Investigation of altering single-nucleotide polymorphism density on the power to detect trait loci and frequency of false positive in nonparametric linkage analyses of qualitative traits

Genome-wide linkage analysis using microsatellite markers has been successful in the identification of numerous Mendelian and complex disease loci. The recent availability of high-density single-nucleotide polymorphism (SNP) maps provides a potentially more powerful option. Using the simulated and Collaborative Study on the Genetics of Alcoholism (COGA) datasets from the Genetics Analysis Workshop 14 (GAW14), we examined how altering the density of SNP marker sets impacted the overall information content, the power to detect trait loci, and the number of false positive results. For the simulated data we used SNP maps with density of 0.3 cM, 1 cM, 2 cM, and 3 cM. For the COGA data we combined the marker sets from Illumina and Affymetrix to create a map with average density of 0.25 cM and then, using a sub-sample of these markers, created maps with density of 0.3 cM, 0.6 cM, 1 cM, 2 cM, and 3 cM. For each marker set, multipoint linkage analysis using MERLIN was performed for both dominant and recessive traits derived from marker loci. Our results showed that information content increased with increased map density. For the homogeneous, completely penetrant traits we created, there was only a modest difference in ability to detect trait loci. Additionally, as map density increased there was only a slight increase in the number of false positive results when there was linkage disequilibrium (LD) between markers. The presence of LD between markers may have led to an increased number of false positive regions but no clear relationship between regions of high LD and locations of false positive linkage signals was observed

Algorithms for the diagnosis and treatment of restless legs syndrome in primary care

<p>Abstract</p> <p>Background</p> <p>Restless legs syndrome (RLS) is a neurological disorder with a lifetime prevalence of 3-10%. in European studies. However, the diagnosis of RLS in primary care remains low and mistreatment is common.</p> <p>Methods</p> <p>The current article reports on the considerations of RLS diagnosis and management that were made during a European Restless Legs Syndrome Study Group (EURLSSG)-sponsored task force consisting of experts and primary care practioners. The task force sought to develop a better understanding of barriers to diagnosis in primary care practice and overcome these barriers with diagnostic and treatment algorithms.</p> <p>Results</p> <p>The barriers to diagnosis identified by the task force include the presentation of symptoms, the language used to describe them, the actual term "restless legs syndrome" and difficulties in the differential diagnosis of RLS.</p> <p>Conclusion</p> <p>The EURLSSG task force reached a consensus and agreed on the diagnostic and treatment algorithms published here.</p

Progressive development of augmentation during long-term treatment with levodopa in restless legs syndrome: results of a prospective multi-center study

The European Restless Legs Syndrome (RLS) Study Group performed the first multi-center, long-term study systematically evaluating RLS augmentation under levodopa treatment. This prospective, open-label 6-month study was conducted in six European countries and included 65 patients (85% treatment naive) with idiopathic RLS. Levodopa was flexibly up-titrated to a maximum dose of 600 mg/day. Presence of augmentation was diagnosed independently by two international experts using established criteria. In addition to the augmentation severity rating scale (ASRS), changes in RLS severity (International RLS severity rating scale (IRLS), clinical global impression (CGI)) were analyzed. Sixty patients provided evaluable data, 35 completed the trial and 25 dropped out. Augmentation occurred in 60% (36/60) of patients, causing 11.7% (7/60) to drop out. Median time to occurrence of augmentation was 71 days. The mean maximum dose of levodopa was 311 mg/day (SD: 105). Patients with augmentation compared to those without were significantly more likely to be on higher doses of levodopa (≥300 mg, 83 vs. 54%, P = 0.03) and to show less improvement of symptom severity (IRLS, P = 0.039). Augmentation was common with levodopa, but could be tolerated by most patients during this 6-month trial. Patients should be followed over longer periods to determine if dropout rates increase with time

Neuroanatomical Study of the A11 Diencephalospinal Pathway in the Non-Human Primate

BACKGROUND: The A11 diencephalospinal pathway is crucial for sensorimotor integration and pain control at the spinal cord level. When disrupted, it is thought to be involved in numerous painful conditions such as restless legs syndrome and migraine. Its anatomical organization, however, remains largely unknown in the non-human primate (NHP). We therefore characterized the anatomy of this pathway in the NHP. METHODS AND FINDINGS: In situ hybridization of spinal dopamine receptors showed that D1 receptor mRNA is absent while D2 and D5 receptor mRNAs are mainly expressed in the dorsal horn and D3 receptor mRNA in both the dorsal and ventral horns. Unilateral injections of the retrograde tracer Fluoro-Gold (FG) into the cervical spinal enlargement labeled A11 hypothalamic neurons quasi-exclusively among dopamine areas. Detailed immunohistochemical analysis suggested that these FG-labeled A11 neurons are tyrosine hydroxylase-positive but dopa-decarboxylase and dopamine transporter-negative, suggestive of a L-DOPAergic nucleus. Stereological cell count of A11 neurons revealed that this group is composed by 4002±501 neurons per side. A 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) intoxication with subsequent development of a parkinsonian syndrome produced a 50% neuronal cell loss in the A11 group. CONCLUSION: The diencephalic A11 area could be the major source of L-DOPA in the NHP spinal cord, where it may play a role in the modulation of sensorimotor integration through D2 and D3 receptors either directly or indirectly via dopamine formation in spinal dopa-decarboxylase-positives cells