The gene HLA-DQ1 most likely isn't linked with celiac disease. However, some researchers believe it may increase your susceptibility to gluten sensitivity, and published studies show it appears in a significant minority of those who have gluten ataxia, an autoimmune condition in which gluten spurs your immune system to attack your brain.
Everyone gets one copy of an HLA-DQ gene from their mother and another copy (frequently of a different HLA-DQ gene) from their father. HLA-DQ1 is one of many different types of HLA-DQ genes.
Scientists believe that carrying copies of certain HLA-DQ genes HLA-DQ2 and/or HLA-DQ8 can make it possible for you to develop celiac disease. Other HLA-DQ genes, including HLA-DQ7 and HLA-DQ9, have been linked both to celiac and to gluten sensitivity, although the research on those is far less conclusive and isn't accepted by many physicians.
HLA-DQ1 may play some role in the development of gluten ataxia. Dr. Marios Hadjivassiliou, a consultant neurologist practicing in Sheffield, U.K., who first identified gluten ataxia as a possible condition, has found in several studies that HLA-DQ1 appears in up to one-fourth of those he's diagnosed with gluten ataxia.
In one study performed by Dr. Hadjivassiliou and his colleagues that involved 68 patients with gluten ataxia, the researchers found that 22% of those people carried HLA-DQ1. Most of the patients carried HLA-DQ2 (the most common celiac gene), and about 6% had HLA-DQ8 (a less common celiac gene).
HLA-DQ1 hasn't been associated with villous atrophy, Dr. Hadjivassiliou notes in another study, but it may represent an additional HLA-DQ susceptibility genotype associated with the neurological manifestations of gluten-spurred illness.
HLA-DQ1 has several subtypes with the broad classifications of HLA-DQ5 and HLA-DQ6. According to Dr. Kenneth Fine, director of the Enterolab gluten sensitivity testing service, both HLA-DQ5 and HLA-DQ6 are what he calls "gluten sensitivity genes," meaning they predispose you to gluten sensitivity. However, Dr. Fine hasn't yet published his genetic research, meaning it hasn't been vetted by other scientists, and mainstream physicians generally haven't accepted his findings.
More on the genetics of celiac disease, gluten sensitivity and gluten ataxia:
Celiac Disease Genetic Testing
Gluten Sensitivity Genes
What Is Gluten Ataxia?
My close relative was diagnosed with celiac disease. Should I be tested?
I tested positive in my celiac gene test. Should I stop eating gluten now?
Hadjivassiliou M. et al. Gluten ataxia in perspective: epidemiology, genetic susceptibility and clinical characteristics. Brain. 2003 Mar;126(Pt 3):685-91.
Hadjivassiliou M. et al. Gluten Ataxia. The Cerebellum. 2008;7(3):494-8.
University of Maryland Center for Celiac Research fact sheet. Celiac Disease Frequently Asked Questions. Accessed March 20, 2012.