Celiac disease is an autoimmune disease whose genetic determinism is important, since more than 95% of celiacs express a class II HLA of the DQ2 type or more rarely of the DQ8 type. Individuals with the HLA-DQB1*0501, DQB*0201 genotype have a risk that is at least 200 times higher of developing celiac disease than subjects who are not carriers of this allele (Howell et al., 2002)

Because HLA nomenclature can be confusing, DQ genotyping is a method to simplify results.

There are four main HLA types: DQ1, DQ2, DQ3, DQ4
There are five subtypes: DQ5, DQ6, DQ7, DQ8, DQ9.

DQ1 has two subtypes: DQ5 and DQ6
DQ3 has three subtypes: DQ7, DQ8 and DQ9.

Each individual has two copies of HLA DQ. A DQ copy from the mother and a DQ copy from the father.


Dr. Kenneth Fine, named by Drs. James Braly and Ron Hoggan, authors of the book Dangerous Grains , as a world-class researcher in this sphere gives us here a summary of his (unpublished) research on the genetics of gluten sensitivity:

“It is important to reiterate that gluten sensitivity underlies the development of celiac disease. In this light, it appears that DQ2 or DQ3 subtype DQ8 (or simply DQ8) are the two main HLA-DQ genes that enter account for villous atrophy accompanying gluten sensitivity (in America, 90% of celiacs have DQ2 [a more Northern European Caucasian gene], and 9% have DQ8 [a more Southern European/Mediterranean Caucasian gene], with only 1 % of celiacs or fewer who usually have DQ1 or DQ3 Not all people with DQ2 or DQ8 will have villous atrophy characteristic of celiac disease.

DQ1 and DQ3 also predispose to gluten sensitivity and certain gluten-related diseases (eg microscopic colitis for DQ1,3 from my research or gluten ataxia for DQ1 discovered by another researcher).

DQ2 is present in 31% of the general US population. DQ8 (without DQ2) is present in another 12%. Therefore, the main genes are present in 43% of Americans. DQ1 is present in another 38% of the general US population, which brings us to the fact that at least 81% of America is genetically predisposed to gluten sensitivity.”

Now here is what world-renowned neurologist and researcher Dr. Hadjivassiliou reveals about gluten-associated neurological diseases in a study published in 2002:

“In the group of patients with neurological disease and gluten sensitivity (defined by the presence of anti-gliadin antibodies) we found an HLA association similar to that seen in patients with celiac disease: HLA DQ2 was present in 70% of patients (30% in the general population), HLA DQ8 was present in 9%, and HLA DQ1 was present in the remainder (20%) of our patients The discovery of an additional HLA marker (DQ1) seen in 20% of our patients may represent a significant difference between the genetic susceptibility of patients with a neurological presentation to those with a gastrointestinal presentation in the gluten sensitivity range.”

Genetic screening tests for HLA types DQ2 and DQ8 are increasingly being used to determine if a person has the genes that predispose to CD. Some use the absence of these two genes as a way to rule out the possibility of CD and the need for screening or the need for a gluten-free diet. However, it should be kept in mind that if Dr. Fine and Dr. Hadjivassiliou are telling the truth, approximately 1% of celiacs do not have type DQ2 or DQ8 and patients with type DQ1 or DQ3 are also at risk of developing sensitivity. to gluten.

Where can one avail of these tests?

For North America, these tests are mainly available in the United States and can be ordered online from the following private laboratories: Prometheus, Labcorp, Quest, The Laboratories at Bonfils, and Enterolab . These labs usually work with tissue samples taken by lightly rubbing a cotton swab against the cheek, inside the mouth.

Not all labs however perform full genetic testing or report the full DQ genotype, many labs are often limited to the presence or absence of DQ2 and DQ8 types.

Quest, The Laboratories at Bonfils, and Enterolab (genetic testing contracted out to the American Red Cross) are known to perform a comprehensive test.


Bibliography:

  • Howell WM, Calder PC, Grimble RF.
    Gene polymorphisms, inflammatory diseases and cancer.
    Proc Nutr Soc 2002; 61: 447-456
  • Kaukinen et.al.
    HLA-DQ Typing in the Diagnosis of Celiac Disease.
    Am J Gastroenterol. 2002;97(3):695-699.
  • M Hadjivassiliou, RA Grünewald and GAB Davies-Jones
    Gluten sensitivity as a neurological illness
    Journal of Neurology Neurosurgery and Psychiatry
    2002;72:560-563
  • Dr. Kenneth Fine, Enterolab website