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WOS: 000350167200008, PubMed ID: 25703555, Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb) and a few related mycobacteria, is a devastating disease, killing more than a million individuals per year worldwide. However, its pathogenesis remains largely elusive, as only a small proportion of infected individuals develop clinical disease either during primary infection or during reactivation from latency or secondary infection. Subacute, hematogenous, and extrapulmonary disease tends to be more frequent in infants, children, and teenagers than in adults. Life-threatening primary TB of childhood can result from known acquired or inherited immunodeficiencies, although the vast majority of cases remain unexplained. We review here the conditions conferring a predisposition to childhood clinical diseases caused by mycobacteria, including not only M.tb but also weakly virulent mycobacteria, such as BCG vaccines and environmental mycobacteria. Infections with weakly virulent mycobacteria are much rarer than TB, but the inherited and acquired immunodeficiencies underlying these infections are much better known. Their study has also provided genetic and immunological insights into childhood TB, as illustrated by the discovery of single-gene inborn errors of IFN- immunity underlying severe cases of TB. Novel findings are expected from ongoing and future human genetic studies of childhood TB in countries that combine a high proportion of consanguineous marriages, a high incidence of TB, and an excellent clinical care, such as Iran, Morocco, and Turkey., European Research CouncilEuropean Research Council (ERC) [ERC-2010-AdG-268777]; French National Research Agency (ANR)French National Research Agency (ANR) [ANR-10-IAHU-01, ANR-08-MIEN-014-02]; Institut National de la Sante et de la Recherche Medicale, Universite Paris DescartesInstitut National de la Sante et de la Recherche Medicale (Inserm); St. Giles Foundation; Rockefeller University from the National Center for Research Resources [8ULTR000043]; National Center for Advancing Sciences (NCATS) of the National Institute of Health; Rockefeller University; National Institute of Allergy and Infectious DiseasesUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Allergy & Infectious Diseases (NIAID) [U01AI088685, R01AI089970, R37AI095983], We thank all clinicians from many countries around the world for their help and contribution in the investigation of TB patients. Special thanks to A. Strickler and J. F. Emile for providing the pictures. We also thank all members of the Necker and Rockefeller branches of the Laboratory of Human Genetics of Infectious Diseases. This work was supported by grants from the European Research Council (ERC-2010-AdG-268777), the French National Research Agency (ANR) under "the Investments for the Future" grant number ANR-10-IAHU-01, ANR-08-MIEN-014-02, Institut National de la Sante et de la Recherche Medicale, Universite Paris Descartes, the St. Giles Foundation, the Rockefeller University grant number 8ULTR000043 from the National Center for Research Resources and the National Center for Advancing Sciences (NCATS) of the National Institute of Health, the Rockefeller University, the National Institute of Allergy and Infectious Diseases grant number U01AI088685, R01AI089970, and R37AI095983. The authors have no financial or commercial conflict of interest to declare.