Are men carrying the apolipoprotein ε4- or ε2 allele less fertile than ε3ε3 genotypes?

Abstract

The ɛ3 allele in the human gene coding for apolipoprotein E (apoE) is the most common worldwide, but ɛ4 is probably the ancestral allele. Since apoE is involved in many important biological processes, selection forces could have favoured ɛ3. We hypothesized that apoE genotypes may affect reproductive efficiency, and we therefore compared the distributions of 40-year-old married men with known genotypes by the numbers of their biological children. The distributions were statistically significantly different (P = 0.0026). On average, men with the ɛ3ɛ3 genotype (n = 212) had 1.93 children, men with the ɛ3ɛ4 or ɛ4ɛ4 genotype (n = 105) had 1.50, and men with the ɛ3ɛ2 or ɛ2ɛ2 genotypes (n = 53) had 1.66 children. Of the men in the three groups, 6%, 26% and 19%, respectively, reported being childless. These findings are unlikely to be due to gross error in the reported prevalence of childlessness, differences in socioeconomic status or other likely sources of bias. They are compatible with higher fertility in men with the ɛ3ɛ3 genotype than in those with the other common apoE genotypes.