The major psoriasis susceptibility locus PSORS1 is not a risk factor for late-onset psoriasis.

PSORS1 is the major susceptibility locus for psoriasis vulgaris (PV) and lies within an approximately 200 kb segment of the major histocompatibility complex on chromosome 6p21.3. Alleles of candidate genes in this region including human leukocyte antigen (HLA)-C, alpha-helical coiled coil rod (HCR), and corneodesmosin (CDSN) show association with early-onset PV.