Congenital disorders of glycosylation (CDGs) are a group of clinically heterogeneous disorders characterized by abnormal monosaccharide activation and protein and lipid glycosylation. More than 147 CDG subtypes have currently been described to affect several glycosylation pathways, including N-glycosylation, O-glycosylation, glycosaminoglycan, dystroglycanopathy, and glycosylphosphatidylinositol (GPI)-anchor pathways. ... Here, we present the functional and metabolic studies on a patient with combined immune deficiency harboring biallelic mutations in the mannosidase alpha class 2B member 2 (MAN2B2) gene, affecting both N-glycan synthesis and glycan degradation ...