Ethanolamine phosphate transferase involved in glycosylphosphatidylinositol-anchor biosynthesis. Transfers ethanolamine phosphate to the first alpha-1,4-linked mannose of the glycosylphosphatidylinositol precursor of GPI-anchor (By similarity). May act as suppressor of replication stress and chromosome missegregation. Glycolipid biosynthesis; glycosylphosphatidylinositol-anchor biosynthesis. The disease is caused by variants affecting the gene represented in this entry. Belongs to the PIGG/PIGN/PIGO family. PIGN subfamily.