80% of male infertility is caused by sperm motility disorders. Through experiments with transgenic mice corroborated by genetic analysis of humans, it was found that mutations in GALNTL5, a glycosyl transferase gene, are responsible for this defect. A rapid assay is being developed now.
JST news release, January 9, 2014
AIST Sugar-chain Biomedical Engineering Center discovers origin of asthenospermia: defect in pp-GalNAc-T glycosyltransferase