HLA-DQ2 GENOTYPE - CELIAC SUSCEPTIBILITY, TOTAL BLOOD

Description, Resuls format, Method and Reference values Modification

Test code: 3232
Mnemonic code: QDQ2

Effective update from 25/06/2024

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Descritpion: HLA-DQ2 GENOTYPE - CELIAC SUSCEPTIBILITY, TOTAL BLOOD Result Format: R1  DQ2 Haplotype R2  DQA1*0501 R3  DQB1*0201 Method: Multiplex-fluorescent PCR (MF-PCR) Reference Values:  The peptides encoded by HLA-DQA1*05 and HLA-DQB1*02 alleles generate haplotype DQ2. DQ8 haplotype is generated by the union of the peptides encoded by HLA-DQA1*03 and HLA-DQB1*0302. They are present in 95% of patients with celiac disease, but also in 25-30% of the general population. A small percentage of celiac patients can carry only one allele coding for the DQ2 haplotype. Other serotypes associated with celiac disease encoded along with the presence of one of the DQ2 and DQ8 alleles.       The absence of the two alleles of DQ2 and DQ8 haplotypes is useful for excluding celiac disease, with a negative predictive value of 99.9% (Farré et al.).                   Version of Test: 14

Description: CELIAC DISEASE (HLA DQ2.5 HAPLOTYPE), SUSCEPTIBILITY TO · QA1*0501/05 DQB1*0201/02 · PCR Result Format: R1  Sample R2  DQ2.5 Haplotype result R3  DQA1*0501/05 Allele R4  DQB1*0201/02 Allele Method: Allele-specific PCR + Fragment analysis Reference Values: Interpretation HLA-DQ2.5 and HLA-DQ8 are haplotypes associated with a greater predisposition to develop Celiac Disease (CD). HLA-DQ2.5 is encoded by the DQA1*0501/05 and DQB1*0201/02 alleles and is present in >90% of CD patients. HLA-DQ8 is encoded by HLA-DQA1*0301 and HLA-DQB1*0302 and appears in 5-10% of celiac patients. A small proportion of patients are carriers of only one of DQ2.5 haplotype alleles. The majority of patients with CD carry one of the alleles of  DQ2.5 and DQ8 haplotypes. Therefore, its absence is helpful in excluding the disease (negative predictive value of 99.9%). However, its presence will not be diagnostic since some alleles appear in up to 30% of the general population, although only 3% of individuals with HLA-DQ2.5 and/or HLA-DQ8 will develop the disease. Risk of developing celiac disease: Very high/high (HLA-DQ2.5 haplotype and/or HLA-DQ8 haplotype presence); Moderate (HLA-DQ8 and/or DQB1*0201/02 haplotype presence); Low (DQA1*0501/05 allele presence); No risk (No risk alleles). This report should be evaluated by a specialist in the context of all available clinical and family information in conjunction with other laboratory findings. Genetic counselling is recommended.       Test method DNA extractionfollowed by real-time PCR amplification (CE-IVD commercial method) of  HLA-DQA1*0501/05 y DQB1*0201/02 alleles. Capillary electrophoresis detection on Applied Biosystems genetic analyzer.      Test limitations Variants other than those studied are not analyzed. Normal/polymorphic genomic variation in the patient may interfere with variant detection in the sample. References Tollefsen et al. (2006). J Clin Invest. Aug;116(8):2226-36 Farré C. (2013). OmniaScience; p. 151-170  Núñez et al. (2018). Rev Esp Enferm Dig:110(7):458-461          Version of Test: 15

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