Susceptibility to male infertility: replication study in Japanese men looking for an association with four GWAS-derived loci identified in European men

Association study of the three functional polymorphisms (TAS2R46G>A, OR4C16G>A, and OR4X1A>T) with recurrent pregnancy loss

This study was purposed to investigate whether genetic polymorphisms in the function of stop-gain are associated with a fetal or placental development play roles and a development of idiopathic recurrent pregnancy loss (RPL) in Korean females. Three stop-gain polymorphisms were selected using next-generation sequencing screening, which allows for the rigorous examination and discovery of previously uncharacterized stop-gain genes and stop-gain expression profiles. Accordingly, we investigated the association of stop-gain polymorphisms in Korean women with RPL. Three functional polymorphisms in the TAS2R46G>A (rs2708381), OR4C16G>A (rs1459101), and OR4X1A>T (rs10838851) genes were genotyped using polymerase chain reaction (PCR)-restriction fragment length polymorphism assays and real-time PCR analysis. We determined that the OR4C16G>A polymorphism was associated with idiopathic RPL in Korean women (Adjusted odds ratio [AOR] 1.782; 95% confidence interval [CI] 1.004-3.163; P = 0.048, and AOR 1.766; 95% CI 1.020-3.059; P = 0.042). In addition, the prevalence of RPL was increased in women with the OR4C16GA + AA genotype and blood coagulation measures of prothrombin time (PT) > 10.4 s (AOR 8.292; 95% CI 2.744-25.054). We suggest that the OR4C16G>A polymorphism might serve as a clinically useful biomarker for the development, prevention, and prognosis of RPL.

Genetics of male infertility: from research to clinic

Male infertility is a multifactorial complex disease with highly heterogeneous phenotypic representation and in at least 15% of cases, this condition is related to known genetic disorders, including both chromosomal and single-gene alterations. In about 40% of primary testicular failure, the etiology remains unknown and a portion of them is likely to be caused by not yet identified genetic anomalies. During the last 10 years, the search for 'hidden' genetic factors was largely unsuccessful in identifying recurrent genetic factors with potential clinical application. The armamentarium of diagnostic tests has been implemented only by the screening for Y chromosome-linked gr/gr deletion in those populations for which consistent data with risk estimate are available. On the other hand, it is clearly demonstrated by both single nucleotide polymorphisms and comparative genomic hybridization arrays, that there is a rare variant burden (especially relevant concerning deletions) in men with impaired spermatogenesis. In the era of next generation sequencing (NGS), we expect to expand our diagnostic skills, since mutations in several hundred genes can potentially lead to infertility and each of them is likely responsible for only a small fraction of cases. In this regard, system biology, which allows revealing possible gene interactions and common biological pathways, will provide an informative tool for NGS data interpretation. Although these novel approaches will certainly help in discovering 'hidden' genetic factors, a more comprehensive picture of the etiopathogenesis of idiopathic male infertility will only be achieved by a parallel investigation of the complex world of gene environmental interaction and epigenetics.

The "omics" of human male infertility: integrating big data in a systems biology approach

Spermatogenesis is a complex process in which >2300 genes are temporally and spatially regulated to form a terminally differentiated sperm cell that must maintain the ability to contribute to a totipotent embryo which can successfully differentiate into a healthy individual. This process is dependent on fidelity of the genome, epigenome, transcriptome, and proteome of the spermatogonia, supporting cells, and the resulting sperm cell. Infertility and/or disease risk may increase in the offspring if abnormalities are present. This review highlights the recent advances in our understanding of these processes in light of the "omics revolution". We briefly review each of these areas, as well as highlight areas of future study and needs to advance further.