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Celiac disease is a systemic immune disease which causes inflammation of the small bowel and villous damage when a genetically susceptible individual ingests gluten. Over 95% of individuals with celiac disease have specific celiac disease-associated alleles in the HLA-DQA1 and HLA-DQB1 genes (HLA-DQA1*05, HLA-DQB1*02 and HLA-DQB1*0302).

The presence of celiac disease-associated HLA alleles implies an increased risk for celiac disease, but is not diagnostic of celiac disease as only a subset of individuals with these alleles will develop celiac disease. However, individuals who test negative for the celiac disease-associated alleles HLA-DQA1*05, HLA-DQB1*02 and HLA-DQB1*0302 can essentially exclude a diagnosis of celiac disease and have almost no lifetime risk of developing celiac disease (less than 0.04% chance), regardless of whether or not they ingest gluten.

The celiac disease-associated alleles HLA-DQA1*05, HLA-DQB1*02 and HLA-DQB1*0302 and the heterodimers formed by pairs of these alleles, DQ2 (encoded by HLA-DQA1*05 and HLA-DQB1*02) and/or DQ8 (encoded by HLA-DQA1*03 and HLA-DQB1*0302) can be detected through the celiac disease DNA test.

Summary of Possible Genotypes

Negative, no celiac disease-associated alleles detected

If an individual has tested negative for all of the celiac disease-associated alleles (HLA-DQA1*05, HLA-DQB1*02 and HLA-DQB1*0302), then a diagnosis of celiac disease can essentially be excluded. An absence of celiac disease-associated alleles reduces the lifetime risk of developing celiac disease to well below 0.04%, independent of diet. Individuals who test negative for celiac disease-associated alleles will not pass a celiac disease-associated allele to the next generation.

Positive, celiac disease-associated alleles detected

If an individual has tested positive for one or more than one copies of the celiac disease-associated alleles HLA-DQA1*05, HLA-DQB1*02 and HLA-DQB1*0302, then a diagnosis of celiac disease cannot be ruled out. Relatives of individuals who have tested positive for one or more celiac disease-associated alleles are also at risk for being positive. The presence of the celiac disease-associated alleles implies an increased risk for celiac disease, but is not diagnostic of celiac disease as only a subset of individuals with these alleles will develop celiac disease. The estimated risk for developing celiac disease for each genotype is listed in the table below:

* Megiorni F, et al. HLA-DQ and risk gradient for celiac disease. Hum Immunol. 2009; 70: 55-59.