GLO1 gene polymorphisms and their association with retinitis pigmentosa: a case–control study in a Sicilian population

Glyoxalase 1 (GLO1) is a ubiquitous cellular enzyme involved in detoxification of methylglyoxal (MGO), a cytotoxic byproduct of glycolysis, whose excess can cause oxidative stress. In retinitis pigmentosa (RP), the prevalent cause of blindness just during working life in the industrialized countries, oxidative stress represents one of the possible mechanisms leading to death of cones following that of rods in the retina. To date, the causes of secondary death of cones remain unclear and among proposed mechanisms are: the deprivation of trophic factors normally produced by healthy rods, a compromised uptake of nutrients to cones due to irreversible destruction of RPE-cone outer segment, microglial activation and following release of pro-inflammatory cytokines and rod-derived toxins. In present paper, role of oxidative stress due to an excess of MGO was evaluated. In particular, we wanted to determine whether single nucleotide polymorphisms (SNPs) in GLO1 influence enzyme activity, contributing to cone death in advanced RP. 120 healthy controls and 80 RP patients from Sicilian population were genotyped for three GLO1 common SNPs, rs1130534 (c.372A>T, p.G124G), rs2736654 (c.A332C, p.E111A) and rs1049346 (c.-7C>T, 5′-UTR). While c.A332C polymorphism was not associated with RP, c.372A>T showed an allelic association (T372 allele frequency = 70% vs 60% in controls, p = 0.0071). Conversely, c.-7C>T showed both genotypic (χ2= 68.0952; p = 1.634e−15) and allelic associations (χ2= 51.7094; p = 6.435e−13): mutated allele frequency was higher in controls than in patients, suggesting its possible protective role. RP susceptibility may be associated with two of the analyzed GLO1 polymorphisms (rs1130534 and rs1049346).