Results from genome-wide linkage studies suggest that TB disease susceptibility is highly likely to be polygenic, with contributions from many minor loci [10], and a large number of TB susceptibility markers have been identified from candidate gene studies as “disease-causing” genes which include TIRAP, HLA DQB1, VDR, IL-12β, IL12Rβ1, IFN-γ, SLC11A1, and MCP-1. The gene discussed is IL12B; the disease is tuberculosis.