Human leukocyte antigen (HLA) and single nucleotide polymorphisms (SNPs) tumor necrosis factor (TNF)-alpha -238 and -308 as genetic markers of susceptibility to psoriasis and severity of the disease in a long-term follow-up Brazilian study

Summary Background The strongest genetic marker for psoriasis is Cw*06. Polymorphisms in the tumor necrosis factor (TNF)‐alpha promoter region, especially replacement of guanine with adenine in positions ‐238 and ‐308 are related to higher TNF‐alpha production and higher risk for psoriasis in Caucasoid populations, not found in Asians. We performed a case‐control study of 69 patients with psoriasis type I and 70 controls, characterized clinical progression along 10‐years of follow‐up in mild or severe disease and determined HLA class I, II, and TNF single nucleotide polymorphisms (SNPs) ‐238 and ‐308 polymorphisms to demonstrate whether these polymorphisms may be genetic risk for susceptibility to psoriasis or severity of the disease in Brazilians. Methods Polymorphisms were identified using PCR/SSP. Alleles, genotypes, and haplotypes frequencies were compared using Fisher’s test. Results More severe disease was found in male patients. It may be suggested that alleles B*37, Cw*06, Cw*12, and DRB1*07 were associated with severe disease course, while B*57 with mild disease. No statistical difference was found between the patients and controls regarding polymorphisms frequencies in TNF SNPs. This study pointed to a higher TNF‐238 G/G genotype frequency (OR: 3.21; CI: 1.06–9.71; P = 0.04) in the group with severe disease. Conclusions Polymorphisms in the TNF‐alpha SNPs do not seem to be a more important genetic risk factor for psoriasis than the already known Cw*06 in Brazilian patients, but these markers may be related to clinical manifestations.