Biology subjects

Smits, R. M.

Publications and source records attributed to Smits, R. M..

3 recordsLinked to original sources

bioRxiv2021

A de novo paradigm for male infertility

IntroductionDe novo mutations (DNMs) are known to play a prominent role in sporadic disorders with reduced fitness1. We hypothesize that DNMs play an important role in male infertility and explain a significant fraction of the genetic causes of this understudied disorder. To test this hypothesis, we performed trio-based exome-sequencing in a unique cohort of 185 infertile males and their unaffected parents. Following a systematic analysis, 29 of 145 rare protein altering DNMs were classified as possibly causative of the male infertility phenotype. We observed a significant enrichment of Loss-of-Function (LoF) DNMs in LoF-intolerant genes (p-value=1.00x10-5) as well as predicted pathogenic missense DNMs in missense-intolerant genes (p-value=5.01x10-4). One DNM gene identified, RBM5, is an essential regulator of male germ cell pre-mRNA splicing2. In a follow-up study, 5 rare pathogenic missense mutations affecting this gene were observed in a cohort of 2,279 infertile patients, with no such mutations found in a cohort of 5,784 fertile men (p-value=0.009). Our results provide the first evidence for the role of DNMs in severe male infertility and point to many new candidate genes affecting fertility.

genetics↗

bioRxiv2019

Biallelic mutations in M1AP are a frequent cause of meiotic arrest leading to male infertility

Male infertility affects [~]7% of men in Western societies, but its causes remain poorly understood. The most clinically severe form of male infertility is non-obstructive azoospermia (NOA), which is, in part, caused by an arrest at meiosis, but so far only few genes have been reported to cause germ cell arrest in males. To address this gap, whole exome sequencing was performed in 60 German men with complete meiotic arrest, and we identified in three unrelated men the same homozygous frameshift variant c.676dup (p.Trp226LeufsTer4) in M1AP, encoding meiosis 1 arresting protein. Then, with collaborators from the International Male Infertility Genomics Consortium (IMIGC), we screened a Dutch cohort comprising 99 infertile men and detected the same homozygous variant c.676dup in a man with hypospermatogenesis predominantly displaying meiotic arrest. We also identified two Portuguese men with NOA carrying likely biallelic loss-of-function (LoF) and missense variants in M1AP among men screened by the Genetics of Male Infertility Initiative (GEMINI). Moreover, we discovered a homozygous missense variant p.(Pro389Leu) in M1AP in a consanguineous Turkish family comprising five infertile men. M1AP is predominantly expressed in human and mouse spermatogonia up to secondary spermatocytes and previous studies have shown that knockout male mice are infertile due to meiotic arrest. Collectively, these findings demonstrate that both LoF and missense M1AP variants that impair its protein cause autosomal-recessive meiotic arrest, non-obstructive azoospermia and male infertility. In view of the evidence from several independent groups and populations, M1AP should be included in the growing list of validated NOA genes.

genetics↗

bioRxiv2018

A systematic review and standardized clinical validity assessment of male infertility genes

Study questionWhich genes are confidently linked to human male infertility?\n\nSummary answerOur systematic literature search and clinical validity assessment reveals that a total of 67 genes are currently confidently linked to 81 human male infertility phenotypes.\n\nWhat is known alreadyThe discovery of novel male infertility genes is rapidly accelerating with the availability of Next-Generation Sequencing methods, but the quality of evidence for gene-disease relationships varies greatly. In order to improve genetic research, diagnostics and counseling, there is a need for an evidence-based overview of the currently known genes.\n\nStudy design, size, durationWe performed a systematic literature search and evidence assessment for all publications in Pubmed until June 2018 covering genetic causes of male infertility and/or defective male genitourinary development.\n\nParticipants/materials, setting, methodsTwo independent reviewers conducted the literature search and included papers on the monogenic causes of human male infertility and excluded papers on genetic association or risk factors, karyotype anomalies and/or copy number variations affecting multiple genes. Next, the quality and the extent of all evidence supporting selected genes was weighed by a standardized scoring method and used to determine the clinical validity of each gene-disease relationship as expressed by the following six categories: no evidence, limited, moderate, strong, definitive or unable to classify.\n\nMain results and the role of chanceFrom a total of 23,031 records, we included 1,286 publications about monogenic causes of male infertility leading to a list of 471 gene-disease relationships. The clinical validity of these gene-disease relationships varied widely and ranged from definitive (n=36) to strong (n=12), moderate (n=33), limited (n=86) or no evidence (n=154). A total of 150 gene-disease relationships could not be classified.\n\nLimitations, reasons for cautionOur literature search was limited to Pubmed.\n\nWider implications of the findingsThe comprehensive overview will aid researchers and clinicians in the field to establish gene lists for diagnostic screening using validated gene-disease criteria and identify gaps in our knowledge of male infertility. For future studies, the authors discuss the relevant and important international guidelines regarding research related to gene discovery and provide specific recommendations to the field of male infertility.\n\nStudy funding/competing interest(s)This work was supported by a VICI grant from The Netherlands Organisation for Scientific Research (918-15-667 to JAV).

genetics↗