NovelCFAP43 andCFAP44 mutations cause male infertility with multiple morphological abnormalities of the sperm flagella (MMAF).

Multiple morphological abnormalities of the sperm flagella (MMAF) comprise a rare congenital disease that can cause primary male infertility. Several pathogenic genes (e.g. AKAP4, DNAH1, CFAP43 and CFAP44) are associated with MMAF but the pathogenic mechanisms have not been elucidated. Whole-exome sequencing (WES) was applied to identify the pathogenic genes in 13 Chinese patients with MMAF; the patients were unrelated but all had consanguineous parents (usually first cousins). Real-time polymerase chain reaction and immunofluorescence staining were employed to assess the pathogenicity of these mutations. Four novel homozygous CFAP43 mutations in four (30.8%) MMAF patients and one novel homozygous CFAP44 mutation in one (7.7%) other case were identified. The four novel homozygous CFAP43 mutations included one frameshift mutation (c.1140_1143del: p.Asn380Lysfs*3), one nonsense mutation (c.739A>T: p.Lys247*) and two missense mutations (c.1474G>C: p.Gln492Arg; c.4600C>G: p.Leu1534Val). The novel mutation in CFAP44 was a homozygous nonsense mutation (c.4963C>T: p.Arg1655*). Co-segregation of the mutations was verified by Sanger sequencing of the families. The relative mRNA expression levels of CFAP43 in patients 1 and 9 and the levels of CFAP44 in patient 5 were significantly lower than those in control sperm samples. Immunofluorescence analysis of CFAP43 showed the protein was absent in the sperm flagella of patients 1 and 9. Furthermore, two previously reported mutations of DNAH1 were also identified in another four (30.8%) patients. This study demonstrated that CFAP43 and CFAP44 mutations are important causes of MMAF in the Chinese population. These novel mutations broaden the spectrum of CFAP43 and CFAP44 mutations.

Wu H ，Li W ，He X ，Liu C ，Fang Y ，Zhu F ，Jiang H ，Liu W ，Song B ，Wang X ，Zhou P ，Wei Z ，Zhang F ，Cao Y ... -  《-》

Novel Mutations in CFAP44 and CFAP43 Cause Multiple Morphological Abnormalities of the Sperm Flagella (MMAF).

Sha YW ，Wang X ，Xu X ，Su ZY ，Cui Y ，Mei LB ，Huang XJ ，Chen J ，He XM ，Ji ZY ，Bao H ，Yang X ，Li P ，Li L ... -  《-》

Patients with multiple morphological abnormalities of the sperm flagella harbouring CFAP44 or CFAP43 mutations have a good pregnancy outcome following intracytoplasmic sperm injection.

Multiple morphological abnormalities of the sperm flagella (MMAF) are a rare type of male infertility. Mutations in DNAH1, CFAP43 and CFAP44 are the main aetiology of the disorder. Previously, good intracytoplasmic sperm injection (ICSI) outcomes were reported for MMAF patients with DNAH1 mutations. However, the ICSI prognosis for MMAF patients with CFAP43 or CFAP44 mutations was not known. We designed a retrospective cohort study. Molecular genetic testing identified six MMAF patients with biallelic CFAP44 (CFAP44+ group) or CFAP43 mutations and 12 patients with homozygous or compound heterozygous DNAH1 mutations (DNAH1+ group). A control group consisted of age-matched, non-MMAF men. For MMAF patients carrying CFAP44 mutations, the recorded rates of fertilisation, transferable embryos, pregnancy and delivery after ICSI were 76.47%, 88.46%, 50.0% and 50.0% respectively. The fertilisation rate was significantly higher in the CFAP44+ group than in the DNAH1+ group (76.47% vs. 54.5%, p = 0.0196). There were no statistically significant differences in the rates of transferable embryos, implantation, clinical pregnancy and miscarriage between the CFAP44+ group and either the DNAH1+ group or the age-matched control group. Our results support a good ICSI prognosis for MMAF patients carrying CFAP44 or CFAP43 mutations.

Sha YW ，Wang X ，Su ZY ，Mei LB ，Ji ZY ，Bao H ，Li P ... -  《-》

Biallelic Mutations in CFAP43 and CFAP44 Cause Male Infertility with Multiple Morphological Abnormalities of the Sperm Flagella.

Sperm motility is vital to human reproduction. Malformations of sperm flagella can cause male infertility. Men with multiple morphological abnormalities of the flagella (MMAF) have abnormal spermatozoa with absent, short, coiled, bent, and/or irregular-caliber flagella, which impair sperm motility. The known human MMAF-associated genes, such as DNAH1, only account for fewer than 45% of affected individuals. Pathogenic mechanisms in the genetically unexplained MMAF remain to be elucidated. Here, we conducted genetic analyses by using whole-exome sequencing and genome-wide comparative genomic hybridization microarrays in a multi-center cohort of 30 Han Chinese men affected by MMAF. Among them, 12 subjects could not be genetically explained by any known MMAF-associated genes. Intriguingly, we identified compound-heterozygous mutations in CFAP43 in three subjects and a homozygous frameshift mutation in CFAP44 in one subject. All of these recessive mutations were parentally inherited from heterozygous carriers but were absent in 984 individuals from three Han Chinese control populations. CFAP43 and CFAP44, encoding two cilia- and flagella-associated proteins (CFAPs), are specifically or preferentially expressed in the testis. Using CRISPR/Cas9 technology, we generated two knockout models each deficient in mouse ortholog Cfap43 or Cfap44. Notably, both Cfap43- and Cfap44-deficient male mice presented with MMAF phenotypes, whereas the corresponding female mice were fertile. Our experimental observations on human subjects and animal models strongly suggest that biallelic mutations in either CFAP43 or CFAP44 can cause sperm flagellar abnormalities and impair sperm motility. Further investigations on other CFAP-encoding genes in more genetically unexplained MMAF-affected individuals could uncover novel mechanisms underlying sperm flagellar formation.

Tang S ，Wang X ，Li W ，Yang X ，Li Z ，Liu W ，Li C ，Zhu Z ，Wang L ，Wang J ，Zhang L ，Sun X ，Zhi E ，Wang H ，Li H ，Jin L ，Luo Y ，Wang J ，Yang S ，Zhang F ... -  《-》

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 ... -  《-》