A novel single nucleotide polymorphism within the NOD2 gene is associated with pulmonary tuberculosis in the Chinese Han, Uygur and Kazak populations

A case-control study was performed on the Chinese Han, Uygur and Kazak populations. Exon 4 of the NOD2 gene was sequenced in 425 TB patients and 380 healthy controls to identify SNPs.The frequency of T/G genotypes for the Arg587Arg (CGT → CGG) single nucleotide polymorphism (SNP) in NOD2 was found to be significantly higher in the Uygur (34.9%) and Kazak (37.1%) populations than the Han population (18.6%). Also, the frequency of G/G genotypes for the Arg587Arg SNP was significantly higher in the Uyghur (8.3%) and Kazak (5.4%) populations than the Han population (0.9%). Meanwhile, no significant difference was found in the Arg587Arg polymorphism between the tuberculosis patients and healthy controls in the Uyghur and Kazak populations (P > 0.05) whereas, a significant difference was observed in the Arg587Arg polymorphism between the tuberculosis patients and healthy controls in the Han population (P < 0.01). The odd ratio of 2.16 (95% CI = 1.31-3.58; P < 0.01) indicated that the Arg587Arg SNP in NOD2 may be associated with susceptibility to tuberculosis in the Chinese Han population.Our study is the first to demonstrate that the Arg587Arg SNP in NOD2 is a new possible risk factor for tuberculosis in the Chinese Han population, but not in the Uyghur and Kazak populations. Our results may reflect racial differences in genetic susceptibility to tuberculosis.According to the latest World Health Organization statistics, tuberculosis (TB) kills 1.7 million people each year, with 9.4 million new cases a year. It is estimated that 1/3 of the world's population has been infected with mycobacterium TB. In the majority of infected people, the immune response is able to adequately control the infection, and consequently only 5-10% will develop clinically active TB disease during their lifetime [1]. The incidence of TB in different ethnic groups and countries is different. In 2009, 55% of all TB cases occurred in Asia, 30% in Africa, 7% in Eastern Mediterranean Region, 4% in Euro