This spontaneous recessive mutation has been mapped to Chromosome 6 but not defined molecularly. Homozygotes are thinner and smaller than normal and die by approximately 4 weeks of age.Read More +
Mice homozygous for the scrawny mutation are thinner and smaller than their heterozygous or +/+ littermates by two weeks of age and most die by four weeks of age, although a few have lived longer. Histological assessment of two male homozygotes at four weeks of age found small, pale-staining muscle fibers in the muscles of the spine and leg. Homozygotes may have a hearing deficit, as indicated by very elevated auditory brainstem response thresholds of one homozygous male tested at 17 days of age. Of 172 pups produced from heterozygous intercrosses only 30 were mutants, indicative of some embryonic lethality. This spontaneous mutation has been mapped to Chromosome 6 between D6Mit71 and D6Mit40.
The scrawny mutation (scrny) arose spontaneously in 2003 in a C57BL/6J strain carrying a transgene, and was backcrossed once to C57BL/6J then maintained by sibling intercrossing progeny tested heterozygotes. Sperm from heterozygous males at generation N1F22 was cryopreserved in 2011.