Nicolaides-Baraitser syndrome [NCBRS OMIM #601358] is characterized by severe intellectual disability, early-onset seizures, short stature and sparse hair. Dysmorphic features include thick, anteverted alae nasi, long and broad philtrum, large mouth and thin upper and thick lower vermilion. Clinical overlap exists between NCBRS and Coffin-Siris syndrome [CSS OMIM #135900], however CSS differs in the presence of severely hypoplastic or absent fifth finger nails with or without hypoplasia of the terminal phalanges.
Van Houdt et al, 2012 identified mutations in SMARCA2 in 36/44 individuals with NCBRS. In the cases where parental samples were available; all mutations were confirmed to be de novo. SMARCA2 is a member of the SNF2 family of helicase-related proteins that are characterized by the presence of the conserved Snf2 family ATPase domain that is required for transcriptional activity.