studies of individual candidate genes have together helped identify specific single nucleotide polymorphisms (SNPs), mostly found in genes with immune regulatory functions. The associated genes and their levels of expression appear to vary among different ethnic groups, both with Asian and non-Asian backgrounds. SNPs in FCGR2A, CASP3, BLK, ITPKC, CD40 and ORAI1 have all been linked to susceptibility, prognosis, and risk of developing coronary artery aneurysms. Various other possible susceptibility genes have been proposed, including polymorphisms in the HLA region, but their significance is disputed. Genetic susceptibility to Kawasaki disease appears complex. Gene–gene interactions also seem to affect susceptibility and prognosis. At an epigenetic level, altered DNA methylation has been proposed as an early mechanistic factor during the acute phase of the disease. Diagnosis Since no specific laboratory test exists for Kawasaki disease, diagnosis must be based on clinical signs and symptoms, together with laboratory findings. Timely diagnosis requires careful history-taking and thorough physical examination. Establishing the diagnosis is difficult, especially early in the course of the illness, and frequently children are not diagnosed until they have seen several health-care providers. Many other serious illnesses can cause similar symptoms, and must be considered in the differential diagnosis, including scarlet fever, toxic shock syndrome, juvenile idiopathic arthritis, and childhood mercury poisoning (infantile acrodynia). Classically, five days of fever plus four of five diagnostic criteria must be met to establish the diagnosis. The criteria are: erythema of the lips or oral cavity or cracking of the lips rash on the trunk swelling or erythema of the hands or feet red eyes (conjunctival injection) swollen lymph node in the neck of at least 15 mm Many children, especially infants, eventually diagnosed with Kawasaki disease, do not exhibit all of the above criteria. In fact, many experts now recommend treating for Kawasaki disease even if only three days of fever have passed and at least three diagnostic criteria are present, especially if other tests reveal abnormalities consistent with Kawasaki disease. In addition, the diagnosis can be made purely by the detection of coronary artery aneurysms in the proper clinical setting. Investigations A physical examination will demonstrate many of the features listed above. Blood tests Complete blood count may reveal normocytic anemia and eventually thrombocytosis. Erythrocyte sedimentation rate will be elevated. C-reactive protein will be elevated. Liver function tests may show evidence of hepatic inflammation and low serum albumin levels. Other optional tests include: Electrocardiogram