MPPE1 is a metallophosphoesterase that catalyzes removal of ethanolamine-phosphate from GPI-anchor protein intermediates, facilitating glycan remodeling during GPI-anchor maturation 12. This enzymatic function enables efficient transport of GPI-anchored proteins from the endoplasmic reticulum to the Golgi apparatus 12. The protein contains a metallophosphoesterase domain, transmembrane region, and signal sequence, with predominantly brain expression 3. Clinically, MPPE1 dysfunction is linked to multiple disease states. A polymorphism (rs3974590) shows association with bipolar disorder, consistent with MPPE1's chr18 location (18p11) within a postulated bipolar susceptibility locus 4. Loss-of-function MPPE1 variants cause reduced cell-surface expression of GPI-anchored proteins and contribute to severe neurodevelopmental disorder with dystonia 5. In hepatocellular carcinoma, MPPE1 mutations occur in 16.5% of recurrent tumors, independently predicting HCC recurrence (HR=1.969), with knockdown suppressing cell proliferation and invasion 6. Additionally, DNA methylation changes in MPPE1 associate with persistent hypertension 7. These findings establish MPPE1 as a multifunctional gene relevant to neuropsychiatric and malignant disease pathogenesis.