Green shanks and adult mortality in chickens

A mutation of recent origin in Cornell randombred Leghorn chickens causes the shanks to be colored green due to melanin-like deposition in the dermis, in contrast to normal yellow. Some pigment is often present in the mandibles and the mature feathers display an ashen cast. This mutant is determined by an allele, idc, on the sex chromosome. Excessive adult mortality with a high incidence of tumors, mainly hemangiomas, is associated with this gene--at least extending over a two-generation observation interval. Pullets receiving this mutant allele (idc) from their sire die at 2 to 3 times the rate of sisters, with yellow shanks, that carry the Id allele.