Meckel syndrome: prenatal ultrasonographic diagnosis in two cases showing marked differences in phenotypic expression

Two consecutive siblings with the Meckel-Gruber syndrome are presented. They demonstrate variation in phenotypic expression which may render diagnosis difficult when the pattern of malformation is significantly different from that traditionally accepted. The diagnosis was only made with confidence because a sibling with typical features had been seen first. The usefulness of ultrasound in prenatal diagnosis, even when the abnormalities are atypical, is well illustrated.