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PTD-322

Test Directory - HLA-DQ2 and DQ8

Synonyms

 

Clinical Indications

Susceptibility to coeliac disease is linked to certain human leukocyte antigen (HLA) class II alleles, especially in the HLA-DQ region. HLA DQ2/DQ8 alleles are found in virtually all patients with coeliac disease (>99% specificity). HLA DQ2/DQ8 testing should not be used in the initial diagnosis of coeliac disease. However, its high negative predictive value may be of use in specific clinical situations where serology is inaccurate such as hypo or hyper-globulinaemic states or where diagnosis is otherwise in doubt, such as in patients already on a gluten free diet. In children the HLA type and positive tTG allows diagnosis without biopsy.

Request Form

Combined Pathology Blood form (Yellow/Black). Please send a separate request form (and sample) if other Pathology tests requested and ensure that  HLA DQ2/DQ8 is clearly written.

Availability

Analysed by NBS Colingdale if specific criteria met.

Specific Criteria

Requested by Consultant Gastroenterologist/Paediatrician for rule-out of coeliac disease where diagnosis is in doubt. In children, may be used to support a positive serological diagnosis without biopsy.

Patient Preparation

 

None required

Turnaround Time

1 week

Specimen

Whole blood

Volume

1 ml

Container

Purple top (EDTA) tube or

Paediatric red top (EDTA)

Lab. Handling

Samples should be posted to the Reference Laboratory as soon as possible to reach reference lab within 72 hours of bleeding

Causes for Rejection

Forms and samples must be fully labelled with a minimum of full name, date of birth and hospital number. If no hospital number is available, then NHS number is acceptable (NHSBT referral laboratory has a strict labelling policy and will reject samples if not properly labelled).

Interpretation

 

Negative HLA-DQ2 and DQ8 virtually excludes coeliac disease (>99% specificity). SInce approximately 40% of the population are positive for these alleles a positive result is not diagnostic for coeliac disease.


Version 1.0 / October 2014                                                                                               Approved by: Chief Biomedical Scientist