Action Myoclonus and Seizure in Kufor-Rakeb Syndrome

A novel ATP13A2 variant causing complicated hereditary spastic paraplegia

BACKGROUND

ATP13A2 is a monogenic causative gene of Parkinson's disease, whose biallelic mutations can result in Kufor-Rakeb syndrome. Biallelic mutations in ATP13A2 have also been reported in pure or complicated hereditary spastic paraplegia (HSP). Here, we report clinical, neuroimaging, and genetic findings from a patient with a novel homozygous mutation in ATP13A2 presenting with HSP plus parkinsonism.

METHODS

Whole genome sequencing was performed on the patient, a 46-year-old Chinese woman from a consanguineous family, to identify the genetic cause. Furthermore, functional studies of the identified ATP13A2 mutation were conducted.

RESULTS

The patient initially presented with abnormal gait because of lower-limb spasticity and recurrent seizures. Parkinsonism (presenting as bradykinesia and rigidity) and peripheral neuropathy in lower limbs further evolved and resulted in her eventual use of a wheelchair. Symmetrically decreased dopamine transporter density was detected within the bilateral putamen and caudate nucleus in dopamine transporter-positron emission tomography. Genetic analysis revealed a novel homozygous missense mutation in ATP13A2 (c.2780 T > C, p.Leu927Pro), which was heterozygous in the patient's parents and son. Functional studies suggested that this mutation results in the reduced expression and altered subcellular localization of ATP13A2.

CONCLUSIONS

Our report broadens the genetic and phenotypic spectrum of ATP13A2-related HSP. Further research is needed to fully elucidate the mechanism linking ATP13A2 variants to HSP.

Nine Hereditary Movement Disorders First Described in Asia: Their History and Evolution

Clinical case studies and reporting are important to the discovery of new disorders and the advancement of medical sciences. Both clinicians and basic scientists play equally important roles leading to treatment discoveries for both cures and symptoms. In the field of movement disorders, exceptional observation of patients from clinicians is imperative, not just for phenomenology but also for the variable occurrences of these disorders, along with other signs and symptoms, throughout the day and the disease course. The Movement Disorders in Asia Task Force (TF) was formed to help enhance and promote collaboration and research on movement disorders within the region. As a start, the TF has reviewed the original studies of the movement disorders that were preliminarily described in the region. These include nine disorders that were first described in Asia: Segawa disease, PARK-Parkin, X-linked dystonia-parkinsonism, dentatorubral-pallidoluysian atrophy, Woodhouse-Sakati syndrome, benign adult familial myoclonic epilepsy, Kufor-Rakeb disease, tremulous dystonia associated with mutation of the calmodulin-binding transcription activator 2 gene, and paroxysmal kinesigenic dyskinesia. We hope that the information provided will honor the original researchers and help us learn and understand how earlier neurologists and basic scientists together discovered new disorders and made advances in the field, which impact us all to this day.

Seizure in Neurodegeneration with Brain Iron Accumulation: A Systematic Review

BACKGROUND

Neurodegeneration with brain iron accumulation (NBIA) is a rare genetic disorder. Its clinical manifestations comprise a wide spectrum mainly movement disorders. Seizure as a clinical manifestation is known to occur in some NBIAs, but the exact prevalence of epilepsy in each individual disorder is not well elucidated. The aim of this review was to investigate the frequency of seizures in NBIA disorders as well as to determine the associated features of patients with seizures.

METHOD

The electronic bibliographic databases PubMed, Scopus, Embase, and Google Scholar were systematically searched for all cases in any type of article from inception to December 16, 2019. All the reported cases of NBIA (with or without genetic confirmation) were identified. Case reports with an explicit diagnosis of any types of NBIA, which have reported occurrence (or absence) of any type of seizure or epilepsy, in the English language, were included. Seizure incidence rate, type, and age of onset were reported as frequencies and percentages.

RESULT

1698 articles were identified and 51 were included in this review. Of 305 reported cases, 150 (49.2%) had seizures (phospholipase A2-associated neurodegeneration (PLAN) = 64 (50.8%), beta-propeller protein-associated neurodegeneration (BPAN) = 57 (72.1%), pantothenate kinase-associated neurodegeneration (PKAN) = 11 (23.4%), and others = 18 (very variable proportions)). The most frequent seizure type in NBIA patients was generalized tonic-clonic seizure with the mean age of seizure onset between 2 and 36 years. However, most of these papers had been published before the new classification of epilepsy became accessible. Affected patients were more likely to be females.

CONCLUSION

Seizures are common in NBIA, particularly in PLAN and BPAN. In PKAN, the most common type of NBIA, around 10% of patients are affected by seizures. BPAN is the most possible NBIA accompanying seizure. Most of the findings regarding the seizure characteristics in the NBIAs are biased due to the huge missing data. Therefore, any conclusions should be made with caution and need further investigations.

Genotype-Phenotype Correlation in Progressive Supranuclear Palsy Syndromes: Clinical and Radiological Similarities and Specificities

The progressive supranuclear palsy (PSP) syndrome encompasses different entities. PSP disease of sporadic origin is the most frequent presentation, but different genetic mutations can lead either to monogenic variants of PSP disease, or to other conditions with a different pathophysiology that eventually may result in PSP phenotype. PSP syndrome of monogenic origin is poorly understood due to the low prevalence and variable expressivity of some mutations. Through this review, we describe how early age of onset, family history of early dementia, parkinsonism, dystonia, or motor neuron disease among other clinical features, as well as some neuroimaging signatures, may be the important clues to suspect PSP syndrome of monogenic origin. In addition, a diagnostic algorithm is proposed that may be useful to guide the genetic diagnosis once there is clinical suspicion of a monogenic PSP syndrome.

Nomenclature of Genetic Movement Disorders: Recommendations of the International Parkinson and Movement Disorder Society Task Force - An Update

In 2016, the Movement Disorder Society Task Force for the Nomenclature of Genetic Movement Disorders presented a new system for naming genetically determined movement disorders and provided a criterion-based list of confirmed monogenic movement disorders. Since then, a substantial number of novel disease-causing genes have been described, which warrant classification using this system. In addition, with this update, we further refined the system and propose dissolving the imaging-based categories of Primary Familial Brain Calcification and Neurodegeneration with Brain Iron Accumulation and reclassifying these genetic conditions according to their predominant phenotype. We also introduce the novel category of Mixed Movement Disorders (MxMD), which includes conditions linked to multiple equally prominent movement disorder phenotypes. In this article, we present updated lists of newly confirmed monogenic causes of movement disorders. We found a total of 89 different newly identified genes that warrant a prefix based on our criteria; 6 genes for parkinsonism, 21 for dystonia, 38 for dominant and recessive ataxia, 5 for chorea, 7 for myoclonus, 13 for spastic paraplegia, 3 for paroxysmal movement disorders, and 6 for mixed movement disorder phenotypes; 10 genes were linked to combined phenotypes and have been assigned two new prefixes. The updated lists represent a resource for clinicians and researchers alike and they have also been published on the website of the Task Force for the Nomenclature of Genetic Movement Disorders on the homepage of the International Parkinson and Movement Disorder Society (https://www.movementdisorders.org/MDS/About/Committees--Other-Groups/MDS-Task-Forces/Task-Force-on-Nomenclature-in-Movement-Disorders.htm). © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

Neurodegeneration with Brain Iron Accumulation and a Brief Report of the Disease in Iran

Neurodegeneration with brain iron accumulation (NBIA) is a term used for a group of hereditary neurological disorders with abnormal accumulation of iron in basal ganglia. It is clinically and genetically heterogeneous with symptoms such as dystonia, dysarthria, Parkinsonism, intellectual disability, and spasticity. The age at onset and rate of progression are variable among individuals. Current therapies are exclusively symptomatic and unable to hinder the disease progression. Approximately 16 genes have been identified and affiliated to such condition with different functions such as iron metabolism (only two genes: Ferritin Light Chain (FTL) Ceruloplasmin (CP)), lipid metabolism, lysosomal functions, and autophagy process, but some functions have remained unknown so far. Subgroups of NBIA are categorized based on the mutant genes. Although in the last 10 years, the development of whole-exome sequencing (WES) technology has promoted the identification of disease-causing genes, there seem to be some unknown genes and our knowledge about the molecular aspects and pathogenesis of NBIA is not complete yet. There is currently no comprehensive study about the NBIA in Iran; however, one of the latest discovered NBIA genes, GTP-binding protein 2 (GTPBP2), has been identified in an Iranian family, and there are some patients who have genetically remained unknown.

Clinical and neuroimaging phenotypes of genetic parkinsonism from infancy to adolescence

Genetic early-onset parkinsonism presenting from infancy to adolescence (≤21 years old) is a clinically diverse syndrome often combined with other hyperkinetic movement disorders, neurological and imaging abnormalities. The syndrome is genetically heterogeneous, with many causative genes already known. With the increased use of next-generation sequencing in clinical practice, there have been novel and unexpected insights into phenotype-genotype correlations and the discovery of new disease-causing genes. It is now recognized that mutations in a single gene can give rise to a broad phenotypic spectrum and that, conversely different genetic disorders can manifest with a similar phenotype. Accurate phenotypic characterization remains an essential step in interpreting genetic findings in undiagnosed patients. However, in the past decade, there has been a marked expansion in knowledge about the number of both disease-causing genes and phenotypic spectrum of early-onset cases. Detailed knowledge of genetic disorders and their clinical expression is required for rational planning of genetic and molecular testing, as well as correct interpretation of next-generation sequencing results. In this review we examine the relevant literature of genetic parkinsonism with ≤21 years onset, extracting data on associated movement disorders as well as other neurological and imaging features, to delineate syndromic patterns associated with early-onset parkinsonism. Excluding PRKN (parkin) mutations, >90% of the presenting phenotypes have a complex or atypical presentation, with dystonia, abnormal cognition, pyramidal signs, neuropsychiatric disorders, abnormal imaging and abnormal eye movements being the most common features. Furthermore, several imaging features and extraneurological manifestations are relatively specific for certain disorders and are important diagnostic clues. From the currently available literature, the most commonly implicated causes of early-onset parkinsonism have been elucidated but diagnosis is still challenging in many cases. Mutations in ∼70 different genes have been associated with early-onset parkinsonism or may feature parkinsonism as part of their phenotypic spectrum. Most of the cases are caused by recessively inherited mutations, followed by dominant and X-linked mutations, and rarely by mitochondrially inherited mutations. In infantile-onset parkinsonism, the phenotype of hypokinetic-rigid syndrome is most commonly caused by disorders of monoamine synthesis. In childhood and juvenile-onset cases, common genotypes include PRKN, HTT, ATP13A2, ATP1A3, FBX07, PINK1 and PLA2G6 mutations. Moreover, Wilson’s disease and mutations in the manganese transporter are potentially treatable conditions and should always be considered in the differential diagnosis in any patient with early-onset parkinsonism.

Juvenile Parkinson Disease

Juvenile Parkinson's disease (JPD) is a rare movement disorder that presents before the age of 21 years. Kufor-Rekab syndrome (KRS) is one of the distinct types of JPD caused by the ATP13A2 mutation and inherited as an autosomal recessive. The pathogenesis of KRS is related to an interrelated metabolism of ATP13A2 with Mn+2 and Zn+2, bioenergetics of mitochondria, autophagy lysosomal dysfunction, and synuclein metabolism. Clinically, KRS has a variable phenotype and may present with pyramidal or extrapyramidal symptoms and cognitive impairment. Early diagnosis of KRS is important as most of these patients are levodopa-responsive and genetic counseling and screening is important for the whole family. We present a case of a 16-year-old boy who presented with tremors and walking difficulty. His physical examination showed an expressionless face, decrease in eye blink frequency, and slow vertical saccadic eye movements. His movements were slow. All laboratory investigations were normal, except the genetic study, which led to the diagnosis of KRS.

Neuropathology and pathogenesis of extrapyramidal movement disorders: a critical update-I. Hypokinetic-rigid movement disorders

Extrapyramidal movement disorders include hypokinetic rigid and hyperkinetic or mixed forms, most of them originating from dysfunction of the basal ganglia (BG) and their information circuits. The functional anatomy of the BG, the cortico-BG-thalamocortical, and BG-cerebellar circuit connections are briefly reviewed. Pathophysiologic classification of extrapyramidal movement disorder mechanisms distinguish (1) parkinsonian syndromes, (2) chorea and related syndromes, (3) dystonias, (4) myoclonic syndromes, (5) ballism, (6) tics, and (7) tremor syndromes. Recent genetic and molecular-biologic classifications distinguish (1) synucleinopathies (Parkinson's disease, dementia with Lewy bodies, Parkinson's disease-dementia, and multiple system atrophy); (2) tauopathies (progressive supranuclear palsy, corticobasal degeneration, FTLD-17; Guamian Parkinson-dementia; Pick's disease, and others); (3) polyglutamine disorders (Huntington's disease and related disorders); (4) pantothenate kinase-associated neurodegeneration; (5) Wilson's disease; and (6) other hereditary neurodegenerations without hitherto detected genetic or specific markers. The diversity of phenotypes is related to the deposition of pathologic proteins in distinct cell populations, causing neurodegeneration due to genetic and environmental factors, but there is frequent overlap between various disorders. Their etiopathogenesis is still poorly understood, but is suggested to result from an interaction between genetic and environmental factors. Multiple etiologies and noxious factors (protein mishandling, mitochondrial dysfunction, oxidative stress, excitotoxicity, energy failure, and chronic neuroinflammation) are more likely than a single factor. Current clinical consensus criteria have increased the diagnostic accuracy of most neurodegenerative movement disorders, but for their definite diagnosis, histopathological confirmation is required. We present a timely overview of the neuropathology and pathogenesis of the major extrapyramidal movement disorders in two parts, the first one dedicated to hypokinetic-rigid forms and the second to hyperkinetic disorders.