ABSTRACT
BACKGROUND: Narcolepsy is a neurologic disorder characterized by excessive daytime sleepiness, symptoms of abnormal rapid eye movement (REM) sleep, and a strong association with HLA-DRB1*1501, -DQA1*0102, and -DQB1*0602. Here, we investigated the clinico-physical characteristics of Korean patients with narcolepsy, their HLA types, and the clinical utility of high-resolution PCR with sequence-specific primers (PCR-SSP) as a simple typing method for identifying DRB1*15/16, DQA1, and DQB1 alleles. METHODS: The study population consisted of 67 consecutively enrolled patients having unexplained daytime sleepiness and diagnosed narcolepsy based on clinical and neurological findings. Clinical data and the results of the multiple sleep latency test and polysomnography were reviewed, and HLA typing was performed using both high-resolution PCR-SSP and sequence-based typing (SBT). RESULTS: The 44 narcolepsy patients with cataplexy displayed significantly higher frequencies of DRB1*1501 (Pc= 0.003), DQA1*0102 (Pc=0.001), and DQB1*0602 (Pc=0.014) than the patients without cataplexy. Among patients carrying DRB1*1501-DQB1*0602 or DQA1*0102, the frequencies of a mean REM sleep latency of less than 20 min in nocturnal polysomnography and clinical findings, including sleep paralysis and hypnagogic hallucination were significantly higher. SBT and PCR-SSP showed 100% concordance for high-resolution typing of DRB1*15/16 alleles and DQA1 and DQB1 loci. CONCLUSIONS: The clinical characteristics and somnographic findings of narcolepsy patients were associated with specific HLA alleles, including DRB1*1501, DQA1*0102, and DQB1*0602. Application of high-resolution PCR-SSP, a reliable and simple method, for both allele- and locus-specific HLA typing of DRB1*15/16, DQA1, and DQB1 would be useful for characterizing clinical status among subjects with narcolepsy.
Subject(s)
Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , Alleles , Cataplexy/genetics , DNA Probes, HLA , Gene Frequency , Genetic Predisposition to Disease , Genotype , HLA-DQ Antigens/genetics , HLA-DRB1 Chains/genetics , Histocompatibility Testing , Narcolepsy/diagnosis , Phenotype , Polymerase Chain ReactionABSTRACT
This study was thought to characterized clinical and laboratory findings of a narcoleptic patients in an out patients unit at São Paulo, Brazil. METHOD: 28 patients underwent polysomnographic recordings (PSG) and Multiple Sleep Latency Test (MSLT) were analyzed according to standard criteria. The analysis of HLADQB1*0602 allele was performed by PCR. The Hypocretin-1 in cerebral spinal fluid (CSF) was measured using radioimmunoassay. Patients were divided in two groups according Hypocretin-1 level: Normal (N) - Hypocretin-1 higher than 110pg/ml and Lower (L) Hypocretin-1 lower than 110 pg/ml. RESULTS: Only 4 patients of the N group had cataplexy when compared with 14 members of the L group (p=0.0002). DISCUSSION: This results were comparable with other authors, confirming the utility of using specific biomarkers (HLA-DQB1*0602 allele and Hypocretin-1 CSF level) in narcolepsy with cataplexy. However, the HLADQB1*0602 allele and Hypocretin-1 level are insufficient to diagnose of narcolepsy without cataplexy.
Este estudo foi idealizado para avaliar as características clinicas e laboratoriais de uma população de narcolépticos atendidos num centro de referência na cidade de São Paulo (Brasil). MÉTODO: 28 pacientes realizaram polissonografia e teste de múltiplas latências do sono segundo critérios internacionais. O alelo HLADQB1*0602 foi identificado por PCR. A Hipocretina-1 no líquido cefalorradiano (LCR) foi mensurada por radioimunoensaio. Os pacientes foram divididos em 2 grupos conforme o nível de Hipocretina-1. Normal (N) - Hypocretin-1 >110pg/ml e baixa (B) - Hypocretina-1 <110pg/ml. RESULTADOS: Somente 4 pacientes do grupo N tinham cataplexia quando comparados com 14 pacientes do grupo B (p=0,0002). DISCUSSÃO: Estes resultados foram comparáveis com outros autores, confirmando a utilidade do uso de biomarcadores específicos (HLA-DQB1*0602 e nível da hipocretina-1 no LCR) em narcolepsia com cataplexia. Porém, o alelo HLADQB1*0602 e a dosagem da Hipocretina-1 são insuficientes para o diagnóstico da narcolepsia sem cataplexia.