Concerned for possible HLH. Appreciate.

This must be the most wierdest question here as it is not actually about myself but I may be affected. So here it is Iam about go get married to a girl 23Yrs old who says she doesn't have any medical history my only concern is that her parents are cousins and she has a younger brother who is 9 yrs younger to her and was diagnosed with HLH few years back and subsequently got treated for it and now doing fine. I have read HLH in children is mostly familial and inherited from parents and there are 25% chances of sibling being carrier's😕. Now this makes me think and concerned that my so to be wife can also be a carrier thus putting our future child at risk. Iam not sure whether Im suppose to worry about it or not. I can surely use an experts opinion on this. Much appreciate.