Isolated Dandy-Walker malformation: prenatal diagnosis in two consecutive pregnancies.

We report a family with recurrent Dandy-Walker malformation (DWM). The first offspring was found prenatally to have isolated DWM at 30 weeks' gestation. Ultrasonography at 19 weeks' gestation in the subsequent pregnancy revealed isolated DWM in both dizygotic twins. Chromosome analysis was normal in all three infants, and autopsy confirmed that no other congenital abnormalities were present. Evidence suggests that rare families transmit the disorder in an autosomal or X-linked recessive pattern, with a high recurrence risk.