GLUT1 is hypo-glycosylated in lymphocytes, isolated from X-linked immunodeficiency with magnesium defect (XMEN) patients, and this (hypoglycosylation/reduced glycosylation of GLUT1) was also observed in Magt1−/−Tusc3−/− and Stt3b−/− HEK293 cell lines, indicating an important regulatory role of MAGT1 in N-glycosylation of GLUT1 during glucose uptake [78,79]. The gene discussed is SLC2A1; the disease is X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection and neoplasia.