Mice homozygous for Tyrc-a are distinguishable from Tyrc albino mice at birth by pigmented eyes. Both young and adult animals have an off white coat color, pigmented eyes, ears, tail and anal region. Unlike chinchilla Tyrc-ch mice no dark hairs appear on the nose. Acromelanic (Tyrc-a) is fully recessive to wild type and completely dominant to albino (Tyrc).
Acromelanic (Tyrc-a), an allele at the albino locus, arose spontaneously in C3H/HeJ at the Jackson Laboratory in 1985 when that inbred was at generaton F183. It was sibling mated by forced heterozygosis (heterozygote x homozygote). It reached at F26 in 1991. In 1990 embryos were generated for cryopreservation by mating homozygous males to heterozygous females or vice versa at generation F25 or more.