CLEC4D and rheumatoid arthritis: The natural killer gene complex (NKC) encodes a multitude of activating and inhibitory C-type lectin receptors (CLRs), many of which play important roles in the maintenance of immune homoeostasis.1 Loss or mutations in inhibitory CLRs, in particular, are often associated with unchecked inflammation and destructive autoimmunity.2 Notably, the NKC has been associated with rheumatoid arthritis (RA),3, 4 but to date only one receptor within this cluster, dendritic cell immunoreceptor (DCIR), has been linked to this disease in humans.3, 5