CDHD3 Related Syndrome; IDDMSF; Intellectual Developmental Disorder with Macrocephaly, Speech Delay, and Dysmorphic Facies; SNIBCP

Snijders Blok-Campeau syndrome (SNIBCPS) is a genetic disorder characterized by global developmental delay, impaired intellectual development, delayed speech acquisition, hypotonia, behavioral disorders including autism spectrum disorder (ASD), and distinctive facial features. This syndrome is caused by mutations in the CHD3 gene.

Affected individuals tend to have expressive language deficits. While some individuals with SNIBCPS develop limited language, others acquire only a few words or never speak. If speech occurs, it usually develops after age 2.

Most individuals with SNIBCPS have vision problems, including farsightedness or eyes that do not look in the same direction.

About half of individuals with SNIBCPS have brain abnormalities, such as enlarged spaces in the brain where cerebrospinal fluid (CSF) accumulates. Less commonly, affected individuals are born with a hole between the two upper chambers of the heart (atrial septal defect) or another problem with the heart's structure or function (congenital heart disease).

Diagnostic testing: The diagnosis of SNIBCPS is based on:

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  Symptoms;

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  Clinical examinations; and

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  Genetic testing for mutation of the CHD3 gene.

Physical findings: The physical signs and symptoms of SNIBCPS include:

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  Developmental delay;

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  Dysarthria (difficulty speaking);

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  Speech apraxia (difficulty producing the sequences of sounds and syllables needed to form words);

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  Oromotor dysfunction (problems coordinating movements of the mouth and tongue);

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  Stuttering;

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  Macrocephaly (an overly large head);

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  Prominent forehead;

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  Hypertelorism (an increased distance between two body parts);

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  Hypotonia (decreased muscle tone);

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  Joint laxity (flexible joints that have a wide range of motion);

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  Farsightedness (hyperopia);

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  Strabismus (misalignment of the eyes);

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  Seizures; and

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  Autistic behaviors that affect communication and social interaction.

ICD-9: 755.5; 758.9

ICD-10: Q87.0

The physical features of SNIBCPS may be present at birth or may develop in the first few years of life. Developmental delays are present in childhood with variable signs and symptoms. For school age children and adolescents, speech disorders often present with the child’s academic performance.

There is no curative treatment for this syndrome. Treatment is symptom specific and supportive. Treatment includes the management of any complications through a multidisciplinary team of medical specialists, neurologists, developmental pediatricians, and therapists (speech therapy, physical therapy, occupational therapy, etc.). Interventions may include intensive therapy, surgeries, and medication (i.e., seizure control) as warranted. School age individuals may benefit from individualized education plans (IEPs) and age-appropriate early childhood intervention programs or special education.

Suggested MER for Evaluation:

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  Clinical history and physical examination that describes the diagnostic features of the impairment; and

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  Genetic sequencing tests confirming mutation of the CHD3 gene. 

Suggested Listings for Evaluation:

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