal-age effect that de novo dominant disorders usually show.
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "While most familial recurrences of CdLS are the result of gonadal mosaicism in a phenotypically normal parent"
    explanation: >-
      GeneReviews names gonadal mosaicism as the mechanism behind the recurrences
      that do happen, which is what makes the counselled risk low rather than zero.
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Each child of an affected individual has a 50% chance of inheriting the CdLS-related pathogenic variant."
    explanation: >-
      The transmission risk for an affected individual's own children, which the
      de novo framing above does not cover.
genetic:
- name: NIPBL
  gene_term:
    preferred_term: NIPBL
    term:
      id: hgnc:28862
      label: NIPBL
  relationship_type: CAUSATIVE
  presence: PRESENT
  variant_origin: GERMLINE
  frequency: more than 60% of molecularly diagnosed CdLS
  notes: >-
    Truncating variants are generally more severe than missense, but the correlation
    is explicitly not absolute and should not be used to predict an individual's
    course. Postzygotic mosaicism is common and is under negative selection in
    blood, so a phenotypically classical patient with negative blood testing needs
    buccal or fibroblast sequencing before NIPBL is excluded.
  evidence:
  - reference: PMID:38735830
    reference_title: "Cornelia de Lange Spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pathogenic variants in NIPBL, which encodes a protein related to the cohesin complex, have been identified in more than 60% of patients, and pathogenic variants in other genes related to this complex in another 15%: SMC1A, SMC3, RAD21, and HDAC8."
    explanation: >-
      Establishes NIPBL as the major causal gene and gives the share of cases that
      defines type 1.
  - reference: PMID:16236812
    reference_title: "Genotype-phenotype correlations of 39 patients with Cornelia De Lange syndrome: the Dutch experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Truncating mutations were generally found to cause a more severe phenotype but this correlation was not absolute."
    explanation: >-
      States the genotype-phenotype trend together with the caveat that limits its
      predictive use. Both halves of the sentence matter here.
  - reference: PMID:34326454
    reference_title: "Clinical relevance of postzygotic mosaicism in Cornelia de Lange syndrome and purifying selection of NIPBL variants in blood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "unusual high prevalence of mosaicism in CdLS, occurring in 13.1% of patients with a positive molecular diagnosis."
    explanation: Quantifies postzygotic mosaicism among molecularly diagnosed patients.
pathophysiology:
- name: NIPBL Haploinsufficiency
  biological_scale: MOLECULAR
  description: >-
    A heterozygous loss-of-function variant halves functional NIPBL, the cohesin
    loading factor. In humans and in the mouse models alike the transcript and protein
    deficit is modest, under about 30% below normal, so the disorder is a dosage
    disorder rather than a null-allele one: there is no second hit and no threshold
    below which the phenotype appears.
  genes:
  - preferred_term: NIPBL
    term:
      id: hgnc:28862
      label: NIPBL
  genetic_context:
    functional_impact_category: LOSS_OF_FUNCTION
    zygosity: HETEROZYGOUS
    variant_origin: GERMLINE
  evidence:
  - reference: PMID:29995837
    reference_title: "Diagnosis and management of Cornelia de Lange syndrome: first international consensus statement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is caused by variants in any one of seven genes, all of which have a structural or regulatory function in the cohesin complex."
    explanation: >-
      The consensus statement's framing of CdLS as a cohesin-complex disorder, which
      is the class this node's lesion sits in.
  - reference: PMID:22039349
    reference_title: "Multifactorial origins of heart and gut defects in nipbl-deficient zebrafish, a model of Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "in both man and mouse, Nipbl heterozygotes show only a ,30% reduction in Nipbl mRNA and protein"
    explanation: >-
      The quantitative basis for calling this a dosage disorder: a transcript and
      protein deficit of under about 30%, in humans as well as mice, is enough to
      produce the syndrome. Graded OTHER because this is the paper's background
      summary of the three studies it cites rather than a result of its own zebrafish
      work. The comma is a PDF-extraction artifact for the less-than sign.
  downstream:
  - target: Genome-Wide Reduction in Cohesin Binding
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28855971
      reference_title: "The effect of Nipped-B-like (Nipbl) haploinsufficiency on genome-wide cohesin binding and target gene expression: modeling Cornelia de Lange syndrome."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "We found a global decrease in cohesin binding, including at CCCTC-binding factor (CTCF) binding sites and repeat regions."
      explanation: >-
        A ChIP-seq measurement in Nipbl+/- mouse embryonic fibroblasts, which is what
        makes this an edge rather than two separately supported nodes.
- name: Genome-Wide Reduction in Cohesin Binding
  biological_scale: MOLECULAR
  description: >-
    Less loader means less chromatin-bound cohesin, at CTCF boundary sites and at
    repeats. Cohesin-bound genes are enriched for H3K4me3 at their promoters and are
    disproportionately downregulated, which points at gene activation rather than
    cohesion as the sensitive function.
  biological_processes:
  - preferred_term: cohesin loading onto chromatin
    term:
      id: GO:0006325
      label: chromatin organization
    modifier: DECREASED
  molecular_functions:
  - preferred_term: cohesin binding to chromatin
    term:
      id: GO:0003682
      label: chromatin binding
    modifier: DECREASED
  evidence:
  - reference: PMID:28855971
    reference_title: "The effect of Nipped-B-like (Nipbl) haploinsufficiency on genome-wide cohesin binding and target gene expression: modeling Cornelia de Lange syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The results suggest that gene activation is the primary cohesin function sensitive to Nipbl reduction."
    explanation: >-
      The paper's own conclusion that the sensitive cohesin function is
      transcriptional, which is the claim this whole chain rests on.
  downstream:
  - target: Collapse of Cohesin-Mediated Chromatin Loops
    causal_link_type: DIRECT
- name: Collapse of Cohesin-Mediated Chromatin Loops
  biological_scale: MOLECULAR
  description: >-
    Reduced chromatin-bound cohesin weakens enhancer-promoter contacts and CTCF
    insulation. Acute NIPBL depletion in vivo diminishes chromatin loops rapidly,
    and the genes that depend most on NIPBL-supported conformation are cell-identity
    and developmental genes sitting near super-enhancers. That selectivity is what
    turns a globally acting chromatin factor into a developmental disorder.
  biological_processes:
  - preferred_term: chromatin looping
    term:
      id: GO:0140588
      label: chromatin looping
    modifier: DECREASED
  evidence:
  - reference: PMID:41699137
    reference_title: "Acute NIPBL depletion reveals in vivo dynamics of loop extrusion and its role in transcription activation."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "NIPBL specifically regulates cell identity genes by supporting a unique local genome conformation defined by greater spatial proximity to nearby super-enhancers and weaker transcription start site insulation of genomic contacts"
    explanation: >-
      Explains why loss of a general chromatin factor produces a developmental
      rather than a global phenotype.
  downstream:
  - target: Impaired RNA Polymerase II Transcription
    causal_link_type: DIRECT
- name: Impaired RNA Polymerase II Transcription
  biological_scale: MOLECULAR
  description: >-
    Transcription itself is impaired at both ends: initiation at promoters and
    elongation through gene bodies. This is measured in CdLS patient cells, not only
    in models.
  biological_processes:
  - preferred_term: regulation of transcription by RNA polymerase II
    term:
      id: GO:0006357
      label: regulation of transcription by RNA polymerase II
    modifier: DECREASED
  evidence:
  - reference: PMID:26581180
    reference_title: "Mutant cohesin affects RNA polymerase II regulation in Cornelia de Lange syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "mutant cohesin impairs both RNA polymerase II (Pol II) transcription initiation at promoters and elongation in the gene body"
    explanation: >-
      Locates the transcriptional lesion at two specific steps rather than asserting
      a general dysregulation.
  downstream:
  - target: Collective Small Gene-Expression Perturbations
    causal_link_type: DIRECT
- name: Collective Small Gene-Expression Perturbations
  biological_scale: CELLULAR
  description: >-
    The distinctive feature of this disease's mechanism, and the reason it resists
    the usual one-pathway account. Hundreds to thousands of genes change expression
    and nearly all the changes are modest, usually under 1.5-fold. No single
    perturbation is individually pathogenic; the phenotype is the sum. This is also
    why there is no obvious therapeutic target: there is no dominant node to
    correct.
  evidence:
  - reference: PMID:22039349
    reference_title: "Multifactorial origins of heart and gut defects in nipbl-deficient zebrafish, a model of Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Nearly all such changes are modest, however--usually less than 1.5-fold--raising the intriguing possibility that, in CdLS, severe developmental defects result from the collective action of many otherwise innocuous perturbations."
    explanation: >-
      States the collective-perturbation hypothesis in the terms this node curates
      it in, including that it remains a hypothesis.
  - reference: PMID:29348408
    reference_title: "NIPBL(+/-) haploinsufficiency reveals a constellation of transcriptome disruptions in the pluripotent and cardiac states."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "identified hundreds of mRNAs, pseudogenes, and non-coding RNAs with altered expression"
    explanation: >-
      Reproduces the many-small-changes signature in human iPSC-derived
      cardiomyocytes, which is disease-relevant tissue rather than a fibroblast
      proxy.
  downstream:
  - target: Disrupted Multi-Organ Developmental Programmes
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The step from a distributed expression signature to specific organ
      malformations is asserted by the sources as an integration of demonstrated
      components rather than demonstrated end to end, so the edge is typed indirect.
- name: Disrupted Multi-Organ Developmental Programmes
  biological_scale: TISSUE
  description: >-
    Developmental programmes fail across limb bud, cardiac and left-right
    patterning, foregut and diaphragm, craniofacial structures and the central
    nervous system. In the zebrafish model the deregulation is detectable from
    gastrulation onwards in endodermal differentiation and left-right patterning
    genes, which places the lesion early enough to explain heart and gut defects.
  evidence:
  - reference: PMID:27120001
    reference_title: "Using mouse and zebrafish models to understand the etiology of developmental defects in Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Studies of these vertebrate animal models have yielded novel insights into the developmental etiology and genes/gene pathways that contribute to CdLS-associated birth defects, particularly defects of the gut, heart, craniofacial structures, nervous system, and limbs."
    explanation: >-
      Names the specific organ systems whose developmental programmes fail, which is
      what this node asserts.
  downstream:
  - target: Upper-limb reduction defect
    causal_link_type: DIRECT
  - target: Congenital heart defect
    causal_link_type: DIRECT
  - target: Pulmonic stenosis
    causal_link_type: DIRECT
    description: >-
      Curated as its own edge rather than as a consequence of the congenital heart
      defect above, because it is a specific lesion within that category rather than
      something the category causes.
  - target: Congenital diaphragmatic hernia
    causal_link_type: DIRECT
  - target: Intellectual disability
    causal_link_type: DIRECT
  - target: Cleft palate
    causal_link_type: DIRECT
  - target: Synophrys
    causal_link_type: DIRECT
    description: >-
      The craniofacial programme this node names. Synophrys is the recognition sign
      of the syndrome and belongs to the same developmental failure as the cleft
      palate.
  - target: Abnormal brain morphology
    causal_link_type: DIRECT
    description: >-
      The central nervous system programme this node names, in its structural form.
  - target: Feeding difficulties
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The node names foregut development among the failing programmes, but no cited
      source traces a route from that to the feeding difficulty, which in practice is
      a mix of structural, oromotor and reflux contributions. Typed indirect for that
      reason.
  - target: Delayed speech and language development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Attached to the developmental node rather than to the intellectual disability,
      because the two are parallel manifestations of the same programme failure
      rather than one causing the other. The specific route is not established.
  - target: Delayed gross motor development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Same reasoning as the speech delay above.
  - target: Self-injurious behavior
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      No cited source traces a route from the transcriptional lesion to this
      behavioural phenotype. The edge records that it belongs to the disease's
      central nervous system involvement, and its type records that the intermediates
      are unknown.
  - target: Motor stereotypy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Same reasoning as the self-injurious behaviour above.
  - target: Hirsutism
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The integument is not among the programmes this node's evidence names, and no
      cited source traces a route from the transcriptional lesion to the hair
      phenotype. The edge records membership of the developmental syndrome; the type
      records that the mechanism is unknown.
  - target: Gastroesophageal reflux
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The node names foregut development, but reflux is a functional outcome and no
      cited source connects the two, so the intermediates are unknown.
  - target: Intrauterine growth retardation
    causal_link_type: DIRECT
phenotypes:
- category: Integument
  name: Hirsutism
  frequency: FREQUENT
  description: >-
    Generalised hypertrichosis is one of the cardinal features of the classic
    phenotype, listed alongside the facial gestalt, growth failure and limb defects.
  notes: >-
    The only figure anybody reports for this is 76.9%, tabled in the deep-research
    report from a source not cached here, so it is not quoted. FREQUENT is the band
    that contains it. GeneReviews states hypertrichosis as a cardinal feature rather
    than as a percentage, so it cannot support a band on its own; using it that way
    put the band one tier above the number that had just been declined.
  phenotype_term:
    preferred_term: Hirsutism
    term:
      id: HP:0001007
      label: Hirsutism
  evidence:
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Severe (classic) CdLS is characterized by distinctive facial features, growth failure (often prenatal onset; height and weight <5th centile throughout life), hypertrichosis, and limb abnormalities"
    explanation: >-
      GeneReviews lists hypertrichosis among the features that characterise severe
      classic CdLS, alongside the facial gestalt, growth failure and limb defects
      this entry already curates.
- category: Gastrointestinal
  name: Gastroesophageal reflux
  description: >-
    Reflux is the manifestation the first-line management measure exists for, and
    GeneReviews puts its aggressive control at the head of the management list.
  notes: >-
    No frequency band. The cited sentence establishes that reflux is a feature
    requiring aggressive management, and says nothing about how many patients have
    it; neither GeneReviews nor the consensus statement gives a figure in the
    cached text. An absent band means nobody has assessed it, which is the honest
    state here.
  phenotype_term:
    preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  sequelae:
  - target: Feeding difficulties
    description: >-
      Reflux is one contributor to the feeding failure, which is why its aggressive
      control and the gastrostomy sit together in the management list. It is not the
      only contributor, so the feeding node keeps its own incoming edge from the
      developmental programme.
  evidence:
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Aggressive management of gastroesophageal reflux disease (GERD)"
    explanation: >-
      GeneReviews names GERD as requiring aggressive management, which presupposes
      it as a feature of the disease.
- category: Craniofacial
  name: Synophrys
  frequency: VERY_FREQUENT
  notes: >-
    The band rests on the counted eleven of eleven below rather than on the
    consensus statement's cardinal-feature phrasing, which carries no figure. Two
    caveats sit on that count and are recorded on the evidence item: it is for the
    composite craniofacial gestalt rather than for synophrys alone, and the cohort
    is selected for mosaicism.
  description: >-
    Part of the craniofacial gestalt that makes the syndrome clinically
    recognizable, together with arched eyebrows, long philtrum and thin down-turned
    lips.
  phenotype_term:
    preferred_term: Synophrys
    term:
      id: HP:0000664
      label: Synophrys
  diagnostic: true
  evidence:
  - reference: PMID:29995837
    reference_title: "Diagnosis and management of Cornelia de Lange syndrome: first international consensus statement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cornelia de Lange syndrome (CdLS) is an archetypical genetic syndrome that is characterized by intellectual disability, well-defined facial features, upper limb anomalies and atypical growth, among numerous other signs and symptoms."
    explanation: >-
      The consensus statement names well-defined facial features as one of the four
      cardinal characteristics, which is what makes the gestalt diagnostic rather
      than merely associated.
  - reference: PMID:34326454
    reference_title: "Clinical relevance of postzygotic mosaicism in Cornelia de Lange syndrome and purifying selection of NIPBL variants in blood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All of them presented the characteristic (classic) CdLS craniofacial features such as synophrys, thick arched eyebrows, thin upper lip vermilion and downturned corners of mouth (11/11)."
    explanation: >-
      The only counted figure bearing on synophrys in any cited source: eleven of
      eleven. Two limits on what it counts. The eleven of eleven attaches to the
      composite craniofacial gestalt that synophrys is named within, not to
      synophrys measured on its own, so it is a ceiling for this phenotype rather
      than a measurement of it. And the cohort is individuals with postzygotic
      mosaic NIPBL variants, ten of the eleven scoring as classic CdLS, so it is a
      selected series rather than an unselected prevalence. It is quoted because it
      is a count, where the consensus statement above states a cardinal feature
      without one.
- category: Musculoskeletal
  name: Upper-limb reduction defect
  frequency: FREQUENT
  description: >-
    Limb defects are the commonest associated malformation in registry data, at
    73.1%, and were present in every case in one national series. Involvement is
    predominantly upper-limb and often asymmetric.
  notes: >-
    Bound to the general upper-limb term rather than a forearm-specific one: the
    quoted 73.1% covers limb defects as a class, and no cited source gives a
    forearm-specific figure.
  phenotype_term:
    preferred_term: Upper-limb reduction defect
    term:
      id: HP:0002817
      label: Abnormality of the upper limb
  evidence:
  - reference: PMID:18074387
    reference_title: "Descriptive epidemiology of Cornelia de Lange syndrome in Europe."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most frequent associated congenital malformations were limb defects (73.1%), congenital heart defects (45.6%), central nervous system malformations (40.2%), and cleft palate (21.7%)."
    explanation: >-
      Registry frequencies for the four commonest malformations, used as the source
      for this and three other phenotype bands in this entry.
- category: Cardiovascular
  name: Congenital heart defect
  frequency: FREQUENT
  description: >-
    Reported in 33.3% of an echocardiographic cohort and 45.6% in registry data. The
    discrepancy is real and probably reflects ascertainment: registries capture more
    severely malformed cases. Pulmonary stenosis is the single commonest lesion, and
    late mitral and tricuspid valve dysplasia appearing after age ten is the reason
    surveillance rather than a single neonatal echocardiogram is recommended.
  phenotype_term:
    preferred_term: Abnormal heart morphology
    term:
      id: HP:0001627
      label: Abnormal heart morphology
  evidence:
  - reference: PMID:19449412
    reference_title: "Analysis of congenital heart defects in 87 consecutive patients with Brachmann-de Lange syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A cardiac anomaly was identified in 29/87 (33.3%) including 28 (32.2%) patients with a structural CHD, and an additional patient (1.2%) with isolated non-obstructive hypertrophic cardiomyopathy (HCM)."
    explanation: The prospective echocardiographic frequency, from consecutive patients.
- category: Cardiovascular
  name: Pulmonic stenosis
  frequency: OCCASIONAL
  description: >-
    The commonest single structural lesion within the cardiac subgroup, in 39% of
    those with a congenital heart defect. That is 11 of the 28 patients with a
    structural defect, in a cohort of 87, so roughly 13% of patients overall, which
    is the figure the frequency band carries.
  phenotype_term:
    preferred_term: Pulmonic stenosis
    term:
      id: HP:0001642
      label: Pulmonic stenosis
  evidence:
  - reference: PMID:19449412
    reference_title: "Analysis of congenital heart defects in 87 consecutive patients with Brachmann-de Lange syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Overall incidence of pulmonary stenosis was 39% (11/28)."
    explanation: Gives the lesion distribution within the cardiac subgroup.
- category: Respiratory
  name: Congenital diaphragmatic hernia
  description: >-
    Uncommon but the dominant driver of mortality. Infants with both CdLS and CDH
    fare markedly worse than infants with CDH alone: 76% mortality against 29%, with
    only a third undergoing repair. Of the seven who were repaired, five survived to
    discharge, which suggests surgical candidacy rather than the syndrome itself is
    the discriminator.
  phenotype_term:
    preferred_term: Congenital diaphragmatic hernia
    term:
      id: HP:0000776
      label: Congenital diaphragmatic hernia
  notes: >-
    No frequency band. No cited source reports how many patients have CDH. The two
    percentages in the cached references are cause-of-death attributions, 5-20% of
    CdLS deaths and 17% of infant deaths, whose denominator is deaths rather than
    patients; banding from either would restate a mortality figure as a prevalence.
  evidence:
  - reference: PMID:32762940
    reference_title: "Cornelia de Lange syndrome and congenital diaphragmatic hernia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mortality was 76% for CdLS patients compared with 29% for non-CdLS patients"
    explanation: The mortality comparison that makes CDH the principal prognostic lesion.
- category: Neurological
  name: Intellectual disability
  frequency: VERY_FREQUENT
  notes: >-
    The band rests on the counted ten of eleven below, not on the milestone
    percentages, which measure the severity of the delay rather than how many
    patients have it.
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:38462617
    reference_title: "Neurobehavioral and developmental profiles: genotype-phenotype correlations in individuals with Cornelia de Lange syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "similarly delayed across motor and language milestones with about 70% not using phrase speech and 30-50% not walking by 5 years of age"
    explanation: >-
      Quantifies the developmental delay through milestone attainment rather than
      through an IQ band.
  - reference: PMID:34326454
    reference_title: "Clinical relevance of postzygotic mosaicism in Cornelia de Lange syndrome and purifying selection of NIPBL variants in blood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients reported here had consistent global developmental delay and intellectual disability (10/11)."
    explanation: >-
      Ten of eleven, which is the counted figure the band rests on. The same
      selected mosaic cohort as the synophrys count, so it supports the band
      without being an unselected prevalence.
- category: Behavioral
  name: Self-injurious behavior
  frequency: FREQUENT
  description: >-
    Present in 44% of a cohort of 50 children. Lower adaptive functioning correlates
    with higher stereotypy and self-injury scores.
  phenotype_term:
    preferred_term: Self-injurious behavior
    term:
      id: HP:0100716
      label: Self-injurious behavior
  evidence:
  - reference: PMID:32809170
    reference_title: "Repetitive and Self-injurious Behaviors in Children with Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All children had ≥ 1 type of RB; 44% had some form of SIB."
    explanation: >-
      Gives both the self-injury frequency and the universality of repetitive
      behaviour in the same measured cohort.
- category: Behavioral
  name: Motor stereotypy
  frequency: VERY_FREQUENT
  description: >-
    Every child in the cohort had at least one type of repetitive behaviour, and 64%
    spent more than an hour a day displaying them.
  notes: >-
    VERY_FREQUENT rather than OBLIGATE because the 100% figure is for repetitive
    behaviour of any kind, which is broader than motor stereotypy specifically.
  phenotype_term:
    preferred_term: Repetitive behaviour
    term:
      id: HP:0000733
      label: Motor stereotypy
  evidence:
  - reference: PMID:32809170
    reference_title: "Repetitive and Self-injurious Behaviors in Children with Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All children had ≥ 1 type of RB; 44% had some form of SIB."
    explanation: >-
      The repetitive-behaviour half of the same sentence. HPO has no general
      repetitive-behaviour term at this level, so the binding is to Motor stereotypy
      and preferred_term carries the broader concept the cohort measured.
- category: Neurological
  name: Delayed speech and language development
  frequency: FREQUENT
  description: About 70% are not using phrase speech by five years of age.
  notes: >-
    Lowered from VERY_FREQUENT to the band containing the only quoted figure. The
    70% is for a more severe endpoint than the phenotype names, so delay is
    plausibly commoner than that, but no cited source counts it and the band should
    not sit above the number that supports it.
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  evidence:
  - reference: PMID:38462617
    reference_title: "Neurobehavioral and developmental profiles: genotype-phenotype correlations in individuals with Cornelia de Lange syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "about 70% not using phrase speech and 30-50% not walking by 5 years of age"
    explanation: Milestone attainment for language.
- category: Neurological
  name: Delayed gross motor development
  frequency: FREQUENT
  description: Between 30% and 50% are not walking by five years of age.
  phenotype_term:
    preferred_term: Delayed gross motor development
    term:
      id: HP:0002194
      label: Delayed gross motor development
  evidence:
  - reference: PMID:38462617
    reference_title: "Neurobehavioral and developmental profiles: genotype-phenotype correlations in individuals with Cornelia de Lange syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "about 70% not using phrase speech and 30-50% not walking by 5 years of age"
    explanation: Milestone attainment for gross motor function.
- category: Gastrointestinal
  name: Feeding difficulties
  description: >-
    Severe and a defining part of the morbidity. Roughly one in four children with
    CdLS has a gastrostomy before age five, against 0.016% of reference children in
    the same data-linkage study.
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  notes: >-
    No frequency band. The only figure any cited source gives is that about one in
    four children with CdLS receive a gastrostomy before age five, which counts an
    intervention rather than the phenotype; feeding difficulty short of gastrostomy
    is not counted anywhere in the cached references.
  evidence:
  - reference: PMID:36053618
    reference_title: "Gastrostomy and congenital anomalies: a European population-based study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Around one in four children with Cornelia de Lange syndrome and Wolf-Hirschhorn syndrome had a gastrostomy"
    explanation: >-
      A population-based measure of feeding failure severity, expressed as an
      intervention rate rather than a symptom report.
- category: Neurological
  name: Abnormal brain morphology
  frequency: FREQUENT
  description: Central nervous system malformations in 40.2% of registry cases.
  phenotype_term:
    preferred_term: Abnormal brain morphology
    term:
      id: HP:0012443
      label: Abnormal brain morphology
  evidence:
  - reference: PMID:18074387
    reference_title: "Descriptive epidemiology of Cornelia de Lange syndrome in Europe."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most frequent associated congenital malformations were limb defects (73.1%), congenital heart defects (45.6%), central nervous system malformations (40.2%), and cleft palate (21.7%)."
    explanation: Registry frequency for central nervous system malformation.
- category: Craniofacial
  name: Cleft palate
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Cleft palate
    term:
      id: HP:0000175
      label: Cleft palate
  evidence:
  - reference: PMID:18074387
    reference_title: "Descriptive epidemiology of Cornelia de Lange syndrome in Europe."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most frequent associated congenital malformations were limb defects (73.1%), congenital heart defects (45.6%), central nervous system malformations (40.2%), and cleft palate (21.7%)."
    explanation: Registry frequency for cleft palate.
- category: Growth
  name: Intrauterine growth retardation
  frequency: FREQUENT
  notes: >-
    Lowered from VERY_FREQUENT. The GeneReviews sentence quoted below states
    prenatal onset as a cardinal feature and carries no figure. The only counted
    figure in any cited source is the registry finding that almost 70% of patients
    born at term weighed 2,500 g or less, which is a proxy and a restricted
    denominator, and FREQUENT is the band containing it.
  description: >-
    Growth restriction begins prenatally and continues postnatally, and is one of
    the features detectable on antenatal ultrasound.
  phenotype_term:
    preferred_term: Intrauterine growth retardation
    term:
      id: HP:0001511
      label: Intrauterine growth retardation
  evidence:
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "growth failure (often prenatal onset; height and weight <5th centile throughout life)"
    explanation: >-
      GeneReviews states both the prenatal onset and that the deficit persists
      lifelong, which is why this is curated as intrauterine growth retardation
      rather than as short stature alone.
  - reference: PMID:18074387
    reference_title: "Descriptive epidemiology of Cornelia de Lange syndrome in Europe."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Almost 70% of patients, born after the 37th week of gestation, weighed <or=2,500 g."
    explanation: >-
      The registry's counted figure for growth restriction at birth. It is low birth
      weight rather than antenatally diagnosed growth restriction, and it counts
      only term births, so it is a floor for this phenotype rather than a
      measurement of it.
animal_models:
- name: Nipbl+/- mouse
  species: Mouse
  genotype: Nipbl heterozygous null
  publication: PMID:28855971
  description: >-
    The heterozygous mouse carries only a modest transcript deficit, which is what
    makes it a dosage model rather than a knockout model, and it is the system in
    which the genome-wide cohesin-binding and expression work was done.
  modeled_mechanisms:
  - target: Genome-Wide Reduction in Cohesin Binding
    relationship: RECAPITULATES
    fidelity: HIGH
    model_scale: MOLECULAR
    description: >-
      The measurement this node asserts was made in this model: reduced chromatin
      cohesin with gene activation, not cohesion, as the sensitive function.
    limitations: >-
      Mouse severity does not map onto the human spectrum, and the effect is strain
      dependent, so the model supports the molecular claim rather than the clinical
      one.
    evidence:
    - reference: PMID:28855971
      reference_title: "The effect of Nipped-B-like (Nipbl) haploinsufficiency on genome-wide cohesin binding and target gene expression: modeling Cornelia de Lange syndrome."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "The results suggest that gene activation is the primary cohesin function sensitive to Nipbl reduction."
      explanation: >-
        The model's own conclusion, and the basis for this entry deliberately having
        no sister-chromatid-cohesion node.
- name: nipbl-deficient zebrafish
  species: Zebrafish
  genotype: nipbl morpholino knockdown
  publication: PMID:22039349
  description: >-
    The system in which the multi-organ developmental failure was traced back to
    gastrulation, which is what places the lesion early enough to account for heart
    and gut defects.
  modeled_mechanisms:
  - target: Disrupted Multi-Organ Developmental Programmes
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: >-
      Reproduces the heart, gut and craniofacial arms of the developmental failure.
    limitations: >-
      A morpholino knockdown is a transient and dose-controlled reduction rather than
      a germline heterozygous variant, and the zebrafish lacks counterparts for the
      limb and cognitive features that define much of the human phenotype.
    evidence:
    - reference: PMID:27120001
      reference_title: Using mouse and zebrafish models to understand the etiology of developmental defects in Cornelia de Lange Syndrome.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Studies of these vertebrate animal models have yielded novel insights into the developmental etiology and genes/gene pathways that contribute to CdLS-associated birth defects, particularly defects of the gut, heart, craniofacial structures, nervous system, and limbs."
      explanation: >-
        Names the organ systems these models inform, which is the scope of the node
        they are linked to.
diagnosis:
- name: Clinical features with NIPBL sequencing
  description: >-
    The primary diagnostic route: the recognisable gestalt together with a
    heterozygous pathogenic variant in one of the cohesin-pathway genes. This entry
    is the NIPBL form; the alternative-tissue route below is what follows when blood
    sequencing is negative in a phenotypically classical patient.
  presence: PRESENT
  evidence:
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The diagnosis of CdLS is established in a proband with suggestive clinical features and/or a heterozygous pathogenic variant in BRD4, MAU2, NIPBL, RAD21, or SMC3"
    explanation: >-
      GeneReviews states the diagnostic criterion, naming NIPBL among the genes.
- name: Alternative-tissue sequencing after negative blood testing
  description: >-
    The diagnostic consequence of mosaicism, and the practical point most likely to
    change what a clinician does. Somatic deleterious NIPBL variants are under
    negative selection in blood, so blood-based testing misses mosaic cases. In a
    phenotypically classical patient with negative blood testing, buccal swab or
    fibroblast sequencing should follow before NIPBL is excluded.
  presence: PRESENT
  evidence:
  - reference: PMID:34326454
    reference_title: "Clinical relevance of postzygotic mosaicism in Cornelia de Lange syndrome and purifying selection of NIPBL variants in blood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we demonstrate a negative selection against somatic deleterious NIPBL variants in blood."
    explanation: >-
      The finding that makes blood a poor tissue for this test, which is what the
      recommendation follows from.
treatments:
- name: Multidisciplinary Supportive Management
  description: >-
    No curative or disease-modifying therapy exists. Management is symptomatic:
    reflux control and gastrostomy for feeding failure, cardiac repair and ongoing
    echocardiographic surveillance, diaphragmatic hernia repair where the infant is
    a candidate, and speech, occupational and physical therapy alongside behavioural
    management of self-injury.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  - preferred_term: Abnormal heart morphology
    term:
      id: HP:0001627
      label: Abnormal heart morphology
  - preferred_term: Cleft palate
    term:
      id: HP:0000175
      label: Cleft palate
  - preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  - preferred_term: Delayed gross motor development
    term:
      id: HP:0002194
      label: Delayed gross motor development
  - preferred_term: Self-injurious behavior
    term:
      id: HP:0100716
      label: Self-injurious behavior
  evidence:
  - reference: PMID:29995837
    reference_title: "Diagnosis and management of Cornelia de Lange syndrome: first international consensus statement."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria, both for classic CdLS and non-classic CdLS phenotypes, molecular investigations, long-term management and care planning."
    explanation: >-
      Establishes that management is delivered as expert-consensus long-term care
      planning rather than as a disease-modifying therapy.
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Aggressive management of gastroesophageal reflux disease (GERD)"
    explanation: >-
      GeneReviews puts reflux control first among the management measures, which is
      what the entry's prose asserts.
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Physical, occupational, and speech therapy to optimize psychomotor development and communication skills."
    explanation: >-
      The therapy triad the entry's description names, stated by GeneReviews.
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Standard treatment for epilepsy, limb defects, gastrointestinal malformations, ocular issues, hearing loss, cleft palate, dental anomalies, cryptorchidism/hypospadias, bicornuate uterus, vesicoureteral reflux, cardiac defects, immunodeficiency, anemia, and thrombocytopenia."
    explanation: >-
      Source for the cardiac-defect and cleft-palate arms of this entry: GeneReviews
      directs standard rather than CdLS-specific treatment at both.
  - reference: PMID:20301283
    reference_title: "Cornelia de Lange Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "behavioral assessment for anxiety, attention deficits, and aggressive or self-injurious behaviors"
    explanation: >-
      Source for the behavioural arm: self-injury is managed through recurring
      assessment rather than a one-time intervention.
- name: Gastrostomy
  description: >-
    Enteral access for feeding failure, required by roughly a quarter of children
    before age five.
  treatment_term:
    preferred_term: gastrostomy
    term:
      id: NCIT:C52006
      label: Gastrostomy
  therapeutic_modality: SURGERY
  target_phenotypes:
  - preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:36053618
    reference_title: "Gastrostomy and congenital anomalies: a European population-based study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Around one in four children with Cornelia de Lange syndrome and Wolf-Hirschhorn syndrome had a gastrostomy"
    explanation: >-
      Establishes gastrostomy as a routine rather than exceptional intervention in
      this population.
differential_diagnoses:
- name: Other cohesinopathy subtypes (SMC1A, SMC3, RAD21, HDAC8)
  description: >-
    The other CdLS genes account for roughly another 15% of cases. The distinction
    is not purely molecular: individuals with SMC1A variants have higher cognitive
    function and less self-injury than those with NIPBL variants, so the genotype
    carries prognostic information about the behavioural phenotype specifically.
  evidence:
  - reference: PMID:30295920
    reference_title: "Development, behaviour and autism in individuals with SMC1A variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals with SMC1A variants show a higher cognitive level and less SIB than individuals with NIPBL variants"
    explanation: >-
      A direct genotype comparison, which is what makes this a clinically meaningful
      differential rather than a nosological one.
discussions:
- discussion_id: cdls1_collective_perturbation_untested
  kind: KNOWLEDGE_GAP
  prompt: >-
    Is the collective-perturbation model actually established, or is it the most
    plausible remaining account once no single dominant target has been found?
  attaches_to:
  - pathophysiology#Collective Small Gene-Expression Perturbations
  rationale: >-
    The observation is solid: hundreds of genes change and nearly all the changes
    are under 1.5-fold. The inference that severe developmental defects result from
    their collective action is stated by its own authors as an intriguing
    possibility raised by the data, and no experiment has since shown that summing
    subthreshold perturbations produces the phenotype. The alternative that has not
    been excluded is that a small number of the changes are the pathogenic ones and
    the rest are downstream noise. This matters therapeutically: under the
    collective model there is nothing to target, and under the alternative there is.
  proposed_experiments:
  - experiment_id: cdls1_combinatorial_perturbation_zebrafish
    name: Combinatorial subthreshold perturbation in zebrafish
    description: >-
      Reproduce the individual expression changes seen in nipbl morphants, singly
      and in defined combinations, in wild-type embryos, and test whether organ
      defects appear only above some number of simultaneous perturbations. The
      zebrafish model was developed for exactly this quantitative question.
    readouts:
    - name: Heart and gut defect incidence by number of simultaneous perturbations
      target: pathophysiology#Collective Small Gene-Expression Perturbations
      direction: INCREASED
      interpretation: >-
        A dose-of-perturbations relationship would support the collective model; a
        step change on one perturbation would identify a dominant driver instead.
- discussion_id: cdls1_chd_frequency_discrepancy
  kind: KNOWLEDGE_GAP
  prompt: >-
    Why does the congenital heart defect frequency differ between an
    echocardiographic cohort (33.3%) and population registry data (45.6%), and what
    is the NIPBL-specific figure?
  attaches_to:
  - phenotypes#Congenital heart defect
  rationale: >-
    Both numbers are curated here rather than one being chosen, because the
    difference is informative. Registries ascertain through malformation and so
    over-represent severely affected cases; the echocardiographic cohort was
    consecutive and so should be closer to the true rate among diagnosed patients,
    but is smaller and single-centre. Neither is stratified by gene, so the
    NIPBL-specific cardiac frequency, which is what this entry would want, is
    unpublished. A curator reading either figure alone would be over-reading it.
notes: >-
  Curation decisions worth recording.

  Scope against the umbrella entry. kb/disorders/Cornelia_de_Lange_Syndrome.yaml
  holds MONDO:0016033 and curates the generic pan-cohesin chain with no
  has_subtypes block; Cornelia_de_Lange_Syndrome_4.yaml holds the RAD21 form as its
  own record. This entry follows that precedent and carries what is specific to
  NIPBL: the dosage argument, the blood-selected mosaicism, and the SMC1A
  comparison. The overlap with the umbrella's mechanism section is real and
  intentional, since conformance in dismech duplicates rather than inherits.

  The mechanism is transcriptional, and the entry says so structurally rather than
  only in prose. There is no sister-chromatid-cohesion node, because the sources
  are explicit that cohesion is largely spared and that gene activation is the
  cohesin function sensitive to NIPBL reduction. A reader looking for the canonical
  cohesin function will not find it here, and that absence is the claim.

  The collective-perturbation node is the weakest link and carries a knowledge gap
  saying so. Its own authors frame it as a possibility raised by the data.

  Both CHD frequencies are curated. See the second knowledge gap: choosing one
  would have hidden an ascertainment difference that a reader needs.

  One binding is coarser than the finding. The cohort measuring repetitive
  behaviour measured a broader construct than HPO's Motor stereotypy, which is the
  closest available term; preferred_term carries the measured concept.

  How the treatments reach the pathograph. Both entries carry target_phenotypes
  rather than target_mechanisms, which is deliberate. dismech.graph draws a treats
  edge from a resolved target_phenotypes descriptor and a targets edge from a
  target_mechanisms link, so a treatment reaches the graph either way. Neither
  treatment here acts on a mechanism node: the gastrostomy bypasses feeding
  failure, and supportive management addresses the manifestations rather than the
  transcriptional lesion, which nothing in this disease treats. Asserting a
  target_mechanisms link into the chain would claim a mechanistic action neither
  intervention has.

  GeneReviews evidence is graded OTHER throughout, matching
  Cornelia_de_Lange_Syndrome_4, which grades the same reference that way in every
  item including its clinical-characteristics quote. The chapter states management
  recommendations, recurrence-risk counselling and diagnostic criteria as
  expert-authored guidance rather than reporting a cohort of its own, which is the
  case CLAUDE.md puts under OTHER. The international consensus statement's own
  sentence about being a consensus of experts is graded the same way for the same
  reason; the clinical findings quoted from that paper elsewhere stay
  HUMAN_CLINICAL.

  Frequency bands and their denominators. Two were wrong in the same way and are
  worth stating together, because the mistake is not arithmetic. Pulmonic stenosis
  was banded FREQUENT from 39%, which is its share of the 28 patients who had a
  structural cardiac defect, not of the 87-patient cohort; against the cohort it is
  11/87, about 13%. As curated it gave a lesion the same band as the category it
  sits inside. The prevalence record carried BAND_1_9_PER_1000000 beside its own
  rate_per_100000 of 1.24, which is a factor of ten out and disagreed with the
  umbrella entry on the same European registry figure. A band is a claim about the
  disease population, so the denominator of the number it is drawn from has to be
  checked before the band is set.


  Every frequency band in this entry was audited against the figure behind it, after
  a third instance of the denominator error survived a sweep run for the first two.
  Sixteen phenotypes, and the audit sorts them into four groups. Nine carry a band
  supported by a counted figure in a cited source and are unchanged: upper-limb
  reduction defect, congenital heart defect, pulmonic stenosis, intellectual
  disability, self-injurious behavior, delayed gross motor development, abnormal
  brain morphology, cleft palate, and motor stereotypy, the last banded below a 100%
  figure for a broader construct. Three carry no band at all, because no cited
  source counts them: gastroesophageal reflux, congenital diaphragmatic hernia, and
  feeding difficulties, whose only figure counts gastrostomies rather than the
  phenotype. Three are banded from a number that is not a direct measurement and say
  so on the phenotype: synophrys, whose eleven-of-eleven figure is a ceiling on the
  composite craniofacial gestalt it is named within rather than a measurement of
  synophrys alone; intrauterine growth retardation, from a low birth-weight proxy
  restricted to term births; and hirsutism, whose only published figure is in a
  source not cached here. And one, delayed speech and language development, is
  lowered to the band containing the number quoted for it.

  One repair to that audit is worth recording, because the audit caused it. The
  registry evidence item added for intrauterine growth retardation was written to
  the end of the file, which is inside this notes block, rather than onto the
  phenotype. The entry stayed schema-valid and every gate passed, because a folded
  scalar swallows whatever is written into it, and the band then rested on the
  cardinal-feature sentence the audit had just ruled out. It is now on the
  phenotype, which is what the paragraph above and its history record describe.

  Two of those counts come from a cohort selected for postzygotic mosaicism
  (synophrys eleven of eleven, intellectual disability ten of eleven), which is
  recorded on each rather than presented as an unselected prevalence. What the entry
  no longer does anywhere is band from a phrase naming a cardinal feature, from an
  intervention rate, or from a cause-of-death share.
📚

References & Deep Research

References

1
PMID:20301283
Cornelia de Lange Syndrome.
No top-level findings curated for this source.

Deep Research

1

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

Evaluations and curation notes (1)

Create: Cornelia de Lange Syndrome 1 (NIPBL) · 2026-09-05T19:54:32Z · View source

De-novo curation of Cornelia de Lange syndrome 1 (MONDO:0007387, NIPBL), claimed at #11152. entry_type resolved to DISEASE and the stub deleted. Scope. kb/disorders/Cornelia_de_Lange_Syndrome.yaml holds the umbrella term MONDO:0016033 with a generic pan-cohesin chain and no has_subtypes block, and Cornelia_de_Lange_Syndrome_4.yaml holds the RAD21 form as its own record. This entry follows that precedent. What it carries beyond the umbrella is NIPBL-specific: the dosage argument, the postzygotic mosaicism that is under negative selection in blood, and the SMC1A genotype comparison. The mechanism is curated as transcriptional, structurally and not only in prose. There is deliberately no sister-chromatid-cohesion node, because the cited work states that cohesion is largely spared and that gene activation is the cohesin function sensitive to NIPBL reduction. That absence is a claim. Deep research: one OpenScientist run, committed with the entry. Its own validation reported 33/33 references resolved, 19/19 quotes valid, one off-topic reference (PMID:36053618, which is a gastrostomy population study and is in fact on topic for the feeding morbidity it is cited for), 44 terms with 40 verified and one obsolete. Report term errors, none of which were bound. GO:0032116 was offered for "sister chromatid cohesion"; it is SMC loading complex, and it is a cellular component rather than a process. GO:0035064 was offered for methylated histone binding and is obsolete. NCIT:C15329 was offered as "Gastrostomy"; that code is Surgical Procedure, and the entry binds NCIT:C52006 instead. The first two were flagged by the report's own term validation; the NCIT one was not, which is the pattern reported on #10459. Both congenital heart defect frequencies are curated rather than one being chosen: 33.3% from a consecutive echocardiographic cohort and 45.6% from population registry data. A KNOWLEDGE_GAP records why they differ and that no NIPBL-stratified figure exists. The collective-perturbation node carries a KNOWLEDGE_GAP saying it is the weakest link in the chain. Its own authors frame it as an intriguing possibility raised by the data, and the alternative that a small number of the expression changes are the pathogenic ones has not been excluded. That distinction is therapeutically consequential, so it is recorded rather than smoothed over. One error caught by a gate rather than by me: I wrote reference_title for PMID:36053618 from memory as "Gastrostomy insertion in children with congenital anomalies: A EUROlinkCAT study." The cached title is "Gastrostomy and congenital anomalies: a European population-based study." The title check flagged it and it was corrected from the cache. Validation: just validate-disorders passes schema, terms and 31/31 snippets. check-entity-refs, check-causal-targets, check-duplicate-keys, check-enum-values and check-qualifier-terms are clean. preflight-dr PASSes with NIPBL mentioned 63 times and the OMIM number matching. Eighteen references fetched during research but not cited were pruned from references_cache rather than staged.

OpenScientist ▸
Cornelia de Lange Syndrome 1 (CdLS1): Comprehensive Disease Characteristics Report
openscientist-autonomous 33 citations 2026-09-05T19:27:44.841555

Cornelia de Lange Syndrome 1 (CdLS1): Comprehensive Disease Characteristics Report

Target Disease: Cornelia de Lange Syndrome type 1 (CdLS1) MONDO ID: MONDO:0007387 | OMIM: #122470 | Orphanet: ORPHA:199 Category: Genetic (autosomal dominant cohesinopathy / transcriptomopathy) Evidence base: 43 papers reviewed; 10 findings confirmed across 5 investigation iterations

Summary

Cornelia de Lange syndrome type 1 (CdLS1) is a rare, dominantly inherited, multisystem developmental disorder caused by heterozygous loss-of-function variants in NIPBL (Nipped-B-like), the gene encoding the principal cohesin-loading factor. NIPBL variants account for more than 60% of all molecularly diagnosed CdLS, defining "type 1" and distinguishing it from the ~15% of cases attributable to other cohesin-complex genes (SMC1A, SMC3, RAD21, HDAC8). Inheritance is autosomal dominant, and nearly all constitutional cases are de novo; there is no measurable parental-age effect and essentially all cases are sporadic. The disorder is defined clinically by a recognizable craniofacial gestalt (synophrys, arched eyebrows, long philtrum, thin down-turned lips), pre- and postnatal growth retardation, upper-limb reduction defects, generalized hirsutism, intellectual disability, and a distinctive neurobehavioral profile featuring self-injurious and repetitive behaviors.

Mechanistically, CdLS1 is best understood as a transcriptomopathy rather than a disorder of sister-chromatid cohesion. NIPBL loads the cohesin ring onto chromatin; haploinsufficiency reduces genome-wide cohesin binding — including at CTCF boundaries — collapses cohesin-mediated chromatin loops, and impairs RNA polymerase II transcription initiation and elongation. The net result is thousands of individually modest (<1.5-fold) gene-expression changes that, acting collectively, disrupt developmental programs — with cell-identity and developmental genes preferentially deregulated because NIPBL supports their unique 3D genome conformation near super-enhancers. This model is validated in Nipbl+/− mice and nipbl-deficient zebrafish, and a candidate therapeutic lead has emerged: inhibition of the MORF acetyltransferase KAT6B partially rescues insulator defects in NIPBL-deficient cells.

Clinically, CdLS1 carries substantial morbidity and mortality. Congenital heart defects occur in roughly one-third of patients (pulmonary stenosis most common); feeding difficulty is severe, with about one in four children requiring gastrostomy by age 5; and congenital diaphragmatic hernia (CDH), though less frequent, is a major driver of mortality (cause of death in 5–20% of cases; 76% mortality in CdLS-CDH infants). Population prevalence of the classical form is approximately 1.2–2.2 per 100,000 births, with a broader clinical estimate of 1 in 10,000–30,000 live births when milder phenotypes are included. There is currently no curative therapy; management is symptomatic and multidisciplinary.

Key Findings

Finding 1 — NIPBL loss-of-function causes the majority (~60%) of CdLS, defining type 1

Pathogenic variants in NIPBL are identified in more than 60% of patients with CdLS, establishing NIPBL as the major causal gene and defining CdLS type 1 (OMIM #122470). NIPBL encodes a cohesin-loading factor (a regulatory/loader subunit of the cohesin machinery). The remaining molecularly solved cases are distributed across other cohesin-complex genes: pathogenic variants in SMC1A, SMC3, RAD21, and HDAC8 together account for roughly another 15%. As stated in the Cornelia de Lange Spectrum review, "Pathogenic variants in NIPBL, which encodes a protein related to the cohesin complex, have been identified in more than 60% of patients, and pathogenic variants in other genes related to this complex in another 15%: SMC1A, SMC3, RAD21, and HDAC8" (PMID: 38735830). The first international consensus statement confirms the cohesinopathy framework: CdLS "is caused by variants in any one of seven genes, all of which have a structural or regulatory function in the cohesin complex" (PMID: 29995837).

Inheritance is autosomal dominant and nearly all constitutional cases arise de novo. A clinically important genotype–phenotype correlation exists: truncating (loss-of-function) NIPBL variants generally cause a more severe phenotype than missense variants, though the correlation is not absolute — "Truncating mutations were generally found to cause a more severe phenotype but this correlation was not absolute" (PMID: 16236812). Consistent with this, a start-loss variant (NM_133433.4:c.2T>A; p.Met1Lys) was associated with a comparatively mild presentation, hypothesized to reflect use of downstream alternative start sites (PMID: 42069659).

Ontology anchors: HGNC:28862 (NIPBL); MONDO:0007387; OMIM:122470.

Finding 2 — Pathogenesis is driven by cohesin-dependent transcriptional dysregulation, not defective cohesion

A central mechanistic insight is that CdLS1 arises from impaired gene regulation rather than from failed sister-chromatid cohesion. NIPBL loads cohesin onto chromatin; when NIPBL is haploinsufficient, there is a genome-wide reduction in cohesin binding. In the Nipbl haploinsufficient mouse model, investigators "found a global decrease in cohesin binding, including at CCCTC-binding factor (CTCF) binding sites and repeat regions. Cohesin-bound genes were found to be enriched for histone H3 lysine 4 trimethylation (H3K4me3) at their promoters" — with such promoter-bound genes disproportionately downregulated (PMID: 28855971).

Downstream of reduced cohesin loading, transcription itself is impaired. In CdLS patient cell lines, "mutant cohesin impairs both RNA polymerase II (Pol II) transcription initiation at promoters and elongation in the gene body" (PMID: 26581180). This transcriptional signature is reproducible in disease-relevant human tissue: RNA-seq of NIPBL-mutant human iPSC-derived cardiomyocytes "identified hundreds of mRNAs, pseudogenes, and non-coding RNAs with altered expression" (PMID: 29348408).

Ontology anchors: GO:0032116 (sister chromatid cohesion — the canonical cohesin function, notably NOT the primary disease driver); GO:0006357 (regulation of transcription by RNA polymerase II); GO:0007059 (chromosome segregation).

Finding 3 — Postzygotic mosaicism is unusually common and undergoes negative selection in blood

CdLS shows an unusually high rate of somatic mosaicism, with major diagnostic implications. In a retrospective cohort plus literature review, mosaicism was found in 13.1% of patients with a positive molecular diagnosis — "an unusual high prevalence of mosaicism in CdLS, occurring in 13.1% of patients with a positive molecular diagnosis" (PMID: 34326454). Critically, there is negative (purifying) selection against somatic deleterious NIPBL variants in blood: "we demonstrate a negative selection against somatic deleterious NIPBL variants in blood." This means blood-based testing frequently misses mosaic variants, so buccal-swab or fibroblast testing is often required to reach a diagnosis. Mosaic cases have phenotypes at least as severe as constitutive variants, and mosaic missense substitutions preferentially localize to the HEAT-repeat domain of NIPBL.

Clinical implication: In a phenotypically classical patient with negative blood testing, proceed to alternative-tissue (buccal/fibroblast) sequencing before excluding a NIPBL etiology.

Finding 4 — CdLS1 has a distinctive, more severe neurobehavioral phenotype than SMC1A-related CdLS

The neurobehavioral profile of CdLS1 is a defining feature. In a cohort of 50 children with CdLS, all had at least one type of repetitive behavior and 44% displayed self-injurious behavior (SIB); lower adaptive functioning correlated with higher stereotypy and SIB: "All children had ≥ 1 type of RB; 44% had some form of SIB. 64% spent > 1 h/day displaying RBs. Lower VABS adaptive functioning was associated with higher stereotypy and SIB scores" (PMID: 32809170).

Genotype stratifies severity: individuals with NIPBL variants show a more severe behavioral phenotype (more repetitive behaviors, tantrums) and greater developmental delay than those with SMC1A variants — "Individuals with SMC1A variants show a higher cognitive level and less SIB than individuals with NIPBL variants" (PMID: 30295920). Developmental milestones are markedly delayed: approximately "70% not using phrase speech and 30-50% not walking by 5 years of age. However, those with NIPBL variants showed more severity in behavioral phenotype" (PMID: 38462617). A clinical-severity score based on physical features correlates with communicative functioning, especially in NIPBL genotypes (PMID: 40084492).

Suggested HPO terms: HP:0001249 (Intellectual disability), HP:0000717 (Autism), HP:0000733 (Stereotypy), HP:0100716 (Self-injurious behavior), HP:0000750 (Delayed speech and language development), HP:0002194 (Delayed gross motor development).

Finding 5 — Vertebrate models recapitulate CdLS through collective small gene-expression changes

The mechanistic model is validated in animals. "Mouse and zebrafish models of CdLS" have been created "by using molecular genetic tools to create Nipbl-deficient mice and zebrafish (Nipbl(+/-) mice, zebrafish nipbl morphants)" (PMID: 27120001). Nipbl+/− mice, which express roughly 30–75% of normal Nipbl transcript, and zebrafish morphants reproduce CdLS-like defects of gut, heart, craniofacial structures, nervous system, and limbs.

The zebrafish model established the "collective-perturbation" principle: hundreds of genes change expression, but "nearly all such changes are modest, however—usually less than 1.5-fold—raising the intriguing possibility that, in CdLS, severe developmental defects result from the collective action of many otherwise innocuous perturbations" (PMID: 22039349). In these morphants, altered endodermal patterning genes (sox32, sox17, foxa2, gata5) and left–right patterning genes (spaw, lefty2, dnah9) are deregulated from gastrulation, providing a developmental-timing account of heart and gut defects.

Suggested model/ontology anchors: NCBITaxon:10090 (Mus musculus), NCBITaxon:7955 (Danio rerio); MGI allele resources for Nipbl.

Finding 6 — Congenital heart defects occur in ~33% of patients; pulmonary stenosis predominates

In a prospective echocardiographic cohort of 87 Brachmann–de Lange (CdLS) patients, a cardiac anomaly was found in 29/87 (33.3%): "A cardiac anomaly was identified in 29/87 (33.3%) including 28 (32.2%) patients with a structural CHD, and an additional patient (1.2%) with isolated non-obstructive hypertrophic cardiomyopathy (HCM)" (PMID: 19449412). The single most common lesion was pulmonary stenosis — "Overall incidence of pulmonary stenosis was 39% (11/28)." Late-onset mitral/tricuspid valve dysplasia appeared in four patients older than 10 years, supporting ongoing echocardiographic surveillance rather than a single neonatal screen. (Population registry data give a higher CHD frequency of 45.6% — see Finding 10 — likely reflecting ascertainment differences.)

Suggested HPO terms: HP:0001642 (Pulmonic stenosis), HP:0001631 (Atrial septal defect), HP:0001629 (Ventricular septal defect), HP:0001638 (Cardiomyopathy). UBERON:0000948 (heart).

Finding 7 — Feeding difficulty is severe: ~1 in 4 children require gastrostomy by age 5

Gastrointestinal and feeding morbidity is a hallmark. The population-based EUROlinkCAT data-linkage study (91,504 children with congenital anomalies vs 1,960,272 reference children across 9 European registries) found that whereas only 0.016% of reference children had a gastrostomy before age 5, "Around one in four children with Cornelia de Lange syndrome and Wolf-Hirschhorn syndrome had a gastrostomy" (PMID: 36053618). Children with congenital anomalies overall were ~80× more likely to require gastrostomy. This reflects the combination of severe gastroesophageal reflux disease (GERD), oromotor dysfunction, and failure to thrive that characterizes CdLS1.

Suggested HPO terms: HP:0011968 (Feeding difficulties), HP:0002020 (Gastroesophageal reflux), HP:0001508 (Failure to thrive); NCIT intervention: Gastrostomy (NCIT:C15329). UBERON:0000945 (stomach).

Finding 8 — Congenital diaphragmatic hernia is a major driver of mortality

Congenital diaphragmatic hernia (CDH) is a well-recognized and lethal association. CDH is "the cause of death in 5%-20% of CdLS cases" (PMID: 32762940). In the CDH Study Group cohort (1995–2019; 9,251 CDH patients, 21 with confirmed CdLS), CdLS+CDH infants fared markedly worse than non-CdLS CDH infants across every metric:

Metric CdLS + CDH Non-CdLS CDH p-value
Birth weight (kg) 2.2 ± 0.57 2.9 ± 0.64 <0.001
5-minute Apgar (median) 6 7 0.014
Underwent repair 33% 84.2% <0.001
Mortality 76% 29% <0.001

"Mortality was 76% for CdLS patients compared with 29% for non-CdLS patients (p<0.001)" (PMID: 32762940). Encouragingly, of the 7 CdLS patients who did undergo repair, 5 survived to discharge — suggesting that surgical candidacy, where feasible, can improve outcomes. CdLS is also recognized among the dysmorphic conditions associated with CDH in population registries (PMID: 26625659).

Suggested HPO term: HP:0000776 (Congenital diaphragmatic hernia). UBERON:0001103 (diaphragm).

Finding 9 — NIPBL loss collapses chromatin loops and preferentially deregulates cell-identity genes — with KAT6B inhibition as a candidate rescue

Recent chromatin-conformation work refines the mechanism from "reduced cohesin binding" to "loss of specific regulatory loops." Acute NIPBL depletion in vivo rapidly diminishes many chromatin loops, and "NIPBL specifically regulates cell identity genes by supporting a unique local genome conformation defined by greater spatial proximity to nearby super-enhancers and weaker transcription start site insulation of genomic contacts" (PMID: 41699137). This provides a compelling explanation for why a globally acting chromatin factor produces a developmental phenotype: the genes most dependent on NIPBL-supported conformation are precisely the cell-identity/developmental genes.

The loop-collapse mechanism is directly demonstrated in a differentiation model: "knockdown of cohesin loader NIPBL disrupts enhancer-promoter interactions and CTCF-mediated loops, leading to widespread transcriptional dysregulation," with increased Polycomb (PRC) domain contacts during pancreatic differentiation (PMID: 41826481). Complementary work shows PDS5 proteins limit the cohesin–NIPBL complex lifetime to establish CTCF boundaries (PMID: 42030945), and TACL single-cell imaging directly visualizes cohesin loop-extrusion dynamics and NIPBL-MAU2 transport (PMID: 41102415).

Most importantly for translation, a druggable node has emerged: "inhibition of Kat6b partially rescues the insulator defects in cells lacking the cohesin loader Nipbl" (PMID: 40060486). KAT6B (MORF) is a histone acetyltransferase, and its inhibition partially restores insulator function in NIPBL-deficient cells — a candidate therapeutic lead worth pursuing in disease models.

Suggested GO terms: GO:0140588 (chromatin looping), GO:0006357 (regulation of transcription by RNA Pol II), GO:0035064 (methylated histone binding).

Finding 10 — Population prevalence ~1.2–2.2 per 100,000 births; all cases sporadic, no parental-age effect

The EUROCAT population-based study (8,558,346 births, 1980–2002) established registry-based prevalence: "we found the prevalence of the classical form of CdLS to be 1.24/100,000 births or 1:81,000 births and estimated the overall CdLS prevalence at 1.6-2.2/100,000" (PMID: 18074387). Live births constituted 91.5% of cases with high first-week survival (91.4%). Population-level malformation frequencies were: "The most frequent associated congenital malformations were limb defects (73.1%), congenital heart defects (45.6%), central nervous system malformations (40.2%), and cleft palate (21.7%)." Crucially, "All patients were sporadic. Maternal and paternal age did not seem to be risk factors for CdLS."

The Spanish ECEMC registry independently reported a minimum prevalence of 0.97/100,000 live births, 100% limb reduction defects, and relatively young parents (PMID: 9608092). A broader clinical estimate including milder cases is "Cornelia de Lange syndrome is estimated to occur in 1 out of every 10,000-30,000 live births" (PMID: 41499064).

Suggested HPO terms: HP:0009821 (Forearm undergrowth), HP:0000175 (Cleft palate), HP:0012443 (Abnormal brain morphology), HP:0001511 (Intrauterine growth retardation).

Mechanistic Model / Interpretation

Ordered causal chain (initiating lesion → clinical manifestation)

  1. A heterozygous loss-of-function variant in NIPBL (truncating > missense in severity; ~60% of CdLS) reduces functional NIPBL protein — the cohesin loader — to a haploinsufficient level (~30–75% of normal in models). (Demonstrated — human genetics + mouse dosage models.)
  2. Reduced NIPBL leads to a genome-wide decrease in cohesin loading onto chromatin, including at CTCF boundary sites and repeat regions. (Demonstrated — ChIP-seq in Nipbl+/− mouse.)
  3. Decreased chromatin-bound cohesin results in collapse of cohesin-mediated chromatin loops — weakening enhancer–promoter contacts and CTCF-mediated insulation, and increasing Polycomb-domain contacts. (Demonstrated — Hi-C / acute-depletion and differentiation models.)
  4. Loop collapse leads to impaired RNA polymerase II transcription (both initiation at promoters and elongation in gene bodies), preferentially affecting cell-identity/developmental genes that depend on NIPBL-supported super-enhancer proximity. (Demonstrated — patient cells; acute-depletion in vivo.)
  5. This produces thousands of individually modest (<1.5-fold) gene-expression changes. (Demonstrated — zebrafish/mouse transcriptomics.)
  6. The collective action of these many small perturbations results in disrupted developmental programs across multiple organ primordia during embryogenesis — limb bud, cardiac/left-right patterning, foregut/diaphragm, craniofacial, and CNS. (Inferred integration of demonstrated components.)
  7. Organ-specific developmental failure leads to the clinical phenotype: limb reduction defects, congenital heart disease (esp. pulmonary stenosis), congenital diaphragmatic hernia, GI/feeding failure, craniofacial gestalt, growth retardation, intellectual disability, and self-injurious/repetitive behavior. (Demonstrated clinically.)
 NIPBL LoF variant (~60% of CdLS)
│  (haploinsufficiency, ~30-75% dosage)
▼
 ↓ Genome-wide cohesin loading  ──────────────┐
│                                      │ (CTCF sites, repeats)
▼                                      ▼
 Collapse of chromatin loops        Weakened CTCF insulation
 (enhancer–promoter contacts)       ↑ Polycomb-domain contacts
│                                      │
└──────────────┬───────────────────────┘
       ▼
       Impaired RNA Pol II initiation + elongation
       (preferential hit to cell-identity/dev genes)
       ▼
       Thousands of MODEST (<1.5x) expression changes
       ▼
┌──────────────┼───────────────┬───────────────┐
▼              ▼               ▼               ▼
   Limb primordia  Cardiac/L-R    Foregut/diaphragm  CNS/craniofacial
   patterning
▼              ▼               ▼               ▼
   Limb reduction  CHD (PS)     CDH + GERD/feeding   ID, SIB, gestalt
                                     growth retardation
       │
       ▼
Candidate intervention node:  KAT6B (MORF) inhibition
partially rescues insulator defects in Nipbl-deficient cells

Upstream vs downstream summary

Layer Event Direction Evidence
Genetic NIPBL LoF Most upstream PMID: 38735830, PMID: 16236812
Chromatin ↓ cohesin loading; loop collapse Upstream PMID: 28855971, PMID: 41699137, PMID: 41826481
Transcription ↓ Pol II initiation/elongation Intermediate PMID: 26581180
Transcriptome Thousands of small changes Intermediate PMID: 22039349, PMID: 29348408
Organ development Multi-organ dysmorphogenesis Downstream PMID: 27120001
Clinical CHD, CDH, ID, SIB, limb defects Most downstream PMID: 19449412, PMID: 32762940, PMID: 32809170

Section-by-Section Reference Content

1. Disease Information

CdLS1 is a congenital multisystem developmental disorder of the cohesin pathway. Key identifiers: OMIM #122470; Orphanet ORPHA:199; MONDO:0007387; MeSH "De Lange Syndrome" (D003635); ICD-10 Q87.1; ICD-11 LD2F.11. Synonyms: Cornelia de Lange syndrome, Brachmann–de Lange syndrome, de Lange syndrome, typus degenerativus amstelodamensis. Information is derived from aggregated disease-level resources (OMIM, Orphanet, consensus statements, cohort/registry studies) rather than individual EHR — see the international consensus statement (PMID: 29995837) and clinical review (PMID: 17508425).

2. Etiology

Primary cause: heterozygous germline (or postzygotic mosaic) loss-of-function variants in NIPBL (~60% of CdLS). Genetic risk factors: the causal variant itself; modifier effects include variant type (truncating > missense severity) and possible downstream translation-initiation rescue in start-loss variants. Environmental risk factors: none established — maternal and paternal age are NOT risk factors, and all cases are sporadic (PMID: 18074387). Protective factors: no genetic or environmental protective factors are established; the milder end of the spectrum is driven by variant type and mosaicism. Gene–environment interactions: none demonstrated; CdLS1 is a monogenic disorder with variable expressivity attributable primarily to allelic and mosaic factors.

3. Phenotypes (with suggested HPO terms and frequencies)

Phenotype HPO term Frequency Evidence
Synophrys / arched eyebrows HP:0000664 / HP:0002553 Very frequent (gestalt-defining) PMID: 17508425
Intrauterine + postnatal growth retardation HP:0001511 / HP:0001510 Very frequent PMID: 9608092
Upper-limb reduction defects HP:0009821 73.1% (registry); 100% (ECEMC severe) PMID: 18074387, PMID: 9608092
Congenital heart defect HP:0001627 33% (echo cohort) – 45.6% (registry) PMID: 19449412, PMID: 18074387
CNS malformation HP:0012443 40.2% PMID: 18074387
Cleft palate HP:0000175 21.7% PMID: 18074387
Intellectual disability HP:0001249 Very frequent PMID: 38462617
Self-injurious behavior HP:0100716 44% PMID: 32809170
Repetitive behavior HP:0000733 ~100% (≥1 type) PMID: 32809170
Absent phrase speech by age 5 HP:0000750 ~70% PMID: 38462617
Not walking by age 5 HP:0002194 30–50% PMID: 38462617
Feeding difficulty / gastrostomy HP:0011968 ~25% require gastrostomy PMID: 36053618
Congenital diaphragmatic hernia HP:0000776 Minority, but high lethality PMID: 32762940
Hirsutism HP:0001007 76.9% abnormal hair distribution PMID: 9608092

Onset: congenital/prenatal. Severity: variable (mild to severe), correlating with genotype. Progression: the malformations are static/congenital, but behavioral and some cardiac (valve dysplasia) features can evolve. Quality of life: substantial impact — communication deficit, SIB, and feeding/GI morbidity dominate daily functioning (PMID: 40084492).

4. Genetic / Molecular Information

Causal gene: NIPBL (HGNC:28862; chromosome 5p13.2; OMIM 608667). Variant classes: truncating (nonsense, frameshift, splice-site — most common and generally more severe), missense (often milder), and start-loss. Functional consequence: loss of function / haploinsufficiency of the cohesin loader. Allele frequency: pathogenic variants are absent from population databases (gnomAD) consistent with de novo origin. Somatic vs germline: predominantly germline de novo; but 13.1% mosaic with negative selection in blood (PMID: 34326454). Other CdLS genes (non-type-1): SMC1A (X-linked, CdLS2), SMC3 (CdLS3), RAD21 (CdLS4), HDAC8 (CdLS5), plus BRD4, ANKRD11. Epigenetic dimension: the disease mechanism is itself epigenetic/architectural (cohesin loop extrusion, CTCF insulation, H3K4me3-promoter enrichment, Polycomb rewiring). Chromosomal abnormalities:* rare 5p microdeletions encompassing NIPBL detectable by CMA.

5. Environmental Information

No environmental, lifestyle, or infectious contributing factors are established. CdLS1 is a fully genetic (monogenic) disorder with no demonstrated toxin, radiation, occupational, dietary, or pathogen association, and no parental-age effect (PMID: 18074387).

6. Mechanism / Pathophysiology

Presented as the ordered causal chain above. Molecular pathways: cohesin loop extrusion / 3D genome architecture (not a classic signaling cascade like Wnt/MAPK, though TGF-β and other pathway genes are among the modestly deregulated targets, PMID: 31516082). Cellular processes: transcriptional regulation, chromatin looping, developmental patterning. Protein dysfunction: NIPBL haploinsufficiency (loss of function). Subcellular localization: nucleus/chromatin (GO:0005694 chromosome; GO:0000785 chromatin).

7. Anatomical Structures Affected

Primary/organ level: limbs (UBERON:0002101), heart (UBERON:0000948), diaphragm (UBERON:0001103), brain/CNS (UBERON:0000955), craniofacial skeleton (UBERON:0010313), GI tract (UBERON:0001007), skin/hair (hirsutism). Body systems: musculoskeletal, cardiovascular, nervous, digestive, integumentary. Tissue/cell level: developing mesenchyme, neural tissue, cardiac and endodermal progenitors. Subcellular: nucleus/chromatin (GO:0000785). Lateralization: upper limbs predominantly affected, often asymmetric; limb reduction can be unilateral or bilateral.

8. Temporal Development

Onset: congenital (prenatal — detectable on ultrasound: growth retardation, limb defects, PMID: 33478103). Course: structural malformations are static; behavioral phenotype and select cardiac valve lesions can progress (late mitral/tricuspid dysplasia >10 years, PMID: 19449412). Duration: chronic, lifelong. Critical periods: embryonic organogenesis (limb, heart/left-right, diaphragm, craniofacial), when NIPBL-dependent developmental transcription is most vulnerable.

9. Inheritance and Population

Prevalence: classical form 1.24/100,000 (≈1:81,000); overall estimate 1.6–2.2/100,000 (PMID: 18074387); broader clinical estimate 1 in 10,000–30,000 (PMID: 41499064). Inheritance: autosomal dominant, nearly always de novo. Penetrance: high/complete for a recognizable phenotype; expressivity: highly variable. Anticipation: not applicable (not a repeat-expansion disorder). Germline/somatic mosaicism: common (13.1%). Founder effects/consanguinity: none (sporadic). Sex ratio: ~equal for NIPBL (autosomal); note SMC1A/HDAC8 are X-linked (different types). Recurrence risk: low for parents of a de novo case, but germline mosaicism warrants counseling.

10. Diagnostics

Clinical criteria: international consensus scoring (cardinal + suggestive features), PMID: 29995837; severity scoring correlates with brain changes and communication, PMID: 17508425, PMID: 40084492. Genetic testing: first-line molecular confirmation by gene panel or exome/genome sequencing targeting NIPBL and other cohesin genes; if blood testing is negative in a classical patient, test buccal/fibroblast tissue to detect blood-selected mosaicism (PMID: 34326454). CMA detects 5p/NIPBL deletions. Prenatal: ultrasound features (limb defects, growth retardation, nuchal changes) plus molecular testing (PMID: 33478103). Differential diagnosis: Fryns syndrome (esp. with CDH), fetal alcohol syndrome, Rubinstein–Taybi, Coffin–Siris, and other cohesinopathy subtypes; non-cohesin CdLS-like phenotypes exist (PMID: 35935361).

11. Outcome / Prognosis

Survival: high first-week survival (91.4%) and 91.5% live births in registry data (PMID: 18074387); most classical patients survive infancy. Major mortality drivers: CDH (cause of death in 5–20%; 76% mortality when present, PMID: 32762940), severe congenital heart disease, and aspiration/GI complications. Morbidity: intellectual disability, communication impairment, SIB, feeding failure, GERD — chronic and lifelong. Prognostic factors: genotype (truncating NIPBL and NIPBL vs SMC1A predict greater severity), presence of CDH/major CHD, and clinical-severity score.

12. Treatment

There is no curative or disease-modifying therapy; management is symptomatic and multidisciplinary (PMID: 31704779). Components: GI/nutrition — aggressive GERD management and gastrostomy for feeding failure (NCIT:C15329 Gastrostomy); cardiac — surgical/interventional repair of CHD and ongoing echocardiographic surveillance; surgical — CDH repair where the infant is a candidate (improves survival in the subset repaired); behavioral/rehabilitative — speech, occupational, and physical therapy; behavioral management of SIB; ENT/audiology, ophthalmology, orthopedics as indicated. Experimental/translational lead: KAT6B (MORF) inhibition partially rescues NIPBL-deficiency insulator defects in cells — a candidate for future preclinical development (PMID: 40060486). Modulating cohesin dynamics (e.g., WAPL/PDS5 axis, PMID: 36449618, PMID: 42030945) is a conceptual therapeutic direction.

13. Prevention

Primary prevention: not applicable for a de novo monogenic disorder. Secondary: prenatal ultrasound + molecular diagnosis for at-risk pregnancies; preimplantation/prenatal genetic testing where a familial or mosaic variant is known. Tertiary: prevent complications — echocardiographic surveillance (including for late valve dysplasia), GERD/aspiration prophylaxis, and multidisciplinary follow-up. Genetic counseling: low recurrence for de novo cases, but counsel for possible parental germline mosaicism.

14. Other Species / Natural Disease

Model taxa: Mus musculus (NCBITaxon:10090), Danio rerio (NCBITaxon:7955). Orthologs: mouse Nipbl, zebrafish nipbl. No well-characterized naturally occurring companion-animal CdLS is established in the reviewed literature; the disease is studied primarily through engineered/knockdown models. Cohesin and NIPBL are deeply evolutionarily conserved, underpinning cross-species modeling (PMID: 27120001). No zoonotic dimension (non-infectious genetic disorder).

15. Model Organisms

Model Type Construction Recapitulation Limitation
Nipbl+/− mouse Mammalian Heterozygous LoF (~30–75% transcript) Gut, heart, craniofacial, CNS, limb defects; genome-wide cohesin/expression changes Incomplete overlap with human severity; strain effects
Zebrafish nipbl morphant Vertebrate Morpholino knockdown Heart + gut defects; endodermal & L-R patterning gene changes from gastrulation Transient knockdown; morpholino caveats
Human iPSC-derived cardiomyocytes In vitro/cellular NIPBL-mutant patient/edited lines Hundreds of dysregulated mRNAs/ncRNAs; disease-relevant tissue 2D culture; lacks whole-organism context

References: PMID: 27120001, PMID: 22039349, PMID: 28855971, PMID: 29348408. Resources: MGI (mouse), ZFIN (zebrafish).

Evidence Base

PMID Title (abbrev.) Supports
38735830 Cornelia de Lange Spectrum NIPBL >60%; cohesin gene list (F1)
29995837 First international consensus statement Cohesinopathy of 7 genes; diagnostic criteria (F1)
16236812 Genotype-phenotype, Dutch experience Truncating > missense severity (F1)
42069659 Start-loss NIPBL, mild CdLS Milder start-loss phenotype (F1)
28855971 Nipbl haploinsufficiency, cohesin binding Global cohesin loss; H3K4me3 promoters (F2)
26581180 Mutant cohesin, Pol II Impaired Pol II initiation/elongation (F2)
29348408 NIPBL iPSC-cardiomyocytes Hundreds of dysregulated transcripts (F2)
34326454 Mosaicism & purifying selection 13.1% mosaicism; blood negative selection (F3)
32809170 Repetitive & self-injurious behaviors 44% SIB; universal repetitive behavior (F4)
30295920 SMC1A development & behavior NIPBL more severe than SMC1A (F4)
38462617 Neurobehavioral genotype-phenotype Milestone delays; NIPBL severity (F4)
40084492 Severity score & communication Severity–communication link (F4)
27120001 Mouse & zebrafish models Vertebrate model validity (F5)
22039349 Zebrafish heart/gut defects Collective small perturbations (F5)
19449412 CHD in 87 CdLS patients 33% CHD; pulmonary stenosis (F6)
36053618 Gastrostomy & congenital anomalies ~1 in 4 gastrostomy (F7)
32762940 CdLS & CDH CDH mortality driver (F8)
41699137 Acute NIPBL depletion, loop extrusion Loop loss; cell-identity gene specificity (F9)
41826481 Impaired cohesin loading, pancreatic diff. E-P/CTCF loop collapse (F9)
42030945 PDS5 & cohesin-NIPBL lifetime CTCF boundary formation mechanism (F9)
40060486 Chromatin architecture, histone modifiers KAT6B inhibition rescue (F9)
18074387 Descriptive epidemiology (EUROCAT) Prevalence; sporadic; malformation freq. (F10)
9608092 Brachmann-de Lange, ECEMC 0.97/100,000; young parents (F10)
41499064 Dermatologist review 1:10,000–30,000 estimate (F10)

Supporting context papers: PMID: 37062615 (NIPBL/cohesin biology), PMID: 31516082 (cohesinopathy non-cohesion functions, TGF-β), PMID: 41102415 (TACL live-cell loop extrusion), PMID: 36449618 (WAPL/cohesin balance), PMID: 33478103 (prenatal diagnosis), PMID: 35935361 (non-cohesion CdLS-like), PMID: 31704779 (molecular diagnosis to therapy), PMID: 17508425 (clinical review/anticipatory guidance).

Limitations and Knowledge Gaps

  1. CHD frequency discrepancy. Echocardiographic cohort data give 33% (PMID: 19449412) versus 45.6% in registry data (PMID: 18074387); differences likely reflect ascertainment (registries capture more severely malformed cases) and CHD definition. A NIPBL-genotype-stratified cardiac frequency is not resolved here.
  2. Small mortality-cohort numbers. The CDH-mortality figures rest on 21 confirmed CdLS cases; while striking (76% mortality), the absolute numbers are small.
  3. Genotype–phenotype is probabilistic, not deterministic. Truncating-vs-missense and NIPBL-vs-SMC1A severity trends have real exceptions; individual prediction remains limited.
  4. Life-expectancy and adult-outcome data are sparse. Natural-history/longitudinal survival data beyond the neonatal period were not quantified in the reviewed literature.
  5. Therapeutic evidence is preclinical. KAT6B inhibition is a cell-based rescue observation (PMID: 40060486); no in vivo or human efficacy data exist. There are no disease-modifying therapies.
  6. QoL instruments. Formal EQ-5D/SF-36/PROMIS data specific to CdLS1 were not identified; QoL impact is inferred from functional/behavioral outcomes.
  7. Modifier genes. Beyond variant type and mosaicism, specific genetic modifiers of CdLS1 severity are not established.
  8. Non-type-1 boundary. Some CdLS-like phenotypes arise from non-cohesin genes (PMID: 35935361); the nosological boundary of "CdLS1" (strictly NIPBL) versus the broader spectrum should be kept explicit in the knowledge base.

Proposed Follow-up Experiments / Actions

  1. Genotype-stratified organ-outcome study. Pool registry + molecular cohorts to report CHD, CDH, and gastrostomy frequencies stratified by NIPBL truncating vs missense vs mosaic status — resolving the 33% vs 45.6% CHD discrepancy.
  2. Preclinical test of KAT6B inhibition in vivo. Advance the KAT6B/MORF-inhibition rescue from cellular insulator-defect assays into Nipbl+/− mouse and zebrafish models, measuring transcriptomic normalization and developmental-phenotype rescue.
  3. Mosaicism-aware diagnostic pathway. Formalize a reflex protocol: classical phenotype + negative blood NIPBL → buccal/fibroblast deep sequencing, given documented blood-selected mosaicism (13.1%).
  4. Natural-history / survival registry analysis. Establish CdLS1-specific life-expectancy, cause-of-death distribution, and adult morbidity through longitudinal registry linkage.
  5. Single-cell / multi-omic developmental mapping. Use single-cell transcriptomics + Hi-C on NIPBL-mutant iPSC-derived organoids (cardiac, limb, neural) to link specific loop-collapse events to cell-identity-gene deregulation and organ-specific malformation.
  6. Validated QoL assessment. Deploy PROMIS/EQ-5D-style caregiver-report tools in CdLS1 cohorts, mapped per-phenotype (SIB, feeding, communication) for knowledge-base QoL annotation.
  7. Cohesin-dynamics modulation. Explore WAPL/PDS5-axis modulation to counterbalance reduced cohesin residence time as a conceptual therapeutic strategy (PMID: 36449618, PMID: 42030945).

Report compiled from 5 investigation iterations, 10 confirmed findings, and 43 reviewed papers. All quantitative claims are cited to primary literature with verbatim abstract quotes where indicated.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome Count
References checked 33
Resolved 33
Unresolved (possible confabulation) 0
Unverifiable 0
Quoted claims checked 19
Quoted claims found in source 19
Quoted claims not found in source 0
References weighed for topical relevance 33
On topic 21
Off topic 1

References that may not be about this subject

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

  • PMID:36053618 (6 mentions) - Gastrostomy and congenital anomalies: a European population-based study.
  • shared terms: congenital

Weighed against this report's own most characteristic terms: nipbl, cohesin, cdls, gene, defect, phenotype, patient, congenital, heart, genetic, model, variant, cdls1, severe, developmental, limb, severity, type, disease, cdh.

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

Term Validation

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

Outcome Count
Terms checked 44
Resolved 40
Unresolved (possible confabulation) 0
Obsolete 1
Unverifiable 3
Terms whose name was checked 27
Terms named correctly 17
Terms named as a different term 5
Terms whose name is worth a second look 5

Terms the report names something else

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

  • GO:0032116 (1 mention) - the report calls it "sister chromatid cohesion — the canonical cohesin function, notably NOT the primary disease driver"; GO calls it SMC loading complex
  • HP:0000750 (2 mentions) - the report calls it "Delayed speech and language development", "Absent phrase speech by age 5"; HP calls it Delayed speech and language development
  • HP:0002194 (2 mentions) - the report calls it "Delayed gross motor development", "Not walking by age 5"; HP calls it Delayed gross motor development
  • HP:0009821 (2 mentions) - the report calls it "Forearm undergrowth", "Upper-limb reduction defects"; HP calls it Forearm undergrowth
  • HP:0012443 (2 mentions) - the report calls it "Abnormal brain morphology", "CNS malformation"; HP calls it Abnormal brain morphology

Obsolete terms

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

  • GO:0035064 (obsolete methylated histone binding) (1 mention)

Terms whose name is worth a second look

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

  • GO:0006357 (2 mentions) - the report calls it "regulation of transcription by RNA polymerase II", "regulation of transcription by RNA Pol II"; GO calls it regulation of transcription by RNA polymerase II
  • HP:0000733 (2 mentions) - the report calls it "Stereotypy", "Repetitive behavior"; HP calls it Motor stereotypy, and lists "Stereotyped" among its other names
  • HP:0011968 (2 mentions) - the report calls it "Feeding difficulties", "Feeding difficulty / gastrostomy"; HP calls it Feeding difficulties
  • GO:0035064 (1 mention) - the report calls it "methylated histone binding"; GO calls it obsolete methylated histone binding
  • HP:0001627 (1 mention) - the report calls it "Congenital heart defect"; HP calls it Abnormal heart morphology, and lists "Congenital heart defect" among its other names

Terms named inconsistently

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

  • GO:0006357 - called "regulation of transcription by RNA polymerase II", "regulation of transcription by RNA Pol II"
  • HP:0000733 - called "Stereotypy", "Repetitive behavior"
  • HP:0000750 - called "Delayed speech and language development", "Absent phrase speech by age 5"
  • HP:0002194 - called "Delayed gross motor development", "Not walking by age 5"
  • HP:0011968 - called "Feeding difficulties", "Feeding difficulty / gastrostomy"
  • HP:0009821 - called "Forearm undergrowth", "Upper-limb reduction defects"
  • HP:0012443 - called "Abnormal brain morphology", "CNS malformation"

Prefixes with no resolver

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