Our daughter came out of the blue with CAH (no one in my family has it) and all our dna was tested.  She was said not to have any of the mutations but since she obviously had it, they went back and sequenced her genes.  They found two rare types from both my husband and I.  So it can happen that there can be no showing with the "top ten" but it still be there.

Take care,

RebeccaM