The moderation effect of GSTM1/GSTT1 gene polymorphisms on the association of sperm mitochondrial DNA copy number and sperm mobility

Abstract Oxidative stress (OS) is believed to be a significant factor in the decline of semen quality, with mitochondrial DNA copy number (mtDNAcn) serving as a sensitive biomarker for both semen quality and mitochondrial dysfunction resulting from oxidative stress. While glutathione S-transferases (GSTs) are commonly known as ‘antioxidant’ enzymes, there is ongoing debate regarding the relationship between GST genotypes and semen quality. In a study involving 568 male volunteers from the outpatient department of Puyang Reproductive Medicine Center, sperm mtDNAcn, semen quality, and GSTM1/GSTT1 genotypes were analyzed to investigate the potential link between GSTM1/GSTT1 gene variations and semen quality, as well as the impact of GSTs gene variations on the connection between sperm mtDNAcn and semen quality. Adjusting for variables such as age, BMI, smoking, and alcohol consumption, it was found that mtDNAcn was significantly correlated with decreased sperm concentration and total sperm count (b = − 0.109, − 0.128, respectively; P = 0.002, 0.001, respectively). GSTM1 was associated with progressive motility (OR 0.390, 95% CI 0.218, 0.697), Straight line velocity (VSL) (OR = 0.606, 95% CI 0.385, 0.953), and Straightness (STR) (OR 0.604, 95% CI 0.367, 0.994), while GSTT1 was linked to progressive motility (OR 0.554, 95% CI 0.324, 0.944) and Beat crossover frequency (OR 0.624, 95% CI 0.397, 0.982). The GSTT1 was found to moderate the relationship between mtDNAcn and sperm motility parameters linearity (LIN), STR, and Wobble (WOB), with additive interaction effects observed between GSTT1 and mtDNAcn on LIN, STR, and WOB (P for interaction = 0.008, 0.034, 0.010, respectively). Overall, this study suggests that GSTT1 and GSTM1 gene variations may play a role in sperm motility, with GSTT1 potentially influencing the impact of oxidative stress on sperm motility.