Class II HLA - HLA-DQ and HLA-DR genotyping - EDTA whole blood
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HLA2
Synonyms
- Class II HLA - HLA-DQ and HLA-DR genotyping
- Class II HLA leukocyte and platelet antigens
- DP, DQ, DR alleles - genotyping
- Locus D - Class II HLA
- OMIM code : *142857 / *604305
Specialty
Genetics
Clinical significance
1) Rheumatoid arthritis (RA) is the most common form of chronic inflammatory rheumatism. Other factors besides HLA promote the incidence of the disease (female sex, hormones, genetic factors, infections). The disease is rarely detected in sub-Saharan and Asian populations. In 1977, an incomplete link with DR4 serological specificity was discovered. In the early 1980s, molecular techniques provided more details on this associated with some DR4 and DR1 alleles (DRB1*0401, 0404 alleles detected in 60% of cases and DRB1*0101 allele detected in 35% of cases). Genetic analysis is not of major diagnostic interest, a poorer prognosis would appear to be observed for heterozygous DRB1*0401/ DRB1*0404 carriers2) Type 1 diabetes: The first studies on type 1 diabetes showed a positive associated with HLA-B8 and HLA-B18, and DR3/DR4 and DQ specificities. Over 90% of patients suffering from type 1 diabetes are DR3 and/or DR4. Two DR-DQ haplotypes are predisposing factors, DRB1*0301-DQA1*0501-DQB1*0201 alleles and DRB1*0401 -DQA1*0301-DQB1*0302 alleles carriers. A synergy effect would appear to be observed in heterozygous DR3/DR4 subjects. In diabetic subject populations, the DQB1*0602 allele is never identified, suggesting a protective role of this allele. For this reason, some authors highlight the important role of aspartic acid in position 57 on the beta chain of HLA-DQ alleles. Indeed, the DQB1*0202, DQB1*0301, DQB1*0602 alleles display aspartic acid (D) in position 57 and are not detected in diabetic subjects.3) Narcolepsy (Gelineau's disease): Alleles encountered: DQA1*0102/DQB1*0602 (""at-risk"" subjects) - Haplotype: DR2 (DR15 and DR16)/DQ1 (DQ5 and DQ6) - Haplotype: DR15/DQ6 2 identified neuropeptides referred to as orexin-A and -B for their orexigenic (appetite stimulant) properties. These peptides secreted by monoaminergic neurons of certain regions of the hypothalamus bind with G-protein coupled receptors (HCRTR1 and HCRTR2). Attempts to demonstrate an autoimmune mechanism in narcolepsy have not been successful.3) Coeliac disease: In the case of coeliac disease, over 90% of subjects express the DQ*O2 molecule (DQ2 serological group Haplotype encountered: DQA1*0501/DQB1*0201 expressed in cis in DR3 subjects, very frequently HBA-B8 - Haplotype DQA1*0501/DQB1*02 expressed in trans in DR5 subjects (DR11, DR12,DR14)/DR7 (DR5-DQ7/DR7DQ2). In approximately 10% of subjects affected, the presence of DQ8 specificity is observed (DQ8: DQB1*0302 and DQB1*0305 alleles). In subjects suffering from coeliac disease, transglutaminase (tTg), which is over-expressed, is involved in the deamidation of gliadin (gliadin: peptide produced by the breakdown of gluten). This deamidation affects the glutamine residues which are modified to glutamic acid, creating negative charges and revealing their immunodominance. Class II HLA molecules formed from alpha chains (DQA1*0501 allele) and beta chains (DQB1*0201 allele) would appear to bind preferentially with these peptides. These peptides would appear to be presented preferentially in the context of DQ2 or DQ8 molecules and recognised by cytotoxic T lymphocytes. Furthermore, transglutaminase, remaining associated with gliadin (with gliadin possibly acting a a ""carrier""), would appear to induce anti-transglutaminase antibody (or anti-endomysium antibody) synthesis.
Further information
According to regulation, each request must ALWAYS be accompanied by a consent form signed by the patient and the prescribing pathologist
Sample must be refrigerated if transport is > 48 hours
We would remind you that we do not perform HLA genotyping as part of a histocompatibility study with a view to transplant or organ donation.
The results of this test can only be interpreted in the context of an association of HLA markers with certain diseases.
Enclose the specific B12-INTGB request form: Molecular Genetics
Documents to download
Methodology
PCR SSO : Technologie Luminex®
Turnaround time
10 days
