To underline the crucial role of CFTR function in male infertility, (i) defective expression of CFTR in human sperm is associated with reduced sperm quality49, (ii) homozygosity and heterozygosity for less-pathogenic CFTR mutations in humans are associated with reduced fertility without CBAVD29–36,38, and iii) the fertilizing capacity of sperm obtained from heterozygous CFTR mutant mice is significantly lower than that of wild-type mice11. This evidence concerns the gene CFTR and male infertility.