Sequence analysis of 37 candidate genes for male infertility: challenges in variant assessment and validating genes

• Published in: Andrology (Oxford) Vol. 8; no. 2; pp. 434 - 441
• Main Authors: Araujo, T. F., Friedrich, C., Grangeiro, C. H. P., Martelli, L. R., Grzesiuk, J. D., Emich, J., Wyrwoll, M. J., Kliesch, S., Simões, A. L., Tüttelmann, F.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.03.2020
• Subjects: Adult; candidate genes; Genes; Genetic Predisposition to Disease - genetics; Humans; Infertility; Infertility, Male - genetics; Male; male infertility; Males; non‐obstructive azoospermia; Sperm; whole exome sequencing; Whole Exome Sequencing - methods; non-obstructive azoospermia; candidate genes; male infertility; whole exome sequencing
• ISSN: 2047-2919; 2047-2927; 2047-2927
• DOI: 10.1111/andr.12704

Background The routine genetic analysis for diagnosing male infertility has not changed over the last twenty years, and currently available tests can only determine the etiology of 4% of unselected infertile patients. Thus, to create new diagnostic assays, we must better understand the molecular and genetic mechanisms of male infertility. Although next‐generation sequencing allows for simultaneous analysis of hundreds of genes and the discovery of novel candidates related to male infertility, so far only a few gene candidates have enough sound evidence to support the gene–disease relationship. Objective Since complementary studies are required to validate genes, we aimed to analyze the presence of potentially pathogenic rare variants in a set of candidate genes related to azoospermia in a hitherto understudied South American population. Subjects and Methods We performed whole exome sequencing in a group of 16 patients with non‐obstructive azoospermia from Ribeirão Preto, Brazil. Based on a recent systematic review of monogenic causes of male infertility, we selected a set of 37 genes related to azoospermia, Sertoli‐Cell‐Only histology, and spermatogenic arrest to analyze. The identified variants were confirmed by Sanger sequencing, and their functional consequence was predicted by in silico programs. Results We identified potential pathogenic variants in seven genes in six patients. Two variants, c.671A>G (p.(Asn224Ser)) in DMRT1 and c.91C>T (p.(Arg31Cys)) in REC8, have already been described in association with azoospermia. We also found new variants in genes that already have moderate evidence of being linked to spermatogenic failure (TEX15, KLHL10), in genes with limited evidence (DNMT3B, TEX14) and in one novel promising candidate gene that has no evidence so far (SYCE1L). Discussion Although this study included a small number of patients, the process of rationally selecting genes allowed us to detect rare potentially pathogenic variants, providing supporting evidence for validating candidate genes associated with azoospermia.