PGAP2 deficiency is caused by germline mutation in PGAP2. PGAP2 (Post-GPI Attachment To Proteins 2) is involved in the second step of fatty-acid remodeling of GPI-APs in the Golgi. Firstly, PGAP3 removes the unsaturated lipid chain at sn-2 position, followed by addition of a saturated lipid chain in the second step in which PGAP2 is involved. Thus, in PGAP2 defective cells, GPI-APs are expressed in lysoform, which are released from the cell surface, leading to decreased expression of GPI-APs. GPI-APs serve critical functions as adhesion molecules, receptors, complement regulators, enzymes and co-receptors in signal transduction pathways. Decreased expression of GPI-APs causes mainly neurological disorders such as intellectual disability, developmental delay, muscular hypotonia and epilepsy. The PGAP2 gene is located on chromosome 11p15.4 and PGAP2 deficiency is an autosomal recessive disorder. PGAP2 is one of the responsible genes for Mabry syndrome (HPMRS, Hyperphosphatasia and mental retardation syndrome).
PGAP2