Asthma is a heterogeneous multifactorial disease that is characterized in most cases by chronic respiratory tract inflammation. We carried out a GWAS in order to identify susceptibility genes for asthma in individuals of different ethnic backgrounds. The study sample consisted of 358 unrelated patients with asthma (160 Russians, 125 Tatars, and 73 Bashkirs) and 369 individuals of a control group (152 Russians, 117 Tatars, and 100 Bashkirs). DNA samples were genotyped with an Illumina human610 quad array (Illumina) as part of the project GABRIEL. Replication of the results of genome-wide analysis was carried out on an additional independent sample of 310 asthma patients (132 Russians, 105 Tatars, and 73 Bashkirs) and 310 individuals in a control group (131 Russians, 106 Tatars, and Bashkirs 77). Genome-wide analysis showed an association of asthma in Russians with the polymorphic loci of gene MUC19 (12q12) encoding gel-forming mucin 19. The highest level of association with asthma was found in rs2933346, which is located in intron 52 of this gene (p = 2.59 x 10(-6)). Seven polymorphic loci of gene MUC19 (rs1492313, rs2588401, rs2588402, rs2638863, rs2638864, rs1352940, and rs2933373), which are in close linkage disequilibrium among themselves and rs2933346, are associated with asthma with the same p-value (p = 4.96 x 10(-6)). The replicative study of rs1492313 in the independent sample of individuals confirmed the presence of the association of the polymorphic loci of this gene with the development of asthma in Russians. According to our data, the association of polymorphic variants of gene MUC19 with asthma has not been previously identified in any study. Our results indicate the important role of polymorphic variants of gene MUC19 in the formation of a predisposition to the development of asthma in individuals of Russian ethnicity.