Main clinical features
Most individuals with SMARCB1-associated Intellectual Developmental Disorder have features consistent with Coffin-Siris Syndrome (CSS). These include by infant hypotonia, feeding difficulties, developmental delay, intellectual disability, coarse craniofacial features, sparse hair, digital anomalies (specifically hypoplasia of the digits and/or nails, particularly the 5th), congenital heart and genitourinary defects.

Some individuals with mutations in the N-terminal domain of SMARCB1 have intellectual disability with hydrocephalus due to choroid plexus hyperplasia, and with physical features not suggestive of CSS.

The prevalence of this disorder is unknown. To date, just over 30 patients are reported in the literature and open access databases.

The disorder is inherited in an autosomal dominant manner. All individuals reported to date have the disorder as a result of a de novo mutation.