MOGS (mannosyl-oligosaccharide glucosidase) is an endoplasmic reticulum-localized enzyme that catalyzes the removal of the distal alpha 1,2-linked glucose residue from Glc(3)Man(9)GlcNAc(2) oligosaccharide precursors during N-glycan processing. This glucosidase activity is essential for the initial stages of N-linked glycoprotein maturation and quality control in the ER 1. MOGS functions within a coordinated N-glycosylation pathway involving other processing enzymes, including UGGT1, which maintains glycoprotein quality control 2. Biallelic MOGS mutations cause MOGS-CDG (congenital disorder of glycosylation type IIb), a rare metabolic disorder characterized by neurological manifestations including hypotonia, developmental delay, seizures, and movement disorders 3. Clinical phenotyping of 12 MOGS-CDG patients revealed heterogeneous multisystemic involvement affecting neurological, immunological, and skeletal systems, with variable severity independent of genotype 1. Urine oligosaccharide analysis consistently shows abnormalities and serves as a reliable biochemical diagnostic marker 1. Pathogenic MOGS variants reduce protein expression and impair cell cycle progression through altered expression of cell cycle-related proteins 4. Additionally, MOGS expression is upregulated in Alzheimer's disease brain capillaries alongside other N-glycosylation proteins, suggesting involvement in cerebrovascular protein processing 5.