Association between genetic polymorphisms of glutathione S-transferase M1/T1 and psoriasis in a population from the area of the strict of messina (Southern Italy)

Abstract

Glutathione S-transferases (GST) are antioxidant enzymes with frequent genetic polymorphisms. Homozygosis for gene deletion ("null" genotype) of <i>GSTM1</i> and <i>GSTT1</i>, causing decrease of the antioxidant potential of the organism, is frequent, with variable frequency in different ethnic contexts. Although oxidative stress notoriously plays a role in the pathogenesis of psoriasis, few studies exist on the association between <i>GSTM1</i>/<i>GSTT1</i> genotype and psoriasis, with different results. We aimed to assess the frequency of <i>GSTM1</i>/<i>GSTT1</i> polymorphisms in Southern Italian psoriatic patients and controls and investigate the association of the <i>GSTM1</i>/<i>GSTT1</i> genotype with individual and disease parameters. To this aim, the <i>GSTM1</i>/<i>GSTT1</i> genotype of 148 psoriatic patients and 148 age- and sex-matched controls was defined by PCR on oral mucosa cells. <i>GSTT1</i> null was associated with psoriasis (55.4% of patients vs. 25% of controls, <i>p</i> = 9.58 × 10^-8, odds ratio 3.73), while <i>GSTM1</i> null was not. The <i>GSTM1</i>/<i>GSTT1</i> "double null" genotype conferred an even higher odds ratio for psoriasis (5.94). The association between psoriasis and <i>GSTT1</i> null was stronger in women (54.1% of patients vs. 19.7% of controls, <i>p</i> = 8.13 × 10^-5) than in men (56.3% of patients vs. 28.7% of controls, <i>p</i> = 0.0002). No association was found between <i>GSTM1</i>/<i>GSTT1</i> genotype and psoriasis severity, age of onset or comorbidities (psoriatic arthritis, metabolic syndrome). The remarkable differences among the few available data on the association between <i>GSTM1</i>/<i>GSTT1</i> polymorphisms and psoriasis suggest the need for further studies, on different and larger populations, to improve knowledge on the pathogenesis of psoriasis and possibly provide more precise and personalised prevention and treatment in the future.