We all need to keep in mind that genetic research is really in it's infancy. There is a lot we don't know. Until they start doing genetic testing on every celiac diagnosed there will remain much to learn. I am a double DQ9 firmly diagnosed celiac. I am not alone. I don't have much time so only can provide one link. Here it is.
Evidence that HLA-DQ9 confers risk to celiac disease by presence of DQ9-restricted gluten-specific T cells.
There are more peer reviewed journal articles out there if one wants to research further.