SUBCORTICAL LAMINAL HETEROTOPIA AND LISSE NCEPHALIA - X-LINKED INHERITANCE OF BRAIN MALFORMATIONS

Subcortical laminar heterotopia (band heterotopia) is a brain malforma tion now recognized by MRI. We report 3 families (2 previously describ ed) in which several members had subcortical laminar heterotopia or a more severe malformation (agyria/pachygria). In these families, subcor tical laminar heterotopia were observed in women and were associated w ith epilepsy or slight mental retardation depending on the extend of h eterotopia. Males had lissencephaly with refractory epilepsy and sever e mental retardation. The pedigrees of these families demonstrate that these 2 malformations originate from a single genetic origin. A singl e X-linked dominant gene is postulated. Diagnosis of subcortical lamin ar heterotopia in a female or lissencephaly in a male (except in the c ase of Miller-Dieker syndrome) requires appropriate genetic counsellin g in the family: brain imaging should be performed in relatives.