Background Oligoasthenoteratozoospermia is a typical feature of sperm malformations leading to male infertility. Only a few genes have been clearly identified as pathogenic genes of oligoasthenoteratozoospermia.
Methods and results Here, we identified a homozygous frameshift variant (c.731dup, p.Asn244Lysfs*3) in CCDC34, which is preferentially expressed in the human testis, using whole-exome sequencing in a cohort of 100 Chinese men with multiple morphological abnormalities of the sperm flagella (MMAF). In an additional cohort of 167 MMAF-affected men from North Africa, Iran and France, we identified a second subject harbouring a homozygous CCDC34 frameshift variant (c.799_817del, p.Glu267Lysfs*72). Both affected men presented a typical MMAF phenotype with an abnormally low sperm concentration (ie, oligoasthenoteratozoospermia). Transmission electron microscopy analysis of the sperm flagella affected by CCDC34 deficiency further revealed dramatic disorganisation of the axoneme. Immunofluorescence assays of the spermatozoa showed that CCDC34 deficiency resulted in almost absent staining of CCDC34 and intraflagellar transport-B complex-associated proteins (such as IFT20 and IFT52). Furthermore, we generated a mouse Ccdc34 frameshift mutant using CRISPR-Cas9 technology. Ccdc34-mutated (Ccdc34mut/mut ) male mice were sterile and presented oligoasthenoteratozoospermia with typical MMAF anomalies. Intracytoplasmic sperm injection has good pregnancy outcomes in both humans and mice.
Conclusions Our findings support that CCDC34 is crucial to the formation of sperm flagella and that biallelic deleterious mutations in CCDC34/Ccdc34 cause male infertility with oligoasthenoteratozoospermia in humans and mice.
- genetic variation
- reproductive medicine
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
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JC, XW, AA-Y and LW contributed equally.
Correction notice This article has been corrected since it was published Online First. The name of author Pierre F Ray has been amended.
Contributors JC, PR and FZ designed the study. XW, AA-Y, Z-EK, CC, SHH, AD, XH, YC and PR provided patients data and performed clinical assessments. JC, LW, CL, STa, STi, JW, YZh and YZe conducted the experiments. JC, XW, AA-Y, LW, SY, XH, JL, YC, LJ, PR and FZ analysed data. JC, PR and FZ wrote the manuscript. PR and FZ supervised the study.
Funding This work was supported by the National Natural Science Foundation of China (31625015, 31521003, 81971441 and 32000393), Shanghai Municipal Science and Technology Major Project (2017SHZDZX01), Scientific Research (TP202002) from Anhui Medical University, Innovative Research Team of High-level Local Universities in Shanghai (SSMU-ZLCX20180500), Science and Technology Major Project of Inner Mongolia Autonomous Region of China (zdzx2018065), 111 Project (B13016), State Key Laboratory of Reproductive Medicine (SKLRM-K202002), Scientific Research Project of Jiangsu Provincial Health and Family Planning Commission (H2018050) and Maternal and Child Health Research Project of Jiangsu Province (F201866). The work was also supported by the French Research Agency (ANR) project FLAGEL-OME (ANR-19-CE17-0014) to PR.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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