XMEN disease: a new primary immunodeficiency affecting Mg2+regulation of immunity against Epstein-Barr virus Feng-Yen Li1, Benjamin Chaigne-Delalande1, Helen Su2, Gulbu Uzel3, Helen Matthews1, and Michael J. Lenardo1,* +Author Affiliations ↵* Corresponding author; email: email@example.com Abstract Epstein Barr virus (EBV) is an oncogenic gammaherpesvirus that infects and persists in 95% of adults worldwide and has the potential to cause fatal disease, especially lymphoma, in immunocompromised hosts. Primary immunodeficiencies (PIDs) that predispose to EBV-associated malignancies have provided novel insights into the molecular mechanisms of immune defense against EBV. We have recently characterized a novel PID now named "X-linked immunodeficiency with magnesium defect, Epstein-Barr virus (EBV) infection, and neoplasia" (XMEN) disease characterized by loss-of-function mutations in the gene encoding magnesium transporter 1 (MAGT1), chronic high level EBV with increased EBV-infected B cells, and heightened susceptibility to EBV-associated lymphomas. The genetic etiology of XMEN disease has revealed an unexpected quantitative role for intracellular free magnesium in immune functions and led to novel diagnostic and therapeutic strategies. Here, we review the clinical presentation, genetic mutation spectrum, molecular mechanisms of pathogenesis, and diagnostic and therapeutic considerations for this previously unrecognized disease. Submitted November 19, 2013. Accepted February 7, 2014. Full text at: http://bloodjournal.hematologylibrary.org/content/early/2014/02/18/blood-2013-11-538686.abstract ETA: I lied; the full text is behind a paywall. PM me for further info if interested.