A genome wide association study of pulmonary tuberculosis susceptibility in Indonesians.

BACKGROUND: There is reason to expect strong genetic influences on the risk of developing active pulmonary tuberculosis (TB) among latently infected individuals. Many of the genome wide linkage and association studies (GWAS) to date have been conducted on African populations. In order to identify additional targets in genetically dissimilar populations, and to enhance our understanding of this disease, we performed a multi-stage GWAS in a Southeast Asian cohort from Indonesia. METHODS: In stage 1, we used the Affymetrix 100 K SNP GeneChip marker set to genotype 259 Indonesian samples. After quality control filtering, 108 cases and 115 controls were analyzed for association of 95,207 SNPs. In stage 2, we attempted validation of 2,453 SNPs with promising associations from the first stage, in 1,189 individuals from the same Indonesian cohort, and finally in stage 3 we selected 251 SNPs from this stage to test TB association in an independent Caucasian cohort (n = 3,760) from Russia. RESULTS: Our study suggests evidence of association (P = 0.0004-0.0067) for 8 independent loci (nominal significance P < 0.05), which are located within or near the following genes involved in immune signaling: JAG1, DYNLRB2, EBF1, TMEFF2, CCL17, HAUS6, PENK and TXNDC4. CONCLUSIONS: Mechanisms of immune defense suggested by some of the identified genes exhibit biological plausibility and may suggest novel pathways involved in the host containment of infection with TB.

Exposure to rifampicin is strongly reduced in patients with tuberculosis and type 2 diabetes.

BACKGROUND: Type 2 diabetes (DM) is a strong risk factor for tuberculosis (TB) and is associated with a slower response to TB treatment and a higher mortality rate. Because lower concentrations of anti-TB drugs may be a contributing factor, we compared the pharmacokinetics of rifampicin in patients with TB, with and without DM. METHODS: Seventeen adult Indonesian patients with TB and DM and 17 age- and sex-matched patients with TB and without DM were included in the study during the continuation phase of TB treatment. All patients received 450 mg of rifampicin (10 mg/kg) and 600 mg of isoniazid 3 times weekly. Steady-state plasma concentrations of rifampicin and its metabolite desacetylrifampicin were assessed at 0, 2, 4, and 6 h after drug intake. RESULTS: Geometric means of rifampicin exposure (AUC(0-6 h)) were 12.3 mg x h/L (95% confidence interval [CI], 8.0-24.2) in patients with TB and DM, and 25.9 mg x h/L (95% CI, 21.4-40.2) in patients with TB only (P=.003). Similar differences were found for the maximum concentration of rifampicin. No significant differences in time to maximum concentration of rifampicin were observed. The AUC(0-6 h) of desacetylrifampicin was also much lower in patients with TB and DM versus patients with TB only (geometric mean, 0.60 vs. 3.2 mg x h/L; P=.001). Linear regression analysis revealed that higher body weight (P<.001), the presence of DM (P=.06), and plasma glucose concentration (P=.016) were correlated with exposure to rifampicin. CONCLUSION: Exposure (AUC(0-6 h)) to rifampicin was 53% lower in Indonesian patients with TB and DM, compared with patients with TB only. Patients with TB and DM who have a higher body weight may need a higher dose of rifampicin.

Polymorphisms in SP110 are not associated with pulmonary tuberculosis in Indonesians.

Despite being high transmissible, Mycobacterium tuberculosis (M. tuberculosis) infection causes active disease in only 5-10% of disease-susceptible individuals. This has instigated interest in studying potentially underlying genetic host factors and mechanisms in tuberculosis (TB). The recent identification of the Intracellular pathogen resistance 1 (Ipr1) gene, which plays a major role in controlling M. tuberculosis susceptibility and infection severity in mice (Pan et al., 2005), has prompted studies on its human homolog; SP110 in humans. Association of SP110 SNPs with pulmonary TB were first reported in a study on West African families (Tosh et al., 2006). Subsequent attempts to replicate these findings in other populations, including another West African (Ghanaian) cohort (Thye et al., 2006), however, were unsuccessful. Here we have genotyped 20 SNPs located in the SP110 gene, including the previously TB associated variants; rs2114592 and rs3948464, for the first time in a South East Asian cohort from Indonesia. Our study did not reveal any statistically significant associations between SP110 SNPs and pulmonary TB. In addition, a meta-analysis of the two previously TB associated SNPs revealed that these are not associated with TB, further confirming the lack of convincing evidence for SP110 to be implicated in TB susceptibility, as yet in humans.