Berinstein J, et al. – The researchers examined the genetic interaction of variably expressed killer cell immunoglobulin–like receptor (KIR) 3DL1 alleles with their cognate ligand, human leukocyte antigen (HLA)–Bw4, in susceptibility to psoriatic disease (PsD). They discovered that the HLA–Bw4 epitope was associated with psoriatic disease, particularly with psoriatic arthritis (PsA). However, no genetic interactions with KIR3DL1 alleles were detected.