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Test ID: CELI Celiac Associated HLA-DQ Alpha 1 and DQ Beta 1 DNA Typing, Blood

Reporting Name

Celiac Associated HLA-DQ Typing

Useful For

Assessing risk of celiac disease

Specimen Type

Whole Blood ACD-B


Advisory Information


Cascade testing is recommended for celiac disease. Cascade testing ensures that testing proceeds in an algorithmic fashion. The following cascades are available; select the appropriate one for your specific patient situation.

-CDCOM / Celiac Disease Comprehensive Cascade: complete testing including HLA DQ

-CDSP / Celiac Disease Serology Cascade: complete testing excluding HLA DQ

-CDGF / Celiac Disease Gluten-Free Cascade: for patients already adhering to a gluten-free diet

To order individual tests, see Celiac Disease Diagnostic Testing Algorithm in Special Instructions.



Specimen Required


Container/Tube: Yellow top (ACD solution B)

Specimen Volume: 6 mL

Collection Instructions: Do not transfer blood to other containers.


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD-B Refrigerated (preferred)
  Ambient 

Reference Values

An interpretive report will be provided.

Day(s) and Time(s) Performed

Monday through Friday; 7:30 a.m.-5 p.m.

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

81376 x 2-HLA Class II typing, low resolution (eg, antigen equivalents); one locus (eg, HLA-DRB1/3/4/5, -DQB1, -DQA1, -DPB1, or -DPA1), each

 

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CELI Celiac Associated HLA-DQ Typing 94492-6

 

Result ID Test Result Name Result LOINC Value
DQA DQ alpha 1 94495-9
DQB DQ beta 1 53938-7
CELIG Celiac gene pairs present? 48767-8
CELIC Interpretation 69048-7

Clinical Information

Celiac disease (gluten-sensitive enteropathy) is mediated by T lymphocytes in patients with genetic susceptibility. This genetic association is with certain HLA genes in the class II region (DQ alpha 1, DQ beta 1).

Interpretation

Most (90%-95%) patients with celiac disease have 1 or 2 copies of HLA-DQ2 haplotype (see below), while the remainder have HLA-DQ8 haplotype. Rare exceptions to these associations have been occasionally seen. In 1 study of celiac disease, only 0.7% of patients with celiac disease lacked the HLA alleles mentioned above. Results are reported as permissive, nonpermissive, or equivocal gene pairs.

 

It is important to realize that these genes are also present in about 20% of people without celiac disease. Therefore, the mere presence of these genes does not prove the presence of celiac disease or that genetic susceptibility to celiac disease is present.

 

The HLA-DQ molecule is composed of two chains: DQ alpha (encoded by HLA-DQA1 gene) and DQ beta (encoded by HLA-DQB1 gene). HLA-DQ typing can be performed by serological or molecular methods. Currently most laboratories perform typing by molecular methods. HLA-DQ2 and DQ8 as typed by serology are usually based on the molecular typing of the DQB1 chain only. The current molecular method allows typing for both the DQB1 and DQA1 chains and this has shown that there are different haplotypes of HLA-DQ2 and DQ8. Typing of these haplotypes is important in celiac disease as they carry different risk association.

 

There are 2 common haplotypes of DQ2:

1. DQA1*05:01 with DQB1*02:01 also called DQ2.5 in celiac literature

2. DQA1*02:01 with DQB1*02:02 also called DQ2.2 in celiac literature

A single haplotype (heterozygote) of DQ2.5 is permissive for presence of celiac genes. However, only a double haplotype (homozygous) of DQ2.2 is permissive for presence of celiac genes. There are few reports where a single haplotype of DQ2.2 is considered to be an equivocal risk. In some cases the DQ2.2 haplotype maybe present with a DQ7.5 haplotype (DQA1*05:05 with DQB1*03:01). In this case a DQ2.5 molecule can be formed by the combination of DQB1*02:02 from 1 chromosome and DQA1*05:05 from the other chromosome. These cases fall in the same category as the DQ2.5 heterozygote.

 

There are 3 common haplotypes of DQ8:

1. DQA1*03:01 with DQB1*03:02

2. DQA1*03:02 with DQB1*03:02

3. DQA1*03:03 with DQB1*03:02

Any single haplotype (heterozygote) of DQ8 is permissive for celiac.

 

Therefore, the gene pairs permissive for celiac are:

1. Heterozygote (single copy)

   -DQA1*05:XX with DQB1*02:01

   -DQA1*05:XX with DQB1*02:02

   -DQA1*03:XX with DQB1*03:02

2. Homozygous (2 copies)

   -DQA1*02:01 with DQB1*02:02

 

Gene pairs equivocal for celiac are

1. Heterozygote (single copy)

   -DQA1*02:01 with DQB1*02:02

2. Rare allele’s types of DQ2 and DQ8 other than those listed above

 

All other gene pair combinations are considered non-permissive for celiac.

Clinical Reference

Polvi A, Arranz E, Fernandez-Arequero M, et al: HLA-DQ2-negative celiac disease in Finland and Spain. Hum Immunol 1998 Mar;59(3):169-175

Analytic Time

5 days

Method Name

Polymerase Chain Reaction (PCR)/Sequence-Specific Oligonucleotide Probe (SSO)

Forms

If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Client Test Request (T728) with the specimen.

Mayo Clinic Laboratories | Gastroenterology Catalog Additional Information:

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