Genome-wide association study of restless legs syndrome identifies common variants in three genomic regions.

Restless legs syndrome (RLS) is a frequent neurological disorder characterized by an imperative urge to move the legs during night, unpleasant sensation in the lower limbs, disturbed sleep and increased cardiovascular morbidity. In a genome-wide association study we found highly significant associations between RLS and intronic variants in the homeobox gene MEIS1, the BTBD9 gene encoding a BTB(POZ) domain as well as variants in a third locus containing the genes encoding mitogen-activated protein kinase MAP2K5 and the transcription factor LBXCOR1 on chromosomes 2p, 6p and 15q, respectively. Two independent replications confirmed these association signals. Each genetic variant was associated with a more than 50% increase in risk for RLS, with the combined allelic variants conferring more than half of the risk. MEIS1 has been implicated in limb development, raising the possibility that RLS has components of a developmental disorder.

Assessing health-related quality of life in patients with restless legs syndrome.

BACKGROUND: Restless Legs Syndrome (RLS) has a substantial impact on normal daily activities. Because of the high prevalence it is necessary to evaluate the impact on the health-related quality of life (HRQoL). OBJECTIVE: To assess health-related quality of life in patients with RLS. METHODS: A total of 519 patients (327 female patients; mean age: 64.2 y) were recruited in five different German centers according to the diagnostic criteria of the International RLS Study Group. Patients were either interviewed or completed a mailed questionnaire. The questionnaire consisted of an evaluation of the sociodemographic, clinical and health-related status. HRQoL was evaluated with the EuroQoL (EQ-5D). In addition, the IRLS scale, the MOS Sleep Scale, the Epworth Sleepiness Scale, and the BDI were applied as clinical rating scales. RESULTS: HRQoL is substantially affected by RLS. The mean EQ-5D-VAS was 55.6 and considerably lower compared to the general population. It was found to be as low as in other chronic neurological disorders such as Parkinson's disease and stroke. From different factors investigated by uni- and multivariate analyses, severity of RLS and depressive symptoms had the most significant impact on HRQoL. Additionally, sleep deficits, the duration of the disease and net household income were identified as predictors for different EQ-5D outcome scores. CONCLUSIONS: RLS considerably affects HRQoL. Further comparative studies are necessary to evaluate the effect of disease symptoms on HRQoL and their change due to medication.

Variants in the neuronal nitric oxide synthase (nNOS, NOS1) gene are associated with restless legs syndrome.

Sixty percent of the patients with restless legs syndrome (RLS) report a positive family history. To date five loci have been mapped on chromosome 12q, 14q, 9p, 2q, and 20p (RLS1-5) but no gene has been identified so far. To identify genes related to RLS, we performed a three-stage association study (explorative study, replication study, high-density mapping) in two Caucasian RLS case-control samples of altogether 918 independent cases and controls. In the explorative study (367 cases and controls, respectively), we screened 1536 SNPs in 366 genes in a 21 Mb region encompassing the RLS1 critical region on chromosome 12. Armitage trend test revealed three genomic regions that were significant (P < 0.05). In the replication study (551 cases and controls, respectively) we genotyped the most significant SNPs of Stage 1. After correction for multiple testing, association was observed with SNP rs7977109 (P(nominal) = 0.00175, P(Westfall-Young) = 0.04895, OR = 0.76228, 95% CI = 0.64310-0.90355), which is in the neuronal nitric oxide synthase (NOS1) gene. High-density mapping using altogether 34 tagging and coding SNPs of the NOS1 gene in both case-control samples further confirmed the significant association results to NOS1. Ten more SNPs revealed significance with nominal P-values from 0.0001 to 0.0482 (genotypic test and Armitage test). Altogether, this study provides evidence for an association of variants in the NOS1 gene and RLS, and suggests the involvement of the NO/arginine pathway in the pathogenesis of RLS. Potential usage of NO modulating agents as new treatment options for RLS have become a challenging aspect for future research of this disorder.

Ropinirole improves depressive symptoms and restless legs syndrome severity in RLS patients: a multicentre, randomized, placebo-controlled study.

Comorbid depressive symptoms in restless legs syndrome (RLS) remain a treatment challenge, as some antidepressants aggravate RLS symptoms. Preliminary data in depressive patients suggest antidepressant properties of ropinirole. The present study investigates the effects of ropinirole immediate release (IR) on depressive symptoms and RLS severity. A multicenter, placebo-controlled, double-blind randomized (3:1) study was performed including patients with moderate to severe idiopathic RLS and at least mild depressive symptoms. Ropinirole IR (in flexible doses up to 4 mg/day) or placebo was given for 12 weeks including an uptitration phase of 7 weeks. Visits were scheduled at screening, baseline, and weeks 1, 4, and 12 with additional telephone contacts for dosing decisions. The modified intent to treat population comprised 231 patients (171 ropinirole, 60 placebo). The MADRS (Montgomery-Asberg Depression Rating Scale) scores decreased from baseline to week 12 from 18.8 to 8.7 in the ropinirole group and from 18.4 to 12.1 in the placebo group (primary endpoint, adjusted mean treatment difference -3.6 (95% CI: -5.6 to -1.6, significance in favor of ropinirole: P < 0.001). The superiority of ropinirole compared to placebo was confirmed by the Hamilton Scale for Depression and Beck Depression Inventory-II scores. RLS severity scores (IRLS) decreased by 14.7 (ropinirole) and by 9.9 (placebo, P < 0.001) points. Three out of four subdomains of the Medical Outcomes Study Sleep Scale improved significantly. The findings indicate that mild to moderate depressive symptoms should not be treated before sufficient therapy for RLS. Antidepressant medication can be necessary if depression symptoms still persist even if RLS symptoms are ameliorated.

Health economic burden of patients with restless legs syndrome in a German ambulatory setting.

The primary characteristics of restless legs syndrome (RLS), including severe sleep disorders, restlessness in the evening and discomfort while at rest, have substantial impact on normal daily activities. Because of the high prevalence of RLS in the general population, it is necessary to evaluate the economic impact of RLS. To determine the health economic burden of patients with RLS in Germany. A total of 519 RLS patients (mean age: 65.2 +/- 11.1 years) in different stages of disease were recruited in five health centres (university hospitals, district hospitals and office-based neurologists) by applying the diagnostic criteria of the International Restless Legs Syndrome Study Group. A questionnaire was administered that assessed healthcare resource consumption as well as socioeconomic, demographic, clinical and health status. In addition, the International RLS severity scale (IRLS), Epworth Sleepiness Scale (ESS), EQ-5D and Beck Depression Inventory (BDI) were addressed in the assessment. Direct and indirect costs (euro, year 2006 values) were derived from various German economic resources and calculated from the perspective of the healthcare and transfer payment providers. We calculated average total costs over the 3-month observation period. It was determined that average total costs were euro2090 for this period. The average direct medical and non-medical costs from the perspective of the health insurance provider were determined to be euro780, with euro300 attributed to drug costs and euro354 to hospitalization costs. Average total indirect costs amounted to euro1308 and were calculated based on productivity loss, using the human capital approach. As cost-driving factors we identified disease severity according to the IRLS (p < 0.01) and ESS (p < 0.04). Health-related quality of life was determined to be substantially affected by RLS; the mean EQ-5D visual analogue scale (VAS) was 55.6, considerably lower than that of the age-matched general population. RLS places a notable financial burden on society as well as on patients and their families. More detailed studies are needed to evaluate the health economic impact of this disorder.

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, P(nominal/lambda corrected) = 5.91 x 10(-10), odds ratio (OR) = 1.44; rs1975197, P(nominal/lambda corrected) = 5.81 x 10(-9), OR = 1.31). This work identifies PTPRD as the fourth genome-wide significant locus for RLS.