Three human gene variants appear to influence tb susceptibility:
Approximately one-third of the world's population is thought to be infected with the M. tuberculosis pathogen, yet only about 10 percent becomes ill with the active disease. Researchers suspect that a variety of factors interplay to determine who develops the full-blown disease. For example, in February 2006 Harvard School of Public Health (HSPH) researchers were part of a team that identified a mechanism that explains why people of African descent may be more vulnerable to the disease.
The paper is reputedly in the PNAS - Early Edition section.