Novel Variants in Sperm Mitochondrial Cytochrome C Oxidase II (MT-CO2) Gene Associated with Asthenozoospermia in Jordan.

BACKGROUND: Asthenozoospermia is defined as a condition in which the total motility of sperm in a semen sample is less than 40%. Due to impairing sperm motility, asthenozoospermia was linked to different mitochondrial DNA (mtDNA) alterations. The current study aimed to investigate the relationship between MT-CO2 gene variants and the development of asthenozoospermia and male infertility in the Jordanian population. MATERIALS AND METHODS: Semen samples were collected from 196 men, including 119 asthenozoospermic (infertile) and 77 normozoospermia (control), from the Royal Jordanian Medical Services in vitro fertilization (IVF) unit. The isolated mitochondrial DNA (mtDNA) was subjected to a polymerase chain reaction to amplify the MT-CO2 gene. Genetic variants were screened using direct Sanger sequencing. Genotypes and allele frequencies between the case and control groups were compared by the chi-square test and Fisher's exact test. RESULTS: Three novel variants in the MT-CO2 gene were identified in nine asthenozoospermic cases, including two missense variants (m.8222T>A and m.7997G>A) and one synonymous variant (m.7846 A>G). In addition, the current study reported twenty-three known substitutions. In particular, the rs1556423316 T>C variant showed a significant association with asthenozoospermic infertile men in the studied population (p < 0.05). CONCLUSION: The detected missense variants in the MT-CO2 gene in asthenozoospermic infertile men underscore the important role of these variants in the development of asthenozoospermic male infertility.