It's not diagnostically determinative, but it's diagnostically relevant. Not all black people have sickle cell disease, nor do all people of sub-Saharan African

It's not diagnostically determinative, but it's diagnostically relevant. Not all black people have sickle cell disease, nor do all people of sub-Saharan African descent, nor do all people who have one parent known to a carrier of variant HBB genes etc. We're just talking about the degree of statistical likelihood that something from a patient history points to a diagnosis.