IP-10 is highly detectable in the plasma of patients with active TB (Borgström et al., 2012; Jeong et al., 2015), measurably reduced in those on treatment, present in granulomas (Ferrero et al., 2003), and detectable in individuals cohabiting with a TB positive person, including children (Azzurri et al., 2005; Whittaker et al., 2008). The gene discussed is CXCL10; the disease is tuberculosis.