Genetic variations in the receptor-ligand pair CCR5 and CCL3L1 are important determinants of susceptibility to Kawasaki disease

Kawasaki disease (KD) is an enigmatic, self-limited vasculitis of childhood that is complicated by development of coronary-artery aneurysms. The high incidence of KD in Asian versus European populations prompted a search for genetic polymorphisms that are differentially distributed among these populations and that influence KD susceptibility. Here, we demonstrate a striking, inverse relationship between the worldwide distribution of CCR5-Δ32 allele and the incidence of KD. In 164 KD patient-parent trios, 4 CCR5 haplotypes including the CCR5-Δ32 allele were differentially transmitted from heterozygous parents to affected children. However, the magnitude of the reduced risk of KD associated with the CCR5-Δ32 allele and certain CCR5 haplotypes was significantly greater in individuals who also possessed a high copy number of the gene encoding CCL3L1, the most potent CCR5 ligand. These findings, derived from the largest genetic study of any systemic vasculitis, suggest a central role of CCR5-CCL3L1 gene-gene interactions in KD susceptibility and the importance of gene modifiers in infectious diseases.