Thymic-renal-anal-lung dysplasia in sibs: a new autosomal recessive error of early morphogenesis.

We report on 3 sisters with a syndrome of unilobed or absent thymus, renal and ureter agenesis/dysgenesis, and intrauterine growth retardation (IUGR). Two of the 3 infants had a unilobed lung and imperforate anus. Recurrence was detected prenatally by the presence of progressive oligohydramnios and IUGR, a unilateral echogenic cystic mass in the renal fossa, and low amniotic fluid disaccharidases in association with an imperforate anus. Several genetic mechanisms can be invoked to explain this occurrence including autosomal recessive inheritance and an unrecognized chromosome imbalance.