ANA is anti-nuclear antibodies. You can have a positive ANA without having an autoimmune disease, and you can have an auto-immune disease without having positive ANA results, but generally speaking, ANA is a pretty good indicator of auto-immune disease. That being said, there are many auto-immune diseases, and most are fairly easy to manage with treatment. Make sure you have a good rheumatologist. That is very important. I fired my first one because he was an idiot and totally unresponsive medically when I had questions. If they don't want to take the time to answer your questions, find another rheumy. I am currently seeing the rheumatologists at the University of Texas Medical Branch (UTMB) and I really like the results I am getting. My current diagnoses are mixed connective Tissue disease, Sjogren's Syndrome, Hashimoto's Thyroiditis and Reynaud's Phenomenon. I have a laundry list of symptoms, but most are pretty well controlled with plaquenil, levothyroxine, naproxyn, baclofen, tramadol and amytriptylene. I'm not saying I don't have bad days, but they are fewer and further between than before. Good luck!
I wish I could tell you exactly what he has and what it means for the future. It could be several disease processes, they will probably run more tests is my guess. I know with my son when he was younger they waited until he was through puberty before they could determine exactly what was wrong with him. For some reason Mayo said it would not be accurate until then, your son is 14 yrs. old and I do not know if he has reached this place in his life. I do know that Mayo has some information and studies that other doctors may not be aware of.
My step father has systemic sclerosis and he is 67 years old now, and over 25 years ago they told him he was not going to live more than 2 years. (back then they did not know much about these diseases). He has done fine and with time and treatments, the symptoms become less and under control and through the years medicine advanced. Therefore, often our worse thoughts and fears end up not being how life is and even things we are told by doctors can change with time. Having faith helps a lot.
My son had a rare heart condition and had surgery at 21 years old and is 100% healthy now. He was born with WPW and they did not find out what it was for sure 100% until he was 21, by then the surgery tech, had advanced. Therefore, they could go through the arteries versus cracking his chest open which they would have done when he was 15 years old as the advancement in heart surgery changed a lot in how they were able to perform it.So, time was a blessing for him and us.
I know I did not answer your question directly, but I do not think there is answer yet because more time and testing will provide you with the information you are asking. If I assumed and gave you probable things this could scare you at this point. Honestly, that would not help him or you at this point. But I do understand waiting is not easy at all and being a Mom and having your son ill is terrible, I feel for you and wish you the very best.