Yeah, if you have tests without strong correlations then your approach is a good one. My point is that when your test returns a result which had low prior proba

Yeah, if you have tests without strong correlations then your approach is a good one. My point is that when your test returns a result which had low prior probability (even if the test is accurate) you should often retain a lot of your scepticism. In this context, it may well be that many of the people identified didn't have the genetic disorders indicated...