XMEN stands for “X-linked MAGT1 deficiency with increased susceptibility to Epstein–Barr virus (EBV) infection and N-linked glycosylation defect.

[2][3][4] XMEN patients have splenomegaly, chronic Epstein Barr Virus (EBV) infection, and are developmentally normal.

Many of the immunodeficiency-related features of XMEN disease are related to the hypoglycosylation phenotype caused by loss of the OST component MagT1.

A prominent hypothesis from XMEN patients suggests that MAGT1's role in glycosylation is essential to the function (either directly or indirectly) of a Mg+2 transporter.

Hematopoietic stem cell transplant is a possible treatment of this condition but its effectiveness is unproven and may be accompanied by severe and potentially fatal hemorrhage.

This decrease leads to loss of expression of an immune cell receptor called NKG2D, which is involved in EBV-immunity.

[1] In vitro magnesium supplementation experiments failed to significantly rescue NKG2D expression in patients with XMEN disease and the clinical trial was stopped.