Ruling out a diagnosis of narcolepsy
Polymerase Chain Reaction (PCR)/Sequence-Specific Oligonucleotide Probes (SSO)
Whole Blood ACD-B
Preferred: Yellow top (ACD solution B)
Acceptable: Yellow top (ACD solution A), lavender top (EDTA)
Specimen Volume: 6 mL
Collection Instructions: Send whole blood specimen in original vial. Do not aliquot.
Additional Information: Specimen acceptability is based on extracted DNA concentration and not sample age.
|Specimen Type||Temperature||Time||Special Container|
|Whole Blood ACD-B||Refrigerated (preferred)|
Ruling out a diagnosis of narcolepsy
Narcolepsy is a neurological condition affecting about 0.02% of African American, White, and Japanese individuals. It is characterized by excessive daytime somnolence and abnormal rapid eye movement (REM) sleep. Cataplexy (weakness precipitated by emotions, especially laughter) is present in 64% to 79% of patients with narcolepsy.
Studies have identified DQB1*06:02 as a useful marker of narcolepsy. DQB1*06:02 is found in 90% to 95% of African American, White, and Japanese patients with narcolepsy who also have cataplexy (narcolepsy type 1), but only in 45% to 50% of patients with narcolepsy without cataplexy (narcolepsy type 2). It must also be clearly understood that about 25% of normal people have this gene.
Because DQB1*06:02 is present in the normal population, no test for an HLA gene constitutes a test for narcolepsy. A more reliable approach would be to consider that, in an appropriate patient who has cataplexy, the absence of the strongly associated DQB1*06:02 provides good evidence that the patient does not have narcolepsy. However, its absence does not rule-out narcolepsy without cataplexy (narcolepsy type 2).
An interpretive report will be provided.
If DQB1*06:02 is not detected, the narcolepsy-associated antigen test result will be reported as negative for DQB1*06:02.
If the allele is detected, the result will be reported as positive for DQB1*06:02.
Based on the catalog of common, intermediate, and well-documented alleles in the world population,(1) certain intermediate or common alleles in some ethnicities may not be resolved.
1. Hurley CK, Kempenich J, Wadsworth K, et al: Common, intermediate and well-documented HLA alleles in world populations: CIWD version 3.0.0. HLA. 2020 Jun;95(6):516-531. doi: 10.1111/tan.13811
2. Mignot E, Lin X, Arrigoni J, et al: DQB1*0602 and DQB1*0102 (DQ1) are better markers than DR2 for narcolepsy in Caucasian and Black Americans. Sleep 1994;17:S60-67
3. Chabas D, Taheri S, Renier C, Mignot E: The genetics of narcolepsy. Ann Rev Genomics Hum Genet 2003;4:459-483
4. Andlauer O, Moore H 4th, Hong SC, et al: Predictors of hypocretin (orexin) deficiency in narcolepsy without cataplexy Sleep 2012 Sep 1;35(9):1247-1255F
5. Bassetti CLA, Adamantidis A, Burdakov D, et al: Narcolepsy - clinical spectrum, aetiopathophysiology, diagnosis and treatment. Nat Rev Neurol. 2019 Sep;15(9):519-539. doi: 10.1038/s41582-019-0226-9
6. Capittini C, De Silvestri A, Terzaghi M, et al: Correlation between HLA-DQB1*06:02 and narcolepsy with and without cataplexy: approving a safe and sensitive genetic test in four major ethnic groups. A systematic meta-analysis. Sleep Med. 2018 Dec;52:150-157.7. Miyagawa T, Tokunaga K: Genetics of narcolepsy. Hum Genome Var. 2019 Jan 8;6:4. doi: 10.1038/s41439-018-0033-7.
This assay applies Luminex technology to the reverse sequence specific oligonucleotide 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 are determined by the positive and negative bead identified using a computer software program. The assignment of the human leukocyte antigen (HLA) typing is based on the reaction pattern compared to patterns associated with published HLA gene sequences.(Package insert: LABType SSO Typing Tests. One Lambda; Version 04, 11/11/2019)
Monday through Friday
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
81376-HLA Class II typing, low resolution (eg, antigen equivalents); one locus (eg, HLA-DRB1/3/4/5, -DQB1, -DQA1, -DPB1, or -DPA1), each
|Test Id||Test Order Name||Order LOINC Value|
|NARC||Narcolepsy Associated Ag, B||63558-1|
|Result Id||Test Result Name||
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|NARC_||Narcolepsy Associated Ag Result||63558-1|