1: If you watch NBA, you should know Yi JianLian and Charlie Villaneuva (VC) are fighting for starting position. Has you noticed VC has no hair? He has a rare kind of disease which kills all his hair. This guy is running on the court like a deer. So his problem is not serious at all.
2: On the other extreme, there are group of diseases called Connective Tissue Disease. These are systematic problem and every one of them can be fatal. The most common one is Rheumatoid Arthritis (Lie4 Feng1 Shi1 Guan1 Jie2 Yan2). For most patients, it causes distorted joints and extreme pain. In worst case, patient's internal organs get involved and people do die from it.
If your friend has a mild form, I guess it does not really matter. He must have done some research on the subject. For a good friend like you, you need to know what the diagnosis is before you can do anything.