Purpose: Azoospermia affects 1% of men and it can be the consequence of spermatogenic maturation arrest (MA). Although the etiology of MA is likely to be of genetic origin, only 13 genes have been reported as recurrent potential causes of MA. Methods: Exome sequencing in 147 selected MA patients (discovery cohort and two validation cohorts). Results: We found strong evidence for 5 novel genes likely responsible for MA ( ADAD2 , TERB1 , SHOC1 , MSH4 , and RAD21L1 ), for which mouse knockout (KO) models are concordant with the human phenotype. Four of them were validated in the two independent MA cohorts. In addition, 9 patients carried pathogenic variants in 7 previously reported genes - TEX14 , DMRT1 , TEX11 , SYCE1 , MEIOB , MEI1 and STAG3 - allowing to upgrade the clinical significance of these genes for diagnostic purposes. Our meiotic studies provide novel insight into the functional consequences of the variants, supporting their pathogenic role. Conclusions: Our findings contribute substantially to the development of a pre-TESE prognostic gene panel. If properly validated, the genetic diagnosis of complete MA prior to surgical interventions is clinically relevant. Wider implications include the understanding of potential genetic links between NOA and cancer predisposition, and between NOA and premature ovarian failure.

STUDY QUESTION What is the diagnostic potential of next generation sequencing (NGS) based on a ‘mouse azoospermia’ gene panel in human non-obstructive azoospermia (NOA)? SUMMARY ANSWER The diagnostic performance of sequencing a gene panel based on genes associated with mouse azoospermia was relatively successful in idiopathic NOA patients and allowed the discovery of two novel genes involved in NOA due to meiotic arrest. WHAT IS KNOWN ALREADY NOA is a largely heterogeneous clinical entity, which includes different histological pictures. In a large proportion of NOA, the aetiology remains unknown (idiopathic NOA) and yet, unknown genetic factors are likely to play be involved. The mouse is the most broadly used mammalian model for studying human disease because of its usefulness for genetic manipulation and its genetic and physiological similarities to man. Mouse azoospermia models are available in the Mouse Genome Informatics database (MGI: http://www.informatics.jax.org/). STUDY DESIGN, SIZE, DURATION The first step was to design of a ‘mouse azoospermia’ gene panel through the consultation of MGI. The second step was NGS analysis of 175 genes in a group of highly selected NOA patients (n = 33). The third step was characterization of the discovered gene defects in human testis tissue, through meiotic studies using surplus testicular biopsy material from the carriers of the RNF212 and STAG3 pathogenic variants. The final step was RNF212 and STAG3 expression analysis in a collection of testis biopsies. PARTICIPANTS/MATERIALS, SETTING, METHODS From a total of 1300 infertile patients, 33 idiopathic NOA patients were analysed in this study, including 31 unrelated men and 2 brothers from a consanguineous family. The testis histology of the 31 unrelated NOA patients was as follows: 20 Sertoli cell-only syndrome (SCOS), 11 spermatogenic arrest (6 spermatogonial arrest and 5 spermatocytic arrest). The two brothers were affected by spermatocytic arrest. DNA extracted from blood was used for NGS on Illumina NextSeq500 platform. Generated sequence data was filtered for rare and potentially pathogenic variants. Functional studies in surplus testicular tissue from the carriers included the investigation of meiotic entry, XY body formation and metaphases by performing fluorescent immunohistochemical staining and immunocytochemistry. mRNA expression analysis through RT-qPCR of RNF212 and STAG3 was carried out in a collection of testis biopsies with different histology. MAIN RESULTS AND THE ROLE OF CHANCE Our approach was relatively successful, leading to the genetic diagnosis of one sporadic NOA patient and two NOA brothers. This relatively high diagnostic performance is likely to be related to the stringent patient selection criteria i.e. all known causes of azoospermia were excluded and to the relatively high number of patients with rare testis histology (spermatocytic arrest). All three mutation carriers presented meiotic arrest, leading to the genetic diagnosis of three out of seven cases with this specific testicular phenotype. For the first time, we report biallelic variants in STAG3, in one sporadic patient, and a homozygous RNF212 variant, in the two brothers, as the genetic cause of NOA. Meiotic studies allowed the detection of the functional consequences of the mutations and provided information on the role of STAG3 and RNF212 in human male meiosis. LIMITATIONS, REASONS FOR CAUTION All genes, with the exception of 5 out of 175, included in the panel cause azoospermia in mice only in the homozygous or hemizygous state. Consequently, apart from the five known dominant genes, heterozygous variants (except compound heterozygosity) in the remaining genes were not taken into consideration as causes of NOA. We identified the genetic cause in approximately half of the patients with spermatocytic arrest. The low number of analysed patients can be considered as a limitation, but it is a very rare testis phenotype. Due to the low frequency of this specific phenotype among infertile men, our finding may be considered of low clinical impact. However, at an individual level, it does have relevance for prognostic purposes prior testicular sperm extraction. WIDER IMPLICATIONS OF THE FINDINGS Our study represents an additional step towards elucidating the genetic bases of early spermatogenic failure, since we discovered two new genes involved in human male meiotic arrest. We propose the inclusion of RNF212 and STAG3 in a future male infertility diagnostic gene panel. Based on the associated testis phenotype, the identification of pathogenic mutations in these genes also confers a negative predictive value for testicular sperm retrieval. Our meiotic studies provide novel insights into the role of these proteins in human male meiosis. Mutations in STAG3 were first described as a cause of female infertility and ovarian cancer, and Rnf212 knock out in mice leads to male and female infertility. Hence, our results stimulate further research on shared genetic factors causing infertility in both sexes and indicate that genetic counselling should involve not only male but also female relatives of NOA patients. STUDY FUNDING/COMPETING INTEREST(S) This work was funded by the Spanish Ministry of Health Instituto Carlos III-FIS (grant number: FIS/FEDER-PI14/01250; PI17/01822) awarded to CK and AR-E, and by the European Commission, Reproductive Biology Early Research Training (REPROTRAIN, EU-FP7-PEOPLE-2011-ITN289880), awarded to CK, WB, and AE-M. The authors have no conflict of interest.

We report an extraordinarily high frequency of FA in a specific subgroup of azoospermic patients (7.1%). The screening for FANCA pathogenic variants in such patients has the potential to identify undiagnosed FA before the appearance of other severe clinical manifestations of the disease. The definition of this high-risk group for "occult" FA, based on specific testis phenotype with mild/borderline hematological alterations, is of unforeseen clinical relevance.

Background:The exact mechanism of varicocele-related infertility is still elusive, therefore, the current challenges for its management lie in determining which patients stand to benefit most from surgical correction. The authors aimed to assess the clinical factors affecting semen improvement after left microsurgical subinguinal varicocelectomy (MSV) in relation to patient age, ultrasound varicocele grading (USVG), and presence of a right subclinical varicocele (RSV).Methods:From 2010 to 2017 a total of 228 infertile patients underwent left MSV for clinical varicocele. Descriptive statistics were used to describe the cohort and verify the surgical benefit in terms of semen improvement, in addition, subsets of patients were selected according to clinical covariates. Logistic regression modeling was applied to evaluate the presence of RSV, operative time, age, and USVG as explanatory variables.Results:Sperm concentration (SC), progressive sperm motility (PSM), and normal sperm morphology (NSM) increased significantly after surgery (p = 0.002; p = 0.011; p = 0.024; respectively). Mean SC improved after MSV in ⩾35 year-old patients and the grade 3 USVG group (p = 0.01; p = 0.02; respectively). Logistic regression modeling showed a that the probability of SC improvement was 76% lower in subjects presenting RSV (p = 0.011). In addition, patients with a grade 3 USVG presented a three-times greater probability of SC improvement compared with patients with a lower USVG (p = 0.035). In addition, older patients showed a greater probability of SC improvement after MSV (p = 0.041).Conclusions:MSV is an effective varicocele-related infertility treatment that should also be offered to older patients. In addition, patients with a higher USVG benefit from surgery. In infertile men with an RSV in association with a left clinical disease, a bilateral varicocele repair should be considered.

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The association between impaired spermatogenesis and TGCT has stimulated research on shared genetic factors. Y chromosome-linked partial AZFc deletions predispose to oligozoospermia and were also studied in TGCT patients with controversial results. In the largest study reporting the association between gr/gr deletion and TGCT, sperm parameters were unknown. Hence, it remains to be established whether this genetic defect truly represents a common genetic link between TGCT and impaired sperm production. Our aim was to explore the role of the following Y chromosome-linked factors in the predisposition to TGCT: (i) gr/gr deletion in subjects with known sperm parameters; (ii) other partial AZFc deletions and, for the first time, the role of partial AZFc duplications; (iii) DAZ gene dosage variation. 497 TGCT patients and 2030 controls from two Mediterranean populations with full semen/andrological characterization were analyzed through a series of molecular genetic techniques. Our most interesting finding concerns the gr/gr deletion and DAZ gene dosage variation (i.e., DAZ copy number is different from the reference sequence), both conferring TGCT susceptibility. In particular, the highest risk was observed when normozoospermic TGCT and normozoospermic controls were compared (OR = 3.7; 95% CI = 1.5-9.1; p = 0.006 for gr/gr deletion and OR = 1.8; 95% CI = 1.1-3.0; p = 0.013 for DAZ gene dosage alteration). We report in the largest European study population the predisposing effect of gr/gr deletion to TGCT as an independent risk factor from impaired spermatogenesis. Our finding implies regular tumour screening/follow-up in male family members of TGCT patients with gr/gr deletion and in infertile gr/gr deletion carriers.

Background: The exact mechanism of varicocele-related infertility is still elusive, therefore, the current challenges for its management lie in determining which patients stand to benefit most from surgical correction. The authors aimed to assess the clinical factors affecting semen improvement after left microsurgical subinguinal varicocelectomy (MSV) in relation to patient age, ultrasound varicocele grading (USVG), and presence of a right subclinical varicocele (RSV). Methods: From 2010 to 2017 a total of 228 infertile patients underwent left MSV for clinical varicocele. Descriptive statistics were used to describe the cohort and verify the surgical benefit in terms of semen improvement, in addition, subsets of patients were selected according to clinical covariates. Logistic regression modeling was applied to evaluate the presence of RSV, operative time, age, and USVG as explanatory variables. Results: Sperm concentration (SC), progressive sperm motility (PSM), and normal sperm morphology (NSM) increased significantly after surgery (p = 0.002; p = 0.011; p = 0.024; respectively). Mean SC improved after MSV in ⩾35 year-old patients and the grade 3 USVG group (p = 0.01; p = 0.02; respectively). Logistic regression modeling showed a that the probability of SC improvement was 76% lower in subjects presenting RSV (p = 0.011). In addition, patients with a grade 3 USVG presented a three-times greater probability of SC improvement compared with patients with a lower USVG (p = 0.035). In addition, older patients showed a greater probability of SC improvement after MSV (p = 0.041). Conclusions: MSV is an effective varicocele-related infertility treatment that should also be offered to older patients. In addition, patients with a higher USVG benefit from surgery. In infertile men with an RSV in association with a left clinical disease, a bilateral varicocele repair should be considered.

Background Testicular germ cell tumour is a multifactorial disease in which various genetic and environmental factors play a role. Testicular germ cell tumour is part of the testicular dysgenesis syndrome which includes also cryptorchidism, hypospadias, oligo/azoospermia and short anogenital distance. Objectives The primary objective was to examine anogenital distance in testicular germ cell tumour cases and healthy fertile controls. The secondary objective was to assess the (CAG)n polymorphism of the Androgen Receptor gene in relationship with anogenital distances and testicular germ cell tumour development. Material and Methods 156 testicular germ cell tumour patients and 110 tumour‐free normozoospermic controls of Spanish origin. All subjects underwent full andrological workup (including semen and hormone analysis) and genetic analysis (Androgen Receptor (CAG)n). The main outcome measures were the anopenile distance (AGDap), the anoscrotal distance (AGDas) and AR(CAG)n. Result We observed significantly shorter anogenital distances in the group of testicular germ cell tumour patients in respect to controls (P < .001) independently from sperm count and testis histology. Threshold values, applicable only to our cohort, were calculated for anogenital distances with the best sensitivity and specificity. Subjects with AGDap and AGDas below threshold showed a significantly increased risk for testicular germ cell tumour (OR = 4.97, 95% CI = 2.01‐12.33, P = .001 and OR = 4.11, 95% CI = 1.89‐8.92, P ≤ .001, respectively). No significant correlation was observed between AR(CAG)n polymorphism and anogenital distances. The median values of the AR(CAG)n were similar between cases and controls, excluding a major role for this polymorphism in the etiopathogenesis of these testicular dysgenesis syndrome components. Conclusions Ours is the first study focusing on anogenital distances in testicular germ cell tumour patients. We identified short anogenital distances (which is a surrogate biomarker of androgen action during foetal life) as a significant risk factor for this disease. After further validation of our preliminary data, anogenital distance measurement could become part of testicular germ cell tumour screening in order to better define those individuals who would benefit from long‐term active follow‐up.