Dive into the comprehensive treatise on Homocystinuria, a rare genetic disorder affecting methionine metabolism and characterized by elevated homocysteine levels. Explore its intricate pathophysiology, genetic underpinnings, and diverse clinical manifestations from childhood to adulthood. This in-depth study delves into innovative therapeutic approaches including enzyme replacement therapies, pharmacological interventions, and emerging genetic and regenerative medicine strategies. Discover the latest advancements in clinical trials, biomarker development, and personalized treatment modalities aimed at improving patient outcomes and quality of life. Essential for medical professionals, researchers, and students, this treatise elucidates the complexities of Homocystinuria while paving the way for future advancements in precision medicine and rare disease management.