Narcolepsy HLA-DQ Genotyping (HLA-DQB1*06:02)
Test Mnemonic
NARCAB
CPT Codes
- 81382 - QTY (1)
Aliases
- HLA-DQB1*06:02
Includes
- HLA-DQB1, Allele 1
- HLA-DQB1, Allele 2
- Narcolepsy HLA Interpretation
Performing Laboratory
ARUP
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 3 mL | Whole blood | EDTA (Lavender) | Refrigerated |
Alternate Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 3 mL | Whole blood | ACD A (Yellow) | Refrigerated |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Refrigerated | 1 week |
| Ambient | 72 hours |
| Frozen | Unacceptable |
Days Performed
Mon - Fri
Turnaround Time
9 - 16 days
Methodology
| Name | Description |
|---|---|
| Polymerase Chain Reaction (PCR) | |
| Massive Parallel Sequencing | |
| Sequence Specific Oligonucleotide Probe (SSOP) |
Reference Range
Special Info
Counseling and informed consent are recommended for genetic testing. Clotted or grossly hemolyzed specimens will be rejected. This test is New York DOH approved.
Clinical Info
May help rule out narcolepsy when clinical history and sleep studies are inconclusive. Background Information: Characteristics: Narcolepsy is a sleep disorder associated with invalidating excessive daytime sleepiness and cataplexy. Disturbed nighttime sleep, sleep paralysis, and hypnagogic hallucinations (occurring in the period between sleep and wakefulness) are common. Incidence: Narcolepsy affects approximately 1 in 2,000 individuals. Inheritance: Multifactorial. Cause: The HLA-DQB1*06:02 allele is strongly associated with narcolepsy, but by itself is not causative. Recent studies indicate HLA-DRB1*15 is not associated with narcolepsy. Mutations Tested: HLA-DQB1*06:02 allele. Clinical Sensitivity: 85-95% depending on ethnicity. Greater than 98% of affected Caucasians with cataplexy have the HLA-DQB1*06:02 allele. Clinical Specificity: < 1%; 15-25% of unaffected Caucasians have the HLA-DQB1*06:02 allele. Methodology: PCR with melting curve analysis. Analytical Sensitivity and Specificity: 99%
Clinical Limitation
Rare diagnostic errors may occur due to primer site mutations. Other genetic and nongenetic factors that influence narcolepsy disease are not evaluated. In cases where an HLA allele cannot be resolved unambiguously, the allele assignment will be reported as the most common, based on allele frequencies from the common, intermediate, and well-documented alleles catalogue version 3.0.0 (Hurley CK et al, 2020).