Hyperhomocystinuria is a metabolic disorder characterized by elevated levels of homocysteine in the blood due to defects in the enzymes responsible for its metabolism. This condition can be caused by genetic mutations, most commonly in the MTHFR, CBS, or MS genes, which affect folate and vitamin B12 metabolism. Elevated homocysteine levels are associated with various health risks, including cardiovascular disease, thromboembolism, and developmental issues. Treatment often involves dietary modifications, vitamin supplementation, and management of associated health risks.