Probable new syndrome in a Mexican family with congenital palmar polyonychia and postaxial limb defects.

Congenital palmar polyonychia (CPP) is a rare and usually sporadic birth defect. We report on a Mexican girl with CPP of both 5th fingers and her sister with ectrodactyly with ulnar ray deficits and agenesis of the ulna. In previous reports, CPP has been seen in ectrodactyly with involvement of the ulna and ulnar digital rays and with postaxial polydactyly. Such findings observed in our patients can be considered a form of CPP. Autosomal dominant inheritance of CPP is more likely based in previous informative families with vertical transmission and instances of male-to-male transmission. The present and two previous families with affected sibs only may represent parental gonadal mosaicism, whereas de novo mutation or incomplete evaluation of relatives could be an explanation for sporadic cases. Variable expression of the CPP phenotype may be a new autosomal dominant entity, i.e., a CPP-postaxial limb defect syndrome.