Congenital disorder of glycosylation (CDG)

A congenital disorder of glycosylation (previously called carbohydrate-deficient glycoprotein syndrome) is one of several rarein born errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defective. Congenital disorders of glycosylation are sometimes known as CDG syndromes. They often cause serious, sometimes fatal, malfunction of several different organ systems (especially the nervous system, muscles, and intestines) in affected infants. The most common subtype is CDG-Ia (also referred to as PMM2-CDG) where the genetic defect leads to the loss of phosphomannomutase 2, the enzyme responsible for the conversion of mannose-6-phosphate into mannose-1-phosphate.

Phosphatidylinositol glycan anchor biosynthesis, class N is a protein that in humans is encoded by the PIGN gene.

This gene encodes a protein that is involved in glycosylphosphatidylinositol (GPI)-anchor biosynthesis. The GPI-anchor is a glycolipid found on many blood cells and serves to anchor proteins to the cell surface. This protein is expressed in the endoplasmic reticulum and transfers phosphoethanolamine (EtNP) to the first mannose of the GPI anchor. Two alternatively spliced variants, which encode an identical isoform, have been reported.

Mutations in PIGN, resulting in  Multiple Congenital Anomalies-Hypotonia-Seizures Syndrome 1 (MCAHS1)