Novel ZAP-70-Related Immunodeficiency Presenting withEpstein–Barr Virus Lymphoproliferative Disorder andHemophagocytic Lymphohistiocytosis

Zeta-chain-associated protein kinase 70 (ZAP-70) plays an integral role in the T-cell antigenic receptor complex. A deficiency ofthis kinase leads to a phenotype of severe combined immunodeficiency, while hypomorphic mutations of the kinase lead to moremild immunodeficiency phenotypes. We present a case of a 21-year-old patient with lymphadenopathy who was found to haveEpstein–Barr virus (EBV) lymphoproliferative disease (LPD) and the development of hemophagocytic lymphohistiocytosis(HLH). On further workup, the patient was ultimately found to have a homozygous intrionic mutation in ZAP-70. (is is a novelZAP-70 mutation (c.1623 + 5G>A) associated with combined immunodeficiency and an EBV-positive LPD. A primary im-munodeficiency is important to consider in a young, otherwise healthy patient presenting with an EBV-positive LPD.