Novel polymorphisms in TICAM2 and NOD1 associated with tuberculosis progression phenotypes in Ethiopian populations.

Background: Infection by Mycobacterium tuberculosis (Mtb) is a necessary but not sufficient cause for tuberculosis (TB). Although numerous studies suggest human genetic variation may influence TB pathogenesis, there is a conspicuous lack of replication, likely due to imprecise phenotype definition. We aimed to replicate novel findings from a Ugandan cohort in Ethiopian populations.

Method: We ascertained TB cases and household controls (n = 292) from three different ethnic groups. Latent Mtb infection was determined using Quantiferon to develop reliable TB progression phenotypes. We sequenced exonic regions of TICAM2 and NOD1.

Result: Significant novel associations were observed between two variants in NOD1 and TB: rs751770147 [unadjusted p = 7.28 × 10^-5] and chr7:30477156(T), a novel variant, [unadjusted p = 1.04 × 10^-4]. Two SNPs in TICAM2 were nominally associated with TB, including rs2288384 [unadjusted p = 0.003]. Haplotype-based association tests supported the SNP-based results.

Conclusion: We replicated the association of TICAM2 and NOD1 with TB and identified novel genetic associations with TB in Ethiopian populations.