Immunogenetics of Kawasaki disease.

Kawasaki disease (KD) is a medium vessel vasculitis that affects young children. Despite extensive research over the last 50 years, the etiology of KD remains an enigma. Seasonal change in wind patterns was shown to have correlation with the epidemics of KD in Japan. Occurrence of disease in epidemiological clusters, seasonal variation, and a very low risk of recurrence suggest that KD is triggered by an infectious agent. The identification of oligoclonal IgA response in the affected tissues suggests an antigen-driven inflammation. The recent identification of a viral antigen in the cytoplasm of bronchial ciliated epithelium also favors infection as the main trigger for KD. Pointers that suggest a genetic basis of KD include a high disease prevalence in North-East Asian populations, a high risk among siblings, and familial occurrence of cases. Dysregulated innate and adaptive immune responses are evident in the acute stages of KD. In addition to the coronary wall inflammation, endothelial dysfunction and impaired vascular remodeling contribute to the development of coronary artery abnormalities (CAAs) and thrombosis. Genetic aberrations in certain intracellular signaling pathways involving immune effector functions are found to be associated with increased susceptibility to KD and development of coronary artery abnormalities (CAAs). Several susceptible genes have been identified through genome-wide association studies (GWAS) and linkage studies (GWLS). The genes that are studied in KD can be classified under 4 major groups-enhanced T cell activation (ITPKC, ORAI1, STIM1), dysregulated B cell signaling (CD40, BLK, FCGR2A), decreased apoptosis (CASP3), and altered transforming growth factor beta signaling (TGFB2, TGFBR2, MMP, SMAD). The review aims to highlight the role of several genetic risk factors that are linked with the increased susceptibility to KD.