HLA-C and psoriasis: PSORS1 locus contains at least fifteen genes, including the highly polymorphic human leukocyte antigen (HLA)-C gene encoding a type of heavy chain of HLA class I. The HLA-Cw6 allelic variant of HLA-C is highly represented in the psoriatic population (>60%) and is itself considered as the causal susceptibility allele for psoriasis, even though over one-hundred single-nucleotide polymorphisms (SNPs) of HLA-C genic and intergenic region have been described in patients [5].