Celiac Disease Genetic Testing: What You Need to Know

There are currently different ways to diagnose celiac disease. Today we show you what genetic testing consists of and how important it is.
Celiac Disease Genetic Testing: What You Need to Know

Last update: 12 July, 2021

Celiac disease is a very difficult disorder to diagnose. This isn’t because there are no specific tests for it, but rather that the need to resort to these is not always clear in patients. Today we show you what genetic testing for celiac disease is about, the first step of a safe diagnosis.

Why are genetic tests carried out for celiac disease?

Celiac disease genetic testing is helpful
Genetic tests are based on the presence of certain molecular markers in a large part of the body’s cells.

Although there are still many things that we don’t know about the disease, we know that celiac disease is an autoimmune disorder with a strong genetic predisposition. In fact, investigators have identified the alleged perpetrators – they generally need an external catalyst to activate.

Those indicated are none other than the human leukocyte antigen genes (known simply as HLA) in its class II. Specifically, they’re HLA-DQ2 and HLA-DQ8. Its prevalence, according to several studies, can reach up to 98.4% of patients diagnosed with the disease. Its relationship with celiac disease, without a doubt, is undeniable.

HLA-DQ2 is frequently the most common, with an incidence of 79.7%. HLA-DQ8, meanwhile, has a prevalence of 8.1%. Celiacs who carry the two genes account for a little more than 10%. Despite this compelling data, Coeliac New Zealand cautions us that between 30% and 50% of the healthy population also carry the genes.

For this reason, experts believe that their participation is key to the manifestation of celiac disease, but that they’re also subject to other conditions. Given its prevalence, specialists carry out genetic tests for celiac disease to determine if the patient is carrying the gene, which, in turn, is a warning sign that the chances of being celiac are higher.

How safe are genetic tests for celiac disease?

As we’ve already indicated, more than 98 out of 100 celiacs are carriers of one or more responsible genes. When a specialist detects its presence through a test, they’ll determine that the risks of the presence of the autoimmune disorder are more likely.

The National Celiac Association states that, when a single copy of the gene is found, there’s a 3% chance of having the disease.

When two copies are found, it increases to 10%. The test itself is very reliable when it comes to detecting genes (on average 99% efficient), but it isn’t so reliable in giving an accurate and objective diagnosis of the condition.

It’s for this reason that DNA testing isn’t the standard when making a diagnosis of celiac disease. The serology test is generally preferred. As the Celiac Disease Foundation tells us, it allows us to detect the antibodies released by the body in response to the ingestion of gluten.

In comparison, the serology test is much more reliable when giving a final verdict, although this usually doesn’t happen either. The specialist doctor will only give a definitive yes after doing a biopsy of the intestinal tissue. Only after this will the patient will be informed that they’re celiac.

Studies to understand the disorder have evolved in such a way that, in some contexts, endoscopy is dispensable. If the symptoms aren’t very clear or the specialist doesn’t want to risk it, then they’ll perform the biopsy.

Are home celiac disease screening tests effective?

Celiac disease genetic testing is helpful
While performing these tests is a good idea, various diagnostic studies, such as endoscopy, are equally important.

For just over a decade, the use of home kits to detect celiac disease has become popular. These are obtained through the Internet, or, failing that, in a pharmacy, and through them you can collect saliva samples from home. You then send them by mail and receive the results electronically.

Despite being carried out in an informal setting, the evidence indicates that these tests are reliable. By reliable, we understand that they can detect the responsible genes with more than 95% accuracy, but they can’t be considered sufficient as a final verdict.

Those who test positive for the genetic test should have a serological test or, even better, an endoscopy to remove a sample of the villi from the intestine. It can be a good first step in diagnosis, but not the final word.

A study published in the Journal of Genetics Counseling with a sample of 1,835 celiac sufferers found that 79% of respondents (ie 1,442 participants) were aware of the existence of genetic testing for celiac disease. This sheds light on patients’ understanding of their own disease and the diagnostic methods available to detect it.

If you have direct relatives with the disease or suffer from an autoimmune disorder, you should take this test as a protocol. If you test positive, even when you don’t have obvious symptoms, we encourage you to visit a specialist to complete the process that will either diagnose it or rule it out.

  • Brown NK, Guandalini S, Semrad C, Kupfer SS. A Clinician’s Guide to Celiac Disease HLA Genetics. Am J Gastroenterol. 2019 Oct;114(10):1587-1592.
  • Cecilio LA, Bonatto MW. The prevalence of HLA DQ2 and DQ8 in patients with celiac disease, in family and in general population. Arq Bras Cir Dig. 2015 Jul-Sep;28(3):183-5.
  • Rashid M, Butzner JD, Warren R, Molloy M, Case S, Zarkadas M, Burrows V, Switzer C. Home blood testing for celiac disease: recommendations for management. Can Fam Physician. 2009 Feb;55(2):151-3. Erratum in: Can Fam Physician. 2009 Apr;55(4):352.
  • Roy A, Pallai M, Lebwohl B, Taylor AK, Green PH. Attitudes Toward Genetic Testing for Celiac Disease. J Genet Couns. 2016 Apr;25(2):270-8.

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