HLA-DQB1-Susceptibility to narcolepsy, genotype, total blood

Description, Result Format, Alleles Studied and Reference values Modification

Test code: 4027

Mnemonic code: HLDQ

Effective update from 26/02/2024

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Description:HLA-DQB1-Susceptibility to narcolepsy, genotype, total blood Result format: R1: Result Alleles studied: DQA1*0102, DQB1*0602  Reference values:                NEGATIVE       *Alleles DQA1*0102, DQB1*0602             Version of Test: 3

Description: NARCOLEPSY (HLA-DQB1 TYPING), SUSCEPTIBILITY · HLA (DQB1*0602)· PCR                   Result format: R1: Sample R2: Result                   Alleles studied: DQB1*0602              Reference values: Interpretation and recommendations Narcolepsy is a rare neurological disease (0.02-0.05% of world's population) characterized by severe drowsiness, uncontrollable sleep attacks, sleep paralysis, and hallucinations. Type 1 narcolepsy presents cataplexy and decreased levels of hypocretin-1 in cerebrospinal fluid due to deterioration of orexin/hypocretin neurons; Type 2 presents with normal hypocretin levels and without cataplexy. Eventhough its cause is not completely clear, genetic factors are relevant since more than 98% of type 1 narcoleptic patients are carriers of HLA-DQB1*06:02 allele, frequently in combination with HLA DRB1*15:01. Despite its strong association, around 20% of general population are also carriers of this allele, so, although HLA-DQB1*06:02 allele is not included in the diagnostic criteria for narcolepsy, it is useful due to its high negative predictive value (98-99%). This report should be evaluated by a specialist within the clinical context and family history of the patient, in conjunction with other laboratory findings. Genetic counseling is recommended. Test Method DNA extraction followed by real-time PCR amplification (CE-IVD commercial method) of  HLA-DQB1*06:02 allele group, associated with narcolepsy susceptibility, and of an HBB gene fragment (β-globin) as internal positive control. Version of Test: 4       Test limitations Variants other than those studied are not analyzed. Normal/polymorphic genomic variation in the patient may interfere with variant detection in the sample. References Mignot, E. et al. (1997). Sleep, 20(11):1012-1020 Cano, P. et al. (2007). Human Immunology, 68:392–417 Tafti, M. et al. (2014). Sleep, 37(1):19-25  Miyagawa, T. et al. (2019). Human genome variation 6:4 Version of Test: 4

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