HLA-C and TNF gene polymorphisms are associated with psoriasis in Brazilian patients

Background Polymorphisms at the human leukocyte antigens (HLA-C) and tumor necrosis factor (TNF) genes have been associated with susceptibility to psoriasis in several worldwide populations. In this study, HLA-C and TNF (-238/-308) polymorphisms were performed in 125 Brazilian patients and 202 healthy controls. Methods HLA-C and TNF promoter region alleles were typed by polymerase chain reaction using sequence-specific primer-polymerase chain reaction. Results The presence of HLA-C*06 was associated with psoriasis onset, particularly in younger patients, being more frequent for patients with disease onset before the age of 20 years (P = 0.03), 25 years (P = 0.01), or 30 years (P = 0.03). No association between HLA-C*06 and psoriasis was observed for patients older than 35 years. Susceptibility to psoriatic arthritis was associated with the TNF -238 G/A genotype (P = 0.02). The TNF -308A allele was overrepresented in patients (P = 0.0061), and the TNF -308 G/A genotype was increased in generalized forms (erythrodermic and generalized pustular psoriasis) compared to plaque psoriasis (P < 0.001). The TNF -238A/HLA-C*06 haplotype was overrepresented in patients (P = 0.025), while the TNF -238G/HLA-C*15 haplotype was increased in controls (P = 0.037). Conclusions The strong association of HLA-C*06 allele with disease susceptibility, particularly in early onset psoriasis, indicates that younger ages could be considered to stratify psoriasis into early and late types. TNF -308 polymorphisms can be associated with psoriasis susceptibility and severity. Potential genetic markers of psoriasis in populations with a complex mixture of ethnicities should be investigated.