Germ line origins of de novo mutations in hemophilia B families.

The germ line of origin for 13 of 14 de novo hemophilia B mutations has been determined. When added to previous reports, the origin, assuming no mosaicism, occurred in 43 female and 33 male gametes. Mutation rate estimates are twofold higher in males than in females. The pooled data also indicate that male and female germ lines have different mutation rates depending upon the type of mutation.