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Expanding established tests, exome sequencing in crypto-/azoospermic men yielded 8.5% additional diagnoses. These predict the success rate of testicular sperm extraction. Thus, an analysis of validated genes in infertile men with crypto- or azoospermia will significantly improve the standard of care. Crypto- and azoospermia (very few/no sperm in the semen) are main contributors to male factor infertility. Genetic causes for spermatogenic failure (SPGF) include Klinefelter syndrome and Y-chromosomal azoospermia factor microdeletions, and CFTR mutations for obstructive azoospermia (OA). However, the majority of cases remain unexplained because monogenic causes are not analysed. To elucidate the monogenic contribution to azoospermia by prospective exome sequencing and strict application of recent clinical guidelines. Since January 2017, we studied crypto- and azoospermic men without chromosomal aberrations and Y-chromosomal microdeletions attending the Centre of Reproductive Medicine and Andrology, Münster. We performed exome sequencing in 647 men, analysed 60 genes having at least previous limited clinical validity, and strictly assessed variants according to clinical guidelines. Overall, 55 patients (8.5%) with diagnostic genetic variants were identified. Of these patients, 20 (3.1%) carried mutations in CFTR or ADGRG2 , and were diagnosed with OA. In 35 patients (5.4%) with SPGF, mutations in 20 different genes were identified. According to ClinGen criteria, 19 of the SPGF genes now reach at least moderate clinical validity. As limitations, only one transcript per gene was considered, and the list of genes is increasing rapidly so cannot be exhaustive. The number of diagnostic genes in crypto-/azoospermia was almost doubled to 21 using exome-based analyses and clinical guidelines. Application of this procedure in routine diagnostics will significantly improve the diagnostic yield and clinical workup as the results indicate the success rate of testicular sperm extraction. When no sperm are found in the semen, a man cannot conceive naturally. The causes are often unknown, but genetics play a major role. We searched for genetic variants in a large group of patients and found causal mutations for one in 12 men; these predict the chances for fatherhood. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to identify mutations that cause non-syndromic male infertility using whole exome sequencing of family cases. Methods: We recruited a consanguineous Turkish family comprising nine siblings with male triplets; two of the triplets were infertile as well as one younger infertile brother. Whole exome sequencing (WES) performed on two azoospermic brothers identified a mutation in the melanoma antigen family B4 ( MAGEB4) gene which was confirmed via Sanger sequencing and then screened for on control groups and unrelated infertile subjects. The effect of the mutation on messenger RNA (mRNA) and protein levels was tested after in vitro cell transfection. Structural features of MAGEB4 were predicted throughout the conserved MAGE domain. Results: The novel single-base substitution (c.1041A>T) in the X-linked MAGEB4 gene was identified as a no-stop mutation. The mutation is predicted to add 24 amino acids to the C-terminus of MAGEB4. Our functional studies were unable to detect any effect either on mRNA stability, intracellular localization of the protein, or the ability to homodimerize/heterodimerize with other MAGE proteins. We thus hypothesize that these additional amino acids may affect the proper protein interactions with MAGEB4 partners. Conclusion: The whole exome analysis of a consanguineous Turkish family revealed MAGEB4 as a possible new X-linked cause of inherited male infertility. This study provides the first clue to the physiological function of a MAGE protein. [ABSTRACT FROM AUTHOR]