Fragilitas ossium: a new autosomal recessive mutation in the mouse.

Fragilitas ossium, fro, is an often lethal recessive mutation that was discovered in a randombred stock of mice after treatment with the chemical mutagen tris(1-aziridinyl) phosphine-sulphine. The fro/fro mice have osteoporosis-bending and fracture of the long bones-that is associated with apparently normal cartilage growth. The roentgenological and pathological features are similar to those of the severe, often lethal recessive form of human osteogenesis imperfecta.