Idiopathic thrombocytopenic purpura
) can be present in more than one family member since it is a kind of an autoimmune problem. So no one can really predict if the offspring of your friend will or will not get ITP, although this might be a possibility.
As time goes by, ITP does settle down in several patients. Nevertheless your friend should continue regular follow-ups with her Physician and repeat blood tests as requested by her doctor. Many a times the platelet count
might be low and still there may be no signs externally (such as bruises).
She should also take some precautions to prevent injuries, since these can lead to serious bleeding if her platelet count is very low. For e.g., she might not want to travel on a bike without a helmet, etc.
If her headaches
are very painful and the platelet count is very low then she might want to see her Physician to find out if she has bleeding.
Regards and best of luck.