Yoon-Kyung Shin

Variant between CPT1B and CHKB associated with susceptibility to narcolepsy

Narcolepsy (hypocretin deficiency), a sleep disorder characterized by sleepiness, cataplexy and rapid eye movement (REM) sleep abnormalities, is tightly associated with HLA-DRB1*1501 (M17378) and HLA-DQB1*0602 (M20432). Susceptibility genes other than those in the HLA region are also likely involved. We conducted a genome-wide association study using 500K SNP microarrays in 222 Japanese individuals with narcolepsy and 389 Japanese controls, with replication of top hits in 159 Japanese individuals with narcolepsy and 190 Japanese controls, followed by the testing of 424 Koreans, 785 individuals of European descent and 184 African Americans. rs5770917, a SNP located between CPT1B and CHKB, was associated with narcolepsy in Japanese (rs5770917[C], odds ratio (OR) = 1.79, combined P = 4.4 × 10−7) and other ancestry groups (OR = 1.40, P = 0.02). Real-time quantitative PCR assays in white blood cells indicated decreased CPT1B and CHKB expression in subjects with the C allele, suggesting that a genetic variant regulating CPT1B or CHKB expression is associated with narcolepsy. Either of these genes is a plausible candidate, as CPT1B regulates β-oxidation, a pathway involved in regulating theta frequency during REM sleep, and CHKB is an enzyme involved in the metabolism of choline, a precursor of the REM- and wake-regulating neurotransmitter acetylcholine.

The implication of nigrostriatal dopaminergic degeneration in the pathogenesis of REM sleep behavior disorder

Background and purpose:  The pathogenesis of rapid eye movement (REM) sleep behavior disorder (RBD) is not clear despite its frequent association with Parkinson’s disease (PD). We investigated whether the nigrostriatal dopaminergic system is involved in the development of idiopathic RBD.

Prevalence, comorbidities and risk factors of restless legs syndrome in the Korean elderly population - results from the Korean Longitudinal Study on Health and Aging

The aim of this study was to determine the prevalence, neuropsychiatric comorbidities, iron metabolism and potential risk factors of restless legs syndrome (RLS) in the elderly Korean population. As a community‐based epidemiological study, a simple random sample of 1118 was drawn from a roster of 61 730 adult individuals aged 65 years and older and 714 participated. The diagnosis of RLS was established in face‐to‐face interviews using the four minimal diagnostic criteria for RLS recommended by National Institute of Health. Depressive symptoms, nocturnal sleep disturbances, daytime sleepiness and quality of life were evaluated. Laboratory tests of iron metabolism, markers of inflammation, renal and endocrine function, hormones and vitamins were performed. A total of 59 patients (42 women and 17 men) were diagnosed as RLS with a prevalence of 8.3% (95% confidence interval: 6.2–10.3%), with an almost twofold higher prevalence in women (10.2%) than in men (5.7%). Depression was more prevalent among the subjects with RLS than without RLS and poor nocturnal sleep and quality of life were also observed in subjects with RLS. Daytime sleepiness was observed in 32.8% of subjects with RLS. No significant differences were found in iron metabolism or other risk factors between the subjects with and without RLS. The prevalence of RLS in the Korean elderly population was comparable with that in the Caucasian population. RLS had undesirable effects on mood, sleep quality and general wellbeing of elderly individuals.

Prevalence of narcolepsy-cataplexy in Korean adolescents

Background –  Narcolepsy typically begins between adolescence and early adulthood causing severe neuropsychiatric impairments, but few prevalence studies are available on adolescent narcoleptics. In the present study, we investigated the prevalence of narcolepsy‐cataplexy in adolescents.

A Case of a Patient with Both Chorea and Restless Legs Syndrome

The patient was a 44-yr-old man with end-stage renal disease who had developed chorea as a result of hypoglycemic injury to the basal ganglia and thalamus and who was subsequently diagnosed with depression and restless legs syndrome (RLS). For proper management, the presence of a complex medical condition including two contrasting diseases, chorea and RLS, had to be considered. Tramadol improved the pain and dysesthetic restlessness in his feet and legs, and this was gradually followed by improvements in his depressed mood, insomnia, lethargy, and feelings of hopelessness. This case suggests that the dopaminergic system participates intricately with the opioid, serotoninergic, and noradrenergic systems in the pathophysiology of RLS and pain and indirectly of depression and insomnia.