Study of Three Single Nucleotide Polymorphisms in the SLC6A14 Gene in Association with Male Infertility

Although several genetic causes of male infertility are known, the condition in around 60.0-75.0% of infertile male patients appears to be idiopathic. In some, genetic causes may be polygenic and require several low-penetrance genes to produce a phenotype outcome. In others, pleiotropy, when a gene can produce several phenotypic traits, may be involved. We have investigated whether single nucleotide polymorphisms (SNPs) in the SLC6A14 [solute carrier family 6 (amino acid transporter), member 14] gene are associated with male infertility. This gene has previously been linked with obesity and cystic fibrosis, which are associated with male infertility. It has a role in the transport of tryptophan and synthesis of serotonin that are important for normal spermatogenesis and testicular function. We have analyzed three SNPs (rs2312054, rs2071877 and rs2011162) in 370 infertile men and 241 fertile controls from two different populations (Macedonian and Slovenian). We found that the rs2011162(G) allele and rs2312054(A)-rs2071877(C)-rs2011162(G) haplotype are present at lower frequencies in the infertile rather than the fertile men (p = 0.044 and p = 0.0144, respectively). We concluded that the SLC6A14 gene may be a population-specific, low-penetrance locus which confers susceptibility to male infertility/subfertility. Additional follow-up studies of a large number of infertile men of different ethnic backgrounds are needed to confirm such a susceptibility.