Talk to General Physician on Marfan Syndrome

I'm a 20 year old male with 49kg weight. I have very minor symptoms of Marfan Syndrome like long arms, long legs and fingers, Skinny body type and nearsightedness. Which Specialist should I see? Can a General physician diagnose this? I want to just gain mass on my body, I was doing gym for this but I left because Marfan Syndrome patients aren't allowed for wright lifting. I'm really confused for my body. Please guide.