Can someone with Marfan's Syndrome gain more weight?

My brother is believed to have Marfan's syndrome. He has the tall skeletal structure with long fingers and arms. He also has an aortic dilation and curved spine. He also has a sunken chest.
He is 6'3 and weighs 135 pounds.

However, he has no signs of weak joints or loose joints. He also has no vision problems whatsoever. He is 25 years old.

Can he gain more weight? What can he do to gain more weight besides eating more? The doctor gave him some prescription to stimulate his appetite. He will try this now. Is there any "cure" for this particular symptom?

Thanks

I love seeing intelligent answers like the ones you have received so far! Many Marfs have a difficult time gaining weight, at least until they reach middle age! My suggestion (I am a Marf) it to increase the caloric intake. Building muscle might do him well also, as long as he avoids undue strain on his cardio-vascular system. Have you tried contacting the National Marfan Foundation for suggestions? It can't hurt. Good luck!

Because the Marfan syndrome appears in many forms, recommendations about exercise vary widely. For example, people with dilation of the aorta may be asked to avoid the usual team sports. Isometric exercises (such as weight lifting or rowing) and contact sports in which a blow to the chest could occur (such as football or hockey) also may be off-limits. Many people with the Marfan syndrome can participate in modified physical and recreational activities. A cardiologist can give advice about this.

There is no cure for Marfan's syndrome. It is genetic. The aortic dilation is of the most concern. I hope he is being very proactive about getting his dilation checked regularly.

He is just going to have to eat more. I don't suggest going on the McDonalds diet.