ABSTRACT
Next‐generation sequencing (NGS) has an established diagnostic value for inherited ataxia. However, the need of a rigorous process of analysis and validation remains challenging. Moreover, ...copy number variations (CNV) or dynamic expansions of repeated sequence are classically considered not adequately detected by exome sequencing technique. We applied a strategy of mini‐exome coupled to read‐depth based CNV analysis to a series of 33 patients with probable inherited ataxia and onset <50 years. The mini‐exome consisted of the capture of 4,813 genes having associated clinical phenotypes. Pathogenic variants were found in 42% and variants of uncertain significance in 24% of the patients. These results are comparable to those from whole exome sequencing and better than previous targeted NGS studies. CNV and dynamic expansions of repeated CAG sequence were identified in three patients. We identified both atypical presentation of known ataxia genes (ATM, NPC1) and mutations in genes very rarely associated with ataxia (ERCC4, HSD17B4). We show that mini‐exome bioinformatics data analysis allows the identification of CNV and dynamic expansions of repeated sequence. Our study confirms the diagnostic value of the proposed genetic analysis strategy. We also provide an algorithm for the multidisciplinary process of analysis, interpretation, and validation of NGS data.
Identification of nucleotide variations, copy number variations, and expansion in inherited ataxias by next generation sequencing:
–Pathogenicity prediction of nucleotide (nt) variation (Figure A): multiscoring predicts both missense and splice site pathogenicity for the same heterozygous SETX variation in patient ATX163
–CNV detection (Figure B): heterozygous SETX exon 4 to 7 deletion in patient ATX163
–Expansion detection (Figure C): ATXN2, CAG expansion (arrows) in patient ATX340
Restless legs syndrome (RLS) has an increased estimated prevalence in patients with Parkinson’s disease (PS). RLS frequently mimics symptoms intrinsic to PD, such as motor restlessness, contributing ...to making its diagnosis challenging in this population. We report the case of a patient with new-onset RLS following subthalamic deep-brain stimulation (DBS-STN). We assessed symptoms using suggested immobilization test (SIT) with both DBS-STN activated and switched off.
A 59-year-old man with idiopathic PD developed disabling RLS following DBS-STN at age 58, with PD onset at 50 manifesting as left arm tremor. Despite improved motor symptoms during the month following surgery, the patient experienced left leg discomfort at rest, transiently alleviated by movements due to an irrepressible urge to move, and worsened at night. Symptoms had no temporal relationship with oral dopa-therapy and disappeared when DBS-STN was deactivated. A 1 h SIT assessed motor behavior with irrepressible urge to move, as well as sensory symptoms by visual analog scale. After 30 m DBS-STN was switched off followed by the appearance of tremor in the left arm while both motor and sensory symptoms of RLS disappeared in the left leg.
The mechanisms of DBS-STN’s impact on RLS remain controversial. We hypothesize the DBS-STN to induce in our patient a hyperdopaminergic tone. DBS-induced and DBS-ameliorated RLS represent interesting conditions to further understand the pathophysiology of RLS. Moreover, the present observation suggests that SIT can be a valuable tool to assess RLS in PD patients before and after DBS-STN in future prospective studies.
•Deep brain stimulation may induce restless legs syndrome in Parkinson's patients.•Suggested immobilization test helps identify restless legs in Parkinson's patients.•Suggested immobilization test aids in distinguishing dyskinesia from restless legs.•A hyperdopaminergic tone may drive pathophysiology of restless legs syndrome.
Summary Background Despite optimum medical management, many patients with Parkinson's disease are incapacitated by gait disorders including freezing of gait. We aimed to assess whether ...methylphenidate—through its combined action on dopamine and noradrenaline reuptake—would improve gait disorders and freezing of gait in patients with advanced Parkinson's disease without dementia who also received subthalamic nucleus stimulation. Methods This multicentre, parallel, double-blind, placebo-controlled, randomised trial was done in 13 movement disorders departments in France between October, 2009, and December, 2011. Eligible patients were younger than 80 years and had Parkinson's disease, severe gait disorders, and freezing of gait despite optimised treatment of motor fluctuations with dopaminergic drugs and subthalamic stimulation. We randomly assigned patients (1:1 with a computer random-number generator in blocks of four) to receive methylphenidate (1 mg/kg per day) or placebo capsules for 90 days. Patients, their carers, study staff, investigators, and data analysts were masked to treatment allocation. To control for confounding effects of levodopa we assessed patients under standardised conditions with an acute levodopa challenge. Our primary outcome was a change in the number of steps during the stand-walk-sit (SWS) test without levodopa. We compared the respective mean numbers of steps at day 90 in the methylphenidate and placebo groups in a covariance analysis and adjusted for baseline differences. This trial is registered with ClinicalTrials.gov , number NCT00914095. Findings We screened 81 patients and randomly assigned 35 to receive methylphenidate and 34 to receive placebo. 33 patients in the methylphenidate group and 32 patients in the placebo group completed the study. Efficacy outcomes were assessed in the patients who completed the study. Compared with patients in the placebo group (median 33 steps IQR 26–45), the patients in the methylphenidate group made fewer steps at 90 days (31 26–42, F(1, 62) =6·1, p=0·017, adjusted size effect 0·61). Adverse events were analysed in all randomly assigned patients. There were significantly more adverse events in the methylphenidate group compared with placebo. Patients on methylphenidate had a significant increase in heart rate (mean 3·6 SD 7·2 beats per min) and decrease in weight (mean 2·2 SD 1·8 kg) compared with the placebo group. Interpretation Methylphenidate improved gait hypokinesia and freezing in patients with advanced Parkinson's disease receiving subthalamic nucleus stimulation. Methylphenidate represents a therapeutic option in the treatment of gait disorders at the advanced stage of Parkinson's disease. The long term risk–benefit balance should be further studied. Funding French Ministry of Health and Novartis Pharma.
After more than 50 years of treating Parkinson's disease with l-DOPA, there are still no guidelines on setting the optimal dose for a given patient. The dopamine transporter type 1, now known as ...solute carrier family 6 (neurotransmitter transporter), member 3 (SLC6A3) is the most powerful determinant of dopamine neurotransmission and might therefore influence the treatment response. We recently demonstrated that methylphenidate (a dopamine transporter inhibitor) is effective in patients with Parkinson's disease with motor and gait disorders. The objective of the present study was to determine whether genetic variants of the dopamine transporter type 1-encoding gene (SLC6A3) are associated with differences in the response to treatment of motor symptoms and gait disorders with l-DOPA and methylphenidate (with respect to the demographic, the disease and the treatment parameters and the other genes involved in the dopaminergic neurotransmission). This analysis was part of a multicentre, parallel-group, double-blind, placebo-controlled, randomized clinical trial of methylphenidate in Parkinson's disease (Protocol ID:2008-005801-20; ClinicalTrials.gov:NCT00914095). We scored the motor Unified Parkinson's Disease Rating Scale and the Stand-Walk-Sit Test before and after a standardized acute l-DOPA challenge before randomization and then after 3 months of methylphenidate treatment. Patients were screened for variants of genes involved in dopamine metabolism: rs28363170 and rs3836790 polymorphisms in the SLC6A3 gene, rs921451 and rs3837091 in the DDC gene (encoding the aromatic L-amino acid decarboxylase involved in the synthesis of dopamine from l-DOPA), rs1799836 in the MAOB gene (coding for monoamine oxidase B) and rs4680 in the COMT gene (coding for catechol-O-methyltransferase). Investigators and patients were blinded to the genotyping data throughout the study. Eighty-one subjects were genotyped and 61 were analysed for their acute motor response to l-DOPA. The SLC6A3 variants were significantly associated with greater efficacy of l-DOPA for motor symptoms. The SLC6A3 variants were also associated with greater efficacy of methylphenidate for motor symptoms and gait disorders in the ON l-DOPA condition. The difference between motor Unified Parkinson's Disease Rating Scale scores for patients with different SLC6A3 genotypes was statistically significant in a multivariate analysis that took account of other disease-related, treatment-related and pharmacogenetic parameters. Our preliminary results suggest that variants of SLC6A3 are genetic modifiers of the treatment response to l-DOPA and methylphenidate in Parkinson's disease. Further studies are required to assess the possible value of these genotypes for (i) guiding l-DOPA dose adaptations over the long term; and (ii) establishing the risk/benefit balance associated with methylphenidate treatment for gait disorders.
Niemann-Pick type C disease (NPC) is a recessive neurolipidosis. We report five adolescent and adult NPC cases to underscore the frequency and heterogeneity of movement disorders in NPC. Clinical, ...morphologic, biochemical and genetic study was performed in the five patients. Disease onset was between 8 and 50 years. Movement disorders were present in all cases, were heterogeneous and often combined cerebellar ataxia (5/5), myoclonus (3/5), dystonia (2/5), chorea (1/5) and tremor (1/5) and were the first sign in 4/5. Two patients were reported to have no vertical supranuclear gaze palsy (VSGP) at the first examination. Two patients experienced acute neuropsychiatric signs leading to death in one case due to myoclonic storm. Filipin staining was always positive. Two
NPC1
mutations were identified in three patients, only one in two siblings. NPC should be considered in case of unexplained movement disorders, even when VSGP or cataplexy are not reported. Filipin staining remains a strong support for the diagnosis. Treatment with miglustat should be considered which is currently the only approved disease-specific treatment of NPC in children and adults.
PDF
