Narcolepsy (HLA-DQB1*06:02) Genotyping
2005023
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
10 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
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: 1 week; 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:
TheHLA-DQB1*06:02 allele is strongly associated with narcolepsy, but, by itself, is not causative. Recent studies indicate HLA-DRB1*15 is no longer 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 will not be identified. Other genetic and non genetic factors that influence narcolepsy are not evaluated.

This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS  
Note
 
CPT Code(s)
81383
Components
Component Test Code*Component Chart Name
2005024Narcolepsy (HLA-DQB1*06:02)
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Aliases
  • DQ1
  • DR15
  • HLA-DQB1*06:02
  • Narcolepsy
  • Narcolepsy Evaluation