Several newly discovered primary immunodeficiencies with EBV lymphoproliferation (STK4, CD27, MAGT1, Coronin-1A deficiency) have been described in the last few years [7–11]; our group and collaborators were able to reveal the pathogenicity of mutations in the Interleukin 2-inducible T-cell kinase (ITK) gene in a cohort of eight patients all presenting with massive EBV B-cell lymphoproliferation [12–15]. Here, ITK is linked to inborn error of immunity.