Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type IG is caused by a defect on chromosome 22q13.33 and involves the gene for a particular enzyme (dolichyl-P-mannose:Man-7-GlcNAc-2-PP-dolichyl-alpha-6-mannosyltransferase). See also Congenital disorder of glycosylation type 1G