Birgit Högl

Narcolepsy is strongly associated with the T-cell receptor alpha locus

Narcolepsy with cataplexy, characterized by sleepiness and rapid onset into REM sleep, affects 1 in 2,000 individuals. Narcolepsy was first shown to be tightly associated with HLA-DR2 (ref. 3) and later sublocalized to DQB1*0602 (ref. 4). Following studies in dogs and mice, a 95% loss of hypocretin-producing cells in postmortem hypothalami from narcoleptic individuals was reported. Using genome-wide association (GWA) in Caucasians with replication in three ethnic groups, we found association between narcolepsy and polymorphisms in the TRA@ (T-cell receptor alpha) locus, with highest significance at rs1154155 (average allelic odds ratio 1.69, genotypic odds ratios 1.94 and 2.55, P < 10−21, 1,830 cases, 2,164 controls). This is the first documented genetic involvement of the TRA@ locus, encoding the major receptor for HLA-peptide presentation, in any disease. It is still unclear how specific HLA alleles confer susceptibility to over 100 HLA-associated disorders; thus, narcolepsy will provide new insights on how HLA–TCR interactions contribute to organ-specific autoimmune targeting and may serve as a model for over 100 other HLA-associated disorders.

Restless legs syndrome: A community-based study of prevalence, severity, and risk factors

Objective: To assess the prevalence and severity of restless legs syndrome (RLS) in the general community and to investigate its potential relationship with iron metabolism and other potential risk factors. Methods: This was a cross-sectional study of a sex- and age-stratified random sample of the general population (50 to 89 years; n = 701). The diagnosis of RLS was established by face-to-face interviews; severity was graded on the RLS severity scale. Each subject underwent a thorough clinical examination and extensive laboratory testing. Results: The prevalence of RLS was 10.6% (14.2% in women, 6.6% in men); 33.8% of all patients with RLS had mild, 44.6% had moderate, and 21.6% had severe disease expression. None had been previously diagnosed or was on dopaminergic therapy. Free serum iron, transferrin, and ferritin concentrations were similar in subjects with and without RLS. However, soluble transferrin receptor (sTR) concentrations were different in subjects with and without RLS (1.48 vs 1.34 mg/L; p < 0.001). Female sex and high sTR independently predicted the risk of RLS. Conclusion: This large survey confirms the high prevalence, female preponderance, and underrecognition of restless legs syndrome in the general community. Although two-thirds of patients had moderate to severe disease, none was on current dopaminergic therapy.

Decreased striatal dopamine transporter uptake and substantia nigra hyperechogenicity as risk markers of synucleinopathy in patients with idiopathic rapid-eye-movement sleep behaviour disorder: a prospective study

BACKGROUND Patients with idiopathic rapid-eye-movement sleep behaviour disorder (IRBD) may develop neurodegenerative conditions associated with substantia nigra dysfunction such as Parkinsons disease. In patients with Parkinsons disease, ¹²³I-2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane (¹²³I-FP-CIT) SPECT detects striatal dopamine dysfunction resulting from nigral pathology whereas transcranial sonography (TCS) shows increased substantia nigra echogenic size, even before parkinsonism is clinically evident. We postulated that these neuroimaging changes could occur in a proportion of IRBD individuals who might then be at increased risk for development of a neurodegenerative disorder associated with substantia nigra dysfunction. METHODS In our prospective study, we identified patients with IRBD from individuals referred to our sleep disorders centre in Barcelona, Spain. At baseline, we assessed dopamine transporter [corrected] uptake by use of ¹²³I-FP-CIT SPECT, and estimated echogenicity of the substantia nigra by use of TCS. After a follow-up of 2·5 years, participants were clinically assessed to establish whether they had developed neurodegenerative syndromes. Data were compared with those of matched healthy controls. FINDINGS 43 individuals with IRBD agreed to participate in the study. We found reduced ¹²³I-FP-CIT binding in the striatum (p=0·045) in 17 (40%) of 43 participants compared with 18 controls, and substantia nigra hyperechogenicity in 14 (36%) of 39 participants with IRBD, compared with 16 (11%) of 149 controls (p=0·0002). Tracer uptake reduction was more pronounced in the putamen than it was in the caudate nucleus. 27 (63%) participants had reduced ¹²³I-FP-CIT binding or substantia nigra hyperechogenicity at baseline. Eight (30%) of these participants developed a neurodegenerative disorder (five Parkinsons disease, two dementia with Lewy bodies, and one multiple system atrophy). Individuals with normal neuroimaging results remained disease-free. Sensitivity of combined ¹²³I-FP-CIT SPECT and TCS to predict conversion to synucleinopathy after 2·5 years was 100% and specificity was 55%. INTERPRETATION In patients with IRBD, ¹²³I-FP-CIT SPECT and TCS can detect subclinical changes much the same as those typically seen in patients with early Parkinsons disease. Decreased striatal ¹²³I-FP-CIT binding and substantia nigra hyperechogenicity might be useful markers to identify individuals at increased risk for development of synucleinopathies. FUNDING None.

PTPRD (protein tyrosine phosphatase receptor type delta) is associated with restless legs syndrome

We identified association of restless legs syndrome (RLS) with PTPRD at 9p23–24 in 2,458 affected individuals and 4,749 controls from Germany, Austria, Czechia and Canada. Two independent SNPs in the 5′ UTR of splice variants expressed predominantly in the central nervous system showed highly significant P values (rs4626664, Pnominal/λ corrected = 5.91 × 10−10, odds ratio (OR) = 1.44; rs1975197, Pnominal/λ corrected = 5.81 × 10−9, OR = 1.31). This work identifies PTPRD as the fourth genome-wide significant locus for RLS.

Efficacy of rotigotine for treatment of moderate-to-severe restless legs syndrome: a randomised, double-blind, placebo-controlled trial

BACKGROUND Continuous administration of a dopamine agonist could be used to treat patients with restless legs syndrome. Our aim was to investigate the efficacy of transdermal rotigotine in the treatment of idiopathic restless legs syndrome. METHODS In this randomised, double-blind, placebo-controlled trial, 458 patients with moderate-to-severe idiopathic restless legs syndrome (average baseline International Restless Legs Syndrome Study Group severity rating scale [IRLS] sum score of 28.1) were randomly assigned to receive transdermal rotigotine 1 mg over 24 h (n=115), 2 mg over 24 h (n=112), or 3 mg over 24 h (n=114), or to receive placebo (n=117). Study medication was delivered via patches, applied once a day for 6 months. Randomisation was done with a computer-generated randomisation list, stratified by centre. Primary efficacy outcomes were absolute change from baseline to end of maintenance in IRLS sum score and in the clinical global impressions (CGI) item 1 score, assessed by analysis of covariance in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT00136045. FINDINGS Efficacy analyses were done on 112 patients in the 1 mg group, 109 in the 2 mg group, 112 in the 3 mg group, and 114 in the placebo group. Mean change in IRLS sum score from baseline at the end of the maintenance phase was -13.7 (SE 0.9) in the 1 mg group, -16.2 (0.9) in the 2 mg group, -16.8 (0.9) in the 3 mg group, and -8.6 (0.9) in the placebo group (p<0.0001 for treatment difference vs placebo with each dose). Mean change in CGI item 1 score from baseline at the end of the maintenance phase was -2.09 (0.14) in the 1 mg group, -2.41 (0.14) in the 2 mg group, -2.55 (0.14) in the 3 mg group, and -1.34 (0.14) in the placebo group (p<0.0001 for treatment difference vs placebo with each dose). Skin reactions, mostly mild or moderate, were seen in 145 (43%) of 341 patients who received rotigotine and in two (2%) of 117 who received placebo. Ten patients had serious adverse event that were deemed to be related to rotigotine: elevation of liver enzymes (one patient), worsening of tinnitus (one patient), non-response to anticoagulation (one patient), electrocardiogram changes (one patient), and application-site reactions (six patients). No admissions to hospital were needed for the application-site reactions, and they all resolved within a short time of patch removal without any other therapeutic intervention. The rate of typical dopaminergic side-effects in patients who received rotigotine was low; no signs of augmentation were noted. INTERPRETATION 24 h transdermal delivery of low-dose rotigotine could be used to relieve the night-time and daytime symptoms of restless legs syndrome. FUNDING Schwarz Biosciences.

Prevalence of movement disorders in men and women aged 50-89 years (Bruneck Study cohort): a population-based study.

BACKGROUND There is emerging awareness that movement disorders rank among the most common neurological diseases. However, the overall burden of these disorders in the general community is not well defined. We sought to assess the prevalence of all common categories of movement disorders in a population, accounting for sex differences and age trends. METHODS As part of an ongoing prospective population-based study of carotid atherosclerosis and stroke risk (the Bruneck Study), a total of 706 men and women aged 50-89 years underwent a thorough neurological assessment. The diagnosis of movement disorders and ratings for disease severity were based on standard criteria and scales. Prevalences were estimated from logistic regression models (regression-smoothed rates) and standardised to the age and sex structure of the general community. FINDINGS The prevalence of all common categories of movement disorders was 28.0% (95% CI 25.9-30.1). Proportions in men (27.6% [95% CI 24.5-30.7]) and women (28.3% [25.5-31.2]) were closely similar and sharply increased with age (from 18.5% [15.0-22.0] in 50-59-year olds to 51.3% [44.9-57.7] in 80-89-year olds). Almost half of all patients (90/214) had moderate-to-severe disease expression, but only 7.0% (15/214) received standard drug treatment. Prevalence of tremor was 14.5%, followed by restless legs syndrome (10.8%), parkinsonism (7%), primary dystonia and secondary dystonia (1.8%), and chorea and tics (<1% each). A fifth of all movement disorders were diagnosed to be probably drug-induced. INTERPRETATION There is a high prevalence of and substantial under-recognition and under-treatment of movement disorders in the general community.

Transcranial ultrasound shows nigral hypoechogenicity in restless legs syndrome

In patients with Parkinsons disease, hyperechogenicity of the substantia nigra using transcranial ultrasound has been related to increased tissue concentrations of iron. Recently, deficient iron transport mechanisms in substantia nigra neurons have been described in postmortem tissue of patients with restless legs syndrome (RLS). This study was performed to study substantia nigra echogenicity in RLS patients compared with normal control subjects and Parkinsons disease patients. RLS patients had significantly reduced midbrain areas of hyperechogenicity compared with control subjects, and even more markedly reduced hyperechogenicity compared with Parkinsons disease patients. These findings lend further support to nigral iron deficiency as a pathogenetic factor in RLS. Ann Neurol 2005

Common variants in P2RY11 are associated with narcolepsy

Growing evidence supports the hypothesis that narcolepsy with cataplexy is an autoimmune disease. We here report genome-wide association analyses for narcolepsy with replication and fine mapping across three ethnic groups (3,406 individuals of European ancestry, 2,414 Asians and 302 African Americans). We identify a SNP in the 3′ untranslated region of P2RY11, the purinergic receptor subtype P2Y11 gene, which is associated with narcolepsy (rs2305795, combined P = 6.1 × 10−10, odds ratio = 1.28, 95% CI 1.19–1.39, n = 5689). The disease-associated allele is correlated with reduced expression of P2RY11 in CD8+ T lymphocytes (72% reduced, P = 0.003) and natural killer (NK) cells (70% reduced, P = 0.031), but not in other peripheral blood mononuclear cell types. The low expression variant is also associated with reduced P2RY11-mediated resistance to ATP-induced cell death in T lymphocytes (P = 0.0007) and natural killer cells (P = 0.001). These results identify P2RY11 as an important regulator of immune-cell survival, with possible implications in narcolepsy and other autoimmune diseases.

Parkinson's disease sleep scale—validation of the revised version PDSS‐2

The previous Parkinsons disease sleep scale (PDSS) is a 15‐item visual analogue scale that assesses the profile of nocturnal disturbances in Parkinsons disease (PD) patients.

Scales to assess sleep impairment in Parkinson's disease: Critique and recommendations

There is a broad spectrum of sleep disturbances observed in Parkinsons disease (PD). A variety of scales have been applied to the evaluation of PD sleep and wakefulness, but only a small number have been assessed specifically for clinimetric properties in the PD population. The movement disorder society has commissioned this task force to examine these scales and to assess their use in PD. A systematic literature review was conducted to explore the use of sleep scales in PD and to determine which scales qualified for a detailed critique. The task force members, all of whom have extensive experience in assessing sleep in PD reviewed each of the scales using a structured proforma. Scales were categorized into recommended, suggested and listed according to predefined criteria. A total of 48 potential scales were identified from the search and reviewed. Twenty‐nine were excluded because they did not meet review criteria or were variations of scales already included, leaving 19 scales that were critiqued and rated by the task force based on the rating criteria. Only six were found to meet criteria for recommendation or suggestion by the task force: the PD sleep scale (PDSS) and the Pittsburgh sleep quality index (PSQI) are recommended for rating overall sleep problems to screen and to measure severity, the SCOPA‐sleep (SCOPA) is recommended for rating overall sleep problems both to screen and to measure severity, and for rating daytime sleepiness; the Epworth sleepiness scale (ESS) is recommended for rating daytime sleepiness to screen and to measure severity; the inappropriate sleep composite score (ISCS) is suggested for rating severe daytime sleepiness or sleep attacks to screen and to measure severity; and the Stanford sleepiness scale (SSS) is suggested for rating sleepiness and to measure severity at a specific moment. The task force does not recommend the development of new scales, but emphasizes the need for educational efforts to train physicians in sleep interview techniques and polysomnography.