Implication of FKBP6 for male fertility in horses

In stallions, impaired acrosome reaction (IAR) may often cause subfertility. Single nucleotide polymorphisms (SNPs) within FK506-binding protein (FKBP6) seem to be associated with IAR in stallions. However, their effect on stallion fertility has not yet been quantified. Using whole-genome sequence data of seven stallions, we searched FKBP6 for mutations to perform an association study in Hanoverian stallions with estimated breeding values for the paternal component of the pregnancy rate per oestrus cycle (EBV-PAT) as target trait. Genotyping five exonic mutations within FKBP6 revealed a significant association of the SNP g.11040379C>A (p.167H>N) with EBV-PAT in 216 Hanoverian stallions. The difference among the two homozygous genotypes was 7.62% in EBV-PAT, corresponding to one standard deviation of EBV-PAT. In conclusion, in Hanoverian stallions, the FKBP6-associated SNP g.11040379C>A confers higher conception rates in A/A homozygous and lower conception rates in C/C homozygous Hanoverian stallions. Thus, an FKBP6-associated missense mutation is significantly associated with stallion fertility.