[Meckel syndrome. Difficulties in prenatal diagnosis caused by variability of expression (observations on two families)].

The Meckel syndrome is inherited as an autosomal recessive monogenic trait. It associates abnormalities of the neural tube (encephalo or occipital meningocele more seldom hydrocephaly) and of the extremities (post axial polydactyly) with multicystic dysplasic kidneys. When diagnosed in a conception product, it allows one's to provide an appropriate genetic counseling as well as an early and followed-up surveillance of the next pregnancies in the affected sibship. Taking the example of two families, the authors emphasize the difficulties in diagnosing this affection (mainly due to its various expressions) and the various methods available for its pre-natal detection.