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Wyrwoll MJ, Gaasbeek CM, Golubickaite I, Stakaitis R, Oud MS, Nagirnaja L, Dion C, Sindi EB, Leitch HG, Jayasena CN, Sironen A, Dicke AK, Rotte N, Stallmeyer B, Kliesch S, Grangeiro CHP, Araujo TF, Lasko P, D'Hauwers K, Smits RM, Ramos L, Xavier MJ, Conrad DF, Almstrup K, Veltman JA, Tüttelmann F, van der Heijden GW. The piRNA-pathway factor FKBP6 is essential for spermatogenesis but dispensable for control of meiotic LINE-1 expression in humans. Am J Hum Genet 2022; 109:1850-1866. [PMID: 36150389 PMCID: PMC9606565 DOI: 10.1016/j.ajhg.2022.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 09/01/2022] [Indexed: 01/25/2023] Open
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.
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Affiliation(s)
- Margot J Wyrwoll
- Institute of Reproductive Genetics, University of Münster, Münster, Germany
| | - Channah M Gaasbeek
- Department of Human Genetics, Radboudumc, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, the Netherlands; Department of Obstetrics and Gynecology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ieva Golubickaite
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA; Department of Growth and Reproduction, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark; Department of Genetics and Molecular Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Rytis Stakaitis
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA; Department of Growth and Reproduction, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark; Laboratory of Molecular Neurooncology, Neuroscience Institute, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Manon S Oud
- Department of Human Genetics, Radboudumc, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, the Netherlands
| | - Liina Nagirnaja
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Camille Dion
- MRC London Institute of Medical Sciences, London, UK; Institute of Clinical Sciences, Imperial College London, London, UK
| | - Emad B Sindi
- Section of Investigative Medicine, Imperial College London, London, UK
| | - Harry G Leitch
- MRC London Institute of Medical Sciences, London, UK; Institute of Clinical Sciences, Imperial College London, London, UK; Centre for Paediatrics and Child Health, Faculty of Medicine, Imperial College London, London, UK
| | - Channa N Jayasena
- Section of Investigative Medicine, Imperial College London, London, UK
| | - Anu Sironen
- Natural Resources Institute Finland, Production Systems, Jokioinen, Finland; Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Ann-Kristin Dicke
- Institute of Reproductive Genetics, University of Münster, Münster, Germany
| | - Nadja Rotte
- Institute of Reproductive Genetics, University of Münster, Münster, Germany
| | - Birgit Stallmeyer
- Institute of Reproductive Genetics, University of Münster, Münster, Germany
| | - Sabine Kliesch
- Centre of Reproductive Medicine and Andrology, Department of Clinical and Surgical Andrology, University Hospital of Münster, Münster, Germany
| | | | - Thaís F Araujo
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Paul Lasko
- Department of Human Genetics, Radboudumc, Nijmegen, the Netherlands; Department of Biology, McGill University, Montréal, QC, Canada
| | | | - Roos M Smits
- Department of Obstetrics and Gynecology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Liliana Ramos
- Department of Obstetrics and Gynecology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Miguel J Xavier
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Don F Conrad
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Kristian Almstrup
- Department of Growth and Reproduction, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark; Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joris A Veltman
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Frank Tüttelmann
- Institute of Reproductive Genetics, University of Münster, Münster, Germany
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