HLA-B and psoriasis: MHC Class I-related (MIC) genes, 100 Kb centromeric to the HLA-B locus, have been associated with PsA.[40] A meta-analysis confirmed an association between TNF-α -238 polymorphism and PsA.[41] A recent fine mapping of the MHC identified an association of PsA with SNP rs1150735 that resides 1.5 kb upstream of the gene ring finger protein 39 that was previously shown to be associated with disease progression in acquired immunodeficiency syndrome.[42] Thus, the susceptibility locus for PsA may lie more centromeric to that of psoriasis, closer to HLA-B.