Comparative analysis of GSTM1/GSTT1 null alleles and Ile105Val GSTP1 variant in patients with Nasal Polyposis and hyposmia in a Romanian population group

Background. Polymorphisms for genes encoding glutathione S-transferase (GSTM1/GSTT1/GSTP1) might be one of the factors that can influence the variability in susceptibility for hyposmia in normal and ENT pathology associated individuals. The role of GST family enzyme might be important in exposure to xenobiotic induced damage of nasal mucosa. Objectives. To evaluate of distribution of GST variants (GSTM1/GSTT1 null alleles and Ile105Val GSTP1 polymorphism) among patients with hyposmia and normal individuals by using a case-control study. Subjects The study included 75 cases of hyposmic patients (evaluated with “Sniffin’ Sticks” olfaction Test), recruited from the Otorhinolaryngology Department of Emergency County Hospital, Cluj-Napoca and 124 healthy unrelated controls. Methods. GSTM1 and GSTT1 variants genotyping was accomplished using a Multiplex PCR method, followed by agarose gel electrophoresis. GSTP1 Ile105Val gene variant was genotyped using PCR-RLFP technique. Results. Comparative analysis for Ile105Val variant of GSTP1 gene revealed no statistical differences among patients and controls (χ² = 3.012, p = 0.087, OR = 1.514, CI = 0.491 to 1.572). Molecular analysis did not reveal an increased frequency for GSTT1 and GSTM1 null alleles in the patients group compared to controls (GSTT1 - 95% CI = 0.332 to 1.261, p = 0.192, OR = 0.641, χ² = 2.120, GSTM1 - 95% CI = 0.171 to 0.592, χ² = 2.017, OR = 0.321, p = 0.062). Significant statistical differences were found when combined GSTM1 and GSTT1 null genotypes (double-null genotypes) were compared between patients and controls (p=0.0015, OR=4.0351; CI=1.706-9.543) and when comparing allergic NP patients with non-allergic NP patients (p=0.027, OR=3.455, CI=1.147-10.406). Conclusions. The presence of both GSTM1/GSTT1 null genotypes (double null genotypes) is considered to be a risk factor for NP and hyposmia development in allergic individuals. The results of our study show no correlation between Ile105Val polymorphism of GSTP1 gene and nasal polyposis associated hyposmia in this Romanian group population.