[Subcortical laminal heterotopia and lissencephaly: cerebral malformations of X-linked inheritance].

Subcortical laminar heterotopia (band heterotopia) is a brain malformation now recognized by MRI. We report 3 families (2 previously described) in which several members had subcortical laminar heterotopia or a more severe malformation (agyria/pachygyria). In these families, subcortical laminar heterotopia were observed in women and were associated with epilepsy or slight mental retardation depending on the extend of heterotopia. Males had lissencephaly with refractory epilepsy and severe mental retardation. The pedigrees of these families demonstrate that these 2 malformations originate from a single genetic origin. A single X-linked dominant gene is postulated. Diagnosis of subcortical laminar heterotopia in a female or lissencephaly in a male (except in the case of Miller-Dieker syndrome) requires appropriate genetic counselling in the family: brain imaging should be performed in relatives.