Homocystinuria Cystathionine beta synthase deficiency

• Facts:
  Autosomal recessive disease caused by cystathionine synthase deficiency
  
  Patients normal at birth, then begin to develop developmental delays
• History / PE:
  Marfan features (tall stature, joint hyperlaxity, long extremities) PLUS mental retardation, thromboembolic events, downward dislocation of the lens
• Treatment:
  High doses of vitamin B6
• Complications:
  Thromboembolic events (strokes) at any age
  Osteoporosis
  Cataract formation
  Retinal detachment
  
• Differential Diagnosis:
  Marfan's syndrome (upward dislocation of the lens)
  Phenylketonuria (musty odor urine)
  MEN IIB