Data from DQ studies vary in different countries; for example, in Japan, patients with DQA1*0104 and DQB1*0503-1 develop severe RHD, which is different from Latvian data, while in the USA the DQA1*0201 allele and DRB1*0701/DQA1*0201 are common in RHD patients [38,41]. The gene discussed is HLA-DQA2; the disease is rheumatic heart disease.