ULNAR RAY DEFECT IN AN INFANT WITH A 6Q21-7Q31.2-TRANSLOCATION - FURTHER EVIDENCE FOR THE EXISTENCE OF A LIMB DEFECT GENE IN 6Q21

Ectrodactyly is a developmental defect of the distal limbs characteriz ed by marked clinical variability and genetic heterogeneity, also refl ected in the observation of different chromosome abnormalities non ran domly associated with longitudinal postaxial limb deficiencies. The on e most frequently found in patients with split hand-split foot (SHSF) involves chromosome band 7q22. Recently, structural anomalies of chrom osome 6q21 have been reported in 2 unrelated patients with SHSF, sugge sting that this region may also contain genes responsible for limb dev elopment [Braverman et al., 1993. Am, J Hum Genet, suppl 53: 410; Vilj oen and Smart, 1993. Clin Dysmorph 2: 274-277]. We report on a third p atient who had a de novo, apparently;balanced t(6;7)(q21;q31.2) transl ocation and bilateral ulnar aplasia with postaxial oligodactyly. In sp ite of the different phenotypic effects observed in these 3 patients, we consider our case as further evidence that genes in 6q21 may play a role in distal limb development. (C) 1995 Wiley-Liss, Inc.