Ordering Recommendation

May help rule out narcolepsy when clinical history and sleep studies are inconclusive.

Mnemonic
NARCOLEPSY
Methodology

Polymerase Chain Reaction/Fluorescence Monitoring

Performed

Varies

Reported

7-10 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval

By report

Interpretive Data

Background Information for Narcolepsy (HLA-DQB1*06:02) Genotyping:
Characteristics:
Narcolepsy is a sleep disorder associated with invalidating excessive daytime sleepiness and cataplexy (the sudden loss of muscle tone triggered by strong emotions). Additionally, 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 percent depending on ethnicity. Greater than 99 percent of affected Caucasians with cataplexy have the HLA-DQB1*06:02 allele.
Clinical Specificity
:  Less than 1 percent; 15-25 percent of unaffected Caucasians have the HLA-DQB1*06:02 allele.
Methodology:
PCR with melting curve analysis.
Analytical Sensitivity and Specificity
: 99 percent.
Limitations:
This methodology will not differentiate between individuals who are heterozygous (one copy) and those who are homozygous (two copies) for the HLA-DQB1*06:02 allele. Rare diagnostic errors may occur due to primer site mutations. Alleles other than HLA-DQB1*06:02 are not identified. Other genetic and non-genetic factors that influence narcolepsy are not evaluated.

Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Note
Hotline History
N/A
Components
Component Test Code* Component Chart Name LOINC
2005024 Narcolepsy (HLA-DQB1*06:02) 43291-4
2011703 Narcolepsy - Specimen
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • DQ1
  • DR15
  • HLA-DQB1*06:02
  • Narcolepsy
  • Narcolepsy Evaluation
Narcolepsy (HLA-DQB1*06:02) Genotyping