Background and Objective: Bilateral periventricular nodular heterotopia (BPNH) is a recently recognized malformation of neuronal migration in which nodular masses of gray matter line the walls of the lateral ventricles. Most affected individuals are females with epilepsy and normal intelligence, but no other congenital anomalies. Studies in families with multiple affected individuals, always all females, have mapped one BPNH gene to chromosome Xq28. Several other BPNH syndromes associated with mental retardation and epilepsy but without significant dysmorphic facial features have been observed in males only, which may also be X-linked. This report describes a new syndrome with BPNH.Methods: Clinical and MRI study and cognitive testing of two unrelated boys, aged 8 and 5.5 years, and review of the enlarging spectrum of syndromes associated with BPNH.Results: Similarities between the two boys are sufficient to delineate a new multiple congenital anomaly-mental retardation syndrome that consists of BPNH, regional cortical dysplasia, mild mental retardation, and frontonasal malformation.Conclusions: The cause of this unusual syndrome is unknown; based on linkage of other BPNH syndromes to chromosome Xq28 and the report of possible X-linked inheritance of frontonasal malformation, we suspect the cause is genetic, with possible X-linked inheritance.
Compound heterozygous variants in LAMC3 in association with posterior periventricular nodular heterotopia