Snijders Blok-Campeau syndrome
Snijders Blok-Campeau syndrome is characterized by intellectual disability, speech problems, and distinctive facial features.
Intellectual disability in individuals with Snijders Blok-Campeau syndrome ranges from mild to severe. Some people with this condition also have low muscle tone (hypotonia), seizures, or autistic behaviors that affect communication and social interaction.
While some people with Snijders Blok-Campeau syndrome develop limited language, others acquire only a few words or never speak. If speech occurs, it usually develops after age 2. Affected individuals can experience stuttering, problems coordinating movements of the mouth and tongue (oromotor dysfunction), or difficulty producing the sequences of sounds and syllables needed to form words (apraxia). In general, people with this condition have a very social personality.
Individuals with Snijders Blok-Campeau syndrome have distinctive facial features. The eyes are frequently affected, and features often include widely spaced eyes (ocular hypertelorism), deep-set eyes, narrowed openings of the eyes (narrowed palpebral fissures), an increased distance between the inner corners of the eyes (telecanthus), and sparse eyebrows. Additional facial features can include full cheeks, a pointed chin, a prominent forehead (frontal bossing), a sunken appearance of the middle of the face (midface hypoplasia), a broad nasal bridge, low-set ears that may be rotated backward, and a thin upper lip. Affected individuals often have an abnormally sized head; most have an unusually large head (macrocephaly), though some have an unusually small head (microcephaly). Some people with Snijders Blok-Campeau syndrome have premature closure of certain bones of the skull (craniosynostosis), which can contribute to an abnormal head shape.
Most individuals with Snijders Blok-Campeau syndrome have vision problems, including farsightedness (hyperopia) or eyes that do not look in the same direction (strabismus).
About half of people with Snijders Blok-Campeau syndrome 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).
Other names
IDDMSF; Intellectual developmental disorder with macrocephaly, speech delay, and dysmorphic facies; SNIBCPS
Inheritance pattern
Autosomal dominant
Related genes
CHD3
Source: MedlinePlus Genetics, U.S. National Library of Medicine.
