Exonic sequencing identifies TLR1 genetic variation associated with mortality in Thais with melioidosis

Abstract

ABSTRACTMelioidosis, an infectious disease caused by the bacterium Burkholderia pseudomallei, is a common cause of sepsis in Southeast Asia. We investigated whether novel TLR1 coding variants are associated with outcome in Thai patients with melioidosis. We performed exonic sequencing on a discovery set of patients with extreme phenotypes (mild vs. severe) of bacteremic melioidosis. We analysed the association of missense variants in TLR1 with severe melioidosis in a by-gene analysis. We then genotyped key variants and tested the association with death in two additional sets of melioidosis patients. Using a by-gene analysis, TLR1 was associated with severe bacteremic melioidosis (P = 0.016). One of the eight TLR1 variants identified, rs76600635, a common variant in East Asians, was associated with in-hospital mortality in a replication set of melioidosis patients (adjusted odds ratio 1.71, 95% CI 1.01–2.88, P = 0.04.) In a validation set of patients, the point estimate of effect of the association of rs76600635 with 28-day mortality was similar but not statistically significant (adjusted odds ratio 1.81, 95% CI 0.96–3.44, P = 0.07). Restricting the validation set analysis to patients recruited in a comparable fashion to the discovery and replication sets, rs76600635 was significantly associated with 28-day mortality (adjusted odds ratio 3.88, 95% CI 1.43–10.56, P = 0.01). Exonic sequencing identifies TLR1 as a gene associated with a severe phenotype of bacteremic melioidosis. The TLR1 variant rs76600635, common in East Asian populations, may be associated with poor outcomes from melioidosis. This variant has not been previously associated with outcomes in sepsis and requires further study.

Keywords

• TLR1
• melioidosis
• sepsis
• genetic variation
• Burkholderia pseudomallei