The detection of the heterodimeric surface receptors HLA-DQ2 (HLA-DQ2.2 and -DQ2.5) and HLA-DQ8 has great significance in the diagnosis of coeliac disease (gluten-sensitive enteropathy), an autoimmune disease which occurs in predisposed individuals as a reaction to gluten sensitivity. Although these markers are not particularly specific (around 50% of the healthy population is also positive for HLA-DQ2 and/or -DQ8), the absence of these risk factors is an important exclusion criterion as they possess a high negative predictive value of nearly 100 %. If DQ2.2, DQ2.5 or DQ8 are not detected in a patient, then coeliac disease can be virtually excluded.
Moreover, differentiation between homo- and heterozygous presence of the alleles which code the alpha and beta subunits of HLA-DQ2.2 and -DQ2.5 enables an improved risk assessment in the case of a positive HLA-DQ2 result.
The EUROArray HLA-DQ2/DQ8 Direct was especially adjusted for the reliable determination of the disease-associated alleles HLA-DQA1- and HLA-DQB1, which code for the subunits HLA-DQ2.2, -DQ2.5 and -DQ8. The test system EUROArray HLA-DQ2/DQ8-h Direct provides a more comprehensive diagnostic approach for the additional determination of the homo- and heterozygous presence of the alleles coding for HLA-DQ2.2 and -DQ2.5 respectively. Both analyses are extremely easy to perform. With the unique direct procedure, the DNA no longer needs to be isolated. The blood sample is treated with two extraction reagents and can then be used directly in the PCR. PCR primers and microarray probes are selected and optimised in such way that all relevant HLA-DQA1 and HLA-DQB1 alleles are clearly identified. Data analysis, data interpretation and electronic archiving are performed fully automated using the EUROArrayScan software. The accurate analysis of the alpha and beta subunits of the DQ2 and DQ8 molecules ensures reliable and unambiguous results.