Human-inherited RORγT deficiency encompasses genetic heterogeneity, T cell deficiency, and clinical homogeneity

We previously reported inherited retinoic acid–related orphan receptor γ T (RORγT) deficiency in seven patients from three ancestries (Chilean, Palestinian, and Saudi Arabian) with mycobacterial disease and chronic mucocutaneous candidiasis (CMC). We report here five additional patients from different ancestries (Afghan, Indian, Iranian, Japanese, and Sri Lankan), each homozygous for a new loss-of-function RORC variant. All but one patient—the exception receiving early prophylaxis—developed mycobacterial disease due to a near-complete depletion of innate-like adaptive T cells, including mucosa-associated invariant T and invariant natural killer T cells, low counts of adaptive T_H1* and CD8⁺ T cells, and impaired Mycobacterium-induced IFN-γ production by the remaining cells of these subsets, NK cells, conventional CD4⁺ T, Vδ1, and Vδ2 γδT cells. Most patients also displayed CMC due to their low counts of T_H17 and T_H1* cells. One patient died from disseminated Bacille Calmette-Guérin vaccine infection, but, unexpectedly, all the other patients are still alive and clinically stable at ages of 2 to 20 years. RORγT is essential for protective immunity against mycobacteria and Candida in humans.