Seeking clarification on genetic HLA-DQ test result

[Neroli D]

My doctor ran the tTG-IgA test blood test for celiac disease as I have been getting joint pain which isn't explained by the usual blood tests for arthritis (I am 54). Prior to this I had largely cut gluten out of my diet as eating bread, pasta etc. makes me feel 'blah' (bloated, lethargic, brain fog). The first tTG-IgA test came back equivocal, so since I had already been mostly gluten free she asked me to do the 'gluten challenge' and re-test - however she only asked me to do it for 2 weeks. My 'Dr Google' research suggests that it needs to be longer? Mind you, 2 weeks was awful enough - by the end of the two weeks I was so ill I could hardly function. However, the tTG-IgA test came back equivocal again. So she decided to order the genetic test to see if it ruled out celiac disease, and also suggested that I try going totally gluten free for a month to see what happens. After a month of being totally gluten free (apart from a couple of ingredient mistakes!) I feel so much better - no more pregnant-looking belly, and no longer walking around feeling like I have a brick in my stomach, although my joint pain has not improved. When I went back for my test results, my doctor didn't seem confident in how to interpret them. The test detected HLA-DQ2 (HLA-DQ2.2 Heterozygous). After re-reading the test results a couple of times she said that this result rules out celiac disease because I only have one copy - that I would need two copies of a 'celiac gene' - one from each parent - to be able to develop celiac disease. She concluded that I am probably gluten intolerant, but cannot develop celiac disease. Again, my 'Dr Google' research suggests that although having a single copy of DQ2.2 holds low risk it doesn't completely rule out celiac disease. And I know that the genetic testing only shows 'possibility', not a diagnosis. But perhaps she is correct and it is something to do with the DQA and B Allelles - I have read a dozen articles and websites explaining the genetics including content here, but I struggle to understand the scientific terms. I only doubt my doctor's opinion because she didn't seem to understand the test result. I essentially just need to know whether it is possible to have celiac disease with just one copy of HLA-DQ2.2?

[trents]

I have never heard that you need both copies of the celiac gene to be able to develop celiac disease. I believe that is incorrect. Certainly, with both copies of the gene you would be more likely to develop celiac disease but I can just about guarantee you that there are a lot of people with active celiac disease that only have one copy. Furthermore, there is a 44% chance that first degree relatives of someone with celiac disease will develop active celiac disease. 

For the ttg antibody blood test, or any of the other celiac antibody blood tests, you need to have been eating gluten daily for 6-8 weeks in order for the test to be valid. There are other antibody tests that can be done for celiac disease that are less specific but more sensitive than the tTG-IGA test.

But the fact is, whether you are a celiac or just gluten sensitive, many of the same risks to your health accrue from both and the antidote is the same: total abstinence from gluten.

 

[knitty kitty]

Welcome to the forum!

I'm agreeing with @trents, you only need one gene for Celiac Disease.  

As I understand it, (knowledgeable others correct me if I am not correct), HLA DQ 2.2 heterozygous reacts to a smaller subset of gluten proteins than HLA DQ 2.5, but it still reacts to gluten.

In your googling, did you find this article to explain the Celiac genes?

"HLA-DQ2: The Primary Celiac Disease Gene"

https://www.verywellhealth.com/hla-dq2-the-primary-celiac-disease-gene-562569

 

[CMCM]

Your doctor is misinformed.  You need only ONE celiac gene to get celiac disease.  Also, having one gene doesn't automatically mean you WILL get celiac disease.  What is true is that having two celiac genes can perhaps make it more likely and also the severity of your reaction can be worse.  This was true of my mother and my nephew, both of whom had two celiac genes.  

I didn't understand from your post if you ONLY have the DQ2.2 gene, or if you have a DQ2  AND the 2.2 one.  Remember, you will have 2 genes, one from each parent.  You can have one DQ2 celiac gene and one gene classified as gluten sensitivity pattern such as the DQ2.2, and the one celiac gene can be triggered causing celiac disease.  Or possibly the celiac gene itself isn't triggered but due to the gluten sensitivity gene you can have most of the same huge set of symptoms caused by the celiac gene.  Either way, you must be strictly gluten free.

My sister has one DQ2 celiac gene and her second gene is the 2.2 gene.  She most definitely has celiac disease.  I have one celiac gene and one gluten sensitivity gene, and while I don't have doctor/biopsy confirmation of celiac, I sure have all the symptoms and was only helped by a strictly gluten free diet.  It doesn't matter if I have celiac or merely gluten sensitivity....I don't want to be sick so I can't eat gluten.  

My sister was told that the DQ 2.2 gene was "closer" to the DQ2 celiac gene than the other gluten sensitivity genes, but exactly how much closer is not fully understood.  Whatever the case, she must be strictly gluten free too.

Edited April 11, 2021 by CMCM

[Neroli D]

6 hours ago, knitty kitty said:

Welcome to the forum!

I'm agreeing with @trents, you only need one gene for Celiac Disease.  

As I understand it, (knowledgeable others correct me if I am not correct), HLA DQ 2.2 heterozygous reacts to a smaller subset of gluten proteins than HLA DQ 2.5, but it still reacts to gluten.

In your googling, did you find this article to explain the Celiac genes?

"HLA-DQ2: The Primary Celiac Disease Gene"

https://www.verywellhealth.com/hla-dq2-the-primary-celiac-disease-gene-562569

 

Thanks for the link. That seems pretty clear.  I listened to a video on the DQ2.2 gene and was totally confused by some of the finer details of how 2.2 is formed and whether it is a 'celiac' gene or not, which is why I wondered whether my doctor actually does know more about the genes than 'Dr Google'. Thanks for posting!

[Neroli D]

2 hours ago, CMCM said:

Your doctor is misinformed.  You need only ONE celiac gene to get celiac disease.  Also, having one gene doesn't automatically mean you WILL get celiac disease.  What is true is that having two celiac genes can perhaps make it more likely and also the severity of your reaction can be worse.  This was true of my mother and my nephew, both of whom had two celiac genes.  

I didn't understand from your post if you ONLY have the DQ2.2 gene, or if you have a DQ2  AND the 2.2 one.  Remember, you will have 2 genes, one from each parent.  You can have one DQ2 celiac gene and one gene classified as gluten sensitivity pattern such as the DQ2.2, and the one celiac gene can be triggered causing celiac disease.  Or possibly the celiac gene itself isn't triggered but due to the gluten sensitivity gene you can have most of the same huge set of symptoms caused by the celiac gene.  Either way, you must be strictly gluten free.

My sister has one DQ2 celiac gene and her second gene is the 2.2 gene.  She most definitely has celiac disease.  I have one celiac gene and one gluten sensitivity gene, and while I don't have doctor/biopsy confirmation of celiac, I sure have all the symptoms and was only helped by a strictly gluten free diet.  It doesn't matter if I have celiac or merely gluten sensitivity....I don't want to be sick so I can't eat gluten.  

My sister was told that the DQ 2.2 gene was "closer" to the DQ2 celiac gene than the other gluten sensitivity genes, but exactly how much closer is not fully understood.  Whatever the case, she must be strictly gluten free too.

Thanks for that. I don't really understand the genes - the test report lists DQ2 as 'detected' and then further down says 'Genotype present: HLA-DQ2.2 Heterozygous'. I thought that might be just identifying the type of DQ2 gene so was referring to the same thing - my ignorance of genetics is quite obvious! I am thinking I will need to seek out a doctor who is more experienced with celiac disease and gluten sensitivity - although I feel so much better being gluten free that maybe I don't need an official diagnosis. Thanks!

[Scott Adams]

This article is older, but is still helpful to understand the genetics of CD, and it’s unfortunate that doctors still can’t get this right when their patient DOES HAVE the genetic markers for CD, as you do:

 

[Neroli D]

7 hours ago, Scott Adams said:

This article is older, but is still helpful to understand the genetics of celiac disease, and it’s unfortunate that doctors still can’t get this right when their patient DOES HAVE the genetic markers for celiac disease, as you do:

 

Thank you - seems I need to find a new GP. Nothing against my current GP who is a very good doctor, but clearly not experienced in this area. Thanks again!

[CMCM]

7 minutes ago, Neroli D said:

Thank you - seems I need to find a new GP. Nothing against my current GP who is a very good doctor, but clearly not experienced in this area. Thanks again!

I suspect very few GPs know about celiac.  Even some gastroenterologists (who you would think WOULD know about it) are uninformed.  It's really hit or miss finding someone who knows more than just sketchy information about gluten sensitivity and celiac disease.  My own GP has been very honest and frank with me....and she told me at this point, I know more than she does.  Somehow, she still isn't motivated to learn more on her own, though, so that's disappointing.  I realized that for the most part, I was on my own with this.  

Edited April 12, 2021 by CMCM

[trents]

I would consider printing out some factual information from studies, such as those published in the NIH journal (which are often linked on this forum) and giving handouts to the doc. If the doc is not open to receiving the information, I would look for another doc.