Cystathionine beta-synthase deficiency is a rare genetic disorder that affects the body's ability to process certain amino acids, particularly homocysteine. This condition is caused by mutations in the CBS gene, which is essential for producing the enzyme cystathionine beta-synthase. Without this enzyme, the body cannot convert homocysteine into other important substances, leading to a buildup of homocysteine in the blood. Individuals with cystathionine beta-synthase deficiency may experience a range of symptoms, including developmental delays, intellectual disability, and cardiovascular issues. Treatment often involves dietary changes, such as reducing protein intake, and supplementation with vitamins like B6, B12, and folate to help manage homocysteine levels.