Dominant VPS16 Pathogenic Variants: Not Only Isolated Dystonia

BACKGROUND

VPS16 pathogenic variants have been recently associated with inherited dystonia. Most patients affected by dominant VPS16-related disease display early-onset isolated dystonia with prominent oromandibular, bulbar, cervical, and upper limb involvement, followed by slowly progressive generalization.

CASES

We describe six newly reported dystonic patients carrying VPS16 mutations displaying unusual phenotypic features in addition to dystonia, such as myoclonus, choreoathetosis, pharyngospasm and freezing of gait. Response to bilateral Globus Pallidus Internus Deep Brain Stimulation (GPi-DBS) is reported in three of them, associated with significant improvement of dystonia but only minor effect on other hyperkinetic movements. Moreover, five novel pathogenic/likely pathogenic variants are described.

CONCLUSIONS

This case collection expands the genetic and clinical spectrum of VPS16-related disease, prompting movement disorder specialists to suspect mutations of this gene not only in patients with isolated dystonia.

Rapidly progressive multiple system atrophy in a patient carrying LRRK2 G2019S mutation

BACKGROUND

Multiple system atrophy (MSA) is considered a primarily sporadic neurodegenerative disease, but the role of genetic is poorly understood.

CASE

We present a female patient of Moroccan origin who developed a rapidly progressive non-levodopa responsive parkinsonism, gait and balance problems, and dysautonomia including severe bulbar symptoms. She was diagnosed with MSA Parkinsonian-type (MSA-P) and suddenly died at night at 58 years of age. Reduced striatal DAT-SPECT, putaminal hyperintensity on T2-MRI, and hypometabolism with FDG-PET were present. Genetic testing documented a G2019S mutation in the LRRK2 gene. A skin biopsy was obtained and used to perform alpha-synuclein RT-QuIC, which was negative, and immunohistochemical analysis, which demonstrated abnormal alpha-synuclein deposits in cutaneous nerves. Elevated blood neurofilament light chain levels were also documented.

CONCLUSIONS

LRRK2 mutations are the most common cause of monogenic Parkinson's disease (PD) and G2019S is the most frequent variant. Our patient presented with biological, clinical, and radiological features of MSA, but genetic testing revealed a G2019S LRRK2 mutation, which has been previously reported only in one other case of pathologically proven MSA but with mild progression. In our patient, post-mortem confirmation could not be performed, but RT-QuIC and immunohistochemical findings on skin biopsy support the diagnosis of MSA. G2019S LRRK2 may be linked to an increased risk of MSA. Cases of atypical parkinsonism with rapid disease course should be screened for PD-related genes especially in populations with a high prevalence of mutations in known genes.

Neurotransmitter and receptor systems in the subthalamic nucleus

The Subthalamic Nucleus (STh) is a lens-shaped subcortical structure located ventrally to the thalamus, that despite being embryologically derived from the diencephalon, is functionally implicated in the basal ganglia circuits. Because of this strict structural and functional relationship with the circuits of the basal ganglia, the STh is a current target for deep brain stimulation, a neurosurgical procedure employed to alleviate symptoms in movement disorders, such as Parkinson's disease and dystonia. However, despite the great relevance of this structure for both basal ganglia physiology and pathology, the neurochemical and molecular anatomy of the STh remains largely unknown. Few studies have specifically addressed the detection of neurotransmitter systems and their receptors within the structure, and even fewer have investigated their topographical distribution. Here, we have reviewed the scientific literature on neurotransmitters relevant in the STh function of rodents, non-human primates and humans including glutamate, GABA, dopamine, serotonin, noradrenaline with particular focus on their subcellular, cellular and topographical distribution. Inter-species differences were highlighted to provide a framework for further research priorities, particularly in humans.

Caspr1 antibodies autoimmune paranodopathy with severe tetraparesis: Potential relevance of antibody titers in monitoring treatment response

AIM

Nodopathies and paranodopathies are autoimmune neuropathies associated with antibodies to nodal-paranodal antigens (neurofascin 140/186 and 155, contactin-1, contactin-associated protein 1 [Caspr1]) characterized by peculiar clinical features, poor response to standard immunotherapies (e.g., intravenous immunoglobulins, IVIg). Improvement after anti-CD20 monoclonal antibody therapy has been reported. Data on Caspr1 antibodies pathogenicity are still preliminary, and longitudinal titers have been poorly described.

METHODS

We report on a young woman who developed a disabling neuropathy with antibodies to the Caspr1/contactin-1 complex showing a dramatic improvement after rituximab therapy, mirrored by the decrease of antibody titers.

RESULTS

A 26-year-old woman presented with ataxic-stepping gait, severe motor weakness at four limbs, and low frequency postural tremor. For neurophysiological evidence of demyelinating neuropathy, she was diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy and treated with IVIg without benefit. MRI showed symmetrical hypertrophy and marked signal hyperintensity of brachial and lumbosacral plexi. Cerebrospinal fluid showed 710 mg/dL protein. Despite intravenous methylprednisolone, the patient progressively worsened, and became wheelchair-bound. Antibodies to nodal-paranodal antigens were searched for by ELISA and cell-based assay. Anticontactin/Caspr1 IgG4 antibodies resulted positive. The patient underwent rituximab therapy with slow progressive improvement that mirrored the antibodies titer, measured throughout the disease course.

CONCLUSIONS

Our patient had a severe progressive course with early disability and axonal damage, and slow recovery starting only a few months after antibody-depleting therapy. The close correlation between titer, disability, and treatment, supports the pathogenicity of Caspr1 antibodies, and suggest that their longitudinal evaluation might provide a potential biomarker to evaluate treatment response.

Variants in ATP5F1B are associated with dominantly inherited dystonia

ATP5F1B is a subunit of the mitochondrial ATP synthase or complex V of the mitochondrial respiratory chain. Pathogenic variants in nuclear genes encoding assembly factors or structural subunits are associated with complex V deficiency, typically characterized by autosomal recessive inheritance and multisystem phenotypes. Movement disorders have been described in a subset of cases carrying autosomal dominant variants in structural subunits genes ATP5F1A and ATP5MC3. Here, we report the identification of two different ATP5F1B missense variants (c.1000A>C; p.Thr334Pro and c.1445T>C; p.Val482Ala) segregating with early-onset isolated dystonia in two families, both with autosomal dominant mode of inheritance and incomplete penetrance. Functional studies in mutant fibroblasts revealed no decrease of ATP5F1B protein amount but severe reduction of complex V activity and impaired mitochondrial membrane potential, suggesting a dominant-negative effect. In conclusion, our study describes a new candidate gene associated with isolated dystonia and confirms that heterozygous variants in genes encoding subunits of the mitochondrial ATP synthase may cause autosomal dominant isolated dystonia with incomplete penetrance, likely through a dominant-negative mechanism.

Scoping Review on ADCY5-Related Movement Disorders

Background

Adenylyl cyclase 5 (ADCY5)-related movement disorder (ADCY5-RMD) is a rare, childhood-onset disease resulting from pathogenic variants in the ADCY5 gene. The clinical features, diagnostic options, natural history, and treatments for this disease are poorly characterized and have never been established through a structured approach.

Objective

This scoping review attempts to summarize all available clinical literature on ADCY5-RMD.

Methods

Eighty-seven articles were selected for inclusion in this scoping review. The majority of articles identified were case reports or case series.

Results

These articles demonstrate that patients with ADCY5-RMD suffer from permanent and/ or paroxysmal hyperkinetic movements. The paroxysmal episodes can be worsened by environmental triggers, in particular the sleep-wake transition phase in the early morning. Occurrence of nocturnal paroxysmal dyskinesias and perioral twitches are highly suggestive of the diagnosis when present. In the majority of patients intellectual capacity is preserved. ADCY5-RMD is considered a non-progressive disorder, with inter-individual variations in evolution with aging. Somatic mosaicism, mode of inheritance and the location of the mutation within the protein can influence phenotype.

Conclusions

The current evidence for therapeutic options for ADCY5-RMD is limited: caffeine, benzodiazepines and deep brain stimulation have been consistently reported to be useful in case reports and case series.

The clinical and genetic spectrum of primary familial brain calcification

Primary familial brain calcification (PFBC), formerly known as Fahr's disease, is a rare neurodegenerative disease characterized by bilateral progressive calcification of the microvessels of the basal ganglia and other cerebral and cerebellar structures. PFBC is thought to be due to an altered function of the Neurovascular Unit (NVU), where abnormal calcium-phosphorus metabolism, functional and microanatomical alterations of pericytes and mitochondrial alterations cause a dysfunction of the blood-brain barrier (BBB) and the generation of an osteogenic environment with surrounding astrocyte activation and progressive neurodegeneration. Seven causative genes have been discovered so far, of which four with dominant (SLC20A2, PDGFB, PDGFRB, XPR1) and three with recessive inheritance (MYORG, JAM2, CMPK2). Clinical presentation ranges from asymptomatic subjects to movement disorders, cognitive decline and psychiatric disturbances alone or in various combinations. Radiological patterns of calcium deposition are similar in all known genetic forms, but central pontine calcification and cerebellar atrophy are highly suggestive of MYORG mutations and extensive cortical calcification has been associated with JAM2 mutations. Currently, no disease-modifying drugs or calcium-chelating agents are available and only symptomatic treatments can be offered.

Duodenal alpha-Synuclein Pathology and Enteric Gliosis in Advanced Parkinson's Disease

BACKGROUND

The role of the gut-brain axis has been recently highlighted as a major contributor to Parkinson's disease (PD) physiopathology, with numerous studies investigating bidirectional transmission of pathological protein aggregates, such as α-synuclein (αSyn). However, the extent and the characteristics of pathology in the enteric nervous system have not been fully investigated.

OBJECTIVE

We characterized αSyn alterations and glial responses in duodenum biopsies of patients with PD by employing topography-specific sampling and conformation-specific αSyn antibodies.

METHODS

We examined 18 patients with advanced PD who underwent Duodopa percutaneous endoscopic gastrostomy and jejunal tube procedure, 4 untreated patients with early PD (disease duration <5 years), and 18 age- and -sex-matched healthy control subjects undergoing routine diagnostic endoscopy. A mean of four duodenal wall biopsies were sampled from each patient. Immunohistochemistry was performed for anti-aggregated αSyn (5G4) and glial fibrillary acidic protein antibodies. Morphometrical semiquantitative analysis was performed to characterize αSyn-5G4⁺ and glial fibrillary acidic protein-positive density and size.

RESULTS

Immunoreactivity for aggregated α-Syn was identified in all patients with PD (early and advanced) compared with controls. αSyn-5G4⁺ colocalized with neuronal marker β-III-tubulin. Evaluation of enteric glial cells demonstrated an increased size and density when compared with controls, suggesting reactive gliosis.

CONCLUSIONS

We found evidence of synuclein pathology and gliosis in the duodenum of patients with PD, including early de novo cases. Future studies are required to evaluate how early in the disease process duodenal pathology occurs and its possible contribution to levodopa effect in chronic patients. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Expanding the genetics and phenotypic spectrum of Lysine-specific demethylase 5C (KDM5C): a report of 13 novel variants

Lysine-specific demethylase 5C (KDM5C) has been identified as an important chromatin remodeling gene, contributing to X-linked neurodevelopmental disorders (NDDs). The KDM5C gene, located in the Xp22 chromosomal region, encodes the H3K4me3-me2 eraser involved in neuronal plasticity and dendritic growth. Here we report 30 individuals carrying 13 novel and one previously identified KDM5C variants. Our cohort includes the first reported case of somatic mosaicism in a male carrying a KDM5C nucleotide substitution, and a dual molecular finding in a female carrying a homozygous truncating FUCA1 alteration together with a de novo KDM5C variant. With the use of next generation sequencing strategies, we detected 1 frameshift, 1 stop codon, 2 splice-site and 10 missense variants, which pathogenic role was carefully investigated by a thorough bioinformatic analysis. The pattern of X-chromosome inactivation was found to have an impact on KDM5C phenotypic expression in females of our cohort. The affected individuals of our case series manifested a neurodevelopmental condition characterized by psychomotor delay, intellectual disability with speech disorders, and behavioral features with particular disturbed sleep pattern; other observed clinical manifestations were short stature, obesity and hypertrichosis. Collectively, these findings expand the current knowledge about the pathogenic mechanisms leading to dysfunction of this important chromatin remodeling gene and contribute to a refinement of the KDM5C phenotypic spectrum.

Adult-onset KMT2B-related dystonia

KMT2B-related dystonia (DYT-KMT2B, also known as DYT28) is an autosomal dominant neurological disorder characterized by varying combinations of generalized dystonia, psychomotor developmental delay, mild-to-moderate intellectual disability and short stature. Disease onset occurs typically before 10 years of age. We report the clinical and genetic findings of a series of subjects affected by adult-onset dystonia, hearing loss or intellectual disability carrying rare heterozygous KMT2B variants. Twelve cases from five unrelated families carrying four rare KMT2B missense variants predicted to impact protein function are described. Seven affected subjects presented with adult-onset focal or segmental dystonia, three developed isolated progressive hearing loss, and one displayed intellectual disability and short stature. Genome-wide DNA methylation profiling allowed to discriminate these adult-onset dystonia cases from controls and early-onset DYT-KMT2B patients. These findings document the relevance of KMT2B variants as a potential genetic determinant of adult-onset dystonia and prompt to further characterize KMT2B carriers investigating non-dystonic features.

Antiphospholipid‐related chorea: two case reports and role of metabolic imaging

Background

Antiphospholipid syndrome (APS) is a complex acquired autoimmune disease with a wide clinical spectrum. Chorea is a rare neurological manifestation of APS.

Cases

We report two elderly patients with APS‐related chorea in whom functional imaging (18F‐FDG positron emission tomography, FDG‐PET) supported the diagnosis and compare our findings with existing literature.

Literature Review

Among 142 clinical cases of antiphospholipid‐related chorea found in literature, only 10 had undergone brain metabolic imaging. Striatal hypermetabolism was evident in all cases (6) that underwent FDG‐PET cerebral imaging. Cerebral perfusion single photon emission computed tomography (SPECT) was normal in two cases, while the other two presented with basal ganglia hypoperfusion.

Conclusions

Brain FDG‐PET usually shows striatal hypometabolism in neurodegenerative types of chorea as opposed to striatal hypermetabolism observed in most cases of chorea from reversible etiologies, such as APS‐related chorea. When a patient's clinical presentation is not clearly suggestive of either a neurodegenerative or autoimmune chorea, and first‐line investigations are normal, FDG‐PET may help in the differential diagnosis, especially in the presence of striatal hypermetabolism. SPECT data are less numerous and show either normal scans or basal ganglia hypoperfusion.

GPi-DBS for KMT2B-Associated Dystonia: Systematic Review and Meta-Analysis

Background

Early evidence suggests good response to pallidal deep brain stimulation (DBS) in DYT-KMT2B.

Objectives

We aimed to conduct a systematic review and meta-analysis to assess outcomes and identify predictors of good outcome following GPi-DBS in DYT-KMT2B.

Methods

We searched MEDLINE, Cochrane and MDS-abstracts databases using the MeSH terms "KMT2B and DYT28". We included studies that reported objective outcomes following GPi-DBS in DYT-KMT2B. The BFMDRS-M (Burke-Fahn-Marsden Dystonia Rating Scale- Movement) total scores pre- and post-surgery were used to quantify outcomes. We calculated pooled effects using a random effects meta-analysis and used meta-regression to identify potential effect modifiers. Multiple linear regression using individual patient data was used to identify predictors of good outcome (>50% improvement from baseline on BFMDRS-M).

Results

Initial searches screened 132 abstracts of which 34 full-text articles were identified to be of potential interest. Ten studies reporting 42 individual patients, met the inclusion/exclusion criteria and were included in the final review. The mean age at onset was 6.4 ± 5.7 years and 40% were male. The median follow-up was 12 months (range: 1-264 months). GPi-DBS resulted in median BFMDRS-M improvement of 42.7% (range: -103.5% to 95.9%) postoperatively. Pooled proportion of patients experiencing clinical improvement >50% on BFMDRS-M was 41% (95% CI: 27%-57%). Male gender [β: 22.6, 95% CI: 8.0-37.3, P = 0.004), and higher pre-operative BFMDRS-M score [β: 0.62, 95% CI: 0.36-0.87, P < 0.001) were independently associated with better outcome.

Conclusion

KMT2B-associated dystonia responds effectively to pallidal stimulation. The outcome is better in males and those with more severe dystonia at baseline.

A novel MRPS34 gene mutation with combined OXPHOS deficiency in an adult patient with Leigh syndrome

We report a novel pathogenic variant (c.223G > C; p.Gly75Arg) in the gene encoding the small mitoribosomal subunit protein mS34 in a long-surviving patient with Leigh Syndrome who was genetically diagnosed at age 34 years. The patient presented with delayed motor milestones and a stepwise motor deterioration during life, along with brain MRI alterations involving the subcortical white matter, deep grey nuclei and in particular the internal globi pallidi, that appeared calcified on CT scan. The novel variant is associated with a reduction of mS34 protein levels and of the OXPHOS complex I and IV subunits in peripheral blood mononuclear cells of the case. This study expands the number of variants that, by affecting the stability of the mitoribosome, may cause an OXPHOS deficiency in Leigh Syndrome and reports, for the first time, an unusual long survival in a patient with a homozygous MRPS34 pathogenic variant.

High prolactin levels in dihydropteridine reductase deficiency: A sign of therapy failure or additional pathology?

We report the case of a 22-year-old man with a diagnosis of dihydropteridine reductase (DHPR) deficiency who progressively developed movement disorders and epilepsy. Despite L-Dopa supplementation the patient continued to show high prolactin levels, with a discrepancy between the neurological clinical picture and the hormonal biochemical levels. For this reason, other potential causes were ruled out by performing a cerebral magnetic resonance imaging, which demonstrated a solid lesion in the pituitary gland strongly suggestive of a prolactinoma. As the association between metabolic disorders affecting biogenic amine synthesis and prolactinoma has not been previously reported in humans, this report suggests that a critical evaluation of the use of prolactin as a guide for therapy dosage should be made in patients with DHPR deficiency disorders.

Impact of social and mobility restrictions in Parkinson's disease during COVID-19 lockdown

BACKGROUND

The consequences of strict COVID-19 mobility restrictions on motor/non-motor features in Parkinson's disease (PD) have not been systematically studied but worse mobility and quality of life have been reported. To elucidate this question, 12 mild to moderate PD patients were assessed in March 2020 before and after two months of isolation as part of a clinical study that had to be interrupted due to the pandemic and the implementation of COVID19 mobility restrictions.

METHODS

Twelve patients were systematically evaluated before and after the lockdown period as part of a larger cohort that previously underwent thermal water rehabilitation. Clinical outcomes were the Body Mass index, the Mini-Balance Evaluation Systems Test, the MDS-Unified Parkinson's Disease Rating Scale part III, the 6 Minute Walking Test and the New Freezing of Gait Questionnaire. Global cognition was evaluated with the Montreal Cognitive Assessment scale. The impact of COVID-19 restrictions on quality of life and functional independence was evaluated with The Parkinson's disease Quality of life (PDQ-39), the Activities of Daily Living (ADL) and Instrumental Activities of Daily Living questionnaires (IADL) and the Parkinson's disease cognitive functional rating scales (PD-CFRS).

RESULTS

After two months of isolation the Mini-BESTest score worsened (p=0.005), and four patients reported one or more falls during the lockdown. BMI increased (p=0.031) while the remaining clinical variables including quality of life did not change.

CONCLUSION

We observed moderate worsening at Mini-BESTest, greater risk of falls and increased body weight as consequence of prolonged immobility. We believe negative effects were partially softened since patients were in contact with our multidisciplinary team during the lockdown and had previously received training to respond to the needs of this emergency isolation. These findings highligh the importnace of patient-centered interventions in PD management.

EIF2AK2 Missense Variants Associated with Early Onset Generalized Dystonia

Objective

The study was undertaken to identify a monogenic cause of early onset, generalized dystonia.

Methods

Methods consisted of genome‐wide linkage analysis, exome and Sanger sequencing, clinical neurological examination, brain magnetic resonance imaging, and protein expression studies in skin fibroblasts from patients.

Results

We identified a heterozygous variant, c.388G>A, p.Gly130Arg, in the eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2) gene, segregating with early onset isolated generalized dystonia in 5 patients of a Taiwanese family. EIF2AK2 sequencing in 191 unrelated patients with unexplained dystonia yielded 2 unrelated Caucasian patients with an identical heterozygous c.388G>A, p.Gly130Arg variant, occurring de novo in one case, another patient carrying a different heterozygous variant, c.413G>C, p.Gly138Ala, and one last patient, born from consanguineous parents, carrying a third, homozygous variant c.95A>C, p.Asn32Thr. These 3 missense variants are absent from gnomAD, and are located in functional domains of the encoded protein. In 3 patients, additional neurological manifestations were present, including intellectual disability and spasticity. EIF2AK2 encodes a kinase (protein kinase R [PKR]) that phosphorylates eukaryotic translation initiation factor 2 alpha (eIF2α), which orchestrates the cellular stress response. Our expression studies showed abnormally enhanced activation of the cellular stress response, monitored by PKR‐mediated phosphorylation of eIF2α, in fibroblasts from patients with EIF2AK2 variants. Intriguingly, PKR can also be regulated by PRKRA (protein interferon‐inducible double‐stranded RNA‐dependent protein kinase activator A), the product of another gene causing monogenic dystonia.

Interpretation

We identified EIF2AK2 variants implicated in early onset generalized dystonia, which can be dominantly or recessively inherited, or occur de novo. Our findings provide direct evidence for a key role of a dysfunctional eIF2α pathway in the pathogenesis of dystonia. ANN NEUROL 2021;89:485–497

Olfactory and rhinological evaluations in SARS-CoV-2 patients complaining of olfactory loss

Since December 2019, a novel coronavirus SARS-CoV-2 (Covid-19) outbreak emerged in China and spread rapidly in several countries. As of April 5, 2020, 1.218.474 cases were confirmed with 65.884 deaths worldwide (1). The clinical manifestations of Covid-19 range from asymptomatic carrier status to severe pneumonia. In a study of 7,736 Covid-19 patients in China, of all the clinical symptoms, hyposmia was not reported in any patient(2). Anyway, it is now clear that olfactory dysfunction may also be present in these patients(3) as the only or prevalent manifestation(4).

MYORG-related disease is associated with central pontine calcifications and atypical parkinsonism

OBJECTIVE

To identify the phenotypic, neuroimaging, and genotype-phenotype expression of MYORG mutations.

METHODS

Using next-generation sequencing, we screened 86 patients with primary familial brain calcification (PFBC) from 60 families with autosomal recessive or absent family history that were negative for mutations in SLC20A2, PDGFRB, PDGBB, and XPR1. In-depth phenotyping and neuroimaging investigations were performed in all cases reported here.

RESULTS

We identified 12 distinct deleterious MYORG variants in 7 of the 60 families with PFBC. Overall, biallelic MYORG mutations accounted for 11.6% of PFBC families in our cohort. A heterogeneous phenotypic expression was identified within and between families with a median age at onset of 56.4 years, a variable combination of parkinsonism, cerebellar signs, and cognitive decline. Psychiatric disturbances were not a prominent feature. Cognitive assessment showed impaired cognitive function in 62.5% of cases. Parkinsonism associated with vertical nuclear gaze palsy was the initial clinical presentation in 1/3 of cases and was associated with central pontine calcifications. Cerebral cortical atrophy was present in 37% of cases.

CONCLUSIONS

This large, multicentric study shows that biallelic MYORG mutations represent a significant proportion of autosomal recessive PFBC. We recommend screening MYORG mutations in all patients with primary brain calcifications and autosomal recessive or negative family history, especially when presenting clinically as atypical parkinsonism and with pontine calcification on brain CT.

Pallidal Deep Brain Stimulation in DYT6 Dystonia: Clinical Outcome and Predictive Factors for Motor Improvement

Pallidal deep brain stimulation is an established treatment in dystonia. Available data on the effect in DYT-THAP1 dystonia (also known as DYT6 dystonia) are scarce and long-term follow-up studies are lacking. In this retrospective, multicenter follow-up case series of medical records of such patients, the clinical outcome of pallidal deep brain stimulation in DYT-THAP1 dystonia, was evaluated. The Burke Fahn Marsden Dystonia Rating Scale served as an outcome measure. Nine females and 5 males were enrolled, with a median follow-up of 4 years and 10 months after implant. All benefited from surgery: dystonia severity was reduced by a median of 58% (IQR 31-62, p = 0.001) at last follow-up, as assessed by the Burke Fahn Marsden movement subscale. In the majority of individuals, there was no improvement of speech or swallowing, and overall, the effect was greater in the trunk and limbs as compared to the cranio-cervical and orolaryngeal regions. No correlation was found between disease duration before surgery, age at surgery, or preoperative disease burden and the outcome of deep brain stimulation. Device- and therapy-related side-effects were few. Accordingly, pallidal deep brain stimulation should be considered in clinically impairing and pharmaco-resistant DYT-THAP1 dystonia. The method is safe and effective, both short- and long-term.

Frequency and phenotypic spectrum of KMT2B dystonia in childhood: A single-center cohort study

BACKGROUND

Childhood-onset dystonia is often genetically determined. Recently, KMT2B variants have been recognized as an important cause of childhood-onset dystonia.

OBJECTIVE

To define the frequency of KMT2B mutations in a cohort of dystonic patients aged <18 years at onset, the associated clinical and radiological phenotype, and the natural history of disease.

METHODS

Whole-exome sequencing or customized gene panels were used to screen a cohort of 65 patients who had previously tested negative for all other known dystonia-associated genes.

RESULTS

We identified 14 patients (21.5%) carrying KMT2B variants, of which 1 was classified as a variant of unknown significance. We also identified 2 additional patients carrying pathogenic mutations in GNAO1 and ATM. Overall, we established a definitive genetic diagnosis in 23% of cases. We observed a spectrum of clinical manifestations in KMT2B variant carriers, ranging from generalized dystonia to short stature or intellectual disability alone, even within the same family. In 78.5% of cases, dystonia involved the lower limbs at onset, with later caudocranial generalization. Eight patients underwent pallidal DBS with a median decrease of Burke-Fahn-Marsden Dystonia Rating Scale-Motor score of 38.5% in the long term. We also report on 4 asymptomatic carriers, suggesting that some KMT2B mutations may be associated with incomplete disease penetrance.

CONCLUSIONS

KMT2B mutations are frequent in childhood-onset dystonia and cause a complex neurodevelopmental syndrome, often featuring growth retardation and intellectual disability as additional phenotypic features. A dramatic and long-lasting response to DBS is characteristic of DYT-KMT2B dystonia. © 2019 International Parkinson and Movement Disorder Society.

Inborn errors of coenzyme A metabolism and neurodegeneration

Two inborn errors of coenzyme A (CoA) metabolism are responsible for distinct forms of neurodegeneration with brain iron accumulation (NBIA), a heterogeneous group of neurodegenerative diseases having as a common denominator iron accumulation mainly in the inner portion of globus pallidus. Pantothenate kinase-associated neurodegeneration (PKAN), an autosomal recessive disorder with progressive impairment of movement, vision and cognition, is the most common form of NBIA and is caused by mutations in the pantothenate kinase 2 gene (PANK2), coding for a mitochondrial enzyme, which phosphorylates vitamin B5 in the first reaction of the CoA biosynthetic pathway. Another very rare but similar disorder, denominated CoPAN, is caused by mutations in coenzyme A synthase gene (COASY) coding for a bi-functional mitochondrial enzyme, which catalyzes the final steps of CoA biosynthesis. It still remains a mystery why dysfunctions in CoA synthesis lead to neurodegeneration and iron accumulation in specific brain regions, but it is now evident that CoA metabolism plays a crucial role in the normal functioning and metabolism of the nervous system.

Primary brain calcification: an international study reporting novel variants and associated phenotypes

Primary familial brain calcification (PFBC) is a rare cerebral microvascular calcifying disorder with a wide spectrum of motor, cognitive, and neuropsychiatric symptoms. It is typically inherited as an autosomal-dominant trait with four causative genes identified so far: SLC20A2, PDGFRB, PDGFB, and XPR1. Our study aimed at screening the coding regions of these genes in a series of 177 unrelated probands that fulfilled the diagnostic criteria for primary brain calcification regardless of their family history. Sequence variants were classified as pathogenic, likely pathogenic, or of uncertain significance (VUS), based on the ACMG-AMP recommendations. We identified 45 probands (25.4%) carrying either pathogenic or likely pathogenic variants (n = 34, 19.2%) or VUS (n = 11, 6.2%). SLC20A2 provided the highest contribution (16.9%), followed by XPR1 and PDGFB (3.4% each), and PDGFRB (1.7%). A total of 81.5% of carriers were symptomatic and the most recurrent symptoms were parkinsonism, cognitive impairment, and psychiatric disturbances (52.3%, 40.9%, and 38.6% of symptomatic individuals, respectively), with a wide range of age at onset (from childhood to 81 years). While the pathogenic and likely pathogenic variants identified in this study can be used for genetic counseling, the VUS will require additional evidence, such as recurrence in unrelated patients, in order to be classified as pathogenic.

Encephalopathies with intracranial calcification in children: clinical and genetic characterization

Background

We present a group of patients affected by a paediatric onset genetic encephalopathy with cerebral calcification of unknown aetiology studied with Next Generation Sequencing (NGS) genetic analyses.

Methods

We collected all clinical and radiological data. DNA samples were tested by means of a customized gene panel including fifty-nine genes associated with known genetic diseases with cerebral calcification.

Results

We collected a series of fifty patients. All patients displayed complex and heterogeneous phenotypes mostly including developmental delay and pyramidal signs and less frequently movement disorder and epilepsy. Signs of cerebellar and peripheral nervous system involvement were occasionally present. The most frequent MRI abnormality, beside calcification, was the presence of white matter alterations; calcification was localized in basal ganglia and cerebral white matter in the majority of cases. Sixteen out of fifty patients tested positive for mutations in one of the fifty-nine genes analyzed. In fourteen cases the analyses led to a definite genetic diagnosis while results were controversial in the remaining two.

Conclusions

Genetic encephalopathies with cerebral calcification are usually associated to complex phenotypes. In our series, a molecular diagnosis was achieved in 32% of cases, suggesting that the molecular bases of a large number of disorders are still to be elucidated. Our results confirm that cerebral calcification is a good criterion to collect homogeneous groups of patients to be studied by exome or whole genome sequencing; only a very close collaboration between clinicians, neuroradiologists and geneticists can provide better results from these new generation molecular techniques.

Partial loss-of-function of sodium channel SCN8A in familial isolated myoclonus

Variants in the neuronal sodium channel gene SCN8A have been implicated in several neurological disorders. Early infantile epileptic encephalopathy type 13 results from de novo gain‐of‐function mutations that alter the biophysical properties of the channel. Complete loss‐of‐function variants of SCN8A have been identified in cases of isolated intellectual disability. We now report a novel heterozygous SCN8A variant, p.Pro1719Arg, in a small pedigree with five family members affected with autosomal dominant upper limb isolated myoclonus without seizures or cognitive impairment. Functional analysis of the p.Pro1719Arg variant in transfected neuron‐derived cells demonstrated greatly reduced Na_v1.6 channel activity without altered gating properties. Hypomorphic alleles of Scn8a in the mouse are known to result in similar movement disorders. This study expands the phenotypic and functional spectrum of SCN8A variants to include inherited nonepileptic isolated myoclonus. SCN8A can be considered as a candidate gene for isolated movement disorders without seizures.

The Length of SNCA Rep1 Microsatellite May Influence Cognitive Evolution in Parkinson's Disease

Background

Alpha-synuclein is a constituent of Lewy bodies and mutations of its gene cause familial Parkinson's disease (PD). A previous study showed that a variant of the alpha-synuclein gene (SNCA), namely the 263 bp allele of Rep1 was associated with faster motor progression in PD. On the contrary, a recent report failed to detect a detrimental effect of Rep1 263 on both motor and cognitive outcomes in PD. Aim of this study was to evaluate the influence of the Rep1 variants on disease progression in PD patients.

Methods

We recruited and genotyped for SNCA Rep1 426 PD patients with age at onset ≥40 years and disease duration ≥4 years. We then analyzed frequency and time of occurrence of wearing-off, dyskinesia, freezing of gait, visual hallucinations, and dementia using a multivariate Cox's proportional hazards regression model.

Results

SNCA Rep1 263 carriers showed significantly increased risk of both dementia (HR = 3.03) and visual hallucinations (HR = 2.69) compared to 263 non-carriers. Risk of motor complications did not differ in the two groups.

Conclusion

SNCA Rep1 263 allele is associated with a worse cognitive outcome in PD.

The relevance of gene panels in movement disorders diagnosis: A lab perspective

Next-Generation Sequencing (NGS) is a group of new methods that allow sequencing a variable number of known genes (targeted resequencing) or even the whole human genome (whole genome sequencing-WGS) and have contributed to an exponential genetic knowledge growth, especially in rare diseases, in the past few years. Since 2015, in the Molecular Neurogenetics Unit of Neurological Institute "Carlo Besta", some gene panels have become available to screen all the known genes associated with Movement Disorders (MD) in children and adults as a diagnostic package. Over 221 patients analyzed (part of the Telethon Network of Genetic Biobanks - TNGB), pathogenic variants were found in 25 (11.31%), allowing a definitive genetic diagnosis. Among them, we found mutations in 10/114 patients with dystonia (8.8%); 10/59 patients with Parkinson's disease (16.9%); 1/25 patients with Neurodegeneration with Brain Iron Accumulation (NBIA) (4%) and 4/23 patients with neurotransmitter and biopterin metabolism synthesis defect (17.4%). Our results are in line with those published in literature; targeted resequencing does not replace Sanger sequencing totally, but its usage needs to be discussed with clinicians taking into account both the patient's clinical picture and radiological and neurophysiological data.

ATP1A3-related disorders: An update

Alternating Hemiplegia of Childhood (AHC), Rapid-onset Dystonia Parkinsonism (RDP) and CAPOS syndrome (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) are three distinct, yet partially overlapping clinical syndromes that have long been thought to be allelic disorders. From 2004 to 2012, both autosomal dominant and de novo mutations in ATP1A3 have been detected in patients affected by these three conditions. Growing evidence suggests that AHC, RDP and CAPOS syndrome are part of a large and continuously expanding clinical spectrum and share some recurrent clinical features, such as abrupt-onset, asymmetric anatomical distribution and the presence of triggering factors, which are highly suggestive of ATP1A3 mutations. In this review, we will highlight the main clinical and genetic features of ATP1A3-related disorders focussing on shared and distinct features that can be helpful in clinical practice to individuate mutation carriers.

Diagnosis and treatment of pediatric onset isolated dystonia

Isolated dystonia refers to a genetic heterogeneous group of progressive conditions with onset of symptoms during childhood or adolescence, progressive course with frequent generalization and marked functional impairment. There are well-known monogenic forms of isolated dystonia with pediatric onset such as DYT1 and DYT6 transmitted with autosomal dominant inheritance and low penetrance. Genetic findings of the past years have widened the etiological spectrum and the phenotype. The recently discovered genes (GNAL, ANO-3, KTM2B) or variant of already known diseases, such as Ataxia-Teleangectasia, are emerging as another causes of pediatric onset dystonia, sometimes with a more complex phenotype, but their incidence is unknown and still a considerable number of cases remains genetically undetermined. Due to the severe disability of pediatric onset dystonia treatment remains unsatisfactory and still mainly based upon oral pharmacological agents. However, deep brain stimulation is now extensively applied with good to excellent results especially when patients are treated early during the course of the disease.

CANS: Childhood acute neuropsychiatric syndromes

The terms Pediatric Autoimmune Neuropsychiatric disorders associated with streptococcal infections (PANDAS), Pediatric acute-onset neuropsychiatric Syndrome (PANS), and Childhood Acute Neuropsychiatric Symptoms (CANS) have been used to describe certain acute onset neuropsychiatric pediatric disorders. This clinical characteristic was unusually abrupt onset of obsessive compulsive symptoms and/or severe eating restrictions and concomitant cognitive, behavioral or neurological symptoms. Because the CANS/PANS criteria define a broad spectrum of neuropsychiatric conditions, the syndrome is presumed to result from a variety of disease mechanisms and to have multiple etiologies, ranging from postinfectious autoimmune and neuroinflammatory disorders to toxic, endocrine or metabolic disorders. We suggest a diagnostic flow-chart in case of acute onset neuropsychiatric syndrome to better define diagnostic criteria, identify possible subtypes and delineate treatment.

Emerging Monogenic Complex Hyperkinetic Disorders

Purpose of Review

Hyperkinetic movement disorders can manifest alone or as part of complex phenotypes. In the era of next-generation sequencing (NGS), the list of monogenic complex movement disorders is rapidly growing. This review will explore the main features of these newly identified conditions.

Recent Findings

Mutations in ADCY5 and PDE10A have been identified as important causes of childhood-onset dyskinesias and KMT2B mutations as one of the most frequent causes of complex dystonia in children. The delineation of the phenotypic spectrum associated with mutations in ATP1A3, FOXG1, GNAO1, GRIN1, FRRS1L, and TBC1D24 is revealing an expanding genetic overlap between epileptic encephalopathies, developmental delay/intellectual disability, and hyperkinetic movement disorders,.

Summary

Thanks to NGS, the etiology of several complex hyperkinetic movement disorders has been elucidated. Importantly, NGS is changing the way clinicians diagnose these complex conditions. Shared molecular pathways, involved in early stages of brain development and normal synaptic transmission, underlie basal ganglia dysfunction, epilepsy, and other neurodevelopmental disorders.

Patient Affected by Beta-Propeller Protein-Associated Neurodegeneration: A Therapeutic Attempt with Iron Chelation Therapy

Here, we report the case of a 36-year-old patient with a diagnosis of de novo mutation of the WDR45 gene, responsible for beta-propeller protein-associated neurodegeneration, a phenotypically distinct, X-linked dominant form of Neurodegeneration with Brain Iron Accumulation. The clinical history is characterized by a relatively stable intellectual disability and a hypo-bradykinetic and hypertonic syndrome with juvenile onset. Genetic investigations and T1 and T2-weighted MR images align with what is described in literature. The patient was also subjected to PET with 18-FDG investigation and DaT-Scan study. In reporting relevant clinical data, we want to emphasize the fact that the patient received a chelation therapy with deferiprone (treatment already used in other forms of NBIA with encouraging results), which, however, had to be interrupted because the parkinsonian symptoms worsened. Conversely, the patient has benefited from non-drug therapies and, in particular, from an adapted motor activity with assisted pedaling (method in the process of validation in treatments of parkinsonian syndromes), which started before the treatment with deferiprone and still continues.

Parkinson disease in Gaucher disease

BACKGROUND

Gaucher disease (GD) is an inborn error of metabolism caused by mutations in the gene (GBA) coding for glucocerebrosidase (GCase), inherited in an autosomal recessive pattern. GD patients have up to 9% risk of developing PD.

CASE PRESENTATION

We report two patients with GD that developed PD at different disease stages.

CONCLUSION

We reviewed the literature on the coexistence of PD and GD and speculate that the severity of symptoms may be related to the type of GBA mutation inherited.

ADCY5-related movement disorders: Frequency, disease course and phenotypic variability in a cohort of paediatric patients

Introduction

ADCY5 mutations have been recently identified as an important cause of early-onset hyperkinetic movement disorders. The phenotypic spectrum associated with mutations in this gene is expanding. However, the ADCY5 mutational frequency in cohorts of paediatric patients with hyperkinetic movement disorders has not been evaluated.

Methods

We performed a screening of the entire ADCY5 coding sequence in 44 unrelated subjects with genetically undiagnosed childhood-onset hyperkinetic movement disorders, featuring chorea alone or in combination with myoclonus and dystonia. All patients had normal CSF analysis and brain imaging and were regularly followed-up in tertiary centers for paediatric movement disorders.

Results

We identified five unrelated subjects with ADCY5 mutations (11% of the cohort). Three carried the p. R418W mutation, one the p. R418Q and one the p. R418G mutation. Mutations arose de novo in four cases, while one patient inherited the mutation from his similarly affected father. All patients had delayed motor and/or language milestones with or without axial hypotonia and showed generalized chorea and dystonia, with prominent myoclonic jerks in one case. Episodic exacerbations of the baseline movement disorder were observed in most cases, being the first disease manifestation in two patients. The disease course was variable, from stability to spontaneous improvement during adolescence.

Conclusion

Mutations in ADCY5 are responsible for a hyperkinetic movement disorder that can be preceded by episodic attacks before the movement disorder becomes persistent and is frequently misdiagnosed as dyskinetic cerebral palsy. A residual degree of neck hypotonia and a myopathy-like facial appearance are frequently observed in patients with ADCY5 mutations.

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ADCY5 mutational frequency in paediatric patients is unknown.

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5/44 (11%) subjects in our cohort carried pathogenic ADCY5 mutations.

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Chorea-dystonia, exacerbations and developmental delay are often observed together.

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Disease course and clinical features are variable among patients with ADCY5 mutations.

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Residual cervical hypotonia and a myopathy-like face are additional diagnostic clues.

DYT2 screening in early-onset isolated dystonia

BACKGROUND

Mutations in HPCA, a gene implicated in calcium signaling in the striatum, have been recently described in recessive dystonia cases previously grouped under the term "DYT2 dystonia". Positive patients reported so far show focal onset during childhood with subsequent generalization and a slowly progressive course to adulthood.

METHODS

73 patients with isolated dystonia of various distribution, manifesting within 21 years of age, were enrolled in this Italian study and underwent a mutational screening of HPCA gene by means of Sanger sequencing.

RESULTS/CONCLUSIONS

Mean age at onset was 10.2 (±5.1) years and mean age at the time of genetic testing was 33 (±14.2) years. Mean disease duration at the time of enrollment was 22.7 (±12.8) years. None of the patients enrolled was found to carry HPCA mutations, rising suspicion that these probably represent a very rare cause of dystonia in childhood-adolescence. Larger studies will help determining the real mutational frequency of this gene also in different ethnic groups.

Growth Arrest Specific 6 Concentration is Increased in the Cerebrospinal Fluid of Patients with Alzheimer's Disease

Growth arrest specific 6 (Gas6) has neurotrophic and neuroinflammatory functions, and may play a role in Alzheimer's disease (AD). In keeping with this hypothesis, we observed that cerebrospinal fluid (CSF) Gas6 is increased in AD patients compared to controls (63 versus 67 subjects; median value 13.3 versus 9.1 ng/ml; p < 0.0001). Thereafter, we assessed whether CSF Gas6 concentration was correlated to the following parameters: disease duration, MMSE score two years after clinical diagnosis, AD CSF biomarkers, and years of formal schooling. We detected an inverse correlation between CSF Gas6 levels at diagnosis and both disease duration (p < 0.0001) and decrease in the MMSE score two years later (p < 0.0001). Conversely, we found no correlation between CSF Gas6 and both AD biomarkers and years of formal schooling. In conclusion, our results suggest that upregulation of CSF Gas6 may be part of a defensive response aimed at counteracting AD progression.