New findings in the stumpy-limb mutation of Japanese quail

The stumpy-limb (SL) mutant (sl/sl) of Japanese quail (Coturnix japonica) is characterized by brachycephaly, parrot-like beaks with mild expressivity, and short and thick limbs. Although this mutant had been believed to be completely embryonic lethal just before hatching, this study revealed that the SL mutant was partly viable when genetic background was altered. A total of 132 of 237 SL embryos (56%) hatched from the eggshell with no assistance; subsequently, 36 of the 132 SL chicks that hatched survived to adulthood. Among these 36 birds, 12 males and four females developed sexually, and of these, six males and four females produced offspring. Mating experiments with the fertile SL mutants and controls confirmed that this mutation is controlled by an autosomal recessive gene. In micromelic or chondrodystrophic mutations of poultry, the SL mutation is an extremely rare instance in which some individuals of both sexes reach sexual maturity and are actually fertile.