Given that patients with SAP deficiency, which underlies EBV-driven hematological disorders known as X-linked lymphoproliferative disease type 1 (XLP1), are not known to be vulnerable to TB, LY9 and RORγT-dependent but SAP-independent TH1* IFN-γ immunity is probably indispensable, more so than LY9 and SAP-dependent T-bet expression, for the control of M.tb infection. The gene discussed is LY9; the disease is X-linked lymphoproliferative syndrome.