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HelpTest Code CELI Celiac Associated HLA-DQ Alpha 1 and DQ Beta 1 DNA Typing, Blood
Reporting Name
Celiac Associated HLA-DQ TypingUseful For
Assessing risk of celiac disease
Testing Algorithm
The following algorithms are available:
-Celiac Disease Comprehensive Cascade Test Algorithm
-Celiac Disease Diagnostic Testing Algorithm
-Celiac Disease Gluten-Free Cascade Test Algorithm
Method Name
Polymerase Chain Reaction (PCR)/Sequence-Specific Oligonucleotide Probe (SSO)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole Blood ACD-BOrdering Guidance
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, Serum and Whole Blood: complete testing including HLA DQ
-CDSP / Celiac Disease Serology Cascade, Serum: complete testing excluding HLA DQ
-CDGF / Celiac Disease Gluten-Free Cascade, Serum and Whole Blood: for patients already adhering to a gluten-free diet
To order individual tests, see Celiac Disease Diagnostic Testing Algorithm.
Specimen Required
Container/Tube: Yellow top (ACD Solution A or B)
Specimen Volume: 6 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Specimen Minimum Volume
3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole Blood ACD-B | Refrigerated (preferred) | ||
| Ambient | |||
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Special Instructions
Reference Values
An interpretive report will be provided.
Day(s) Performed
Monday through Friday
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 one 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 2 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. 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 may be 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 one 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 nonpermissive for celiac.
There are reports that specific HLA-DQ2 and DQ8 combinations may confer different risks for the development of celiac disease.(1)
A recent publication from our group demonstrated that risk gradient of tissue transglutaminase (tTG) IgA positivity depends on specific HLA-DQ2 and DQ8 combinations.(2) For more information see Tissue Transglutaminase IgA positivity.
Cautions
Based on the catalog of common, intermediate, and well-documented alleles in the world population,(3), certain intermediate or common alleles in some ethnicities may not be resolved.
Method Description
LABType applies Luminex technology to the reverse sequence-specific oligonucleotide (SSO) DNA typing method. First, target DNA is polymerase chain reaction (PCR)-amplified using a group-specific primer. The PCR product is biotinylated, which allows it to be detected using R-phycoerythrin-conjugated streptavidin. The PCR product is denatured and allowed to rehybridize to complementary DNA probes conjugated to fluorescently coded microspheres. A flow analyzer identifies the fluorescent intensity of phycoerythrin on each microsphere. The HLA Class II allele or allele groups of the sample is determined by the positive and negative bead ID's using a computer software program. The assignment of the HLA typing is based on the reaction pattern compared to patterns associated with published HLA gene sequences.(Package insert: LABType SSO Typing. One Lambda; Version 04, 11/11/2019)