Similarly, a constellation of PIDs with underlying molecular mechanisms as varied as the gene variants of WAS in Wiskott-Aldrich syndrome, RMRP in cartilage-hair hypoplasia and ITK in interleukin-2-inducible T-cell kinase—or sometimes as yet undiscovered variants as in some common variable immunodeficiencies—predispose patients to malignant lymphoproliferative diseases linked to uncontrolled EBV disease [23]. This evidence concerns the gene ITK and Wiskott-Aldrich syndrome.