Cornelia De Lange Syndrome

Clinical characteristics.

Cornelia de Lange syndrome (CdLS) encompasses a spectrum of findings from mild to severe. Severe (classic) CdLS is characterized by distinctive facial features, growth restriction (prenatal onset; <5th centile throughout life), hypertrichosis, and upper-limb reduction defects that range from subtle phalangeal abnormalities to oligodactyly (missing digits). Craniofacial features include synophrys, highly arched and/or thick eyebrows, long eyelashes, short nasal bridge with anteverted nares, small widely spaced teeth, and microcephaly. Individuals with a milder phenotype have less severe growth, cognitive, and limb involvement, but often have facial features consistent with CdLS. Across the CdLS spectrum IQ ranges from below 30 to 102 (mean: 53). Many individuals demonstrate autistic and self-destructive tendencies. Other frequent findings include cardiac septal defects, gastrointestinal dysfunction, hearing loss, myopia, and cryptorchidism or hypoplastic genitalia.

Diagnosis/testing.

The diagnosis of CdLS is established in a proband with suggestive clinical features and/or by identification of a heterozygous pathogenic variant in NIPBL, RAD21, SMC3, or BRD4, or a hemizyous pathogenic variant in HDAC8 or SMC1A by molecular genetic testing.

Management.

Treatment of manifestations: Aggressive management of gastroesophageal reflux with assessment of potential gastrointestinal malrotation; consideration of fundoplication if reflux is severe. Supplementary formulas and/or gastrostomy tube placement to meet nutritional needs as necessary. Physical, occupational, and speech therapy to optimize psychomotor development and communication skills. Standard treatment for epilepsy, vision issues, nasolacrimal duct obstruction, hearing loss, cleft palate, anomalies of tooth formation and/or position, cardiac defects, cryptorchidism/hypospadias, bicornuate uterus, vesicoureteral reflux, anemia and/or thrombocytopenia, and immunodeficiency. If surgery is being considered, malignant hyperthermia precautions and preoperative evaluation for thrombocytopenia and cardiac disease with careful monitoring of the airway during anesthesia are recommended.

Surveillance: At each visit: measurement of growth parameters and evaluation of nutritional status and safety of oral intake; monitor for signs and symptoms of GERD and for evidence of aspiration with respiratory insufficiency; assessment for new manifestations such as seizures or signs of autonomic dysfunction; monitor developmental progress and educational needs; behavioral assessment for anxiety, attention, and aggressive or self-injurious behavior; assessment of mobility and self-help skills. At least annually: ophthalmology evaluation; dental evaluation with cleaning; audiology evaluation in childhood and adolescence.

Genetic counseling.

NIPBL-CdLS, RAD21-CdLS, SMC3-CdLS and BRD4-CdLS are inherited in an autosomal dominant manner; HDAC8-CdLS and SMC1A-CdLS are inherited in an X-linked manner. The majority of affected individuals have a de novo heterozygous pathogenic variant in NIPBL. Fewer than 1% of individuals with autosomal dominant CdLS have an affected parent. When the parents are clinically unaffected, the risk to the sibs of a proband with CdLS is estimated to be 1.5% because of the possibility of germline mosaicism. The risk to sibs of a male proband with X-linked CdLS depends on the status of the proband's mother; the risk to sibs of a female proband with X-linked CdLS depends on the status of the proband's mother and father. Prenatal testing for a pregnancy at increased risk and preimplantation genetic testing are possible for families in which the pathogenic variant has been identified.

Suggestive Findings

Cornelia de Lange syndrome (CdLS) should be suspected in individuals with the following clinical and radiographic features.

Clinical findings

• Distinctive craniofacial appearance (often recognizable; see Figure 1) including:
  • Microcephaly (mean occipital frontal circumference <2nd centile)
  • Synophrys with highly arched and/or thick eyebrows
  • Long, thick eyelashes
  • Short nasal bridge, upturned nasal tip with anteverted nares
  • Long and/or smooth philtrum, thin vermilion of the upper lip, downturned corners of the mouth
  • Highly arched palate with or without cleft palate
  • Small widely spaced teeth
  • Micrognathia with or without mandibular spurs
• Growth failure, which may be detected prenatally and persists postnatally
• Developmental delay / intellectual disability, varying from mild to profound
• Limb abnormalities (either symmetric or asymmetric) ranging from severe reduction defects with complete absence of the forearms, to various forms of oligodactyly (missing digits) involving primarily the upper extremities, to small hands (micromelia) and phalangeal abnormalities (5th digit clinodactyly and short first metacarpal resulting in a proximally placed thumb) at the mild end
• Hypertrichosis. Thick scalp hair that often extends onto the temporal regions and at times involves the face, ears, back, and arms

Figure 1.

Classic CdLS craniofacial features

Radiographic findings. In those without limb deficiencies, the presence of a short first metacarpal on plain x-ray resulting in a proximally placed thumb can be useful in diagnosis.

Establishing the Diagnosis

The diagnosis of CdLS is established in a proband with the above clinical features and/or by the identification on molecular genetic testing of a heterozygous pathogenic variant in NIPBL, RAD21, SMC3, or BRD4 or a hemizyous pathogenic variant in HDAC8 or SMC1A (see Table 1).

Molecular genetic testing approaches can include a combination of gene-targeted testing (serial single-gene testing or multigene panel) and comprehensive genomic testing (exome sequencing, exome array, genome sequencing) depending on the phenotype.

Gene-targeted testing requires that the clinician determine which gene(s) are likely involved, whereas genomic testing does not. Because the phenotype of Cornelia de Lange syndrome can be broad, individuals with distinctive features described in Suggestive Findings are likely to be diagnosed using gene-targeted testing (see Option 1), whereas those in whom the diagnosis of Cornelia de Lange syndrome has not been considered are more likely to be diagnosed using genomic testing (see Option 2).

Clinical Description

While classic Cornelia de Lange syndrome (CdLS) was formally characterized more than 70 years ago and well delineated clinically [Ptacek et al 1963, Jackson et al 1993], the identification of the molecular genetic basis of CdLS has led to the recognition of affected individuals who have milder or atypical features. Therefore, this condition encompasses a spectrum of findings from mild to severe (see Phenotype Correlations by Gene). Those with a milder phenotype, which is less striking clinically than the classic form of CdLS, may represent the majority of individuals with CdLS [Deardorff et al 2007, Rohatgi et al 2010].

Growth. Prenatal-onset growth failure is present in a majority of individuals with CdLS. Symmetric slow growth resulting in proportionate short stature becomes more significant by age six months. Mean height and weight are below the fifth centile throughout life [Boog et al 1999] in individuals with classic CdLS. Growth may be less severely affected in those with overall milder clinical features and/or mosaic pathogenic variants. In addition, failure to thrive may be superimposed on the constitutional growth restriction secondary to gastroesophageal reflux disease and other issues with feeding (see Gastrointestinal below).

CdLS-specific growth charts have been developed. See www.cdlsusa.org (girls; boys).

Intellectual disability. Most individuals with CdLS have developmental delay. The overall range of IQ levels is broad, from below 30 to 102, with an average IQ of 53 [Kline et al 1993, Saal et al 1993]. Those affected individuals with classic features are more likely to have severe-to-profound intellectual disability (see Genotype-Phenotype Correlations).

• Expressive language is often more compromised than receptive language, and receptive language more compromised than cognition [Ajmone et al 2014].
• Effective verbal and nonverbal communication skills can facilitate quality of life enormously [Kline et al 2018]. Early augmentative and alternative communication interventions are highly effective [Ajmone et al 2014].
• Half of children walk by 24 months and 95% by age ten. Half of children are able to feed themselves by age three years and 95% by age ten [Kline et al 1993].

Behavior. A range of behavioral issues have been reported [Kline et al 2018].

• Behavior problems are often directly related to frustration from an inability to communicate (see Intellectual disability above).
• Difficulties in sensory processing can lead to hyposensitivity, hypersensitivity, disorientation, and fixation.
• Autistic behavior may lead to avoidance or rejection of social interaction and physical contact.
• Repetitive behaviors, which can be exacerbated by anxiety, are common and are associated with more marked intellectual disability and autistic features.
• Clinically significant self-injurious behavior occurs in 56% of individuals, with hand-directed self-injurious behavior the most common.

Neurologic. Overall, approximately 25% of individuals with CdLS have seizures. Partial epilepsy is the most common type with age of onset typically before age two years. Most affected individuals respond well to standard medical therapy and are able to be weaned off medical therapy after a few years [Verrotti et al 2013] (see Management, Treatment of Manifestations).

Limb involvement. Severe abnormalities of the upper extremities are seen in 25% of individuals with CdLS.

• Upper-extremity deficiencies ranging from severe reduction defects with complete absence of the forearms to various forms of oligodactyly (missing digits) are present in about one third of those with classic features.
• In the absence of limb deficiency, micromelia (small hands), proximally placed thumbs, and fifth-finger clinodactyly occur in nearly all individuals (see Figure 3).
• Radioulnar synostosis is common and may result in flexion contractures of the elbows.
• The lower extremities are less involved than the upper extremities. The feet are often small and syndactyly of the second and third toes occurs in more than 80% of affected individuals [Jackson et al 1993].

Figure 3.

Range of limb anomalies in CdLS

Gastrointestinal. Gastroesophageal reflux disease (GERD) is present in a majority of affected indivdiuals. Other complications of GERD including esophagitis, aspiration, chemical pneumonitis, and irritability can be avoided by diagnosis and treatment of GERD in the neonatal period (see Management). Approximately one third have evidence of aspiration and 15% require a feeding tube [Luzzani et al 2003]. Other gastrointestinal abnormalities include:

• Pyloric stenosis (4%), the most frequent cause of persistent vomiting in the newborn period
• Intestinal malrotation (2%)
• Congenital diaphragmatic hernia (CDH) (1%)
  CDH has been diagnosed both pre- and postnatally, but may be underascertained, especially in infants who die in the perinatal period.

Ophthalmologic. As many as 60% of affected individuals demonstrate some degree of ptosis as well as other ocular problems including myopia (60%) and nystagmus (37%) [Levin et al 1990]. Other ophthalmologic abnormalities:

• Nasolacrimal duct stenosis
• Glaucoma
• Microcornea
• Astigmatism
• Optic atrophy
• Coloboma of the optic nerve
• Strabismus
• Proptosis

Otolaryngologic. Sensorineural hearing impairment is noted in 40% of children with CdLS, and conductive hearing impairment in 60% [Marchisio et al 2014]. Notably, for a significant proportion hearing loss (both sensorineural and conductive) improves over time [Janek et al 2016]

Genitourinary. Renal abnormalities, primarily vesicoureteral reflux, have been reported in 12%.

• Cryptorchidism occurs in 73% of males with CdLS
• Hypoplastic (small) genitalia occur in 57% and hypospadias in 9% of males [Jackson et al 1993]
• Bicornuate uterus, which can cause abdominal pain, has been observed in five (25%) of 20 affected females [Oliver et al 2010, Kline et al 2015].

Cardiovascular. Approximately 30% of individuals with CdLS have congenital heart disease [Chatfield et al 2012]. The most common abnormalities include (in descending order):

• Pulmonic or peripheral pulmonic stenosis
• Ventricular septal defects
• Atrial septal defects
• Coarctation or hypoplastic aortic arch
• Aortic valve anomaly
• Tetralogy of Fallot
• Double-outlet right ventricle
• Atrioventricular canal defect

Immunologic. Antibody deficiency has been described in several individuals with CdLS, indicating a need for immunologic screening and management of immunodeficiency in those affected individuals with severe or recurrent infections [Jyonouchi et al 2013]. The most common reported recurrent infections include chronic ear infections, chronic viral respiratory infections, and pneumonia. Impaired T-cell function may be associated with antibody deficiencies observed in persons with CdLS.

Hematologic. Thrombocytopenia often resolves after infancy, but can rarely transition to persistent idiopathic thrombocytopenia purpura [Lambert et al 2011]. In most cases, anemia is transient.

Other features

• A characteristic low-pitched cry that tends to disappear in late infancy has been described in 75% of children with CdLS and is associated with more severe cases [Jackson et al 1993].
• Hypoplastic nipples and umbilicus are seen in 50%.

Prognosis. The majority of familial cases suggest that expressivity is relatively consistent within a family. In the absence of severe congenital anomalies of internal organs, life expectancy is not significantly reduced.

• Beck & Fenger [1985] studied mortality in 48 individuals with CdLS born between 1917 and 1982 and found a modest increase in mortality over the general population when comparing cumulative survival rates; the increase is more significant among the younger age groups. They also reported two individuals who died at ages 54 and 61 years.
• Schrier et al [2011] reported 295 affected individuals in whom a cause of death was known. Respiratory causes, including aspiration/reflux and pneumonias, were the most common primary causes (31%), followed by gastrointestinal disease, including obstruction/volvulus (19%). Congenital anomalies accounted for 15% of deaths and included congenital diaphragmatic hernia and congenital heart defects. Acquired cardiac disease accounted for 3% of deaths. Neurologic causes and accidents each accounted for 8%, sepsis for 4%, cancer for 2%, renal disease for 1.7%, and other causes 9% of deaths.

Phenotype Correlations by Gene

Other Genes

Milder phenotypes that retain some of the characteristic facial features but with variable cognitive and limb or structural involvement compared to individuals with a pathogenic variant in NIPBL have been consistently described and can be seen in individuals with a heterozygous pathogenic variant in BRD4, SMC3 or RAD21 or a hemizygous pathogenic variant in HDAC8 or SMC1A [Deardorff et al 2007, Selicorni et al 2007, Rohatgi et al 2010, Kaiser et al 2014, Minor et al 2014, Gil-Rodríguez et al 2015, Olley et al 2018] (see Figure 2).

Figure 2.

Affected individual with a pathogenic variant in SMC1A

SMC1A and SMC3

• Individuals with SMC1A or SMC3 pathogenic variants typically have fewer structural anomalies and less severe growth restriction than those with NIPBL pathogenic variants; however, they have significant intellectual disability that can range from moderate to severe [Deardorff et al 2007, Gil-Rodríguez et al 2015, Huisman et al 2017].
• Compared to individuals with a heterozygous NIPBL pathogenic variant, the facial features in those with SMC1A or SMC3 pathogenic variants include slightly flatter and broader eyebrows and a broader and longer nasal bridge [Rohatgi et al 2010].
• Those with pathogenic variants in SMC3 specifically often have subtle or absent synophrys, wider bulbous nose, and a long but well-formed philtrum.
• Cardiac malformations, although typically mild, are also observed (~56%) in individuals with SMC3 pathogenic variants, and less frequently in individuals with SMC1A pathogenic variants [Gil-Rodríguez et al 2015].

RAD21. Individuals with a heterozygous RAD21 pathogenic variant:

• Typically do not have major structural differences.
• Have milder cognitive impairment compared to those with classic CdLS.
  Specifically, 10% have normal cognition, 45% have mild cognitive impairment and none have severe or profound cognitive disability [Krab et al 2020].
• Often display growth restriction, minor skeletal anomalies, and facial features that overlap with CdLS [Deardorff et al 2012, Krab et al 2020].

HDAC8

• Males with a hemizygous pathogenic variant in HDAC8 have facial features that overlap with CdLS but typically display delayed closure of the anterior fontanelle, hooded eyelids, widely spaced eyes, a wide nose, mosaic skin pigmentation, dental anomalies, and happy or friendly personalities. Growth also tends to be less