Association of interleukin 18, interleukin 2, and tumor necrosis factor polymorphisms with subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a progressive inflammatory and degenerative disorder of the central nervous system. The measles virus (MV) and host and environmental factors are involved in the development of SSPE, but the precise mechanism by which the MV causes SSPE is still unknown. Studies have indicated that in SSPE patients, specific polymorphisms of certain genes are most likely involved in impairing the host's ability to eradicate the MV. The purpose of our study was to elucidate the role of polymorphisms in the genes encoding interleukin (IL)-2, IL-18, and tumor necrosis factor alpha (TNF-α) in the development of SSPE. Using the polymerase chain reaction with sequence-specific primers, the single-nucleotide polymorphisms (SNPs) of the promoter regions of IL-2 (-330), TNF-α (-308), and IL-18 (-137 and -607) were studied in 54 patients with SSPE and 72 healthy controls. The frequency of SSPE patients with the AA genotype of IL-18 at position -607 was significantly higher than the frequency of those with the CC genotype (p<0.001, odds ratio [OR]: 5.76), and a significantly higher proportion of patients had the C allele at -137 compared with the controls (p=0.002, OR: 2.72). In a haplotype analysis of two SNPs in the IL-18 gene, the frequency of the CA haplotype was significantly higher in SSPE patients (p<0.001, OR: 3.99) than in the controls. The IL-2 (-330) and TNF-α (-308) polymorphisms revealed no significant differences. In conclusion, these data suggest that the IL-18 gene polymorphisms at position -607 and -137 might be genetic risk factors for the SSPE disease.