Patient with bilateral periventricular nodular heterotopia and polymicrogyria with apparently balanced reciprocal translocation t(1;6)(p12;p12.2) that interrupts the mannosidase alpha, class 1A, and glutathione S-transferase A2 genes.

P olymicrogyria (PMG) is a cortical development defect that results in an irregular brain surface, with multiple, small, partly fused gyri separated by shallow sulci. The perisylvian form is the most common pattern of PMG seen on magnetic resonance imaging scans of the brain. Bilateral perisylvian PMG (BPP) often is accompanied by mild mental retardation, epilepsy, and pseudobulbar palsy, and this results in problems with expressive speech and feeding. Bilateral periventricular nodular heterotopia (BPNH) is a neuronal migration disorder, in which neurons that fail to migrate into the developing cortex remain on the ventricular surface and form nodules that line the lateral ventricles. It can be inherited as an X linked dominant trait. Female patients with BPNH are of normal intelligence, have seizures, and may have complications in the vascular system, including patent ductus arteriosus and coagulopathy. Few male patients with BPNH have been reported ; however, most male fetuses with BPNH are not viable. Male patients with BNPH may present with mental retardation, epilepsy, and other congenital anomalies, including cerebellar hypoplasia and syndactyly. Mutations in filamin A (FLNA, also known as filamin 1, OMIM 300017) on Xq28 were found to be causative for BPNH. Many patients with BPNH do not harbor mutations in FLNA, which suggests that additional loci can be causative for BPNH. Not enough families, however, have been available for linkage studies to identify other loci. We present the first reported case of a young male who has PMG and BPNH. The patient has seizures and developmental delay. Cytogenetic analysis showed balanced reciprocal translocations in the child and in his father. The translocation breakpoint was mapped and found to interrupt two genes—mannosidase alpha, class 1A (MAN1A2) and glutathione S-transferase A2 (GSTA2). Deletions of greater than two kilobasepairs (kbp) were excluded, although we could not exclude smaller deletions next to the derivative chromosome 6 breakpoint. On the non-translocated chromosome, no mutations in either of these genes were identified in the filamin A related gene, FLJ13181, in an adjacent location. In addition, mutations were not identified in any of these genes in six additional unrelated patients with similar brain findings on magnetic resonance imaging scans of the brain; however, these genes remain candidates for this condition and should be screened in a larger patient sample. MATERIALS AND METHODS Patient and family history The proband was born at term after an uneventful pregnancy. He had mildly dysmorphic features including a ‘‘box shaped’’ forehead, pinched nose, protuberant and posteriorly rotated low set ears, micrognathia, and a high arched palate. He presented with a seizure disorder at five months, which included infantile spasms and myoclonic seizures. Neuroradiological findings at age 5.5 months included hypoplasia of the corpus callosum with absence of the