WomanoutsideBrooklyn: Thank you for the explanation. I now realize that looking through the thread may have answered my question automatically..
DaasYochid: from what I gather from WomanoutsideBrooklyn’s explanation and from the actual name of the disease, it appears that this disease only develops later on in life and shows no sign of existing beforehand.
In other words, perhaps the parents were carriers, but in the child it won’t be picked up by tests because it needs to be developed before it’s picked up by tests…
Not sure if I am correct but that is what it seems to me…