SummaryBackgroundRestless legs syndrome is a prevalent chronic neurological disorder with potentially severe mental and physical health consequences. Clearer understanding of the underlying pathophysiology is needed to improve treatment options. We did a meta-analysis of genome-wide association studies (GWASs) to identify potential molecular targets.MethodsIn the discovery stage, we combined three GWAS datasets (EU-RLS GENE, INTERVAL, and 23andMe) with diagnosis data collected from 2003 to 2017, in face-to-face interviews or via questionnaires, and involving 15 126 cases and 95 725 controls of European ancestry. We identified common variants by fixed-effect inverse-variance meta-analysis. Significant genome-wide signals (p≤5 × 10−8) were tested for replication in an independent GWAS of 30 770 cases and 286 913 controls, followed by a joint analysis of the discovery and replication stages. We did gene annotation, pathway, and gene-set-enrichment analyses and studied the genetic correlations between restless legs syndrome and traits of interest.FindingsWe identified and replicated 13 new risk loci for restless legs syndrome and confirmed the previously identified six risk loci. MEIS1 was confirmed as the strongest genetic risk factor for restless legs syndrome (odds ratio 1·92, 95% CI 1·85–1·99). Gene prioritisation, enrichment, and genetic correlation analyses showed that identified pathways were related to neurodevelopment and highlighted genes linked to axon guidance (associated with SEMA6D), synapse formation (NTNG1), and neuronal specification (HOXB cluster family and MYT1).InterpretationIdentification of new candidate genes and associated pathways will inform future functional research. Advances in understanding of the molecular mechanisms that underlie restless legs syndrome could lead to new treatment options. We focused on common variants; thus, additional studies are needed to dissect the roles of rare and structural variations.FundingDeutsche Forschungsgemeinschaft, Helmholtz Zentrum München–Deutsches Forschungszentrum für Gesundheit und Umwelt, National Research Institutions, NHS Blood and Transplant, National Institute for Health Research, British Heart Foundation, European Commission, European Research Council, National Institutes of Health, National Institute of Neurological Disorders and Stroke, NIH Research Cambridge Biomedical Research Centre, and UK Medical Research Council.

The objective of the current review was to update the previous evidence-based medicine review of treatments for restless legs syndrome published in 2008. All randomized, controlled trials (level I) with a high quality score published between January 2007 and January 2017 were reviewed. Forty new studies qualified for efficacy review. Pregabalin, gabapentin enacarbil, and oxycodone/naloxone, which did not appear in the previous review, have accrued data to be considered efficacious. Likewise, new data enable the modification of the level of efficacy for rotigotine from likely efficacious to efficacious. Intravenous ferric carboxymaltose and pneumatic compression devices are considered likely efficacious in idiopathic restless legs syndrome. Bupropion and clonidine were reviewed, but the lack of data determined a rating of insufficient evidence for efficacy. The following interventions continue to be considered efficacious as in 2008: levodopa, ropinirole, pramipexole, cabergoline, pergolide, and gabapentin. Bromocriptine, oxycodone, carbamazepine, and valproic acid are considered likely efficacious. Oral iron is nonefficacious in iron-sufficient subjects, but its benefit for patients with low peripheral iron status has not been adequately evaluated. Restless legs syndrome augmentation has been identified as a significant long-term treatment complication for pramipexole more than pregabalin and possibly for all dopaminergic agents more than α2δ ligands. Therefore, special monitoring for augmentation is required for all dopaminergic medications as well as tramadol. Other drugs also require special safety monitoring: cabergoline, pergolide, oxycodone, methadone, tramadol, carbamazepine, and valproic acid. Finally, we also highlighted gaps and needs for future clinical research and studies of restless legs syndrome. © 2018 International Parkinson and Movement Disorder Society.

Isolated dystonia is a disorder characterized by involuntary twisting postures arising from sustained muscle contractions. Although autosomal-dominant mutations in TOR1A, THAP1, and GNAL have been found in some cases, the molecular mechanisms underlying isolated dystonia are largely unknown. In addition, although emphasis has been placed on dominant isolated dystonia, the disorder is also transmitted as a recessive trait, for which no mutations have been defined. Using whole-exome sequencing in a recessive isolated dystonia-affected kindred, we identified disease-segregating compound heterozygous mutations in COL6A3, a collagen VI gene associated previously with muscular dystrophy. Genetic screening of a further 367 isolated dystonia subjects revealed two additional recessive pedigrees harboring compound heterozygous mutations in COL6A3. Strikingly, all affected individuals had at least one pathogenic allele in exon 41, including an exon-skipping mutation that induced an in-frame deletion. We tested the hypothesis that disruption of this exon is pathognomonic for isolated dystonia by inducing a series of in-frame deletions in zebrafish embryos. Consistent with our human genetics data, suppression of the exon 41 ortholog caused deficits in axonal outgrowth, whereas suppression of other exons phenocopied collagen deposition mutants. All recessive mutation carriers demonstrated early-onset segmental isolated dystonia without muscular disease. Finally, we show that Col6a3 is expressed in neurons, with relevant mRNA levels detectable throughout the adult mouse brain. Taken together, our data indicate that loss-of-function mutations affecting a specific region of COL6A3 cause recessive isolated dystonia with underlying neurodevelopmental deficits and highlight the brain extracellular matrix as a contributor to dystonia pathogenesis.

Peripheral hypoxia is associated with the appearance of RLS symptoms. Strong correlation with RLS severity suggests a close pathophysiologic link between peripheral hypoxia and the symptoms of RLS. This is further supported by the simultaneous reversal of hypoxia and discomfort by dopaminergic treatment.