Clinical Effects:

• Babies do not have any problems at birth and, without screening, HCU is not usually diagnosed until 2-3 years of age.
• Classical homocystinuria is associated with a number of problems.
  These can include:
   
• Severe short-sightedness (Myopia)
• Dislocation of the lens of the eye
• Learning difficulties
  Osteoporosis (a condition which increases the likelihood of breaking the bones)
• Lengthening of the long bones
• Blood clots, which can affect the legs (DVTs) or cause strokes
• Without treatment, around a quarter of patients will die before the age of 30, usually as a result of a blood clot.

Treatment:

In some children with HCU, the level of homocysteine can be controlled by giving Vitamin B6 (Pyridoxine). Children who do not respond to vitamin B6 are treated with a low protein diet; these children also need a special amino acid mixture that does not produce homocysteine. They may also be given folic acid, vitamin B12 and a medicine called betaine.

Effectiveness of treatment:

Most problems are prevented if treatment is started during infancy.  If started later, treatment is likely to prevent new problems from developing and it may improve existing problems.