Bilateral periventricular nodular heterotopia and lissencephaly in an infant with unbalanced t(12;17)(q24.31; p13.3) translocation

Periventricular nodular heterotopia and Miller-Dieker syndrome are two different disorders of brain development. Miller-Dieker syndrome exhibits classical lissencephaly and is related to defects in the lissencephaly gene (LIS1). Periventricular nodular heterotopia is characterized by aggregates of grey matter adjacent to the lateral ventricle and is mainly linked to mutations in the Filamin A (FLNA) gene. We describe a male infant presenting with facial dysmorphisms resembling those of Miller-Dieker syndrome, neuromotor delay, and drug - resistant infantile spasms. Magnetic resonance imaging of the brain showed periventricular nodular heterotopia overlaid by classical lissencephaly with complete agyria. Cytogenetic and molecular investigations detected a maternally inherited unbalanced translocation involving chromosome arms 17p and 12q. This resulted in partial monosomy of 17p13.3 -> pter and partial trisomy of 12q24.3 -> qter No mutation was found in the FLNA gene. The patient died at the age of 22 months from respiratory insufficiency during an infection of the lower respiratory tract. Our observation extends the list of the overlying cortical malformations associated with periventricular nodular heterotopia. It remains to be established whether this peculiar neuronal migration disorder represents a phenotype totally linked to 17q13.3 deletion or results from a combination of gene defects at 17q13.3 and 12q24.3