Why is my marfan syndrome child so lazy and always tired?

May be the treatment: The beta-blocker medications used to control a Marfan syndrome patient's blood pressure and heart rate can cause fatigue. If such a side effect seems to be happening, the patient's primary care doctor or cardiologist can re-evaluate.

Dont know: Marfan syndrome is a relatively rare condition that effects different body systems differently and to a lesser or greater extent. This type of question should be answered by whatever congenital disease specialist you take him to. Lazy and tired does not just occur in marfan's. I have it (lazy and tired that is).