The function of PIGZ (phosphatidylinositol glycan anchor biosynthesis class Z (Gwada blood group), Ensembl gene identifier ENSG00000119227) is as follows. Alpha-1,2-mannosyltransferase that catalyzes the transfer of the fourth mannose, via an alpha-1,2 bond, from a dolichol-phosphate- mannose (Dol-P-Man) to a 2-acyl-6-[alpha-D-mannosyl-(1->2)-alpha-D- mannosyl-(1->6)-2-phosphoethanolamine-alpha-D-mannosyl-(1->4)-alpha-D- glucosaminyl]-1-(1-radyl,2-acyl-sn-glycero-3-phospho)-1D-myo-inositol (also termed H6) intermediate to generate a 2-acyl-6-[alpha-D-mannosyl- (1->2)-alpha-D-mannosyl-(1->2)-alpha-D-mannosyl-(1->6)-2- phosphoethanolamine-alpha-D-mannosyl-(1->4)-alpha-D-glucosaminyl]-1-(1- radyl,2-acyl-sn-glycero-3-phospho)-1D-myo-inositol (also termed M4C) and participates in the twelfth step of the glycosylphosphatidylinositol-anchor biosynthesis (Probable). The presence of a fourth mannose in GPI is facultative, suggesting that it only exists in some tissues (Probable). .