No strong association between alleles of tumour necrosis factor alpha and interleukin-1 receptor antagonist and corneal melting associated with systemic vasculitis

Aims-To investigate polymorphism within the tumour necrosis factor alpha (T NF-alpha) promoter region and within the interleukin-1 receptor antagonist (IL-1Ra) gene in a group of patients with vasculitis associated corneal mel ting. Methods-The polymorphic regions at position -308 on the TNF-alpha promoter region and in intron 2 of the IL-1Ra gene were amplified by the polymerase chain reaction (PCR). The resultant products were separated by electrophore sis on agarose gels and visualised by ethidium bromide staining. Genotype a nd allele frequencies for the 20 patients were compared with healthy contro ls from the same geographical area. Results-The allele frequencies in the patient and control groups respective ly for the TNF-alpha and IL-1Ra sites studied were as follows: TNF1, 82.5% and 80.2%; TNF2, 17.5% and 19.8%; IL-1Ra*1, 82.5% and 78.3%; IL-1Ra*2, 15% and 20%; IL-1Ra*3 2.5% and 1.5%. Although there was a trend for the IL1Ra*2 allele to be more common in the control group, no allele was found to have a statistically significantly association with the patient group: TNF1 p 0 .89; TNF2 p = 0.89; IL-1Ra*1 p = 0.65; IL-1Ra*2 p = 0.68; IL-1Ra(star)3 p = 0.50. Conclusions-The results suggest that the polymorphic alleles of TNF-alpha a nd IL-1Ra studied play little or no part in the susceptibility to corneal m elting among these patients with systemic vasculitis.