DNA markers YNZ22.1, YNH37.3, 144D6, and VAW508 were studied in five patients with the Miller-Dieker syndrome, 17 patients with the isolated lissencephaly sequence, one patient with a non-classified lissencephaly, and nine patients with an atypical cortical dysplasia. All patients had normal chromosomes except for a deletion 17p13.3 in one of the five Miller-Dieker patients. The five Miller-Dieker patients showed deletions of markers YNZ22.1 and YNH37.3 in contrast to the other patients tested. In one patient, the deletion was in the maternally contributed chromosome. Prenatal diagnosis by DNA analysis allowed exclusion of the recurrence of Miller-Dieker syndrome in a subsequent pregnancy.