Microarray Platform Accurately Identifies HLA Alleles

Gene sections are first amplified from purified, genomic patient DNA samples by the polymerase chain reaction (PCR). The fluorescently labeled PCR products are then incubated with slides containing microarray biochips, composed of immobilized complementary probes.

Specific binding (hybridization) of the PCR products to their corresponding microarray spots is detected using a specialized microarray scanner, and results are evaluated and documented using specially developed software (the EuroArrayScan). Some alleles can even be analyzed directly from whole blood using the EuroArray Direct procedure, eliminating the need for DNA isolation.

In studies using precharacterized samples, each EuroArray demonstrated 100% sensitivity and 100% specificity. In prevalence studies, all EuroArrays yielded values in agreement with published ranges, namely 37% for HLA-DQ2/DQ8, 9.4% for HLA-B27, and 18% for HLA-Cw6.

HLA-DQ2 and HLA-DQ8 are valuable exclusion parameters for celiac disease diagnostics: if both DQ2 and DQ8 are absent then celiac disease can be virtually ruled out. HLA-B27 is an important diagnostic parameter for ankylosing spondylitis (Bechterew’s disease). The EuroArray detects all known alleles for HLA-B27, and differentiates between disease- and nondisease-associated alleles. HLA-Cw6 is a powerful genetic marker for psoriasis. Microarray testing is helpful for differentiating between different forms of this chronic inflammatory skin disease (e.g., type 1 and type 2 psoriasis vulgaris).

Developed by Euroimmun AG (Lübeck, Germany), the EuroArray processes are in vitro diagnostic (IVD) validated and CE marked.

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