Interestingly CTLA-4 mutations have also been associated with more severe TB infection in an African population study.13 With respect to PD-1/PD-L1, PD-1-deficient mice are highly susceptible to TB infection, 14 15 and a case of inherited PD-1 deficiency associating with TB has very recently been reported.16 The gene discussed is CTLA4; the disease is tuberculosis.