Relative fitness of carriers of the mitochondrial DNA mutation 3243A > G.

Deleterious point mutations in mitochondrial DNA (mtDNA) have been found in many human populations and always at a low frequency suggesting that they are under strong negative selection. It is assumed that this selection is caused by reduced genetic fitness of mutation carriers, but the fitness of carriers of any mtDNA mutation has not been determined. We estimated the reproductive disadvantage caused by the mitochondrial DNA mutation 3243A > G in a population-based group of female carriers (n = 32). The person-years method, Kaplan-Meier survival analysis and population statistics were used to estimate net reproduction rates of the mutation carriers and the general population. We found that women with 3243A > G reproduced at the same rate as women in the general population, suggesting that on average host-level selection against women harbouring the 3243A > G mutation is not strong.