Male infertility has become a serious health and social problem troubling approximately 15% of couples worldwide; however, the genetic and phenotypic heterogeneity of human infertility poses a substantial obstacle to effective diagnosis and therapy. A previous study reported that heterozygous mutations in solute carrier family 26 member 8 (SLC26A8, NG_033897.1) were causatively linked to asthenozoospermia. Interestingly, in our research, three deleterious heterozygous mutations of SLC26A8 were separately detected in three unrelated patients who were suffered from teratozoospermia. These three heterozygous mutations resulted in the reduce of SLC26A8 expression in transfected cells, while no disrupt expression of SLC26A8 was observed in sperm from the affected individuals. Noticeably, two of the three SLC26A8 heterozygous mutations detected in the patients were inherited from their fertile fathers. Thus, we suggested that male infertility associated with SLC26A8 mutations should be involved in a recessive-inherited pattern, considering the infertile homozygous Slc26a8 KO male mice. Given that SLC26A8 heterozygous mutations were detected in the infertile patients, and SLC26A8 is predominantly expressed in the various germ cells during spermatogenesis, the heterozygous mutations in SLC26A8 may not be the direct genetic cause but contribute to male infertility to a certain degree.

Nonobstructive azoospermia (NOA) is an important cause of male infertility, and the genetic pathogenesis is still incompletely understood. The previous study reported that heterozygous mutation of c.346-1G>A in SOHLH1 gene was identified in two NOA patients. However, in our research, this heterozygous mutation was confirmed in a Chinese infertile patient who was suffered from teratozoospermia, and intriguingly, a homozygous mutation of c.346-1G>A in SOHLH1 gene was detected in another patient with severe oligozoospermia. Additionally, we correlated the good prognosis of intracytoplasmic sperm injection (ICSI) in the patient carrying the heterozygous mutation of c.346-1G>A in SOHLH1 gene. Thus, we suggested that the heterozygous mutation of c.346-1G>A in SOHLH1 may not be the direct genetic cause for NOA, and this homozygous mutation might impair spermatogenesis and further lead to the reduced sperm count and abnormal sperm morphology, eventually causing male infertility.