HLA-C and psoriasis: PSORS1 is located within the major histocompatibility complex (MHC) on chromosome 6p21.3 (Mohd Affandi et al., 2018), in which the non-protein coding gene PSORS1C3 is an established susceptibility gene for psoriasis and its RNA transcript is found both in psoriatic patients and control individuals (Holm et al., 2005).