Previous studies have localized the psoriasis susceptibility 1 (PSORS1) locus to the proximal major histocompatibility complex class I region, but approximately a dozen genes in the candidate region have thus far been genetically inseparable. According to a team of researchers in the United States and Germany, the primary genetic association has now been worked out, implicating HLA-Cw6 "after all." The results integrate genetics and immunology, further reinforcing our emerging understanding of psoriasis.