Purpose: To study the association between the risk of pterygium and genetic polymorphism in cytochrome P450 1A1 (CYP1A1) and glutathione S-transferase Mu1 (GST M1). Both CYP1A1 and GST M1 have been demonstrated to be involved in the metabolism of polycyclic aromatic hydrocarbons (PAHs). BaP 7,8-diol 9,10-epoxide (BPDE), an ultimate metabolite of benzo(a)pyrene (BaP), attacks deoxyguanosine to form a BPDE-N2-dG adduct resulting in p53 mutations. Our previous report indicated that BPDE-like DNA adduct levels in pterygium was associated with CYP1A1 gene polymorphisms. Therefore, we hypothesize that the genetic polymorphisms of CYP1A1 and GST M1 increase the risk for pterygium.
Methods: 205 pterygial specimens and 206 normal controls were collected in this
study. For the analysis of CYP1A1 and GST M1 gene polymorphisms, DNA samples
were extracted from pterygium specimens and blood cells of normal controls respectively and then subjected to polymerase chain reaction and restriction fragment length polymorphism for the determination of mutation and genotype of the CYP1A1 and GST M1 genes.
Results: There was a significant difference between the case and control groups in the CYP1A1 MspI genotype (p=0.017) but not in GST M1 (p=0.952). The odds ratio of the CYP1A1 T/C genotype polymorphism was 1.372 (95% CI=0.906-2.079, p=0.135) and the C/C genotype polymorphism was 2.711 (95% CI=1.331-5.524, p=0.006), compared to the T/T wild-type genotype. The GST M1 polymorphisms did not have an increased odds ratio compared with the wild type.
Conclusion: In conclusion, CYP1A1 polymorphism is correlated with pterygium and might become a marker for the prediction of pterygium susceptibility. According to this research, we may further infer that the environmental pollution may also play a role in the pathogenesis of pterygium formation.
