P-213: Mutation Analysis of Mitochondrial ND4L Gene in Iranian Infertile Men with Varicocele

Background: Varicocele is the abnormal tortuosity and dilatation of the veins of the pampiniform plexus within the spermatic cord. Varicocele-related pathology is suspected in infertility as it leads to elevated temperatures in the scrotum and testes, which has a deleterious effect on spermatogenesis. In Varicocele patients, ROS production is enhanced and total antioxidant capacity (TAC) is reduced. This imbalance between enhanced ROS production and diminished antioxidant capacity results in a condition called oxidative stress, which damages spermatozoa. The presence of oxidative stress could cause molecular and genetic defects leading to infertility. Mitochondria and especially mitochondrial complex І plays an important role in reducing oxidative stress. Since the mitochondrial complex I is one of the most essential complexes in respiratory chain for reduced in ROS, we analyzed the mutations in ND4L gene in infertile patients with varicocele. Materials and Methods: Total genomic DNA was isolated from peripheral blood of 72 infertile patients with varicocele and 54 fertile men. Molecular analysis of mitochondrial ND4L gene mutations was performed by PCR-SSCP. Direct sequencing of DNA from samples with altered band pattern in the SSCP was used to identify any mitochondrial DNA mutations. Results: We found a homoplasmic synonym polymorphism m.10550A>G in the mitochondrial ND4L gene in 12 patients. The mutated site was conserved among other species during evolution. In this position any mutation was not reported previously in infertility. Conclusion: Based on previous studies, the high level of ROS may cause mtDNA mutations and also, as ROS production in infertility was enhanced, it can be concluded that this mutation may increase frequency of mutations in ND4L gene. Nonetheless, involvement of this mutation in infertility remains to be determined and need for more researches.