Novel DNAH17 Splice-Site Mutations Truncating the AAA6 Domain Cause Asthenozoospermia with MMAF.

To investigate the pathogenicity of splice-site variants in DNAH17, and analyze their impact on sperm morphology and motility, we employed whole-exome sequencing (WES) and Sanger sequencing to identify and validate candidate variants. Computational predictions of splicing defects were performed using varSEAK and MobiDetails. Functional validation was conducted using minigene splicing assays in HEK293T cells. Structural modeling of mutant proteins was performed with AlphaFold3 and visualized by PyMOL. Two novel splice-site variants (DNAH17: c.11677 + 5G > T/c.11677 + 5G > A) were identified in a proband with asthenozoospermia and multiple morphological abnormalities of the sperm flagella (MMAF). Bioinformatics tools predicted disruption of the canonical donor splice site (MaxEntScan score reduction: 54.2% for G > A, 39.5% for G > T; SpliceAI donor loss scores > 0.8). Minigene assays confirmed exon 72 skipping, leading to a frameshift mutation (p.Asn3844Lysfs*13) that truncates the AAA6 domain. This study expands the mutational spectrum of DNAH17-related male infertility by demonstrating that splice-site variants disrupting the AAA6 domain represent a novel pathogenic mechanism underlying asthenozoospermia and MMAF. These findings underscore the necessity of integrating splice-site analysis into genetic diagnostics for male infertility.