Novel DNAH1 variants in Chinese males with MMAF-associated asthenoteratozoospermia

Asthenoteratozoospermia is a major contributor to male infertility, with multiple morphological abnormalities of the flagellum (MMAF) representing a genetically heterogeneous disorder characterized by structural defects in sperm flagella. To identify the genetic determinants underlying MMAF-associated infertility, we conducted a comprehensive and systematic investigation involving Chinese infertile couples exhibiting the MMAF phenotype and undergoing assisted reproductive technology (ART). Our integrated approach combined whole-exome sequencing (WES) with Sanger sequencing for variant validation, complemented by scanning and transmission electron microscopy (SEM/TEM) to elucidate ultrastructural features. Molecular analyses included quantitative real-time PCR (qRT-PCR) and immunofluorescence (IF) to evaluate both transcriptional and translational alterations. We identified novel variants in six loci of dynein axonemal heavy chain 1 (DNAH1), including both missense and frameshift variants, across three unrelated families. Affected spermatozoa demonstrated characteristic morphological and ultrastructural abnormalities, while qRT-PCR and IF analyses revealed altered expression patterns of DNAH1. Personalized ART strategies enabled successful pregnancies in individuals harboring DNAH1 variants. While the limited sample size reflects the rarity of this genetic disorder, functional validation beyond expression analysis and structural prediction remains limited. Larger cohorts and in-depth biochemical assays will be required to generalize the findings. Nonetheless, our findings provide important insights into the genetic mechanisms of MMAF and its clinical management.