Abstract
Purpose:
Glaucoma is a progressive atrophy of the optic disc characterized by loss of retinal ganglion cells, which leads to a corresponding visual field defect. It’s the major cause of irreversible blindness worldwide. Linkage analysis, association studies and candidate genes approaches have been performed in order to identify disease-causing genes and variants of susceptibility associated with POAG. Among them there are genes that codify for cytokines (IL1A, IL1B and TNFA), which have been associated in previous studies with higher risk for the development of POAG in some populations. The aim of this study was to evaluate the association of seven polymorphisms in the TNFA, IL1A and IL1B genes, in Brazilian POAG patients.
Methods:
A case control study including 172 unrelated POAG patients and 138 healthy matched individuals was conducted to evaluate the frequency distribution of polymorphisms in the IL1A, IL1B and TNFA genes as well as genotype/phenotype correlation. Comprehensive ophthalmic evaluation was performed and genomic DNA was obtained from case and control groups. Seven single nucleotide polymorphisms (SNPs): IL1A (-889C/T; rs1800587), IL1A (+4845G/T; rs17561), IL1B (-31C/T; rs1143627), IL1B (-511C/T; rs16944), IL1B (3953C/T; rs1143634), TNFA (-238G/A; rs361525) and TNFA (-308G/A; rs1800629) were genotyped through direct sequencing. The association of individual SNPs was tested by chi-square test and logistic regression. The p-value was corrected for multiple tests.
Results:
There was an association of the -31 C/T polymorphism in the IL1B gene with POAG (p=0,00909). No significant differences were observed for the other SNPs between POAG patients and controls. Among patients with POAG, an analysis comparing genotypes and clinical data as intraocular pressure, vertical cup to disc ratio and number of surgical procedures necessary to IOP control was performed and no statistical differences among these groups were observed.
Conclusions:
Results suggest that in this Brazilian population sample the -31C/T polymorphism in the IL1B gene may be considered a risk allele for the development of POAG. A similar study with additional and larger cohorts of patients using also other population groups is necessary to further substantiate the observation.
Keywords: 536 gene modifiers •
539 genetics •
629 optic nerve