A group of autosomal recessive disorders affecting methionine metabolism. Most common form is cystathionine beta-synthase deficiency. Characterized by lens dislocation, intellectual disability, thromboembolism, and skeletal abnormalities. Responds to pyridoxine (B6) in some patients.

• 1Newborn screening
• 2Plasma total homocysteine
• 3Methionine levels
• 4Genetic testing
• 5Ophthalmologic examination

B6-responsive forms have better prognosis. Untreated: thromboembolism, lens dislocation by age 10, intellectual disability. Early treatment prevents complications.

• Newborn screening
• Genetic counseling
• Prenatal diagnosis
• Anticoagulation when needed
• Regular monitoring