Sounds like whatever she has (obviously some kind of genetic disorder) causes a lot of other health problems. It is possible that others who have had it have died at a younger age and the condition was diagnosed as something else.
Bingo.
There's no way this has never happened before.
"(obviously some kind of genetic disorder)"
I'm not sure anything's obvious about this case. Who knows, maybe something she ingested when she was six months old triggered a severe brain malfunction.