If you are going to develop or have developed Celiac Disease, you must have certain genes: either HLA-DQ2 or HLA-DQ8. These are actually the names of molecules on cells that are encoded by the genes, but they are used as the names of the genes being tested for. Celiac Disease cannot develop unless one of these genes is present. But having one of these genes does not mean that developing Celiac Disease is inevitable. In fact, approximately 30% of the population has one of these genes, but only about 1% of the population has Celiac Disease. That is why genetic testing is only used to rule out Celiac Disease. If you test negative for both the HLA-DQ2 and HLA-DQ8, you don’t have Celiac Disease, and you won’t develop Celiac Disease. But if you test positive for one of the genes, then Celiac Disease is a possibility, and diagnostic tests need to be performed.