Functional studies by Flores-Villanueva et al. showed that the GG genotype at MCP1 “−2518” (alias −2581 used in this paper, rs1024611) had the highest MCP-1 plasma levels and lowest IL-12p40 plasma concentrations in TB patients [14]; IL-12p40 (encoded by IL12B) is required for IFNγ-induced protection from PTB and the GG homozygotes had 5× higher odds of developing TB than AA homozygotes [14]. Here, IL12B is linked to tuberculosis.