Polydactyly Nagoya, Pdn: A new mutant gene in the mouse.

A new hereditary polydactyly (gene symbol Pdn) was found in the course of breeding JCL : ICR mice. The genetic analysis indicated that the polydactyly was an autosomal dominant trait. The homozygotes died within two days after birth. The homozygous fetuses or newborn had 1-3 extra-digits both in te fore- and hindlimbs on the preaxial side. They occasionally showed exencephaly, cleft palate, open eyelid, short tibia and fibula or deformed sternum. The heterozygotes had one extra-digit preaxial side. They occasionally showed exencephaly, heterozygotes had one extra-digit preaxially in the hindlimb and an enlarged first digit on the forelimb which often showed bifurcated distal phalanx. A tab on the postaxial side of the forelimb was found in all homozygotes and in some heterozygotes.