Mannosyl-oligosaccharide glucosidase (MOGS) deficiency is an extremely rare type of congenital disorder of glycosylation (CDG), with only 12 reported cases. Its clinical, genetic, and glycomic features are still expanding. Our aim is to update the novel clinical and glycosylation features of 2 previously reported patients with MOGS-CDG. We collected comprehensive clinical information, and conducted the immunoglobulin G1 glycosylation assay using nano-electrospray ionization source quadruple time-of-flight mass spectrometry.