I was diagnosed a few years ago with Celiac. My sister who had a few of the same symptoms was diagnosed with it too. (incidentally the rest of my immediate family refuses to get a blood test done) She then got a few more tests done which came back pos, neg and inconclusive and even a low number on the blood test. Not one to accept her diagnosis, she then got a genetic test that showed she does not even carry the gene that would ever give her Celiac in her lifetime.
My question is if her blood tests came back positive, negative, inconclusive and then is being told she does not have the gene for Celiac, what are the chances I have/don't have the genes that would give me Celiac? I accepted the one blood test results I had, which said I had a "low number" of antibodies present, which my doctor interpreted as positive and to completely avoid gluten for the rest of my life. But I am now questioning my sister's results and the gene test. Aren't we supposed to have the same gene family? Can anyone shed some light on this for me? Thanks!

You could still carry the gene even if your sister doesnt have it. Also a small number of proven Celiacs have neither of the main Celiac genes. Not having the gene doesnt necessarily mean you you have a 100% chance of never getting celiac disease. There are other genes involved and not all genes have been identified yet.

Do you get symptoms from consuming gluten? Do the symptoms go away when you follow the diet? If so, then you have your answer right there.

Just because she doesn't have those genes doesn't mean that you don't have at least one of them. You both got your genes from your parents, but you certainly don't have all the same ones. That being said - not all of the genes that contribute to celiac disease have been identified. A small percentage (1-2%, as I recall) of biopsy proven celiacs do not have either of the genes that are tested for in "the gene test". In addition to that, there may be other genes that are correlated to gluten intolerance that does not fall under the classic definition of celiac disease (with, classically, requires sufficient damage to the intestines to be called celiac disease). The fact is, if she had antibodies to gluten while she was eating gluten, her body is reacting to it, and reacting enough that the antibodies are able to escape the usually relatively closed system of the intestines into the bloodstream. (Were her second/third tests after she had stopped eating, or greatly reduced the amount of, gluten?)

Thanks to you both for your replies. I'm going to look further into it for her.

From what I have read and been told, antibodies can develop and escalate at any time, and at any rate. My initial antigliadin antibodies were high, but follow-up testing only three months later found them through the roof. I haven't been genetically tested yet (that's next) -- because I'm not celiac, only gluten ataxia. The anti-transglutaminase and antiendomysial cell antibodies were negative as well as my small intestine biopsy. I do want to know if I show or carry any of the genes (and there are quite a few), because I have kids who are 19 and 23. I want to know whether they need to be genetically tested and also tested for antibodies.

You may have had a "low" number of antibodies (I'm presuming they were antigliadin) during your first testing -- of course, your body may have just begun to produce them. The more you ingest gluten, the more antibodies to it your body will produce. I would suggest to your sister to monitor symptoms, but ultimately, I would encourage her to at minimum have her antigliadin antibodies tested. When you start talking "genetic testing", for some reason, people get freaked out!