Ulnar ray a/hypoplasia: evidence for a developmental field defect on the basis of genetic heterogeneity. Report of three Brazilian families.

We report on five Brazilian patients from three unrelated families with congenital anomalies of the upper limbs. Ulnar aplasia/hypoplasia was the main reason for examining these patients. Evidence for existence of an ulnar developmental field is based on genetic heterogeneity. Clinical and genetic aspects of the ulnar ray defects are discussed.