First-trimester ultrasound diagnosis in a recurrent case of Walker-Warburg syndrome.

We report on two siblings with Walker-Warburg syndrome (WWS) born to a consanguineous couple. In the index case, the second-trimester scan showed ventricular dilatation and we diagnosed WWS after observing retinal detachment at 26 weeks' gestation and lissencephaly by 32 weeks' gestation in addition to hypoplasia of the cerebellar vermis. The second case was first suspected at 12 weeks' gestation, when we observed a 2.8-mm nuchal translucency and an unusually large hindbrain vesicle. By 14 weeks' gestation, the lateral ventricles were clearly enlarged (12-13 mm), at 16 weeks' gestation the vitreous chamber appeared to be hyperechogenic, and by 17 weeks' gestation hydrocephalus was evident. The couple chose to continue the pregnancy, and during the third trimester lissencephaly, major hydrocephalus and polyhydramnios developed. Serial ultrasound examination should be offered to a family with a history of WWS and therefore a 1 in 4 risk of recurrence. In some cases, recurrence can be suspected as early as the first trimester, however the diagnosis cannot be excluded on the basis of normal ultrasound appearance until later in pregnancy.