CFAP65基因突变导致精子鞭毛多发形态异常的遗传学初步研究

目的:探寻精子鞭毛多发形态异常(MMAF)可能的致病基因。方法:通过对1例典型的MMAF患者进行全外显子组测序(WES),分析可能的致病基因;运用扫描电镜和透射电镜观察MMAF患者精液样本,明确其鞭毛超微结构特点;通过精子免疫荧光技术分析cilia and flagella-associated protein 65(CFAP65)在精子发生过程中的表达模式。结果:该例患者存在CFAP65基因的一个纯合致病性突变c.2675G>A(p.Trp892*);扫描电镜发现该患者精子具有典型的MMAF特征,即表现为无尾,折尾,卷尾,短尾或不规则尾巴;透射电镜发现患者精子鞭毛"9+2"结构缺失和紊乱:精子鞭毛纤维鞘组装异常,伴有中心微管缺失和动力蛋白臂缺失。细胞免疫荧光提示该CFAP65基因在小鼠各级生殖细胞均有表达。结论:CFAP65基因参与了精子鞭毛结构的组装,其突变可引起MMAF表型而导致男性不育。

Novel biallelic loss-of-function mutations in CFAP43 cause multiple morphological abnormalities of the sperm flagellum in Pakistani families

Multiple morphological abnormalities of the sperm flagella(MMAF)is a specific type of asthenoteratozoospermia,presenting with multiple morphological anomalies in spermatozoa,such as absent,bent,coiled,short,or irregular caliber flagella.Previous genetic studies revealed pathogenic mutations in genes encoding cilia and flagella-associated proteins(CFAPs;e.g.,CFAP43,CFAP44,CFAP65,CFAP69,CFAP70,and CFAP251)responsible for the MMAF phenotype in infertile men from different ethnic groups.However,none of them have been identified in infertile Pakistani males with MMAF.In the current study,two Pakistani families with MMAF patients were recruited.Whole-exome sequencing(WES)of patients and their parents was performed.WES analysis reflected novel biallelic loss-of-function mutations in CFAP43 in both families(Family 1:ENST00000357060.3,p.Arg300Lysfs*22 and p.Thr526Serfs*43 in a compound heterozygous state;Family 2:ENST00000357060.3,p.Thr526Serfs*43 in a homozygous state).Sanger sequencing further confirmed that these mutations were segregated recessively in the families with the MMAF phenotype.Semiquantitative reverse-transcriptase polymerase chain reaction(qRT-PCR)was carried out to detect the effect of the mutation on mRNA of the affected gene.Previous research demonstrated that biallelic loss-of-function mutations in CFAP43 accounted for the majority of all CFAP43-mutant MMAF patients.To the best of our knowledge,this is the first study to report CFAP43 biallelic loss-of-function mutations in a Pakistani population with the MMAF phenotype.This study will help researchers and clinicians to understand the genetic etiology of MMAF better.