Prenatal diagnosis of unilateral tibial hemimelia.

We describe a case of unilateral tibial agenesis which was initially observed at 21 weeks' gestation. Unlike bilateral tibial hemimelia syndrome, a rare autosomal dominant condition, unilateral tibial agenesis, which accounts for about three-quarters of all newborns with this condition, has not previously been described. This case could have been a sporadic abnormality but, in view of the association with other observations (distal bifurcation of the femur, club foot), could be considered as an autosomal recessive inherited condition with variable penetrance. Ultrasonographic features and the genetic prognosis are discussed.