Hi edithr. triumphe64 is right that you should contact the AA&MDSIF for their excellent information packet and the other support they can provide. Until you get the packet you can also read a more abbreviated overview of the disease on our
Aplastic Anemia page.
Your experience is a lot like that of many parents here. It's such a shock to hear that your child has AA and especially severe AA (SAA). It can seem like you're entering another world. But taking the "crash course" was exactly the right thing to do to start helping your son, as was looking for websites to get information and find other patients.
The very first step after diagnosis was to make sure that your son was out of immediate danger. The next step was testing your daughter as a bone marrow match, so you've started off on the right foot.
If she matches, the success rate of transplants for children and teens is excellent, and that can permanently cure the aplastic anemia. If your daughter isn't a match, ATG (using "horse serum") is the treatment of choice in most cases. It too has an excellent success rate; some patients never have symptoms again, some don't return to completely normal blood counts but live just fine with lower-than-normal blood counts, and some patients relapse but can be treated with ATG again. What's frightening is that no treatment is 100% safe and 100% effective, so there's always the possibility of continuing problems, and that's what can put parents in a panic.
I think the way to overcome the fear is to learn what you can about the disease and its treatment and work with the doctors so you can actively help get your son the best possible care. It's worth checking if the hospital or treatment center where he's being treated has a lot of expertise with aplastic anemia (and with transplants if that turns out to be the best choice). This isn't a disease for which you can rely only on the family doctor.
Your son is at the age where he'll want to understand it too. Unless he's an ace in freshman biology, he'll probably want to learn what you learn about blood counts and some of the medical jargon. If you ask for a copy of your son's CBC (complete blood count) test, that's a good starting place.
If you happen to live within travel distance of Phoenix, Boston, Cleveland, San Francisco, Minneapolis, or Tampa, consider attending one of the upcoming free
patient conferences. Aplastic anemia experts from around the U.S. will be there to talk to patients and family members and there will be sessions on coping with the disease as well.
Most of the forum members here are patients or caregivers, not physicians, but feel free to ask any questions we might be able to answer.