SNPs in the catalase promoter: a study based on Indian diabetic individuals

Background It is known that anti-oxidant defense is compromised in diabetic individuals. In our study, we indeed found decreased catalase activity in diabetic individuals compared to non-diabetic controls. Therefore, we analyzed the single nucleotide polymorphisms (SNPs) in the promoter region of catalase in diabetic individuals. To investigate catalase promoter SNP’s contribution (if any) to the low catalase activity and assess their functional significance by reporter assay. Methods The activity of catalase was quantitated from 109 non-diabetic and 138 diabetic individuals. Genomic DNA isolated from these individuals was screened for SNPs in the catalase promoter by direct sequence analysis of PCR products. The functional effect of these polymorphisms was checked by reporter assay. Results We found six reported SNPs of which, three were polymorphic in our study groups at −330, −89, and −20 position viz. rs1001179: C>T, rs7943316: A>T, and rs1049982: T>C. Out of the three SNPs, only rs1001179: C>T showed a positive association with the occurrence of low activity of catalase in diabetic individuals ( p <0.05). However, reporter assay confirmed that the presence of these SNPs does not significantly affect the transcriptional activity of the gene ( p >0.05). Furthermore, our in silico analysis revealed that the presence of these SNPs did not significantly affect the binding of transcription factors except at −330 position. Conclusion Our reporter assay suggesting no functional relevance of promoter SNPs in reduced catalase activity observed in Indian diabetic individuals is a novel finding.