MED27, SLC6A7, and MPPE1 Variants in a Complex Neurodevelopmental Disorder with Severe Dystonia.

BACKGROUND: Despite advances in next generation sequencing technologies, the identification of variants of uncertain significance (VUS) can often hinder definitive diagnosis in patients with complex neurodevelopmental disorders. OBJECTIVE: The objective of this study was to identify and characterize the underlying cause of disease in a family with two children with severe developmental delay associated with generalized dystonia and episodic status dystonicus, chorea, epilepsy, and cataracts. METHODS: Candidate genes identified by autozygosity mapping and whole-exome sequencing were characterized using cellular and vertebrate model systems. RESULTS: Homozygous variants were found in three candidate genes: MED27, SLC6A7, and MPPE1. Although the patients had features of MED27-related disorder, the SLC6A7 and MPPE1 variants were functionally investigated. SLC6A7 variant in vitro overexpression caused decreased proline transport as a result of reduced cell-surface expression, and zebrafish knockdown of slc6a7 exhibited developmental delay and fragile motor neuron morphology that could not be rescued by L-proline transporter-G396S RNA. Lastly, patient fibroblasts displayed reduced cell-surface expression of glycophosphatidylinositol-anchored proteins linked to MPPE1 dysfunction. CONCLUSIONS: We report a family harboring a homozygous MED27 variant with additional loss-of-function SLC6A7 and MPPE1 gene variants, which potentially contribute to a blended phenotype caused by multilocus pathogenic variants. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Subthalamic deep brain stimulation under general anesthesia and neurophysiological guidance while on dopaminergic medication: comparative cohort study.

OBJECTIVES: The authors have previously reported on the technical feasibility of subthalamic nucleus deep brain stimulation (STN DBS) under general anesthesia (GA) with microelectrode recording (MER) guidance in Parkinsonian patients who continued dopaminergic therapy until surgery. This paper presents the results of a prospective cohort analysis to verify the outcome of the initial study, and report on wider aspects of clinical outcome and postoperative recovery. METHODS: All patients in the study group continued dopaminergic therapy until GA was administered. Baseline characteristics, intraoperative neurophysiological markers, and perioperative complications were recorded. Long-term outcome was assessed using selective aspects of the unified Parkinson's disease rating scale motor score. Immediate postoperative recovery from GA was assessed using the "time needed for extubation" and "total time of recovery." Data for the "study group" was collected prospectively. Examined variables were compared between the "study group" and "historical control group" who stopped dopaminergic therapy preoperatively. RESULTS: The study group, n = 30 (May 2014-Jan 2016), were slightly younger than the "control group," 60 (51-64) vs. 64 (56-69) years respectively, p = 0.043. Both groups were comparable for the recorded intraoperative neurophysiological parameters; "number of MER tracks": 60% of the "study group" had single track vs. 58% in the "control" group, p = 1.0. Length of STN MER detected was 9 vs. 7 mm (median) respectively, p = 0.037. A trend towards better recovery from GA in the study group was noted, with shorter "total recovery time": 60 (50-84) vs. 89 (62-120) min, p = 0.09. Long-term improvement in motor scores and reduction in L-dopa daily equivalent dose were equally comparable between both groups. No cases of dopamine withdrawal or problems with immediate postop dyskinesia were recorded in the "on medications group." The observed rate of dopamine-withdrawal side effects in the "off-medications" group was 15%. CONCLUSIONS: The continuation of dopaminergic treatment for patients with PD does not affect the feasibility/outcome of the STN DBS surgery. This strategy appears to reduce the risk of dopamine-withdrawal adverse effects and may improve the recovery in the immediate postoperative period, which would help enhance patients' perioperative experience.

Cost-utility analysis of deep brain stimulation surgery plus best medical therapy versus best medical therapy in patients with Parkinson's: Economic evaluation alongside the PD SURG trial.

INTRODUCTION: Williams and colleagues reported that DBS surgery for patients with advanced PD improves motor function and quality of life compared to best medical therapy alone at 1 year, but with surgery-related side effects in a minority. This article reports on the economic evaluation alongside this trial. METHODS: Detailed resource use and quality of life over 12 months after randomization was obtained from the trial reported by Williams and colleagues. Outcomes were measured using the EQ-5D and quality-adjusted life years calculated. RESULTS: Year 1 costs for surgery were significantly higher than in best medical therapy, at £19,069 compared to £9,813, a difference of £9,256 (95% confidence interval [CI]: £7,625, £10,887). There was a small, significant gain in utility at 1 year but a statistically insignificant gain of 0.02 quality-adjusted life years (95% CI: -0.015, 0.05) in the surgical arm. The incremental cost per quality-adjusted life year of surgery at 1 year was £468,528. Extrapolation reveals that after 5 years, this ratio is likely to reduce to £45,180, but subsequently rise to £70,537 at 10 years owing to the increased probability of battery replacements (and re-replacements) beyond 5 years. CONCLUSION: In this patient group, DBS is not cost-effective at 1 year. Extrapolation, however, reveals an increasing likelihood of cost-effectiveness up to 5 years and reducing cost-effectiveness between 5 and 10 years. These models are sensitive to assumptions about future costs and quality-adjusted life years gained. © 2016 International Parkinson and Movement Disorder Society.

Phenotypic insights into ADCY5-associated disease.

BACKGROUND: Adenylyl cyclase 5 (ADCY5) mutations is associated with heterogenous syndromes: familial dyskinesia and facial myokymia; paroxysmal chorea and dystonia; autosomal-dominant chorea and dystonia; and benign hereditary chorea. We provide detailed clinical data on 7 patients from six new kindreds with mutations in the ADCY5 gene, in order to expand and define the phenotypic spectrum of ADCY5 mutations. METHODS: In 5 of the 7 patients, followed over a period of 9 to 32 years, ADCY5 was sequenced by Sanger sequencing. The other 2 unrelated patients participated in studies for undiagnosed pediatric hyperkinetic movement disorders and underwent whole-exome sequencing. RESULTS: Five patients had the previously reported p.R418W ADCY5 mutation; we also identified two novel mutations at p.R418G and p.R418Q. All patients presented with motor milestone delay, infantile-onset action-induced generalized choreoathetosis, dystonia, or myoclonus, with episodic exacerbations during drowsiness being a characteristic feature. Axial hypotonia, impaired upward saccades, and intellectual disability were variable features. The p.R418G and p.R418Q mutation patients had a milder phenotype. Six of seven patients had mild functional gain with clonazepam or clobazam. One patient had bilateral globus pallidal DBS at the age of 33 with marked reduction in dyskinesia, which resulted in mild functional improvement. CONCLUSION: We further delineate the clinical features of ADCY5 gene mutations and illustrate its wide phenotypic expression. We describe mild improvement after treatment with clonazepam, clobazam, and bilateral pallidal DBS. ADCY5-associated dyskinesia may be under-recognized, and its diagnosis has important prognostic, genetic, and therapeutic implications. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Apathy in patients with Parkinson's disease following deep brain stimulation of the subthalamic nucleus.

OBJECTIVE: Apathy has been reported as a possible adverse effect of deep brain stimulation of the subthalamic nucleus (STN-DBS). We investigated the prevalence and severity of apathy in 22 patients with Parkinson's disease (PD) who underwent STN-DBS, as well as the effects of apathy on quality of life (QOL). METHODS: All patients were assessed with the Lille Apathy Rating Scale (LARS), the Apathy Scale (AS), and the Parkinson's Disease Questionnaire and were compared to a control group of 38 patients on pharmacotherapy alone. RESULTS: There were no significant differences in the prevalence or severity of apathy between patients who had undergone STN-DBS and those on pharmacotherapy alone. Significant correlations were observed between poorer QOL and degree of apathy, as measured by the LARS (p<0.001) and the AS (p=0.021). PD-related disability also correlated with both apathy ratings (p<0.001 and p=0.017, respectively). CONCLUSION: Our findings suggest that STN-DBS is not necessarily associated with apathy in the PD population; however, more severe apathy appears to be associated with a higher level of disability due to PD and worse QOL, but no other clinico-demographic characteristics.

The effect of dopaminergic therapy on intraoperative microelectrode recordings for subthalamic deep brain stimulation under GA: can we operate on patients 'on medications'?

OBJECTIVES: Microelectrode recording (MER) plays an important role in target refinement in deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease (PD). Traditionally, patients were operated on in the 'off-medication' state to allow intraoperative assessment of the patient response to direct STN stimulation. The development of intraoperative microelectrode recording (MER) has facilitated the introduction of general anaesthesia (GA). However, the routine withdrawal of dopaminergic medications has remained as standard practice. This retrospective review examines the effect of continuing these medications on intraoperative MER for subthalamic DBS insertion under GA and discusses the clinical implication of this approach. METHODS: Retrospective review of PD patients who had bilateral STN DBS insertion was conducted. A cohort of seven patients (14 STN microelectrodes) between 2012 and 2013, who inadvertently underwent the procedure while 'on medication', was identified. This 'on-medication' group was compared to all other patients who underwent the same procedure between 2012 and 2013 and had their medications withdrawn preoperatively, the 'off-medication' group, n = 26 (52 STN DBS). The primary endpoint was defined as the number of microelectrode tracks required to obtain adequate STN recordings. A second endpoint was the length of MERs that was finally used to guide the DBS lead insertion. The Reduction of the levo-dopa equivalent daily dose (LEDD) was also examined as a surrogate marker for clinical outcome 12 months postoperatively for both groups. For the on-medication group further analysis of the clinical outcome was done relying on the change in the motor examination at 12 months following STN DBS using the following parameters (Hoehn and Yahr scale, the number of waking hours spent in the OFF state as well as the duration of dyskinesia during the ON periods). RESULTS: The on-medication group was statistically comparable in all baseline characteristics to the off-medication group, including age at operation 57 ± 9.9 years vs. 61.5 ± 9.2 years, p = 0.34 (mean ± SD); duration of disease (11.6 ± 5 years vs. 11.3 ± 4 years, p = 0.68); gender F:M ratio (1:6 vs. 9:17, p = 0.40). Both groups had similar PD medication regimes preoperatively expressed as levodopa equivalent daily dose (LEDD) 916 mg (558-1850) vs. 744 mg (525-3591), respectively, p = 0.77. In the on-medication group, all seven patients (14 STN electrodes) had satisfactory STN recording from a single brain track versus 15 out of 26 patients (57.7 %) in the off-medication group, p = 0.06. The length of MER was 4.5 mm (3.0-5.5) in the on-medication group compared to 3.5 mm (3.0-4.5) in the off-medication group, p = 0.16. The percentage of reduction in LEDD postoperatively for the on-medication group was comparable to that in the off-medication group, 62 % versus 58 %, respectively, p > 0.05. All patients in the on-medication group had clinically significant improvement in their PD motor symptoms as assessed by the Hoehn and Yahr scale; the number of hours (of the waking day) spent in the OFF state dropped from 6.9 (±2.3) h to 0.9 (±1.6) h; the duration of dyskinesia during the ON state dropped from 64 % (±13 %) of the ON period to only 7 % (±12 %) at 12 months following STN DBS insertion. CONCLUSION: STN DBS insertion under GA can be performed without the need to withdraw dompaminergic treatment preoperatively. In this review the inadvertent continuation of medications did not affect the physiological localisation of the STN or the clinical effectiveness of the procedure. The continuation of dopamine therapy is likely to improve the perioperative experience for PD patients, avoid dopamine-withdrawal complications and improve recovery. A prospective study is needed to verify the results of this review.

Deep brain stimulation improves survival in severe Parkinson's disease.

OBJECTIVES: Levodopa and other dopaminergic treatments have not had the expected effect on survival in Parkinson's disease (PD). Bilateral subthalamic nucleus deep brain stimulation (STN-DBS) has been shown to improve motor function, motor fluctuations, health-related quality of life, and to reduce medication usage and drug-induced dyskinesia in patients with severe PD refractory to medical therapy. Little however, has been described on the impact of STN-DBS on the survival of these patients. We aim in this study to examine the impact of STN-DBS on the survival of patients with severe PD. METHODS: Patients who were eligible for STN-DBS were given the choice of undergoing surgery or continuing on medical treatment. Those who exercised patient choice and preferred to continue with medical treatment formed a control population. All eligible patients seen in a 10-year period are included in this study. Our primary outcome measure is a difference in mortality between the two groups with a secondary measure of admission rates to residential (nursing home) care. RESULTS: 106 patients underwent STN-DBS, and 41 patients exercised patient choice and declined the procedure. The two groups were matched for age, gender, ethnicity, duration of disease, rates of pre-existing depression and Levodopa equivalent doses of anti-Parkinson's medications taken. Patients undergoing STN-DBS had significantly longer survival and were significantly less likely to be admitted to a residential care home than those managed purely medically. The statistical significance of these findings persisted after adjusting for potential confounding factors (survival: p=0.002, HR 0.29 (0.13 to 0.64) (residential care home admission: OR: 0.1 (95% CI 0.0 to 0.3; p<0.001). INTERPRETATION: We show for the first time that there is a survival advantage of DBS surgery in advanced PD. The effect of potential bias factors is examined. The survival advantage may arise for several postulated reasons, ranging from improvement in axial functions, such as swallowing, to some as yet unrecognised benefit of reduction in dopaminergic medication. These findings are of great interest to both patients with PD and the health professionals considering the treatment options for patients with severe PD.

SGCE mutations cause psychiatric disorders: clinical and genetic characterization.

Myoclonus dystonia syndrome is a childhood onset hyperkinetic movement disorder characterized by predominant alcohol responsive upper body myoclonus and dystonia. A proportion of cases are due to mutations in the maternally imprinted SGCE gene. Previous studies have suggested that patients with SGCE mutations may have an increased rate of psychiatric disorders. We established a cohort of patients with myoclonus dystonia syndrome and SGCE mutations to determine the extent to which psychiatric disorders form part of the disease phenotype. In all, 89 patients with clinically suspected myoclonus dystonia syndrome were recruited from the UK and Ireland. SGCE was analysed using direct sequencing and for copy number variants. In those patients where no mutation was found TOR1A (GAG deletion), GCH1, THAP1 and NKX2-1 were also sequenced. SGCE mutation positive cases were systematically assessed using standardized psychiatric interviews and questionnaires and compared with a disability-matched control group of patients with alcohol responsive tremor. Nineteen (21%) probands had a SGCE mutation, five of which were novel. Recruitment of family members increased the affected SGCE mutation positive group to 27 of whom 21 (77%) had psychiatric symptoms. Obsessive-compulsive disorder was eight times more likely (P < 0.001) in mutation positive cases, compulsivity being the predominant feature (P < 0.001). Generalized anxiety disorder (P = 0.003) and alcohol dependence (P = 0.02) were five times more likely in mutation positive cases than tremor controls. SGCE mutations are associated with a specific psychiatric phenotype consisting of compulsivity, anxiety and alcoholism in addition to the characteristic motor phenotype. SGCE mutations are likely to have a pleiotropic effect in causing both motor and specific psychiatric symptoms.

Health-related quality of life and supportive care in patients with rare long-term neurological conditions.

PURPOSE: Rare long-term neurological conditions (rLTNCs) may have significant impact on patients' health-related quality of life (HRQL); however, evidence is sparse. We assessed HRQL and access to supportive care in patients with rLTNCs. METHODS: Survey of patients with rare rLTNCs (motor neurone disease, Huntington's disease, cerebellar ataxia, progressive supranuclear palsy, multiple system atrophy, Charcot-Marie-Tooth disease and postpolio syndrome) to assess current access to health and social care, and HRQL using the Euroqol EQ-5D. RESULTS: A total of 266 participants with rLTNCs completed the survey. The HRQL of patients is substantially reduced compared to the general population. Many patients reported pain, were anxious or depressed and experienced problems with mobility, self-care and usual activities (mean EQ-5D index scores ranged from 0.2 to 0.44). Although some patients have accessed rehabilitative services, results suggest care coordination could be improved. CONCLUSIONS: Rare long-term neurological conditions have a significant impact on HRQL. Many patients with rLTNCs do not seem to be accessing the level of health and social care services that could improve their HRQL.

VEGF is a modifier of amyotrophic lateral sclerosis in mice and humans and protects motoneurons against ischemic death.

Amyotrophic lateral sclerosis (ALS) is an incurable degenerative disorder of motoneurons. We recently reported that reduced expression of Vegfa causes ALS-like motoneuron degeneration in Vegfa(delta/delta) mice. In a meta-analysis of over 900 individuals from Sweden and over 1,000 individuals from Belgium and England, we now report that subjects homozygous with respect to the haplotypes -2,578A/-1,154A/-634G or -2,578A/-1,154G/-634G in the VEGF promoter/leader sequence had a 1.8 times greater risk of ALS (P = 0.00004). These 'at-risk' haplotypes lowered circulating VEGF levels in vivo and reduced VEGF gene transcription, IRES-mediated VEGF expression and translation of a novel large-VEGF isoform (L-VEGF) in vivo. Moreover, SOD1(G93A) mice crossbred with Vegfa(delta/delta) mice died earlier due to more severe motoneuron degeneration. Vegfa(delta/delta) mice were unusually susceptible to persistent paralysis after spinal cord ischemia, and treatment with Vegfa protected mice against ischemic motoneuron death. These findings indicate that VEGF is a modifier of motoneuron degeneration in human ALS and unveil a therapeutic potential of Vegfa for stressed motoneurons in mice.

Analysis of European case-control studies suggests that common inherited variation in mitochondrial DNA is not involved in susceptibility to amyotrophic lateral sclerosis.

While some cases of familial ALS can be entirely attributed to known inherited variation, the majority (∼ 90%) are sporadic, where the cause(s) are not entirely understood. Both genetic and environmental factors may contribute to susceptibility. Mitochondrial damage, a common feature of neurodegenerative disease, is observed in most patients and inherited polymorphism in the mitochondrial genome has been suggested as a contributing factor. We used an economic and efficient method to test whether such involvement is probable. We genotyped 22 mtDNA coding region SNPs and sequenced the mtDNA hypervariable region 1 to determine the position of each mitochondrial genome within the genealogy of mitochondrial haplotypes in samples of ALS patients (n = 700) and controls (n = 462) from two European populations. We compared haplotype and haplogroup distribution in cases and controls drawn from the same populations. No statistical difference was observed between cases and controls at either the haplogroup or haplotype level (p = ≥ 0.2). In conclusion, it is unlikely that common, shared genetic variants in the mitochondrial genome contribute substantially to ALS. Combining the data with other studies will allow meta-analysis to look for variants with modest effect sizes. The sequencing of complete mitochondrial genomes will be required to assess the role of rare mutations.

Huntington's disease: current epidemiology and pharmacological management in UK primary care.

BACKGROUND: Recent debate suggests Huntington's disease (HD) may be more prevalent than previously reported. In addition, relatively little is known about current disease management. This study aims to provide epidemiological data and describe the pharmacological management of HD in the United Kingdom. METHODS: A primary care research database was accessed to identify incident and prevalent HD cases between January 1, 2004, and December 31, 2008. Patients with Read codes denoting a definite diagnosis or possible diagnosis, and undiagnosed patients with a positive family history were identified. A subset of patients with a definite diagnosis and prescribed medication indicating symptom onset was also identified. Epidemiological data were estimated. Pharmacological prescriptions to HD patients from 2004 to 2008 were identified, and prescription frequencies were grouped according to the British National Formulary categories. RESULTS: HD incidence estimates ranged from 0.44 to 0.78 per 100,000 person-years, and HD prevalence ranged from 5.96 to 6.54 per 100,000 of the population. Forty-four percent of pharmacological prescriptions targeted the central nervous system. Nearly half of the HD patients were prescribed antidepressants, and over 40% were prescribed analgesics. CONCLUSIONS: Although prevalence estimates fell short of figures suggested in recent debate, it is feasible that the true prevalence may be much higher than previously reported. Pharmacological management appears to rely heavily on central nervous system drugs and nutrition support. Many of these drugs are prescribed to HD patients for reasons other than the medication's primary use. Further work is required to evaluate the impact of alternative management strategies, such as therapist intervention, counselling, and organisation support, on the patients' quality of life.

A systematic review of the incidence and prevalence of long-term neurological conditions in the UK.

BACKGROUND: Updated, robust estimates of the incidence and prevalence of rare long-term neurological conditions in the UK are not available. Global estimates may be misrepresentative as disease aetiology may vary by location. OBJECTIVES: To systematically review the incidence and prevalence of long-term neurological conditions in the UK since 1988. SEARCH STRATEGY: Medline (January 1988 to January 2009), Embase (January 1988 to January 2009), CINAHL (January 1988 to January 2009) and Cochrane CENTRAL databases. SELECTION CRITERIA: UK population-based incidence/prevalence studies of long-term neurological conditions since 1988. Exclusion criteria included inappropriate diagnoses and incomprehensive case ascertainment. DATA COLLECTION AND ANALYSIS: Articles were included based on the selection criteria. Data were extracted from articles with ranges of incidence and prevalence reported. MAIN RESULTS: Eight studies met the criteria (3 on motor neurone disease; 4 on Huntington's disease; 1 on progressive supranuclear palsy). The incidence of motor neurone disease ranged from 1.06 to 2.4/100,000 person-years. The prevalence ranged from 4.02 to 4.91/100,000. The prevalence of Huntington's disease ranged from 4.0 to 9.94/100,000. The prevalence of progressive supranuclear palsy ranged from 3.1 to 6.5/100,000. CONCLUSIONS: The review updates the incidence/prevalence of long-term neurological conditions. Future epidemiological studies must incorporate comprehensive case ascertainment methods and strict diagnostic criteria.

An approach to deep brain stimulation for severe treatment-refractory Tourette syndrome: the UK perspective.

Deep brain stimulation (DBS) is an emerging therapeutic option for severe, treatment-resistant Tourette Syndrome (TS), with about 40 cases reported in the scientific literature over the last decade. Despite the production of clinical guidelines for this procedure from both European and USA centres, a number of unresolved issues still persist, mainly in relation to eligibility criteria and brain targets. The present article illustrates the UK perspective on DBS in TS and proposes consensus-based recommendations for double-blind controlled trials.

Large-scale pathways-based association study in amyotrophic lateral sclerosis.

Sporadic amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease, most likely results from complex genetic and environmental interactions. Although a number of association studies have been performed in an effort to find genetic components of sporadic ALS, most of them resulted in inconsistent findings due to a small number of genes investigated in relatively small sample sizes, while the replication of results was rarely attempted. Defects in retrograde axonal transport, vesicle trafficking and xenobiotic metabolism have been implicated in neurodegeneration and motor neuron death both in human disease and animal models. To assess the role of common genetic variation in these pathways in susceptibility to sporadic ALS, we performed a pathway-based candidate gene case-control association study with replication. Furthermore, we determined reliability of whole genome amplified DNA in a large-scale association study. In the first stage of the study, 1277 putative functional and tagging SNPs in 134 genes spanning 8.7 Mb were genotyped in 822 British sporadic ALS patients and 872 controls using whole genome amplified DNA. To detect variants with modest effect size and discriminate among false positive findings 19 SNPs showing a trend of association in the initial screen were genotyped in a replication sample of 580 German sporadic ALS patients and 361 controls. We did not detect strong evidence of association with any of the genes investigated in the discovery sample (lowest uncorrected P-value 0.00037, lowest permutation corrected P-value 0.353). None of the suggestive associations was replicated in a second sample, further excluding variants with moderate effect size. We conclude that common variation in the investigated pathways is unlikely to have a major effect on susceptibility to sporadic ALS. The genotyping efficiency was only slightly decreased ( approximately 1%) and genotyping quality was not affected using whole genome amplified DNA. It is reliable for large scale genotyping studies of diseases such as ALS, where DNA sample collections are limited because of low disease prevalence and short survival time.

N-glycosylation and expression in human tissues of the orphan GPR61 receptor.

A number of members of the G protein-coupled receptor class of cell surface receptors are 'orphans' with no known endogenous ligand. One of these orphan receptors is GPR61; there are little data about its expression in human cells and tissues. In this study, we investigated the post-translational modification of GPR61 by N-glycosylation at an identified consensus N-glycosylation site (N12) and the impact of this modification upon the subcellular expression of the protein. The N-glycosylation inhibitor tunicamycin reduced the apparent molecular weight of immunoreactivity associated with myc-tagged GPR61 by 1-2 kDa, which was comparable to the evident molecular weight of the myc-tagged N12S GPR61 mutant with disrupted consensus N-glycosylation site. Analysis of GPR61 expression demonstrated that tunicamycin treatment reduced considerably heterologous expression of GPR61 in the cell membrane despite the N12S GPR61 mutant being readily expressed at the cell surface. These results demonstrate that GPR61 is subject to N-glycosylation but suggest this is not a prerequisite for cell surface expression, although N-glycosylation of other proteins may be important for cell membrane expression of GPR61. Expression of GPR61 protein was demonstrated at the cellular level in human hippocampus and human peripheral blood mononuclear cells. In the latter, there was a significantly higher expression of GPR61 in the Th17 cell subset in comparison with resting CD4+ cells, which may point toward a potential role for the GPR61 receptor in autoimmune diseases. This is the first report that GPR61 protein is subject to post-translational modification and is expressed in immune cell subsets and the hippocampus. These findings will help guide studies to investigate the function of GPR61.

Mutations in the histone methyltransferase gene KMT2B cause complex early-onset dystonia.

Histone lysine methylation, mediated by mixed-lineage leukemia (MLL) proteins, is now known to be critical in the regulation of gene expression, genomic stability, cell cycle and nuclear architecture. Despite MLL proteins being postulated as essential for normal development, little is known about the specific functions of the different MLL lysine methyltransferases. Here we report heterozygous variants in the gene KMT2B (also known as MLL4) in 27 unrelated individuals with a complex progressive childhood-onset dystonia, often associated with a typical facial appearance and characteristic brain magnetic resonance imaging findings. Over time, the majority of affected individuals developed prominent cervical, cranial and laryngeal dystonia. Marked clinical benefit, including the restoration of independent ambulation in some cases, was observed following deep brain stimulation (DBS). These findings highlight a clinically recognizable and potentially treatable form of genetic dystonia, demonstrating the crucial role of KMT2B in the physiological control of voluntary movement.

Mutations in the vesicular trafficking protein annexin A11 are associated with amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder. We screened 751 familial ALS patient whole-exome sequences and identified six mutations including p.D40G in the ANXA11 gene in 13 individuals. The p.D40G mutation was absent from 70,000 control whole-exome sequences. This mutation segregated with disease in two kindreds and was present in another two unrelated cases (P = 0.0102), and all mutation carriers shared a common founder haplotype. Annexin A11-positive protein aggregates were abundant in spinal cord motor neurons and hippocampal neuronal axons in an ALS patient carrying the p.D40G mutation. Transfected human embryonic kidney cells expressing ANXA11 with the p.D40G mutation and other N-terminal mutations showed altered binding to calcyclin, and the p.R235Q mutant protein formed insoluble aggregates. We conclude that mutations in ANXA11 are associated with ALS and implicate defective intracellular protein trafficking in disease pathogenesis.

SGCE and myoclonus dystonia: motor characteristics, diagnostic criteria and clinical predictors of genotype.

Myoclonus dystonia syndrome (MDS) is a young-onset movement disorder. A proportion of cases are due to mutations in the maternally imprinted SGCE gene. We assembled the largest cohort of MDS patients to date, and determined the frequency and type of SGCE mutations. The aim was to establish the motor phenotype in mutation carriers and utility of current diagnostic criteria. Eighty-nine probands with clinical features compatible with MDS were recruited from the UK and Ireland. Patients were phenotypically classified as "definite", "probable" or "possible" MDS according to previous guidelines. SGCE was analyzed using direct sequencing and copy number variant analysis. In those where no mutation was found, DYT1 (GAG deletion), GCH1, THAP1 and NKX2.1 genes were also sequenced. Nineteen (21.3%) probands had an SGCE mutation. Three patterns of motor symptoms emerged: (1) early childhood onset upper body myoclonus and dystonia, (2) early childhood onset lower limb dystonia, progressing later to more pronounced myoclonus and upper body involvement, and (3) later childhood onset upper body myoclonus and dystonia with evident cervical involvement. Five probands had large contiguous gene deletions ranging from 0.7 to 2.3 Mb in size with distinctive clinical features, including short stature, joint laxity and microcephaly. Our data confirms that SGCE mutations are most commonly identified in MDS patients with (1) age at onset ≤10 years and (2) predominant upper body involvement of a pure myoclonus-dystonia. Cases with whole SGCE gene deletions had additional clinical characteristics, which are not always predicted by deletion size or gene involvement.