Killer cell immunoglobulin-like receptor genotypes in Japanese patients with type 1 diabetes.

We investigated killer cell immunoglobulin-like receptor (KIR) genotypes in 92 patients with young-onset type 1 diabetes mellitus (YT1DM: < or =35 years old), 112 patients with adult-onset type 1 diabetes mellitus (AT1DM: >35 years old) and 240 control subjects. There were no differences in the frequency of KIR genotypes between controls and all the patients with T1DM or patients grouped according to age at onset of the disorder. However, when the subjects were classified into three groups according to combinations of the presence or absence of KIR3DS1/KIR3DL1 and its ligand human leukocyte antigen (HLA)-Bw4, or KIR2DL1 and its ligand HLA-C group 2, the genotype distribution was significantly different between the patients with AT1DM and controls [chi(2)= 5.993, 2 degrees of freedom (d.f.), P= 0.0500]. These data suggest that KIR polymorphisms may be associated with the age at onset of T1DM.