HLA-DQ8: One of the Main Celiac Disease Genes

How does having DQ8 affect your risk of celiac?

strand of dna
HLA-DQ8 is one of the main celiac genes. Ian Cuming/Getty Images

Celiac disease is a genetically linked condition—to get it, you need to have the correct genes. The gene HLA-DQ8, which is common in Central American and in northern South America, is seen in up to about 8% of people diagnosed with celiac disease, making it one of the two so-called "celiac disease genes."

HLA-DQ8 actually is the runner-up in the celiac disease genetic lottery. The most common gene associated with celiac disease is HLA-DQ2—it's present in nearly 90% or more of all celiac disease cases.

 HLA-DQ8, meanwhile, is a much less common gene in the overall population (it appears in about 10% of humans overall, despite the fact that it's quite common in people hailing from Central and South America). It accounts for most of the non-HLA-DQ2 celiac disease cases.

How Does DQ8 Affect Your Celiac Risk?

A little genetic background is in order.

Everyone has two copies of their HLA-DQ genes, since they inherit one from their mother and one from their father. Different forms of the HLA-DQ genes include HLA-DQ2, HLA-DQ7, HLA-DQ9 and HLA-DQ1; some of these are implicated in the development of celiac disease, while others may play some role in the development of gluten ataxia or possibly gluten sensitivity.

Since everyone has two HLA-DQ genes (again, one from your mother and one from your father), it's possible to have one copy of HLA-DQ8 (known as HLA-DQ8 heterozygous), two copies of HLA-DQ8 (known as HLA-DQ8 homozygous), or no copies of HLA-DQ8 (known as HLA-DQ8 negative).

If you have two copies of HLA-DQ8 (in technical terms, this means you're HLA-DQ8 homozygous), your risk for developing celiac disease is about 10 times higher than that of the general population, according to gene-testing company MyCeliacID, which developed a proprietary celiac disease risk algorithm based on published research.

Having DQ8 Plus DQ2 Raises Risk Higher

If you have HLA-DQ8 combined with a high-risk version of HLA-DQ2, then your risk is even higher—about 14 times that of the general population, according to the MyCeliacID algorithm.

Meanwhile, if you have just one copy of HLA-DQ8 with anything other than HLA-DQ2, your risk of celiac disease is about twice that of the overall population, according to MyCeliacID's risk stratification table.

Celiac disease doesn't appear to be any more or less severe in people with HLA-DQ8 genes when compared to those with HLA-DQ2 genes. In addition, there almost certainly are multiple other genes involved in the development of the condition, but researchers haven't identified them all yet.

Sources:

Johnson TC et al. Relationship of HLA-DQ8 and severity of celiac disease: comparison of New York and Parisian cohorts. Clinical Gastroenterology and Hepatology. 2004 Oct;2(10):888-94.

MyCeliacID Risk Stratification Table.

University of Maryland Center for Celiac Research fact sheet. Celiac Disease Frequently Asked Questions.

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