Many biologically plausible genes, such as those that encode vitamin-D-binding protein (Lewis et al., 2005; Gao et al., 2010), the phagolysomal membrane protein NRAMP/SLC11A1 (Hoal et al., 2004; Velez et al., 2009), and the dendritic adhesion molecule DC-SIGN (Barreiro et al., 2006; Olesen et al., 2007), appear to associate with TB in some human populations, but not others. The gene discussed is SLC11A1; the disease is tuberculosis.