|Downtime form:||A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery|
|Lavender top tube 3 mL (EDTA)|
Absolute Minimum: 1 mL whole blood from lavender top tube
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.
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 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.
Analytical Sensitivity and Specificity: 99 percent.