Furthermore, deletion of either Gykl1 or Gk2 in mice, by CRISPR/Cas9-mediated gene knockout (KO), impacted mitochondrial morphology and mitochondrial ATP production as well as midpiece and sperm tail integrity in spermatozoa, compromising spermatozoa motility and leading to male infertility. Here, GK2 is linked to male infertility.