Family Negative for HLA-DQ Gene

[KitCat745]

Hello, I am the only one in my direct family with celiac disease. I have classic celiac and was diagnosed in my mid 20’s. Neither one of my parents have celiac disease, nor do they have the HLA-DQ genes. How is it that I developed celiac without either one of my parents having the gene or appearing to be carriers? I have a younger sibling who does not have celiac as well. Just curious about the genetics. Thank you!!

[trents]

Welcome to the forum, KitCat745!

How were you diagnosed with celiac disease? Did you have both serum antibody testing done and biopsy and did both methods produce celiac positive results? There are some other diseases (Crohns and a certain tropical parasite, some foods for some people (cow's milk protein) and some medications (NSAIDS, a certain blood pressure med) that can blunt villi as does celiac disease.

Have you yourself, had the genetic testing done? More recently there has been research turning up genes other than HLDQ2 and HLDQ8 connected to celiac disease. I don't think we have the full genetic picture yet.

Edited August 27, 2023 by trents

[KitCat745]

Hello, thank you for your response  I was having a variety of GI symptoms and I lost 10 lbs. I had a endoscopy and biopsy done, the endoscopy showing the flattened villi while the biopsy came back positive for celiac. Following the endoscopy, I had a comprehensive celiac panel drawn and which also came back positive and they tested me for the celiac markers. I presented with HLDQA1 and HLDQB1. 
 
I have yet to have genetic testing done but would like to in the future. I didn’t realize that there are other genes that are turning up that are connected to celiac, that’s helpful to know and I’ll have to do research on it. Thank you! 

[trents]

Are you absolutely certain the couple who raised you are your biological parents? I hope you are offended by this question but we've all heard stories and may even know people who were adopted as babies and never told that, who find out in a different way.

[KitCat745]

Oh no, I understand the reasoning for this question. Yes, I know for certain that the couple who raised me are my biological parents. Would individuals who are carriers for celiac present with the HLDQ genes? 

[trents]

I'm not sure I understand your question. Are you referring to yourself as the carrier of celiac disease? When I hear the term "carrier" I think of someone who are themselves asymptomatic but can infect others.

We recently had someone post on the forum who posted their genetic assay results verbatim and they had an allele variant of the HLADQ2 gene which was described as "half a celiac gene" if I recall correctly. And I have seen disclaimers in the literature on celiac genetics that issue the disclaimer, "Not having DQ2 or DQ8 renders the odds of having celiac disease highly unlikely" as in, "It still may be possible." Reading between the lines there, I am assuming that is a tacit admittance that we're not sure we know everything about this yet.

Also, there is the unlikely scenario (but still possible) that your having the genes does not represent an inherited trait but a stand alone mutation or mutations. After all, it had to have started somewhere at some time with somebody in order for that trait to be present in the population but there's no reason it couldn't happen again.

I'm sure you know this but about 40% of the general population have either DQ2 or DQ8 or both but only about 1% of the general population develop active celiac disease. It takes some kind of stress event to trigger the genes into activity, such as a viral infection.

Edited August 27, 2023 by trents

[KitCat745]

Okay, thank you! That answers my question. I greatly appreciate all the information you have provided and the time you took to throughly answer my question. 

[Scott Adams]

Yes, it is possible for someone to have the DQ2 or DQ8 genetic markers associated with celiac disease, and for them to have celiac disease, even if neither of their parents has those markers. This situation can occur due to the complex inheritance patterns of genetic markers.

Celiac disease is strongly associated with specific human leukocyte antigen (HLA) genes, particularly HLA-DQ2 and HLA-DQ8. About 95% of people with celiac disease have either the HLA-DQ2 or HLA-DQ8 genetic marker. However, not all individuals with these genetic markers will develop celiac disease, and not all individuals with celiac disease will have these markers.

HLA genes are inherited from both parents, and each person inherits one set of HLA genes from their mother and one set from their father. It's possible for a person to inherit the necessary genetic markers from one parent, even if that parent does not have celiac disease themselves.

Furthermore, celiac disease is a complex disorder influenced by both genetic and environmental factors. Having the DQ2 or DQ8 markers increases the risk of developing celiac disease, but it's not the only factor. Other genes and environmental triggers also play a role in the development of the condition.

[KitCat745]

Thank you so much! That’s very helpful.

[glutenmaestro]

You should see if it’s possible to get the gene test. Only needs to be done once in your lifetime provided a reputable lab is used. 

I’m not sure which country you’re in but if you don’t have DQ2.5, DQ2.2, DQ8 or DQ7.5 then celiac is unlikely but not impossible. Many commercial gene test kits don’t look for DQ2.2 or DQ7.5 so this can also cause a false negative result.