Natural mutation rates in the house mouse estimates for five specific loci and dominant mutations

Abstract

More than 7 million mice were examined for grossly visible spontaneous mutations. A total of 249 mutations were recovered, of which 206 could be characterized as their mode of inheritance (dominant or recessive). The rates of spontaneous mutations at 5 specific coat-color loci ( a, b, c, d, and ln) were 11 · 10 −6 per locus per gamete for mutations from wild-type, and 2.5 · 10 −6 for mutations from recessive alleles. Large differences were found between the rates of the individual loci; the a, a +, and c + alleles had the highest rates. Estimates of “forward” and “reverse” mutations at each of these five loci also showed large differences. A comparison of the rates at the five specific loci and those at other loci for which dominant mutations were recovered showed that the specific loci used in this study had a spontaneous mutation rate 6 times higher. No effect of the age of parent was discernible for those loci where sufficient numbers of mutants were recovered to make a meaningful comparison.