Molecular mapping of a translocation breakpoint at 14q13 in a patient with mirror-image polydactyly of hands and feet.

Mirror hands and feet (MIM, 135750) is a rare congenital anomaly, and mirror-image polydactyly is considered to be a variant of mirror hands and feet. To our knowledge, seven patients with the disorder have been reported in the literature. Parent-to-child transmission was reported in two families, which may indicate a single-gene defect inherited in an autosomal dominant fashion. We had previously encountered a boy with mirror-image polydactyly whose karyotype showed 46,XY,t(2;14) (p23.3;q13) de novo. We hypothesized that at least one of the putative genes responsible for the determination of an anterior-posterior limb pattern is disrupted by a translocation breakpoint. In this study, we identified a yeast artificial chromosome clone spanning a translocation breakpoint at 14q13, and the breakpoint was confirmed to be located between two loci, AFM200ZH4 and D14S306, within a genetic distance of 0.6 cM.