An important link between immune deficiency and NLG in XMEN became apparent with our observation that the decreased expression of the activator receptor “Natural-Killer Group 2, member D” (NKG2D) and other important immune molecules was due to impaired glycosylation [4]. The gene discussed is KLRK1; the disease is X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection and neoplasia.