HLA-DQ2 and DQ8

Alternative names, keywords

Samples required

EDTA blood (purple cap/ black cap ring, 4 mL tube). Smaller tubes are available for paediatric samples.

HLA typing for coeliac disease is currently restricted to adult and paediatric gastroenterology, unless by special arrangement with the Consultant Immunologist.

Test indications

Most coeliac disease patients have the HLA-DQ2 allele; the remainder have HLA-DQ8, or one half of the DQ2 heterodimer. The absence of these risk alleles therefore has excellent negative predictive value for coeliac disease. However, the positive predictive value is extremely poor as they are expressed by up to 40% of the general population.

In adults, the main indication is when patients have restricted dietary gluten but a formal diagnosis has not been established, in which case the absence of risk alleles excludes the diagnosis. It may also be performed in difficult cases by arrangement. The test is not indicated for adult patients with convincing serology (as such patients always have risk alleles), for at risk groups such as type 1 diabetes (where over 95% of patients have risk alleles) or for general screening.

Reference range

Reference ranges not applicable - see report.

Turnaround time

Enquiries

Haematology (Immunohaematology)