Ornithine aminotransferase (OAT) is a mitochondrial matrix enzyme that catalyzes the reversible interconversion of L-ornithine and 2-oxoglutarate to L-glutamate semialdehyde and L-glutamate 1. The chromosome 10 OAT gene encodes the functional enzyme fully capable of expressing the active oligomeric protein 1. OAT plays a critical role in polyamine synthesis; pancreatic ductal adenocarcinoma (PDA) demonstrates distinct dependence on OAT-mediated de novo ornithine synthesis from glutamine to support polyamine production and tumor growth, contrasting with most adult normal tissues that rely on arginine-derived ornithine 2. This dependency in PDA is driven by mutant KRAS and arginine depletion in the tumor microenvironment 2. Clinically, hereditary OAT deficiency causes gyrate atrophy, a blinding disease characterized by generalized mitochondrial enzyme deficiency 1. The distinct metabolic dependence of PDA on OAT-mediated ornithine synthesis, without comparable reliance in normal tissues, provides a promising therapeutic window for pancreatic cancer treatment with potentially minimal toxicity 2. Understanding OAT function has implications for both metabolic disease management and cancer therapeutic development.