LPIN2 encodes a magnesium-dependent phosphatidate phosphatase that catalyzes conversion of phosphatidic acid to diacylglycerol during triglyceride and glycerophospholipid biosynthesis in the endoplasmic reticulum 1. Beyond its enzymatic role, LPIN2 functions as a nuclear transcriptional coactivator modulating lipid metabolism [UniProt]. LPIN2 regulates antiviral responses through interferon-STAT1-dependent mechanisms, inhibiting viral replication and restricting NLRP3 inflammasome activation by reducing mitochondrial DNA release 2. Biallelic LPIN2 mutations cause Majeed syndrome, a rare autoinflammatory disorder characterized by chr18 recurrent sterile osteomyelitis and anemia 3. The inflammatory phenotype stems from enhanced monocyte caspase-1 activity, M2-like macrophage differentiation, and accelerated osteoclastogenesis through elevated osteoclastogenic mediator production and enhanced JNK/MAPK signaling 4. Notably, LPIN2 expression inversely correlates with COVID-19 disease severity 2, and LPIN2 mutations have been associated with pyoderma gangrenosum in immunodeficiency contexts 5. Unlike LPIN1, which causes childhood rhabdomyolysis, LPIN2 deficiency does not produce primary muscular manifestations 6. These findings establish LPIN2 as a critical regulator of lipid metabolism and innate immunity with therapeutic implications for autoinflammatory and infectious diseases.