Of 12 children with definite or probable TB that were IFN-γ ELISpot negative at presentation, 6 (50%) became IFN-γ ELISpot positive (i.e. converted rather than reverted) at one point or more during anti-tuberculosis treatment, the rest remaining persistently IFN-γ ELISpot negative during follow-up. This evidence concerns the gene IFNG and tuberculosis.