Not as many as 99%.
Here is one abstract that says they found 61 out of 1008 celiacs who were not DQ2 or 8.
http://www.ncbi.nlm.nih.gov/pubmed/12651074

Other sources say that DQ2 or 8 involved is something like 95% too.
really depends on wether you count in tha half DQ2 genes or not.
And then you have to test for the alpha chains.

nora