BILATERAL PERIVENTRICULAR NODULAR HETEROTOPIA WITH MENTAL-RETARDATIONAND SYNDACTYLY IN BOYS - A NEW X-LINKED MENTAL-RETARDATION SYNDROME

Bilateral periventricular nodular heterotopia (BPNH) is a recently rec ognized malformation of neuronal migration, and perhaps proliferation, in which nodular masses of gray matter line the walls of the lateral ventricles, Most affected individuals have epilepsy and normal intelli gence with no other congenital anomalies. A striking skew of the sex r atio has been observed because 31 of 38 probands have been female, and one gene associated with BPNH was recently mapped to chromosome Xq28. We report three unrelated boys with a new multiple congenital anomaly -mental retardation syndrome that consists of BPNH, cerebellar hypopla sia, severe mental retardation, epilepsy, and syndactyly. Variable abn ormalities included focal or regional cortical dysplasia, cataracts, a nd hypospadius. We hypothesize that this syndrome involves the same Xq 28 locus as isolated BPNH, and we review the expanding number of syndr omes associated with BPNH.