@article{fb7463eb625343cbad15a2201bb86c41,
title = "The piRNA-pathway factor FKBP6 is essential for spermatogenesis but dispensable for control of meiotic LINE-1 expression in humans",
abstract = "Infertility affects around 7% of the male population and can be due to severe spermatogenic failure (SPGF), resulting in no or very few sperm in the ejaculate. We initially identified a homozygous frameshift variant in FKBP6 in a man with extreme oligozoospermia. Subsequently, we screened a total of 2,699 men with SPGF and detected rare bi-allelic loss-of-function variants in FKBP6 in five additional persons. All six individuals had no or extremely few sperm in the ejaculate, which were not suitable for medically assisted reproduction. Evaluation of testicular tissue revealed an arrest at the stage of round spermatids. Lack of FKBP6 expression in the testis was confirmed by RT-qPCR and immunofluorescence staining. In mice, Fkbp6 is essential for spermatogenesis and has been described as being involved in piRNA biogenesis and formation of the synaptonemal complex (SC). We did not detect FKBP6 as part of the SC in normal human spermatocytes, but small RNA sequencing revealed that loss of FKBP6 severely impacted piRNA levels, supporting a role for FKBP6 in piRNA biogenesis in humans. In contrast to findings in piRNA-pathway mouse models, we did not detect an increase in LINE-1 expression in men with pathogenic FKBP6 variants. Based on our findings, FKBP6 reaches a “strong” level of evidence for being associated with male infertility according to the ClinGen criteria, making it directly applicable for clinical diagnostics. This will improve patient care by providing a causal diagnosis and will help to predict chances for successful surgical sperm retrieval.",
keywords = "azoospermia, FKBP6, genetics, LINE-1, male infertility, meiosis, oligozoospermia, piRNA-pathway, round spermatid arrest, spermatogenesis",
author = "{Genetics of Male Infertility Initiative (GEMINI) consortium} and Wyrwoll, {Margot J.} and Gaasbeek, {Channah M.} and Ieva Golubickaite and Rytis Stakaitis and Oud, {Manon S.} and Liina Nagirnaja and Camille Dion and Sindi, {Emad B.} and Leitch, {Harry G.} and Jayasena, {Channa N.} and Anu Sironen and Dicke, {Ann Kristin} and Nadja Rotte and Birgit Stallmeyer and Sabine Kliesch and Grangeiro, {Carlos H.P.} and Araujo, {Tha{\'i}s F.} and Paul Lasko and Kathleen D'Hauwers and Smits, {Roos M.} and Liliana Ramos and Xavier, {Miguel J.} and Conrad, {Don F.} and Kristian Almstrup and Veltman, {Joris A.} and Frank T{\"u}ttelmann and {van der Heijden}, {Godfried W.}",
note = "Funding Information: We are grateful for the participation of all affected individuals and their family members in this study. We thank Annette Schenk and Lara Renssen for technical and organizational support (Radboud University Medical Center). We thank Joachim Wistuba (University Hospital M{\"u}nster) and Susana de Sousa Lopes (Leiden University Medical Center) for thoughtful discussions. This project was funded by The Netherlands Organization for Scientific Research (918-15-667) to J.A.V. as well as an Investigator Award in Science from the Wellcome Trust (209451) to J.A.V. a grant from the Catherine van Tussenbroek Foundation to M.S.O. a grant from Merck to R.S. and the German Research Foundation Clinical Research Unit “Male Germ Cells” (DFG, CRU326) to F.T. by independent financial support by the Novo Nordisk Foundation (grant# 0069913 to K.A.), the Independent Research Fund Denmark (grant# 1030-00381B to K.A.), and the Svend Andersen Foundation (grant# 84 - A.08 to K.A.) to K.A. by grants from the National Institutes of Health of the United States of America (R01HD078641 and P50HD096723) to D.F.C. and by research grant BB/V011251/1 from Biotechnology and Biological Sciences Research Council to A.S. P.L. is supported by the Excellence Program of Radboud University and by research grant MOP-44050 from the Canadian Institutes of Health Research. H.G.L. is supported by MRC Core Funding (MC- A6525QA10) and the National Institute for Health Research (NIHR) Imperial Biomedical Research Centre (BRC). C.N.J. is supported by the NIHR and BRC. G.W.v.d.H. designed and coordinated the study. C.G. and M.S.O. analyzed exome-sequencing data of RU02135 and identified the index case. G.W.v.d.H. performed immunofluorescence stainings, imaging, and testicular cell quantifications. I.G. R.S. L.N. K.A. and D.F.C. performed small RNA sequencing and data analysis. I.G. R.S. and K.A. performed RT-qPCRs and data analysis. P.L. provided technical assistance. C.D. H.G.L. E.B.S. C.N.J. and A.S. identified proband Imp001 and assembled corresponding data. C.H.P.G. and T.F.A. assembled data on M1813. M.J.W. did gene and variant assessment. M.J.W. N.R. B.S. S.K. and F.T. provided data and materials of M1400, M2546, and M2548. A.K.D. performed the minigene assays. K.D. R.M.S. and L.R. assembled data of RU02135. M.J.X. performed statistical analyses of immunofluorescence quantifications. M.J.X. D.F.C. J.A.V. and F.T. were involved in conceptualizing the replication studies. The first draft of the manuscript was prepared by M.J.W. and G.W.v.d.H. All authors contributed to the final version and approved it. C.N.J. has an Investigator-led grant from Logixx Pharma Ltd, UK. Funding Information: We are grateful for the participation of all affected individuals and their family members in this study. We thank Annette Schenk and Lara Renssen for technical and organizational support ( Radboud University Medical Center ). We thank Joachim Wistuba ( University Hospital M{\"u}nster ) and Susana de Sousa Lopes ( Leiden University Medical Center ) for thoughtful discussions. This project was funded by The Netherlands Organization for Scientific Research ( 918-15-667 ) to J.A.V. as well as an Investigator Award in Science from the Wellcome Trust ( 209451 ) to J.A.V., a grant from the Catherine van Tussenbroek Foundation to M.S.O., a grant from Merck to R.S. and the German Research Foundation Clinical Research Unit “Male Germ Cells” (DFG, CRU326 ) to F.T., by independent financial support by the Novo Nordisk Foundation (grant# 0069913 to K.A.), the Independent Research Fund Denmark (grant# 1030-00381B to K.A.), and the Svend Andersen Foundation (grant# 84 - A.08 to K.A.) to K.A., by grants from the National Institutes of Health of the United States of America ( R01HD078641 and P50HD096723 ) to D.F.C., and by research grant BB/V011251/1 from Biotechnology and Biological Sciences Research Council to A.S. P.L. is supported by the Excellence Program of Radboud University and by research grant MOP-44050 from the Canadian Institutes of Health Research . H.G.L. is supported by MRC Core Funding (MC- A6525QA10 ) and the National Institute for Health Research (NIHR) Imperial Biomedical Research Centre (BRC). C.N.J. is supported by the NIHR and BRC . Publisher Copyright: {\textcopyright} 2022",
year = "2022",
month = oct,
day = "6",
doi = "10.1016/j.ajhg.2022.09.002",
language = "English (US)",
volume = "109",
pages = "1850--1866",
journal = "American Journal of Human Genetics",
issn = "0002-9297",
publisher = "Cell Press",
number = "10",
}