Autosomal dominant guanosine triphosphate cyclohydrolase I deficiency (Segawa disease)

Compound heterozygous mutations in three Chinese patients of Segawa syndrome and their treatment outcomes

Segawa syndrome is a rare autosomal recessive form of dopa-responsive dystonia resulting from TH gene dysfunction. Patients typically exhibit symptoms such as generalized dystonia, rigidity, tremors, infantile Parkinsonism, and pseudo-spastic paraplegia. Levodopa is often an effective treatment. Due to its rarity, high heterogeneity, and poorly understood pathological mutation and phenotype spectrums, as well as genotype-phenotype and genotype-treatment outcome correlations, Segawa syndrome poses diagnostic and therapeutic challenges. In our study, through clinical and molecular analyses of three Chinese Segawa patients, we re-evaluated the pathogenicity of a TH mutation (c.880G>C;p.G294R) previously categorized as "Conflicting classifications of pathogenicity" in ClinVar. Also, we summarized the clinical phenotypes of all reported Segawa syndrome cases until 2023 and compared them with our patients. We identified a novel phenotype, "cafe-au-lait macules," not previously observed in Segawa patients. Additionally, we discussed the correlation between specific genotypes and phenotypes, as well as genotypes and treatment outcomes of our three cases. Our findings aim to enhance the understanding of Segawa syndrome, contributing to improved diagnosis and treatment approaches in the future.

Establishment of a non-integrated iPSC (SDQLCHi066-A) line derived from Segawa syndrome patients harboring heterozygous mutations in the TH gene (p.G247S and p.D491H)

Segawa syndrome, an autosomal recessive genetic disorder, arises from homozygous or compound heterozygous mutations in the TH gene. We established an induced pluripotent stem cell (iPSC) line from peripheral blood mononuclear cells (PBMCs) of an 4-month-old girl with Segawa syndrome, who carried compound heterozygous mutations of c.739G > A/chr11:2188714 and c.1471G > C/chr11:2185579 in TH. The iPSCs displayed a normal karyotype, expressed pluripotency markers, were devoid of genomically integrated episomal plasmids, and demonstrated trilineage differentiation potential in vitro.

Age- and sex-related oculomotor manifestation of dopamine deficiency in Segawa disease

OBJECTIVE

To investigate the oculomotor manifestations of Segawa disease (SD), considered to represent mild dopamine deficiency and discuss their pathophysiological basis.

METHODS

We recorded visually- (VGS) and memory-guided saccade (MGS) tasks in 31 SD patients and 153 age-matched control subjects to study how basal ganglia (BG) dysfunction in SD evolves with age for male and female subjects.

RESULTS

SD patients were impaired in initiating MGS, showing longer latencies with occasional failure. Patients showed impaired ability to suppress reflexive saccades; saccades to cues presented in MGS were more frequent and showed a shorter latency than in control subjects. These findings were more prominent in male patients, particularly between 13 and 25 years. Additionally, male patients showed larger delay in MGS latency in trials preceded by saccades to cue than those unpreceded.

CONCLUSIONS

The findings can be explained by a dysfunction of the BG-direct pathway impinging on superior colliculus (SC) due to dopamine deficiency. The disturbed inhibitory control of saccades may be explained by increased SC responsivity to visual stimuli.

SIGNIFICANCE

Oculomotor abnormalities in SD can be explained by dysfunction of the BG inhibitory pathways reaching SC, with a delayed maturation in male SD patients, consistent with previous pathological/physiological studies.

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.

Cerebrospinal Fluid Concentrations of Neurotransmitters in a Greek Pediatric Reference Population

BACKGROUND

 Biogenic amines and pterins analysis in cerebrospinal fluid (CSF) are reliable biomarkers for the diagnosis of inherited disorders of monoamine neurotransmitters.

OBJECTIVE

 The objectives of this study were the establishment of reference values of CSF biogenic amine metabolites in a cohort of Greek children, the detection of primary defects of biogenic amine metabolism, and the assessment of biogenic amine metabolites in children with different neurological disorders.

METHODS

 CSF biogenic amine metabolites and pterins (biopterin and neopterin) were analyzed using high-performance liquid chromatography with electrochemical and fluorescence detection. Three hundred sixty-three samples were analyzed: 60 infants and children with no history of neurological disorder, 6 with inherited disorders of monoamine neurotransmitters, and 297 with diverse neurological disorders.

RESULTS

 Reference values were stratified into six age groups. A strong correlation between homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5HIAA) levels with age was detected (p < 0.001). Two patients were diagnosed with a defect of the biogenic amine synthetic pathway and three with a defect of tetrahydrobiopterin cofactor production. HVA and 5HIAA abnormalities were detected within different groups of neurological disorders, but none followed a specific pattern of HVA and 5HIAA abnormalities.

CONCLUSION

 In the current study, Greek reference values of biogenic amines and pterins in CSF are presented. Five new patients with inherited monoamine neurotransmitter disorders are described. Nonspecific secondary biogenic amine disturbances can be seen in patients with different neurological disorders.

Isolated and combined dystonias: Update

Dystonia is a hyperkinetic movement disorder with a unique motor phenomenology that can manifest as an isolated clinical syndrome or combined with other neurological features. This chapter reviews the characteristic features of dystonia phenomenology and the syndromic approach to evaluating the disorders that may allow us to differentiate the isolated and combined syndromes. We also present the most common types of isolated and combined dystonia syndromes. Since accelerated gene discoveries have increased our understanding of the molecular mechanisms of dystonia pathogenesis, we also present isolated and combined dystonia syndromes by shared biological pathways. Examples of these converging mechanisms of the isolated and combined dystonia syndromes include (1) disruption of the integrated response pathway through eukaryotic initiation factor 2 alpha signaling, (2) disease of dopaminergic signaling, (3) alterations in the cerebello-thalamic pathway, and (4) disease of protein mislocalization and stability. The discoveries that isolated and combined dystonia syndromes converge in shared biological pathways will aid in the development of clinical trials and therapeutic strategies targeting these convergent molecular pathways.

Childhood-onset hereditary spastic paraplegia and its treatable mimics

Early-onset forms of hereditary spastic paraplegia and inborn errors of metabolism that present with spastic diplegia are among the most common "mimics" of cerebral palsy. Early detection of these heterogenous genetic disorders can inform genetic counseling, anticipatory guidance, and improve outcomes, particularly where specific treatments exist. The diagnosis relies on clinical pattern recognition, biochemical testing, neuroimaging, and increasingly next-generation sequencing-based molecular testing. In this short review, we summarize the clinical and molecular understanding of: 1) childhood-onset and complex forms of hereditary spastic paraplegia (SPG5, SPG7, SPG11, SPG15, SPG35, SPG47, SPG48, SPG50, SPG51, SPG52) and, 2) the most common inborn errors of metabolism that present with phenotypes that resemble hereditary spastic paraplegia.

Time estimation and arousal responses in dopa-responsive dystonia

Dopa-responsive dystonia (DRD) is caused by an impaired dopamine biosynthesis due to a GTP-cyclohydrolase-1 (GCH1) deficiency, resulting in a combination of dystonia and parkinsonism. However, the effect of GCH1 mutations and levodopa treatment on motor control beyond simple movements, such as timing, action preparation and feedback processing, have not been investigated so far. In an active time estimation task with trial-by-trial feedback, participants indicated a target interval (1200 ms) by a motor response. We compared 12 patients tested (in fixed order) under their current levodopa medication ("ON") and after levodopa withdrawal ("OFF") to matched healthy controls (HC), measured twice to control for repetition effects. We assessed time estimation accuracy, trial-to-trial adjustment, as well as task- and feedback-related pupil-linked arousal responses. Patients showed comparable time estimation accuracy ON medication as HC but reduced performance OFF medication. Task-related pupil responses showed the reverse pattern. Trial-to-trial adjustments of response times were reduced in DRD, particularly OFF medication. Our results indicate differential alterations of time estimation accuracy and task-related arousal dynamics in DRD patients as a function of dopaminergic medication state. A medication-independent alteration of task repetition effects in DRD cannot be ruled out with certainty but is discussed as less likely.

Modulation of Reactive Oxygen Species Homeostasis as a Pleiotropic Effect of Commonly Used Drugs

Age-associated diseases represent a growing burden for global health systems in our aging society. Consequently, we urgently need innovative strategies to counteract these pathological disturbances. Overwhelming generation of reactive oxygen species (ROS) is associated with age-related damage, leading to cellular dysfunction and, ultimately, diseases. However, low-dose ROS act as crucial signaling molecules and inducers of a vaccination-like response to boost antioxidant defense mechanisms, known as mitohormesis. Consequently, modulation of ROS homeostasis by nutrition, exercise, or pharmacological interventions is critical in aging. Numerous nutrients and approved drugs exhibit pleiotropic effects on ROS homeostasis. In the current review, we provide an overview of drugs affecting ROS generation and ROS detoxification and evaluate the potential of these effects to counteract the development and progression of age-related diseases. In case of inflammation-related dysfunctions, cardiovascular- and neurodegenerative diseases, it might be essential to strengthen antioxidant defense mechanisms in advance by low ROS level rises to boost the individual ROS defense mechanisms. In contrast, induction of overwhelming ROS production might be helpful to fight pathogens and kill cancer cells. While we outline the potential of ROS manipulation to counteract age-related dysfunction and diseases, we also raise the question about the proper intervention time and dosage.

Clinical Manifestations and Molecular Backgrounds of Parkinson's Disease Regarding Genes Identified From Familial and Population Studies

Over the past 20 years, numerous robust analyses have identified over 20 genes related to familial Parkinson's disease (PD), thereby uncovering its molecular underpinnings and giving rise to more sophisticated approaches to investigate its pathogenesis. α-Synuclein is a major component of Lewy bodies (LBs) and behaves in a prion-like manner. The discovery of α-Synuclein enables an in-depth understanding of the pathology behind the generation of LBs and dopaminergic neuronal loss. Understanding the pathophysiological roles of genes identified from PD families is uncovering the molecular mechanisms, such as defects in dopamine biosynthesis and metabolism, excessive oxidative stress, dysfunction of mitochondrial maintenance, and abnormalities in the autophagy–lysosome pathway, involved in PD pathogenesis. This review summarizes the current knowledge on familial PD genes detected by both single-gene analyses obeying the Mendelian inheritance and meta-analyses of genome-wide association studies (GWAS) from genome libraries of PD. Studying the functional role of these genes might potentially elucidate the pathological mechanisms underlying familial PD and sporadic PD and stimulate future investigations to decipher the common pathways between the diseases.

Recognizing Atypical Dopa-Responsive Dystonia and Its Mimics

Purpose of Review

Dopa-responsive dystonia (DRD) encompasses a group of phenotypically and genetically heterogeneous neurochemical disorders. Classic GTP cyclohydrolase 1 (GCH-1)-associated DRD consists of early-onset lower limb asymmetrical dystonia, with sleep benefit, diurnal variation, and excellent and sustained response to low l-dopa doses.

Recent Findings

Unlike the classic phenotype, GCH-1-associated DRD may include features inconsistent with the original phenotype. We describe a GCH-1-associated late-onset DRD case with a family history of parkinsonism and cervical dystonia whose response to levodopa was poor and complicated with dyskinesia, blepharospasm, and severe nonmotor symptoms. We use this case as a springboard to review the spectrum of atypical DRD, DRD-plus, and DRD mimics.

Summary

GCH-1-related dystonia may exhibit wide intrafamilial phenotypic variability, no diurnal fluctuation, poor response to l-dopa, and such complications as dyskinesia, epilepsy, sleep disorders, autonomic dysfunction, oculogyric crisis, myoclonus, or tics. More recently, rare GCH-1 variants have been found to be associated with Parkinson disease. Clinicians should be aware of atypical DRD, DRD-plus, and DRD mimics.

Gait disturbance in a patient with de novo 1.0-kb SOX2 microdeletion

BACKGROUND

Sex-determining region Y-box 2 (SOX2) plays an important role in the early embryogenesis of the eye, forebrain, and hypothalamic-pituitary axis. Anophthalmia, microphthalmia, and hormonal abnormalities are commonly observed in patients with SOX2-related disorders. Although gait disturbance, particularly ataxic gait, has recently been observed in several cases, detailed data regarding the clinical course of gait disturbance in SOX2-related disorders are limited.

CASE REPORT

A 9-year-old Japanese boy presented with focal dyskinesia only during walking and running after he started walking at the age of 3 years. He also exhibited intellectual disability and mild dysmorphic features, including microcephaly, micropenis, and short stature associated with hormonal abnormalities. Gait disturbance with involuntary extremity movements only during walking and running was indicative of choreoathetosis and dystonia. Genetic analysis detected a de novo heterozygous 1.0-kb deletion including SOX2 at 3q26.32, as described in a previous technical paper.

CONCLUSIONS

SOX2-related disorders should be considered in patients with some anomalies having a differential diagnosis of dyskinesia. Focal dyskinesia only during walking and running may be a characteristic feature of SOX2-related disorders.

Relationship of Genotype, Phenotype, and Treatment in Dopa-Responsive Dystonia: MDSGene Review

BACKGROUND

Pathogenic variants in 5 genes (GCH1, TH, PTS, SPR, and QDPR), involved in dopamine/tetrahydrobiopterin biosynthesis or recycling, have been linked to Dopa-responsive dystonia (DRD). Diagnosis and treatment are often delayed due to high between- and within-group variability.

OBJECTIVES

Comprehensively analyzed individual genotype, phenotype, treatment response, and biochemistry information.

METHODS

734 DRD patients and 151 asymptomatic GCH1 mutation carriers were included using an MDSGene systematic literature review and an automated classification approach to distinguish between different forms of monogenic DRDs.

RESULTS

Whereas dystonia, L-Dopa responsiveness, early age at onset, and diurnal fluctuations were identified as red flags, parkinsonism without dystonia was rarely reported (11%) and combined with dystonia in only 18% of patients. While sex was equally distributed in autosomal recessive DRD, there was female predominance in autosomal dominant DYT/PARK-GCH1 patients accompanied by a lower median age at onset and more dystonia in females compared to males. Accordingly, the majority of asymptomatic heterozygous GCH1 mutation carriers (>8 years of age) were males. Multiple other subgroup-specific characteristics were identified, showing high accuracy in the automated classification approach: Seizures and microcephaly were mostly seen in DYT/PARK-PTS, autonomic symptoms appeared commonly in DYT/PARK-TH and DYT/PARK-PTS, and sleep disorders and oculogyric crises in DYT/PARK-SPR. Biochemically, homovanillic acid and 5-hydroxyindoleacetic acid in CSF were reduced in most DRDs, but neopterin and biopterin were increased only in DYT/PARK-PTS and DYT/PARK-SPR. Hyperphenylalaninemia was seen in DYT/PARK-PTS, DYT/PARK-QDPR, and rarely reported in autosomal recessive DYT/PARK-GCH1.

CONCLUSIONS

Our indicators will help to specify diagnosis and accelerate start of treatment. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

A Practical Approach to Early-Onset Parkinsonism

Early-onset parkinsonism (EO parkinsonism), defined as subjects with disease onset before the age of 40 or 50 years, can be the main clinical presentation of a variety of conditions that are important to differentiate. Although rarer than classical late-onset Parkinson’s disease (PD) and not infrequently overlapping with forms of juvenile onset PD, a correct diagnosis of the specific cause of EO parkinsonism is critical for offering appropriate counseling to patients, for family and work planning, and to select the most appropriate symptomatic or etiopathogenic treatments. Clinical features, radiological and laboratory findings are crucial for guiding the differential diagnosis. Here we summarize the most important conditions associated with primary and secondary EO parkinsonism. We also proposed a practical approach based on the current literature and expert opinion to help movement disorders specialists and neurologists navigate this complex and challenging landscape.

Second hit hypothesis in dystonia: Dysfunctional cross talk between neuroplasticity and environment?

One of the great mysteries in dystonia pathophysiology is the role of environmental factors in disease onset and development. Progress has been made in defining the genetic components of dystonic syndromes, still the mechanisms behind the discrepant relationship between dystonic genotype and phenotype remain largely unclear. Within this review, the preclinical and clinical evidence for environmental stressors as disease modifiers in dystonia pathogenesis are summarized and critically evaluated. The potential role of extragenetic factors is discussed in monogenic as well as adult-onset isolated dystonia. The available clinical evidence for a "second hit" is analyzed in light of the reduced penetrance of monogenic dystonic syndromes and put into context with evidence from animal and cellular models. The contradictory studies on adult-onset dystonia are discussed in detail and backed up by evidence from animal models. Taken together, there is clear evidence of a gene-environment interaction in dystonia, which should be considered in the continued quest to unravel dystonia pathophysiology.

Early-onset autosomal dominant GTP-cyclohydrolase I deficiency: Diagnostic delay and residual motor signs

OBJECTIVE

Autosomal dominant (AD) guanosine triphosphate cyclohydrolase 1 (GCH1) deficiency is the most common cause of dopa-responsive dystonia (DRD). Patients with GCH1 deficiency are likely to experience diagnostic delay, but its consequences have not been described thoroughly in patients with early-onset disease. We describe the diagnostic delay and residual motor signs (RMS) observed in patients with early-onset (before 15 years of age) disease.

METHODS

Twelve patients with early-onset AD GCH1 deficiency from a single center were included in the case series analysis. For the meta-analysis, the PubMed database was searched for articles on early-onset AD GCH1 deficiency published from 1995 to 2019.

RESULTS

In the case series, the mean duration of diagnostic delay was 5.6 years. Two patients exhibited RMS, and four patients underwent orthopedic surgery. The literature search yielded 137 AD GCH1 deficiency cases for review; gait disturbance was reported in 92.7% of patients, diurnal fluctuation of symptoms in 91.9%, and RMS in 39%. The mean duration of diagnostic delay was 14.6 years overall: 12.0 years in RMS-negative patients and 21.2 years in RMS-positive patients.

CONCLUSIONS

Diagnostic delay in early-onset AD GCH1 deficiency is more closely associated with later RMS. Early clinical suspicion, timely diagnosis, and levodopa treatment may reduce the occurrence of RMS in patients with early-onset AD GCH1 deficiency.

Perspectives on the pharmacological management of dystonia

Introduction: Treatment of dystonia is particularly complex due to various etiologies and heterogeneous clinical manifestation, as well as different degrees of disability. In absence of causative treatment, all symptomatic therapy should be predominantly tailored to ameliorate those symptoms (motor and non/motor) that mostly affect patients' daily life and regular activities. Many different treatment options, including oral medications, neurosurgical interventions, physical and occupational therapy are available in treatment of dystonia.Areas covered: The aim of this perspective is to point out different possibilities in pharmacological management of dystonic movements. Due to pure clinical presentation, the authors concentrate mainly on the isolated dystonias, which are presented solely as dystonic movements. Combined and complex dystonias are not instructive due to compound clinical presentation and consequently, complicated treatment. The article is based on a literature search from sources including PubMed, the Cochrane Library, Web of Science, PiCarta, and PsycINFO.Expert opinion: Although dystonia therapy should be adapted according to the individual needs, severity, age, type, symptoms distribution and acceptable side-effect profile, certain principles should be followed to reach the optimal result. Furthermore, the authors believe that a better understanding of the pathophysiology of dystonia will bring with it the development of new and improved treatment approaches and medications.

Dopa-responsive dystonia, DRD-plus and DRD look-alike: a pragmatic review

Dopa-responsive dystonia (DRD) and DRD plus are diseases of the dopamine pathway with sizeable genetic diversity and myriad presentations. DRD has onset in childhood or adolescence with focal dystonia, commonly affecting lower limb, diurnal fluctuations with evening worsening of symptoms and a demonstrable sleep benefit. DRD "plus" has "atypical features" which include infantile onset, psychomotor delay, cognitive abnormalities, oculogyric crisis, seizures, irritability, spasticity, hypotonia, ptosis, hyperthermia and cerebellar dysfunction. Neurodegeneration, however, is not a feature of either DRD or DRD-plus disorders. Tetrahydrobiopterin (BH4), a key cofactor, deficiency leads to inadequate dopamine and serotonin synthesis. Norepinephrine deficiency may coexist, depending on the enzyme defect. Hyperphenylalaninemia (HPA) is a clue for BH4 paucity. However, HPA is conspicuously absent in autosomal-dominant guanosine triphosphate cyclohydrolase 1 deficiency and sepiapterin reductase deficiency. DRD look-alike is a group of neurodegenerative disorders involving the nigrostriatal dopaminergic system, which could present with dystonia responsive to dopaminergic drugs or neurodegenerative or non-neurodegenerative disorders without involving the nigrostriatal dopaminergic system yet responsive to levodopa. Although levodopa is the mainstay of therapy, response to this drug can be unsatisfactory in DRD plus and DRD look-alike and other drugs are tried. Simultaneous management of HPA leads to remarkable improvement in both motor and cognitive functions. The aim of this review is to help neurology practitioners in treating patients with DRD, DRD-plus and DRD look-alike as many of them have excellent outcome with appropriate therapy.

Molecular and metabolic bases of tetrahydrobiopterin (BH4) deficiencies

Tetrahydrobiopterin (BH4) deficiency is caused by genetic variants in the three genes involved in de novo cofactor biosynthesis, GTP cyclohydrolase I (GTPCH/GCH1), 6-pyruvoyl-tetrahydropterin synthase (PTPS/PTS), sepiapterin reductase (SR/SPR), and the two genes involved in cofactor recycling, carbinolamine-4α-dehydratase (PCD/PCBD1) and dihydropteridine reductase (DHPR/QDPR). Dysfunction in BH4 metabolism leads to reduced cofactor levels and may result in systemic hyperphenylalaninemia and/or neurological sequelae due to secondary deficiency in monoamine neurotransmitters in the central nervous system. More than 1100 patients with BH4 deficiency and 800 different allelic variants distributed throughout the individual genes are tabulated in database of pediatric neurotransmitter disorders PNDdb. Here we provide an update on the molecular-genetic analysis and structural considerations of these variants, including the clinical courses of the genotypes. From a total of 324 alleles, 11 are associated with the autosomal recessive form of GTPCH deficiency presenting with hyperphenylalaninemia (HPA) and neurotransmitter deficiency, 295 GCH1 variant alleles are detected in the dominant form of L-dopa-responsive dystonia (DRD or Segawa disease) while phenotypes of 18 alleles remained undefined. Autosomal recessive variants observed in the PTS (199 variants), PCBD1 (32 variants), and QDPR (141 variants) genes lead to HPA concomitant with central monoamine neurotransmitter deficiency, while SPR deficiency (104 variants) presents without hyperphenylalaninemia. The clinical impact of reported variants is essential for genetic counseling and important for development of precision medicine.

Inter and intra-generational phenotypic variability in a Portuguese family with DYT-GCH1

DYT-GCH1 is the most common form of Dopa-responsive dystonia. We analysed a three-generation Portuguese family with the same variant of DYT-GCH1. Dystonia and parkinsonism were found, along with non-motor symptoms. There was a wide array of phenotypic manifestations. Further studies are needed to explain the wide clinical expression of this entity.

A severe form of autosomal recessive spinocerebellar ataxia associated with novel PMPCA variants

Spinocerebellar ataxia, autosomal recessive 2 (SCAR2) [MIM:213200] is a rare autosomal recessive disease of spinocerebellar ataxia associated with degeneration of the cerebellum with variable involvement of the brainstem and spinal cord. SCAR2 is characterized by onset of impaired motor development and ataxic gait in early childhood. Recently, several PMPCA gene variants have been reported in SCAR2 patients with mild and non-progressive symptoms. PMPCA codes frataxin, which is crucial for iron biosynthesis in cells. We report a case of a 15-year-old Japanese girl with infancy-onset, very severe and progressive developmental delay, cerebellar ataxia, and extrapyramidal symptoms. Brain magnetic resonance imaging showed cerebellar atrophy and excessive brain iron accumulation in the bilateral globus pallidi and substantia nigra. Based on the clinical phenotypes and imaging, neurodegeneration with brain iron accumulation was suspected. Whole-exome sequencing on the proband and her parents revealed novel compound heterozygous variants at c.667C > T (p.Arg223Cys) and c.853del (p.Asp285llefs*16) in PMPCA. Thus, her disease was diagnosed as SCAR2. Phenotype in our case was different from ones previously reported for SCARs in the points of much severer clinical presentations with extrapyramidal signs and imaging suspected iron accumulation, and might overlap neurodegeneration with brain iron accumulation or NBIA subtypes. Our case might provide a new insight into PMPCA gene-related disorders and expand the disease concept.

Dystonia updates: definition, nomenclature, clinical classification, and etiology

A plethora of heterogeneous movement disorders is grouped under the umbrella term dystonia. The clinical presentation ranges from isolated dystonia to multi-systemic disorders where dystonia is only a co-occurring sign. In the past, definitions, nomenclature, and classifications have been repeatedly refined, adapted, and extended to reflect novel findings and increasing knowledge about the clinical, etiologic, and scientific background of dystonia. Currently, dystonia is suggested to be classified according to two axes. The first axis offers precise categories for the clinical presentation grouped into age at onset, body distribution, temporal pattern and associated features. The second, etiologic, axis discriminates pathological findings, as well as inheritance patterns, mode of acquisition, or unknown causality. Furthermore, the recent recommendations regarding terminology and nomenclature of inherited forms of dystonia and related syndromes are illustrated in this article. Harmonized, specific, and internationally widely used classifications provide the basis for future systematic dystonia research, as well as for more personalized patient counseling and treatment approaches.

Series of Dopa Responsive Dystonia Masquerading as Other Diseases with Short Review

Dopa-responsive dystonia (DRD) encompasses a group of clinically and genetically heterogeneous disorders that typically manifest as limb-onset, diurnally fluctuating dystonia presenting in early life and exhibits a robust and sustained response to levodopa treatment. DRD is one of the treatable dystonia syndromes of childhood. It starts with the involvement of lower limb and associated with characteristic diurnal variation. Many times it is misdiagnosed as cerebral palsy due to selective lower limb preference. We report a series of three cases of DRD which were previously misdiagnosed. The first case presented as myelopathy and other two were diagnosed as cerebral palsy. It is a treatable condition with very good response to drugs. Early diagnosis and adequate therapy can prevent from catastrophic complications.

Neurodevelopmental signatures of narcotic and neuropsychiatric risk factors in 3D human-derived forebrain organoids

It is widely accepted that narcotic use during pregnancy and specific environmental factors (e.g., maternal immune activation and chronic stress) may increase risk of neuropsychiatric illness in offspring. However, little progress has been made in defining human-specific in utero neurodevelopmental pathology due to ethical and technical challenges associated with accessing human prenatal brain tissue. Here we utilized human induced pluripotent stem cells (hiPSCs) to generate reproducible organoids that recapitulate dorsal forebrain development including early corticogenesis. We systemically exposed organoid samples to chemically defined "enviromimetic" compounds to examine the developmental effects of various narcotic and neuropsychiatric-related risk factors within tissue of human origin. In tandem experiments conducted in parallel, we modeled exposure to opiates (μ-opioid agonist endomorphin), cannabinoids (WIN 55,212-2), alcohol (ethanol), smoking (nicotine), chronic stress (human cortisol), and maternal immune activation (human Interleukin-17a; IL17a). Human-derived dorsal forebrain organoids were consequently analyzed via an array of unbiased and high-throughput analytical approaches, including state-of-the-art TMT-16plex liquid chromatography/mass-spectrometry (LC/MS) proteomics, hybrid MS metabolomics, and flow cytometry panels to determine cell-cycle dynamics and rates of cell death. This pipeline subsequently revealed both common and unique proteome, reactome, and metabolome alterations as a consequence of enviromimetic modeling of narcotic use and neuropsychiatric-related risk factors in tissue of human origin. However, of our 6 treatment groups, human-derived organoids treated with the cannabinoid agonist WIN 55,212-2 exhibited the least convergence of all groups. Single-cell analysis revealed that WIN 55,212-2 increased DNA fragmentation, an indicator of apoptosis, in human-derived dorsal forebrain organoids. We subsequently confirmed induction of DNA damage and apoptosis by WIN 55,212-2 within 3D human-derived dorsal forebrain organoids. Lastly, in a BrdU pulse-chase neocortical neurogenesis paradigm, we identified that WIN 55,212-2 was the only enviromimetic treatment to disrupt newborn neuron numbers within human-derived dorsal forebrain organoids. Cumulatively this study serves as both a resource and foundation from which human 3D biologics can be used to resolve the non-genomic effects of neuropsychiatric risk factors under controlled laboratory conditions. While synthetic cannabinoids can differ from naturally occurring compounds in their effects, our data nonetheless suggests that exposure to WIN 55,212-2 elicits neurotoxicity within human-derived developing forebrain tissue. These human-derived data therefore support the long-standing belief that maternal use of cannabinoids may require caution so to avoid any potential neurodevelopmental effects upon developing offspring in utero.

Anesthetic nuances in Segawa's syndrome: A case report and review of the literature

Segawa's syndrome, dopamine-responsive dystonia, is a rare genetic disorder that typically begins in childhood by around 4–6 years of age. It is characterized by abnormal gait and dystonia. A 33-year-old man presented for autologous skin grafting of a nonhealing wound under general anesthesia. Successful anesthetic management of patients with this rare disease, though analogous in many ways to that of patients with Parkinson's disease, still pose significant challenges. We present anesthetic nuances to be considered in the management of a patient with Segawa's disease along with a pertinent review of the literature.

Sepiapterin reductase: Characteristics and role in diseases

Sepiapterin reductase, a homodimer composed of two subunits, plays an important role in the biosynthesis of tetrahydrobiopterin. Furthermore, sepiapterin reductase exhibits a wide distribution in different tissues and is associated with many diseases, including brain dysfunction, chronic pain, cardiovascular disease and cancer. With regard to drugs targeting sepiapterin reductase, many compounds have been identified and provide potential methods to treat various diseases. However, the underlying mechanism of sepiapterin reductase in many biological processes is unclear. Therefore, this article summarized the structure, distribution and function of sepiapterin reductase, as well as the relationship between sepiapterin reductase and different diseases, with the aim of finding evidence to guide further studies on the molecular mechanisms and the potential clinical value of sepiapterin reductase. In particular, the different effects induced by the depletion of sepiapterin reductase or the inhibition of the enzyme suggest that the non-enzymatic activity of sepiapterin reductase could function in certain biological processes, which also provides a possible direction for sepiapterin reductase research.

Dopa-responsive dystonia caused by tyrosine hydroxylase deficiency: Three cases report and literature review

RATIONAL

Tyrosine hydroxylase deficiency (THD) is a rare cause of dopa-responsive dystonia (DRD). Although the symptoms of DRD may be improved by treatment with L-dopa, the low morbidity of THD can lead to its misdiagnosis. Thus, it is important for physicians to be aware of THD as a cause of DRD.

PATIENT CONCERNS

We report 3 cases of THD. A 5-year-old boy with DRD was diagnosed with THD and found to have compound heterozygous mutations of the TH gene, including TH:c.647G>C from his mother and TH:c.646G>A from his father. Two female siblings also were found to have TH:c.698G>A from their mother and TH:c.710T>C from their father. The younger daughter, at age 3.5 years, was diagnosed with DRD caused by THD, and then the diagnosis of the older daughter, at age 11 years, was changed from cerebral palsy to DRD caused by THD.

DIAGNOSIS

The diagnosis of dopa-responsive dystonia caused by tyrosine hydroxylase deficiency was determined by whole exome sequencing.

INTERVENTION

They all treated with low dose levodopa and benserazide tablets.

OUTCOMES

The boy had a very good therapeutic effect, and he could walk very well by the second day of treatment. The younger sister of the siblings had a partial therapeutic effect, but her elder sister was only little effective with a milder improvement of dystonia and improvement of myodynamia.

CONCLUSION

The characteristics of THD are heterogeneous, and its phenotypes are classified as type A or type B according to increasing severity. Generally, L-dopa has a good therapeutic effect in cases with type A phenotypes. We reviewed 87 cases of reported in the literature and found that c.698G>A and c.707T>C are hot spot mutations. Changes on cerebral magnetic resonance imaging were nonspecific. Analysis of neurotransmitter levels in cerebrospinal fluid is an invasive means of achieving a biochemical diagnosis.

GCH1 variants contribute to the risk and earlier age-at-onset of Parkinson's disease: a two-cohort case-control study

Background

Common and rare variants of guanosine triphosphate cyclohydrolase 1 (GCH1) gene may play important roles in Parkinson’s disease (PD). However, there is a lack of comprehensive analysis of GCH1 genotypes, especially in non-coding regions. The aim of this study was to explore the genetic characteristics of GCH1, including rare and common variants in coding and non-coding regions, in a large population of PD patients in Chinese mainland, as well as the phenotypic characteristics of GCH1 variant carriers.

Methods

In the first cohort of this case-control study, we performed whole-exome sequencing in 1555 patients with early-onset or familial PD and 2234 healthy controls; then in the second cohort, whole-genome sequencing was performed in sporadic late-onset PD samples (1962 patients), as well as 1279 controls. Variants at target GCH1 regions were extracted, and then genetic and detailed phenotypic data were analyzed using regression models and the sequence kernel association test. We also performed a meta-analysis to correlate deleterious GCH1 variants with age at onset (AAO) in PD patients.

Results

For coding variants, we identified a significant burden of GCH1 deleterious variants in early-onset or familial PD cases compared to controls (1.2% vs 0.1%, P < 0.0001). In the analysis of possible regulatory variants in GCH1 non-coding regions, rs12323905 (P = 0.001, odds ratio = 1.19, 95%CI 1.07–1.32) was significantly associated with PD, and variant sets in untranslated regions and intron regions, GCH1 brain-specific expression quantitative trait loci, and two possible promoter/enhancer (GH14J054857 and GH14J054880) were suggestively associated with PD. Genotype-phenotype correlation analysis revealed that the carriers of GCH1 deleterious variants manifested younger AAO (P < 0.0001), and had milder motor symptoms, milder fatigue symptoms and more autonomic nervous dysfunctions. Meta-analysis of six studies demonstrated 6.4-year earlier onset in GCH1 deleterious variant carriers (P = 0.0009).

Conclusions

The results highlight the importance of deleterious variants and non-coding variants of GCH1 in PD in Chinese mainland and suggest that GCH1 mutation can influence the PD phenotype, which may help design experimental studies to elucidate the mechanisms of GCH1 in the pathogenesis of PD.

Consensus guideline for the diagnosis and treatment of tetrahydrobiopterin (BH4) deficiencies

BACKGROUND

Tetrahydrobiopterin (BH4) deficiencies comprise a group of six rare neurometabolic disorders characterized by insufficient synthesis of the monoamine neurotransmitters dopamine and serotonin due to a disturbance of BH4 biosynthesis or recycling. Hyperphenylalaninemia (HPA) is the first diagnostic hallmark for most BH4 deficiencies, apart from autosomal dominant guanosine triphosphate cyclohydrolase I deficiency and sepiapterin reductase deficiency. Early supplementation of neurotransmitter precursors and where appropriate, treatment of HPA results in significant improvement of motor and cognitive function. Management approaches differ across the world and therefore these guidelines have been developed aiming to harmonize and optimize patient care. Representatives of the International Working Group on Neurotransmitter related Disorders (iNTD) developed the guidelines according to the SIGN (Scottish Intercollegiate Guidelines Network) methodology by evaluating all available evidence for the diagnosis and treatment of BH4 deficiencies.

CONCLUSION

Although the total body of evidence in the literature was mainly rated as low or very low, these consensus guidelines will help to harmonize clinical practice and to standardize and improve care for BH4 deficient patients.

Parkinsonism in diseases predominantly presenting with dystonia

If the presence of dystonia is a well-recognized phenomenon in disorders predominantly presenting with parkinsonism, including sporadic Parkinson Disease, the term dystonia-parkinsonism usually refers to rare conditions, often genetic, in which the severity of dystonia usually equates that of parkinsonism. At variance with parkinsonian syndromes with additional dystonia, the conditions reviewed in this chapter have usually their onset in childhood and their diagnostic work-up is different. In fact, the phenotype is not usually specific of the underlying defect and additional investigations are therefore required. Here, we review the diseases predominantly presenting with dystonia where parkinsonism can develop, according to their main pathophysiological mechanism including disorders of dopamine biosynthesis, neurotransmitter transporter disorders, disorder of metal metabolism (i.e., iron, copper and manganese) and other inherited dystonia-parkinsonism conditions.

Eye movement disorders and neurological symptoms in late-onset inborn errors of metabolism

Inborn errors of metabolism in adults are still largely unexplored. Despite the fact that adult‐onset phenotypes have been known for many years, little attention is given to these disorders in neurological practice. The adult‐onset presentation differs from childhood‐onset phenotypes, often leading to considerable diagnostic delay. The identification of these patients at the earliest stage of disease is important, given that early treatment may prevent or lessen further brain damage. Neurological and psychiatric symptoms occur more frequently in adult forms. Abnormalities of eye movements are also common and can be the presenting sign. Eye movement disorders can be classified as central or peripheral. Central forms are frequently observed in lysosomal storage disorders, whereas peripheral forms are a key feature of mitochondrial disease. Furthermore, oculogyric crisis is an important feature in disorders affecting dopamine syntheses or transport. Ocular motor disorders are often not reported by the patient, and abnormalities can be easily overlooked in a general examination. In adults with unexplained psychiatric and neurological symptoms, a special focus on examination of eye movements can serve as a relatively simple clinical tool to detect a metabolic disorder. Eye movements can be easily quantified and analyzed with video‐oculography, making them a valuable biomarker for following the natural course of disease or the response to therapies. Here, we review, for the first time, eye movement disorders that can occur in inborn errors of metabolism, with a focus on late‐onset forms. We provide a step‐by‐step overview that will help clinicians to examine and interpret eye movement disorders. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Pregnancy management and outcome in patients with four different tetrahydrobiopterin disorders

INTRODUCTION

Inborn errors of tetrahydrobiopterin (BH4) biosynthesis or recycling are a group of very rare neurometabolic diseases. Following growing awareness and improved availability of drug treatment the number of patients with BH4 disorders reaching adulthood is constantly increasing. Pregnancy care of patients with these disorders is therefore a new challenge for clinicians.

METHODS

This retrospective study summarises for the first time clinical and biochemical monitoring data of 16 pregnancies in seven women with different disorders of BH4 metabolism and evaluates treatment regimens before and during pregnancy in relation to the obstetrical outcome and paediatric follow-up.

RESULTS

Worsening of pre-existing neurological symptoms or occurrence of new symptoms during pregnancy was not observed in most of the cases. Treatment regimens remained mostly unchanged. Pregnancies were not complicated by disease-specific features. Organ abnormalities, miscarriage, prematurity, IUGR and chromosomal changes were occasionally reported, without showing any association with the standard drug treatment for BH4 deficiencies.

CONCLUSION

Although our data on 16 pregnancies in seven patients did not present any association of standard drug treatment with an increased rate of pregnancy complications, abnormal obstetrical or paediatric outcome, an intensive clinical and biochemical supervision by a multidisciplinary team before, during and after the pregnancy in any BH4 deficiency is essential since available data on pregnancies in patients with BH4 deficiencies is limited.

GCH1 mutations in dopa-responsive dystonia and Parkinson's disease

Guanosine triphosphate cyclohydrolase I (GCH1) mutations are associated with increased risk for dopa-responsive dystonia (DRD) and Parkinson's disease (PD). Herein, we investigated the frequency of GCH1 mutations and clinical symptoms in patients with clinically diagnosed PD and DRD. We used the Sanger method to screen entire exons in 268 patients with PD and 26 patients with DRD, with the examinations of brain magnetic resonance imaging scans, striatal dopamine transporter scans, and [¹²³I] metaiodobenzylguanidine (MIBG) myocardiac scintigraphy scans. We identified 15 patients with heterozygous GCH1 mutations from seven probands and five sporadic cases. The prevalence of GCH1 mutations in probands was different between PD [1.9% (5/268)] and DRD [26.9% (7/26)] (p value < 0.0001). The onset age tends to be different between PD and DRD patients: 35.4 ± 25.3 and 16.5 ± 13.6, respectively (average ± SD; p = 0.08). Most of the patients were women (14/15). Dystonia was common symptom, and dysautonomia and cognitive decline were uncommon in our PD and DRD. All patients presented mild parkinsonism or dystonia with excellent response to levodopa. Seven of seven DRD and three of five PD presented normal heart-to-mediastinum ratio on MIBG myocardial scintigraphy. Five of six DRD and three of four PD demonstrated normal densities of dopamine transporter. Our findings elucidated the clinical characteristics of PD and DRD patients due to GCH1 mutations. PD patients with GCH1 mutations also had different symptoms from those seen in typical PD. The patients with GCH1 mutations had heterogeneous clinical symptoms.

Electromyographic and Joint Kinematic Patterns in Runner's Dystonia

Runner’s dystonia (RD) is a task-specific focal dystonia of the lower limbs that occurs when running. In this retrospective case series, we present surface electromyography (EMG) and joint kinematic data from thirteen patients with RD who underwent instrumented gait analysis (IGA) at the Functional and Biomechanics Laboratory at the National Institutes of Health. Four cases of RD are described in greater detail to demonstrate the potential utility of EMG with kinematic studies to identify dystonic muscle groups in RD. In these cases, the methodology for muscle selection for botulinum toxin therapy and the therapeutic response is discussed. Lateral heel whip, a proposed novel presentation of lower-limb dystonia, is also described.

Atypical presentation of dopa-responsive dystonia in Taiwan

The typical clinical presentation of dopa-responsive dystonia, which is also called Segawa disease, is a young age of onset, with predominance in females, diurnal fluctuation of lower limb dystonia, and fair response to low-dose levodopa. This disease has both autosomal dominant and autosomal recessive inheritance. Autosomal dominant Segawa disease is caused by GCH1 mutation on chromosome 14q22.1-q22.2. Here, we report the case of a male patient with genetically confirmed Segawa disease and atypical presentations including no diurnal symptom fluctuation and insufficient response to levodopa. The patient's father who had the same mutation presented parkinsonism in old age. We also review the literature to address the broad clinical heterogeneity of Segawa disease and the influence of onset age on clinical presentation.

Combining Human and Rodent Genetics to Identify New Analgesics

Most attempts at rational development of new analgesics have failed, in part because chronic pain involves multiple processes that remain poorly understood. To improve translational success, one strategy is to select novel targets for which there is proof of clinical relevance, either genetically through heritable traits, or pharmacologically. Such an approach by definition yields targets with high clinical validity. The biology of these targets can be elucidated in animal models before returning to the patients with a refined therapeutic. For optimal treatment, having biomarkers of drug action available is also a plus. Here we describe a case study in rational drug design: the use of controlled inhibition of peripheral tetrahydrobiopterin (BH4) synthesis to reduce abnormal chronic pain states without altering nociceptive-protective pain. Initially identified in a population of patients with low back pain, the association between BH4 production and chronic pain has been confirmed in more than 12 independent cohorts, through a common haplotype (present in 25% of Caucasians) of the rate-limiting enzyme for BH4 synthesis, GTP cyclohydrolase 1 (GCH1). Genetic tools in mice have demonstrated that both injured sensory neurons and activated macrophages engage increased BH4 synthesis to cause chronic pain. GCH1 is an obligate enzyme for de novo BH4 production. Therefore, inhibiting GCH1 activity eliminates all BH4 production, affecting the synthesis of multiple neurotransmitters and signaling molecules and interfering with physiological function. In contrast, targeting the last enzyme of the BH4 synthesis pathway, sepiapterin reductase (SPR), allows reduction of pathological BH4 production without completely blocking physiological BH4 synthesis. Systemic SPR inhibition in mice has not revealed any safety concerns to date, and available genetic and pharmacologic data suggest similar responses in humans. Finally, because it is present in vivo only when SPR is inhibited, sepiapterin serves as a reliable biomarker of target engagement, allowing potential quantification of drug efficacy. The emerging development of therapeutics that target BH4 synthesis to treat chronic pain illustrates the power of combining human and mouse genetics: human genetic studies for clinical selection of relevant targets, coupled with causality studies in mice, allowing the rational engineering of new analgesics.

Inherited dystonias: clinical features and molecular pathways

Recent decades have witnessed dramatic increases in understanding of the genetics of dystonia - a movement disorder characterized by involuntary twisting and abnormal posture. Hampered by a lack of overt neuropathology, researchers are investigating isolated monogenic causes to pinpoint common molecular mechanisms in this heterogeneous disease. Evidence from imaging, cellular, and murine work implicates deficiencies in dopamine neurotransmission, transcriptional dysregulation, and selective vulnerability of distinct neuronal populations to disease mutations. Studies of genetic forms of dystonia are also illuminating the developmental dependence of disease symptoms that is typical of many forms of the disease. As understanding of monogenic forms of dystonia grows, a clearer picture will develop of the abnormal motor circuitry behind this relatively common phenomenology. This chapter focuses on the current data covering the etiology and epidemiology, clinical presentation, and pathogenesis of four monogenic forms of isolated dystonia: DYT-TOR1A, DYT-THAP1, DYT-GCH1, and DYT-GNAL.

Variability of presynaptic nigrostriatal dopaminergic function and clinical heterogeneity in a dopa-responsive dystonia family with GCH-1 gene mutation

We studied the presynaptic nigrostriatal dopaminergic function using single photon emission computed tomography (SPECT) imaging of a ^99mTc-TRODAT-1 (TRODAT) scan in a dopa-responsive dystonia (DRD) family with the guanosine triphosphate cyclohydrolase 1 (GCH-1) gene mutation. Clinically, there was presentation of intrafamilial variability in the DRD family. The index patient was a 10-year-old girl with classic DRD and normal presynaptic nigrostriatal dopaminergic function. However, her grandmother, a 79-year-old woman, presented with slowly progressive Parkinson's disease (PD) without dystonic symptoms and excellent response to dopaminergic therapy for 21 years. Her brain TRODAT SPECT imaging revealed a markedly and asymmetrically reduced uptake of dopamine transporter at the bilateral striatum. Her father, a 54-year-old man, was an asymptomatic gene carrier and his brain TRODAT SPECT imaging revealed asymmetrically reduced nigrostriatal dopaminergic transmission in the bilateral striatum. We conclude variability of presynaptic nigrostriatal dopaminergic function in patients with DRD is related to their clinical heterogeneity. Significantly, impairment of presynaptic dopamine function actually occurs in the asymptomatic gene carrier.

GCH1 mutations are common in Serbian patients with dystonia-parkinsonism: Challenging previously reported prevalence rates of DOPA-responsive dystonia

BACKGROUND

GTP cyclohydrolase 1-deficient DOPA-responsive dystonia, caused by autosomal dominant mutation in the gene coding for GTP cyclohydrolase 1, is a rare disorder with a reported prevalence of 0.5 per million. A correct diagnosis of DRD is crucial, given that this is an exquisitely treatable neurogenetic disorder. Although genetic testing is now widely available, we hypothesize that DRD is still underdiagnosed and its prevalence underestimated.

METHODS

Molecular genetic analysis of the GCH1 gene was performed in a representative cohort of 47 Serbian patients with clinical features of DRD and in their 16 available relatives. The DRD prevalence rate in Serbia was estimated based on population size, catchment area, and the centralized Serbian referral system for rare diseases.

RESULTS

We identified 9 different GCH1 mutations in 23 individuals from 11 families, 5 of which are novel. Patients displayed a broad range of clinical phenotypes. The estimated prevalence of GCH1-related DOPA-responsive dystonia in Serbia was 2.96 per million individuals and there was no evidence for a common founder.

CONCLUSIONS

Our data expand the genotypic spectrum of GCH1 and confirm the broad phenotypic spectrum of DRD in the Serbian population. The number of detected mutation carriers in this sample implies that the frequency of DRD in the Serbian population is considerably higher than expected based on published prevalence rates, suggesting that the prevalence of this treatable disease should be revisited also in other populations.

Establishment of DYT5 patient-specific induced pluripotent stem cells with a GCH1 mutation

Peripheral blood mononuclear cells (PBMCs) were collected from a clinically diagnosed 20-year-old dystonia patient with a GCH1 mutation (DYT5). Episomal vectors were used to introduce reprogramming factors (OCT3/4, SOX2, KLF4, L-MYC, LIN28, and p53 carboxy-terminal dominant-negative fragment) to the PBMCs. The generated iPSCs expressed pluripotency markers, and were capable of differentiating into derivates of all three germ layers in vitro. The iPSC line also showed a normal karyotype and preserved the GCH1 mutation. This cellular model can provide opportunities to perform pathophysiological studies for aberrant dopamine metabolism-related disorders.

Translational effects and coding potential of an upstream open reading frame associated with DOPA Responsive Dystonia

Upstream open reading frames (uORFs) have emerged as major post-transcriptional regulatory elements in eukaryotic species. In general, uORFs are initiated by a translation start codon within the 5' untranslated region of a gene (upstream ATG; uATG), and they are negatively correlated with translational efficiency. In addition to their translational regulatory role, some uORFs can code for biologically active short peptides. The importance of uATGs/uORFs is further underscored by human diseases associated with single nucleotide polymorphisms (SNPs), which disrupt existing uORFs or introduce novel uORFs. Although several functional proteins translated from naturally occurring uORFs have been described, the coding potential of uORFs created by SNPs has been ignored because of the a priori assumption that these proteins are short-lived with no likely impact on protein homeostasis. Thus, studies on SNP-created uORFs are limited to their translational effects, leaving unexplored the potential cellular consequences of a SNP/uORF-encoded protein. Here, we investigate functionality of a uATG/uORF introduced by a +142C>T SNP within the GCH1 gene and associated with a familial form of DOPA Responsive Dystonia. We report that the +142C>T SNP represses GCH1 translation, and introduces a short, frame shifted uORF that encodes a 73-amino acid peptide. This peptide is localized within the nucleus and compromises cell viability upon proteasome inhibition. Our work extends the list of uATG/uORF associated diseases and advances research on peptides translated from SNP-introduced uORFs, a neglected component of the proteome.

Anesthetic implications for patients with Segawa syndrome

STUDY OBJECTIVE

To characterize the perioperative course of patients with Segawa syndrome undergoing anesthetic management.

DESIGN

Retrospective observational case study.

SETTING

Large tertiary medical center.

PATIENTS

Patients with Segawa syndrome who underwent procedures requiring anesthetic management at our institution from January 1, 2004, through July 31, 2015.

MEASUREMENTS

The health records of patients with Segawa syndrome.

MAIN RESULTS

Twelve patients with Segawa syndrome underwent 25 procedures requiring anesthetic management, including 20 operations with general anesthesia. Succinylcholine was administered in 6 cases and nondepolarizing neuromuscular blockers in 5 cases, all without adverse effects. Perioperative complications were unrelated to anesthetic management or underlying neurologic condition. In 16 operations, the patients were receiving levodopa therapy at the time of the procedure.

CONCLUSIONS

In this cohort, patients with Segawa syndrome tolerated the anesthetic management, including neuromuscular blocker administration. Although these patients are frequently receiving levodopa therapy, no associated complications were noted.