Background & Aims: Pi-GST and Mu-GST classes of glutathione S-transferase are present on human sperm surface and they play an important role against oxidative stress. Therefore, any defects in the enzyme's activity may be associated with male infertility. GSTM1 null genotype without enzyme activity and 105 valine substitutions in b and c alleles of GSTP1 gene decrease enzyme activity. Thus, GSTM1 and GSTP1 polymorphisms in association with enzyme activity and spermiogram parameters were studied.
Material & Methods: This case-contorol study involved 95 men with oligoastenoteratozoospermia and 26 controls with normozoospermia. Semen analyses were carried out according to WHO guidelines. DNA was extracted from blood by salting out procedures. Polymorphisms at GSTM1 gene by Multiplex PCR and Polymorphisms at 5 and 6 exons of GSTP1 gene were determined by PCR-RFLP. Glutathione S-transferase enzyme activity was measured by spectrophotometric method at 340 nm.
Results: Sperm concentration, sperm morphologyand sperm motility were significantly lower in the oligoastenoteratospemic men compared with individuals on the control group (p<0.001). Frequencies of GSTM1 null genotype in oligoasthenoteratospermic and normospermic groups were 52.1% and 53.8% respectively. There were no statistically significant differences in spermiogram parameters and enzyme activity in GSTM1 null and positive genotypes in the two groups. There were no statistically significant differences at mean±SD glutathione S-transferase activity in oligoasthenoteratospermia and normospermic groups, 7.43±2.84 and 7.07±1.68 nmol/min/ 1×106 sperm respectively. All the 121 men in this study had I1e/I1e genotypes at 105 codon of GSTP1. Frequency of normal homozygote (114Ala/Ala), heterozygote (114Ala/Val) and mutant homozygote (114Val/Val) genotypes in oligoastenoteratospermic group were 81.1%, 17.9% and 1.1% respectively but in the control group they were 88.5%, 11.5 % and null.
Conclusion: Total glutathione S-transferase activity and spermiogram parameters are not affected by deficient Glutathione S-transferase activity in GSTM1null genotype. Compensate activiy of other sperm surface glutathione S-transferase isozymes , like GSTP1, may justify the cause.