Detection of all currently known HLA-B*27 subtypes and indication of the presence of the non-disease-associated alleles HLA-B*27:06 and HLA-B*27:09
The EUROArray HLA-B27 Direct test is designed for the molecular genetic detection of disease-associated HLA-B*27 alleles. In total, 130 different subtypes (B*27:01 - B*27:105) have been described for HLA-B27, which differ only in some bases and can all be detected together using the EUROArray HLA-B27 Direct.
The membrane-bound HLA-B27 protein is associated with the occurrence of several autoimmune diseases such as Bechterew's disease, urethro-oculo-articular syndrome, reactive arthritis, acute uveitis anterior or acute iridocyclitis, periarthritis, humeroscapularis, arthritis psoriatica, and juvenile idiopathic arthritis. Enteropathies (chronic inflammatory bowel diseases) are also associated with HLA-B*27.
There is a clear relationship between Bechterew's disease and HLA-B27. Around 3-6% of HLA-B*27 carriers develop ankylosing spondylitis. Around 90% of Bechterew's disease patients are carriers of this tissue antigen, particularly subtypes B*27:02, B*27:04, and B*27:05. The subtypes B*27:06 and B*27:09 on the other hand are not associated with Bechterew's disease. Therefore, subtype differentiation is necessary for confirmation of diagnosis in particular populations. This is provided by the EUROArray HLA-B27 at a very high level of quality.
Molecular genetic detection of HLA-B27 competes with the lymphocytotoxicity tests frequently used in the past. The antibodies can cause cross reactions (such as with HLA-B27), which may produce false-negative results in immunophenotyping in low HLA-B*27 expression. Due to the use of allele-specific primers the molecular genetic detection of HLA-B*27 is more specific and sensitive than serological methods.