Mutations in CFAP43 and CFAP44 cause male infertility and flagellum defects in Trypanosoma and human

Abstract

Spermatogenesis defects concern millions of men worldwide, yet the vast majority remains undiagnosed. Here we report men with primary infertility due to multiple morphological abnormalities of the sperm flagella with severe disorganization of the sperm axoneme, a microtubule-based structure highly conserved throughout evolution. Whole-exome sequencing was performed on 78 patients allowing the identification of 22 men with bi-allelic mutations in DNAH1 (n = 6), CFAP43 (n = 10), and CFAP44 (n = 6). CRISPR/Cas9 created homozygous CFAP43/44 male mice that were infertile and presented severe flagellar defects confirming the human genetic results. Immunoelectron and stimulated-emission-depletion microscopy performed on CFAP43 and CFAP44 orthologs in Trypanosoma brucei evidenced that both proteins are located between the doublet microtubules 5 and 6 and the paraflagellar rod. Overall, we demonstrate that CFAP43 and CFAP44 have a similar structure with a unique axonemal localization and are necessary to produce functional flagella in species ranging from Trypanosoma to human.

DNAH17 is associated with asthenozoospermia and multiple morphological abnormalities of sperm flagella

“…Scale bar, Previous reports had revealed that mutations in the genes encoding dynein axonemal heavy chain proteins contributed to MMAF in humans. Mutations in DNAH1 have formally been correlated with MMAF in human (Amiri-Yekta et al, 2016;Ben Khelifa et al, 2014;Coutton et al, 2018;Dong et al, 2018;Sha et al, 2017;Tang et al, 2017). DNAH1 mutations can lead to the MMAF phenotype without PCDassociated diseases in humans.…”

A DNAH17 missense variant causes flagella destabilization and asthenozoospermia

“…So far, mutations in only DNAH1 or DNAH9 have been described in patients with asthenozoospermia. Patients harboring biallelic DNAH1 mutations were infertile and displayed impaired sperm motility and multiple morphological abnormalities of sperm flagella (MMAF), including absent, bent, short, coiled, and irregular-caliber flagella (Coutton et al, 2018;Ben Khelifa et al, 2014;Sha et al, 2017;Tang et al, 2017;Wang et al, 2017); an infertile patient with two homozygous DNAH9 mutations displayed markedly reduced sperm counts and motility, as well as absence of morphologically normal sperm (i.e., oligoasthenozoospermia; Fassad et al, 2018), whereas their functional roles in maintaining sperm motility and flagellar structure have not been fully understood. Interestingly, DNAH17, encoding an ODA component, showed testis-specific mRNA expression in humans (Milisav and Affara, 1998) but has not yet been functionally characterized.…”

Whole exome sequencing of men with multiple morphological abnormalities of the sperm flagella reveals novel homozygous QRICH2 mutations

“…The genetic characterization of this phenotype began in 2014 with the identification of DNAH1 (dynein axonemal heavy chain 1) as a major gene implicated in MMAF . After the development and the introduction of high throughput sequencing (HTS) techniques such as whole exome sequencing (WES), deleterious mutations were formally identified in eight additional MMAF genes ( AK7 , ARMC2 , CFAP43 , CFAP44 , CFAP69 , FSIP2 , TTC21A , and WDR66 ) showing the high genetic heterogeneity of this phenotype. Despite these important advances in gene identification, about half of the MMAF cases remain idiopathic without a genetic diagnosis.…”

“…what was observed in a control group (15.5%) suggesting that the presence of QRICH2 heterozygous variants is not associated with MMAF syndrome. techniques such as whole exome sequencing (WES), deleterious mutations were formally identified in eight additional MMAF genes (AK7, ARMC2, CFAP43, CFAP44, CFAP69, FSIP2, TTC21A, and WDR66) [3][4][5][6][7][8][9][10][11][12][13][14][15] showing the high genetic heterogeneity of this phenotype. Despite these important advances in gene identification, about half of the MMAF cases remain idiopathic without a genetic diagnosis.…”