Autosomal recessive type I lissencephaly.

Lissencephaly (LIS) is a brain malformation manifested by a smooth cerebral surface, thickened cortical mantle and microscopic evidence of incomplete neuronal migration, excluding polymicrogyria and other cortical dysplasias. It is important to consider LIS in the diagnosis of developmental delay as many patients may be diagnosed as cerebral palsy. It may have familial occurrence and can occur in sibs of same family often leading to a diagnostic problem. Several lissencephaly syndromes have been described. Here a familial syndrome of lissencephaly is reported. Autosomal recessive inheritance is suggested by recurrence in sibs within the same family, but germ cell mosaicism for a dominant mutation cannot be excluded.