Purpose: Recent laboratory evidence indicates that the inflammatory cytokine, interleukin-1 (IL-1), has either protective or adverse effects on primary open angle glaucoma (POAG). Inheritance of the IL-1alpha (-889) polymorphism (the T allele), previously shown to increase IL-1 production, has been associated with an elevated risk of Alzheimer's disease. The neuronal injuries associated with Alzheimer's disease have a number of similarities with the optic nerve changes often seen with POAG. In this report we have explored the possible association between the IL-1alpha (-889) polymorphism and the development of POAG.
Methods: Chinese patients with POAG (156) were recruited and compared with 167 healthy chinese controls. Genomic DNA was amplified by polymerase chain reaction, followed by enzymatic restriction fragment length polymorphism technique (PCR-RFLP). Patients and controls were genotyped for the C/T polymorphism at position -889 of the IL-1alpha gene promoter region.
Results: The frequency of the IL-1alpha (-889) T allele (21% versus 13%, respectively; p=0.007) and the carriers of the IL-1alpha (-889) T allele (37% versus 25%; p=0.019, OR 1.76, 95%CI 1.1-2.83) were greater in POAG patients compared with controls. There is a higher risk of POAG associated with homozygosity for the IL-1alpha (-889) T allele (TT genotype) compared with the control population (CC genotype; 5% versus 1%, respectively, p=0.04; OR 5.1, 95% CI 1.19-21.66).
Conclusions: The IL-1alpha (-889) T allele polymorphism, previously shown to increase IL-1 gene expression, may be a risk factor in the development of POAG.