• PMID: 30137358
• Gene Name: FSIP2
• Condition: Multiple morphological abnormalities of sperm flagella (MMAF)
• Association: Associated
• Population size: 78
• Population details: 78 infertile men with a MMAF phenotype
• Sex: Male
• Infertility type: Male infertility
• Other associated phenotypes: Multiple morphological abnormalities of sperm flagella (MMAF)

Whole-exome sequencing identifies mutations in FSIP2 as a recurrent cause of multiple morphological abnormalities of the sperm flagella

Martinez G, Kherraf ZE, Zouari R, Fourati Ben Mustapha S, Saut A, Pernet-Gallay K, Bertrand A, Bidart M, Hograindleur JP, Amiri-Yekta A, Kharouf M, Karaouzène T, Thierry-Mieg N, Dacheux-Deschamps D, Satre V, Bonhivers M, Touré A, Arnoult C, Ray PF, Coutton C.

STUDY QUESTION: Can whole-exome sequencing (WES) of infertile patients identify new genes responsible for multiple morphological abnormalities of the sperm flagella (MMAF)? SUMMARY ANSWER: WES analysis of 78 infertile men with a MMAF phenotype permitted the identification of four homozygous mutations in the fibrous sheath (FS) interacting protein 2 (FSIP2) gene in four unrelated individuals. WHAT IS KNOWN ALREADY: The use of high-throughput sequencing techniques revealed that mutations in the dynein axonemal heavy chain 1 (DNAH1) gene, and in the cilia and flagella associated protein 43 (CFAP43) and 44 (CFAP44) genes account for approximately one-third of MMAF cases thus indicating that other relevant genes await identification. STUDY DESIGN, SIZE, DURATION: This was a retrospective genetics study of 78 patients presenting a MMAF phenotype who were recruited in three fertility clinics between 2008 and 2015. Control sperm samples were obtained from normospermic donors. Allelic frequency for control subjects was derived from large public databases. PARTICIPANTS/MATERIALS, SETTING, METHODS: WES was performed for all 78 subjects. All identified variants were confirmed by Sanger sequencing. Relative mRNA expression levels for the selected candidate gene (FSIP2) was assessed by quantitative RT-PCR in a panel of normal human and mouse tissues. To characterize the structural and ultrastructural anomalies present in patients' sperm, immunofluorescence (IF) was performed on sperm samples from two subjects with a mutation and one control and transmission electron microscopy (TEM) analyses was performed on sperm samples from one subject with a mutation and one control. MAIN RESULTS AND THE ROLE OF CHANCE: We identified four unrelated patients (4/78, 5.1%) with homozygous loss of function mutations in the FSIP2 gene, which encodes a protein of the sperm FS and is specifically expressed in human and mouse testis. None of these mutations were reported in control sequence databases. TEM analyses showed a complete disorganization of the FS associated with axonemal defects. IF analyses confirmed that the central-pair microtubules and the inner and outer dynein arms of the axoneme were abnormal in all four patients carrying FSIP2 mutations. Importantly, and in contrast to what was observed in patients with MMAF and mutations in other MMAF-related genes (DNAH1, CFAP43 and CFAP44), mutations in FSIP2 led to the absence of A-kinase anchoring protein 4 (AKAP4). LIMITATIONS, REASONS FOR CAUTION: The low number of biological samples and the absence of a reliable anti-FSIP2 antibody prevented the formal demonstration that the FSIP2 protein was absent in sperm from subjects with a FSIP2 mutation. WIDER IMPLICATIONS OF THE FINDINGS: Our findings indicate that FSIP2 is one of the main genes involved in MMAF syndrome. In humans, genes previously associated with a MMAF phenotype encoded axonemal-associated proteins (DNAH1, CFAP43 and CFAP44). We show here that FSIP2, a protein of the sperm FS, is also logically associated with MMAF syndrome as we showed that it is necessary for FS assembly and for the overall axonemal and flagellar biogenesis. As was suggested before in mouse and man, our results also suggest that defects in AKAP4, one of the main proteins interacting with FSIP2, would induce a MMAF phenotype. Finally, this work reinforces the demonstration that WES sequencing is a good strategy to reach a genetic diagnosis for patients with severe male infertility phenotypes. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the following grants: the 'MAS-Flagella' project financed by the French ANR and the DGOS for the program PRTS 2014 (14-CE15) and the 'Whole genome sequencing of patients with Flagellar Growth Defects (FGD)' project financed by the Fondation Maladies Rares for the program Séquençage à haut débit 2012. The authors have no conflict of interest. FAU - Martinez, Guillaume AU - Martinez G AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. AD - CHU Grenoble Alpes, UM de Génétique Chromosomique, Grenoble, France. FAU - Kherraf, Zine-Eddine AU - Kherraf ZE AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. AD - CHU de Grenoble, UM GI-DPI, Grenoble, France. FAU - Zouari, Raoudha AU - Zouari R AD - Clinique des Jasmins, 23, Av. Louis BRAILLE 1002 Belvedere, Tunis, Tunisia. FAU - Fourati Ben Mustapha, Selima AU - Fourati Ben Mustapha S AD - Clinique des Jasmins, 23, Av. Louis BRAILLE 1002 Belvedere, Tunis, Tunisia. FAU - Saut, Antoine AU - Saut A AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. AD - CHU Grenoble Alpes, UM de Génétique Chromosomique, Grenoble, France. FAU - Pernet-Gallay, Karin AU - Pernet-Gallay K AD - Grenoble Neuroscience Institute, INSERM 1216, Grenoble, France. FAU - Bertrand, Anne AU - Bertrand A AD - Grenoble Neuroscience Institute, INSERM 1216, Grenoble, France. FAU - Bidart, Marie AU - Bidart M AD - CHU Grenoble Alpes, UM de Biochimie Génétique et Moléculaire, Grenoble, France. FAU - Hograindleur, Jean Pascal AU - Hograindleur JP AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. FAU - Amiri-Yekta, Amir AU - Amiri-Yekta A AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. AD - CHU Grenoble Alpes, UM de Biochimie Génétique et Moléculaire, Grenoble, France. AD - Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran. FAU - Kharouf, Mahmoud AU - Kharouf M AD - Clinique des Jasmins, 23, Av. Louis BRAILLE 1002 Belvedere, Tunis, Tunisia. FAU - Karaouzène, Thomas AU - Karaouzène T AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. AD - University Grenoble Alpes/CNRS, TIMC-IMAG, Grenoble, France. FAU - Thierry-Mieg, Nicolas AU - Thierry-Mieg N AD - University Grenoble Alpes/CNRS, TIMC-IMAG, Grenoble, France. FAU - Dacheux-Deschamps, Denis AU - Dacheux-Deschamps D AD - Université de Bordeaux, Microbiologie Fondamentale et Pathogénicité, CNRS UMR, Bordeaux, France. AD - Institut Polytechnique de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR-CNRS 5234, Bordeaux, France. FAU - Satre, Véronique AU - Satre V AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. AD - CHU Grenoble Alpes, UM de Génétique Chromosomique, Grenoble, France. FAU - Bonhivers, Mélanie AU - Bonhivers M AD - Université de Bordeaux, Microbiologie Fondamentale et Pathogénicité, CNRS UMR, Bordeaux, France. AD - Institut Polytechnique de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR-CNRS 5234, Bordeaux, France. FAU - Touré, Aminata AU - Touré A AD - INSERM U1016, Institut Cochin, Paris, France. AD - Centre National de la Recherche Scientifique UMR8104, Paris, France. AD - Faculté de Médecine, Université Paris Descartes, Sorbonne Paris Cité, Paris, France. FAU - Arnoult, Christophe AU - Arnoult C AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. FAU - Ray, Pierre F AU - Ray PF AD - University Grenoble Alpes, INSERM U1209, CNRS UMR 5309, Institute for Advanced Biosciences, Team Genetics Epigenetics and Therapies of Infertility, Grenoble, France. AD - CHU de Grenoble, UM GI-DPI, Grenoble, France.