Tich: a mutant causing disproportional growth in the mouse

A spontaneous mutation ‘tich’ (gene symbol tch) appeared as a recessive mutation in inbred mice of strain A. TL. Homozygotes are rather dumpy mice of approximately normal weight but with short limbs and tail. Skeletal measurements on backcross siblings show that the mandible bones are almost normal but long bones and some parts of the pelvic and pectoral girdles are short. Although tich resembles brachypodism phenotypically it is not linked to agouti, and does not match the description of any other skeletal mutation. There was some evidence for weak linkage with albinism on chromosome 7. The mutation has reappeared amongst the A. TL mice of a UK commercial breeder and may have been accepted as the norm for A. TL amongst some European users of this mouse.