Mutation rate in Duchenne type of muscular dystrophy.

The mutation rate in the Duchenne type of muscular dystrophy has generally been estimated by the indirect method of Haldane (1935) using his formula for X-linked recessive traits U=1/3 (l-f)x where U is the mutation rate, f the effective fertility of affected males, and x the incidence of affected individuals in the male population. Since the effective fertility of males with this disorder is zero, the mutation rate amounts to 1/3 of the incidence among males. Estimates on this basis have varied from 4-3 x 10-5 (Walton, 1955) to 9 5 x 10-5 per gene per generation (Stephens and Tyler, 1951). Perhaps the most satisfactory population study was that of Stevenson (1958) whose figures give a muta- tion rate of 6-0 x 10-5. Morton and