The CFTR Met 470 allele is associated with lower birth rates in fertile men from a population isolate.
Kosova G, Pickrell JK, Kelley JL, McArdle PF, Shuldiner AR, Abney M, Ober C. The CFTR Met 470 allele is associated with lower birth rates in fertile men from a population isolate. PLoS Genet. 2010 Jun 03; 6(6):e1000974.