Genetic Defects in the Sperm Tail: Damaged Radial Spokes and Male Infertility

Male infertility is a global reproductive health issue, and sperm from the majority of infertile males exhibit motility defects. Although anatomical and endocrinological etiologies underlying male infertility have been identified and become targets for clinical treatment, approximately 15% to 40% of cases are still classified as idiopathic infertility, with causal factors remaining unresolved. Recent advances in genomic analyses have identified diverse genetic variants explaining idiopathic male infertility. In this review, we summarize the current understanding of infertility-causing genetic variants, particularly those encoding proteins that constitute the radial spoke complexes which are critical structural complexes in the sperm tail essential for motility.