Neuroacanthocytosis: new developments in a neglected group of dementing disorders

Reconsidering red blood cells as the diagnostic potential for neurodegenerative disorders

BACKGROUND

Red blood cells (RBCs) are usually considered simple cells and transporters of gases to tissues.

HYPOTHESIS

However, recent research has suggested that RBCs may have diagnostic potential in major neurodegenerative disorders (NDDs).

RESULTS

This review summarizes the current knowledge on changes in RBC in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and other NDDs. It discusses the deposition of neuronal proteins like amyloid-β, tau, and α-synuclein, polyamines, changes in the proteins of RBCs like band-3, membrane transporter proteins, heat shock proteins, oxidative stress biomarkers, and altered metabolic pathways in RBCs during neurodegeneration. It also highlights the comparison of RBC diagnostic markers to other in-market diagnoses and discusses the challenges in utilizing RBCs as diagnostic tools, such as the need for standardized protocols and further validation studies.

SIGNIFICANCE STATEMENT

The evidence suggests that RBCs have diagnostic potential in neurodegenerative disorders, and this study can pave the foundation for further research which may lead to the development of novel diagnostic approaches and treatments.

Classification of Dystonia

Dystonia is a hyperkinetic movement disorder characterized by abnormal movement or posture caused by excessive muscle contraction. Because of its wide clinical spectrum, dystonia is often underdiagnosed or misdiagnosed. In clinical practice, dystonia could often present in association with other movement disorders. An accurate physical examination is essential to describe the correct phenomenology. To help clinicians reaching the proper diagnosis, several classifications of dystonia have been proposed. The current classification consists of axis I, clinical characteristics, and axis II, etiology. Through the application of this classification system, movement disorder specialists could attempt to correctly characterize dystonia and guide patients to the most effective treatment. The aim of this article is to describe the phenomenological spectrum of dystonia, the last approved dystonia classification, and new emerging knowledge.

[Case-report of neuroacanthocytosis associated with a compound mutation in the VPS13A gene]

Neuroacanthocytosis is a group of neurodegenerative diseases manifested by a combition of neurological symptoms (most often choreic hyperkinesis) and the presence of an increased number of acanthocytes (erythrocytes with horns) in the peripheral blood. This group includes chorea-acanthocytosis, MacLeod's syndrome, pantothenate kinase-associated neurodegeneration, Huntington-like disease type 2, and some other very rare diseases. This article presents a genetically confirmed clinical case of chorea-acanthocytosis associated with a compound mutation in the VPS13A gene, discusses in detail the stages of a diagnostic search, presents an algorithm for examining patients with chorea.

Insights into VPS13 properties and function reveal a new mechanism of eukaryotic lipid transport

The occurrence of protein mediated lipid transfer between intracellular membranes has been known since the late 1960's. Since these early discoveries, numerous proteins responsible for such transport, which often act at membrane contact sites, have been identified. Typically, they comprise a lipid harboring module thought to shuttle back and forth between the two adjacent bilayers. Recently, however, studies of the chorein domain protein family, which includes VPS13 and ATG2, has led to the identification of a novel mechanism of lipid transport between organelles in eukaryotic cells mediated by a rod-like protein bridge with a hydrophobic groove through which lipids can slide. This mechanism is ideally suited for bulk transport of bilayer lipids to promote membrane growth. Here we describe how studies of VPS13 led to the discovery of this new mechanism, summarize properties and known roles of VPS13 proteins, and discuss how their dysfunction may lead to disease.

Neuroacanthocytosis Syndromes in an Italian Cohort: Clinical Spectrum, High Genetic Variability and Muscle Involvement

Neuroacanthocytosis (NA) syndromes are a group of genetically defined diseases characterized by the association of red blood cell acanthocytosis, progressive degeneration of the basal ganglia and neuromuscular features with characteristic persistent hyperCKemia. The main NA syndromes include autosomal recessive chorea-acanthocytosis (ChAc) and X-linked McLeod syndrome (MLS). A series of Italian patients selected through a multicenter study for these specific neurological phenotypes underwent DNA sequencing of the VPS13A and XK genes to search for causative mutations. Where it has been possible, muscle biopsies were obtained and thoroughly investigated with histochemical assays. A total of nine patients from five different families were diagnosed with ChAC and had mostly biallelic changes in the VPS13A gene (three nonsense, two frameshift, three splicing), while three patients from a single X-linked family were diagnosed with McLeod syndrome and had a deletion in the XK gene. Despite a very low incidence (only one thousand cases of ChAc and a few hundred MLS cases reported worldwide), none of the 8 VPS13A variants identified in our patients is shared by two families, suggesting the high genetic variability of ChAc in the Italian population. In our series, in line with epidemiological data, McLeod syndrome occurs less frequently than ChAc, although it can be easily suspected because of its X-linked mode of inheritance. Finally, histochemical studies strongly suggest that muscle pathology is not simply secondary to the axonal neuropathy, frequently seen in these patients, but primary myopathic alterations can be detected in both NA syndromes.

"Neuroacanthocytosis" - Overdue for a Taxonomic Update

The term "neuroacanthocytosis" (NA) is used for a spectrum of neurological disorders in which there are thorny red blood cells. While NA historically referred to disorders of lipoprotein absorption, we have promoted it as an overarching term for a group of basal ganglia disorders, with specific reference to two diseases that we defined as "core" NA syndromes. "Neuroacanthocytosis" has also been used to refer to a specific, now genetically-defined disease, otherwise known as "chorea-acanthocytosis". These various usages have resulted in diagnostic confusion, and in a number of cases have quite likely prevented the pursuance of precise, molecular, diagnosis. Disease nomenclature is an ever-evolving field, especially in the current era of expanding genetics, and naming proposals are often far from ideal. We, however, suggest that the term "neuroacanthocytosis" should no longer be generally used and if so, only with appropriate understanding of its limitations. Further, we propose that chorea-acanthocytosis be renamed as "VPS13A disease" in accordance with its genetic etiology.

Genetic perspective on the synergistic connection between vesicular transport, lysosomal and mitochondrial pathways associated with Parkinson's disease pathogenesis

Parkinson's disease (PD) and atypical parkinsonian syndromes (APS) are symptomatically characterized by parkinsonism, with the latter presenting additionally a distinctive range of atypical features. Although the majority of patients with PD and APS appear to be sporadic, genetic causes of several rare monogenic disease variants were identified. The knowledge acquired from these genetic factors indicated that defects in vesicular transport pathways, endo-lysosomal dysfunction, impaired autophagy-lysosomal protein and organelle degradation pathways, α-synuclein aggregation and mitochondrial dysfunction play key roles in PD pathogenesis. Moreover, membrane dynamics are increasingly recognized as a key player in the disease pathogenesis due lipid homeostasis alterations, associated with lysosomal dysfunction, caused by mutations in several PD and APS genes. The importance of lysosomal dysfunction and lipid homeostasis is strengthened by both genetic discoveries and clinical epidemiology of the association between parkinsonism and lysosomal storage disorders (LSDs), caused by the disruption of lysosomal biogenesis or function. A synergistic coordination between vesicular trafficking, lysosomal and mitochondria defects exist whereby mutations in PD and APS genes encoding proteins primarily involved one PD pathway are frequently associated with defects in other PD pathways as a secondary effect. Moreover, accumulating clinical and genetic observations suggest more complex inheritance patters of familial PD exist, including oligogenic and polygenic inheritance of genes in the same or interconnected PD pathways, further strengthening their synergistic connection.Here, we provide a comprehensive overview of PD and APS genes with functions in vesicular transport, lysosomal and mitochondrial pathways, and highlight functional and genetic evidence of the synergistic connection between these PD associated pathways.

Novel pathogenic VPS13A mutation in Moroccan family with Choreoacanthocytosis: a case report

Background

Choreoacanthocytosis (ChAc), is a rare neurodegenerative disease, characterized by movement disorders and acanthocytosis in the peripheral blood smears, and various neurological, neuropsychiatric and neuromuscular signs. It is caused by mutations in VPS13A gene with autosomal recessive pattern of inheritance.

Case presentation

Here we report two patients belonging to a consanguineous Moroccan family who present with movement disorder pathology. They were suspected to have choreoacanthocytosis according to biological, clinical and radiological finding. Thus, whole-exome sequencing was performed for precise diagnosis and identified a homozygous novel nonsense mutation c.337C > T (p.Gln113*) in exon 5 of VPS13A in the two affected siblings.

Conclusion

Here, we report a novel nonsense p.Gln113* mutation in VPS13A identified by whole-exome sequencing, which caused ChAc in a Moroccan family. This is the first description of ChAc in Morocco with genetic confirmation, that expands the mutation diversity of VPS13A and provide clinical, neuroimaging and deep brain stimulation findings.

Neuroacanthocytosis with unusual clinical features: A case report

RATIONALE

Neuroacanthocytosis (NA) is a heterogeneous group of inherited neurodegenerative disorders characterized by misshapen spiculated erythorcytes and symptoms that resemble Huntington's disease.

PATIENT CONCERNS

A 59-year-old female who developed hyperkinetic involuntary movements that became progressively more obvious during the course of a year.

DIAGNOSES

Acanthocytes were observed in a peripheral blood smear. The patient had elevated levels of serum creatine kinase (CK). Gene sequencing did not reveal a genetic mutation.

INTERVENTIONS

The patient was administered oral tiapride, alprazolam, B1 and B12 Vitamins.

OUTCOMES

After 2 months of treatment the patient's symptoms were obviously alleviated. At the 6 month follow-up, the patient could feed herself and walk without assistance.

LESSONS

The NA syndrome is extremely rare. It may be identified in the clinic based on abnormal orofacial movement, chorea, cognitive decline, elevated CK levels, and acanthocytosis. If available, protein- or genetic-based testing may provide a confirmatory diagnosis.

Chorea-Acanthocytosis in a Chinese Family With a Pseudo-Dominant Inheritance Mode

Chorea-acanthocytosis (ChAc) is a rare neurodegenerative movement disorder with variable clinical features, including movement disorders, cognitive decline, myopathy, neuropathy, behavioral changes, seizures and acanthocytosis. The majority of ChAc patients display an autosomal recessive mode of inheritance. A pseudodominant way of transmission represents only a rare condition. Few studies have reported the clinical status of the obligate carriers of ChAc. Here, we describe a Chinese ChAc family with a novel mutation in the VPS13A gene, presenting a pseudo-dominant inheritance mode. Our report further expanded the knowledge of phenotypes of ChAc.

Pathoarchitectonics of the cerebral cortex in chorea-acanthocytosis and Huntington's disease

AIMS

Quantitative estimation of cortical neurone loss in cases with chorea-acanthocytosis (ChAc) and its impact on laminar composition.

METHODS

We used unbiased stereological tools to estimate the degree of cortical pathology in serial gallocyanin-stained brain sections through the complete hemispheres of three subjects with genetically verified ChAc and a range of disease durations. We compared these results with our previous data of five Huntington's disease (HD) and five control cases. Pathoarchitectonic changes were exemplarily documented in TE1 of a 61-year-old female HD-, a 60-year-old female control case, and ChAc3.

RESULTS

Macroscopically, the cortical volume of our ChAc cases (ChAc1-3) remained close to normal. However, the average number of neurones was reduced by 46% in ChAc and by 33% in HD (P = 0.03 for ChAc & HD vs. controls; P = 0.64 for ChAc vs. HD). Terminal HD cases featured selective laminar neurone loss with pallor of layers III, V and VIa, a high density of small, pale, closely packed radial fibres in deep cortical layers VI and V, shrinkage, and chromophilia of subcortical white matter. In ChAc, pronounced diffuse astrogliosis blurred the laminar borders, thus masking the complete and partial loss of pyramidal cells in layer IIIc and of neurones in layers III, V and VI.

CONCLUSION

ChAc is a neurodegenerative disease with distinct cortical neurodegeneration. The hypertrophy of the peripheral neuropil space of minicolumns with coarse vertical striation was characteristic of ChAc. The role of astroglia in the pathogenesis of this disorder remains to be elucidated.

Subcortical neurodegeneration in chorea: Similarities and differences between chorea-acanthocytosis and Huntington's disease

INTRODUCTION

Chorea-acanthocytosis (ChAc) and Huntington's disease (HD) are neurodegenerative conditions that share clinical and neuropathological features, despite their distinct genetic etiologies.

METHODS

In order to compare these neuropathologies, serial gallocyanin-stained brain sections from three subjects with ChAc were analyzed and compared with our previous studies of eight HD cases, in addition to three hemispheres from two male controls.

RESULTS

Astrogliosis was much greater in the ChAc striatum, as compared to that found in HD, with dramatic increase in total striatal glia numbers and the number of glia per striatal neuron. Striatal astrocytes are most likely derived from the striatal subependymal layer in ChAc, which showed massive proliferation. The thalamic centromedian-parafascicular complex is reciprocally connected to the striatum and is more heavily affected in HD than in ChAc.

CONCLUSION

The distinct patterns of selective vulnerability and gliosis observed in HD and ChAc challenge simplistic views on the pathogenesis of these two diseases with rather similar clinical signs. The particular roles played by astroglia in ChAc and in HD clearly need to be elucidated in more detail.

Caspase-mediated activation of Caenorhabditis elegans CED-8 promotes apoptosis and phosphatidylserine externalization

During apoptosis, phosphatidylserine (PS), normally restricted to the inner leaflet of the plasma membrane, is exposed on the surface of apoptotic cells and serves as an “eat-me” signal to trigger phagocytosis. It is poorly understood how PS exposure is activated in apoptotic cells. Here we report that CED-8, a C. elegans protein implicated in controlling the kinetics of apoptosis and a homolog of the XK family proteins, is a substrate of the CED-3 caspase. Cleavage of CED-8 by CED-3 activates its proapoptotic function and generates a carboxyl terminal cleavage product, acCED-8, that promotes PS externalization in apoptotic cells and can induce ectopic PS exposure in living cells. Consistent with its role in promoting PS externalization in apoptotic cells, ced-8 is important for cell corpse engulfment in C. elegans. Our finding identifies a crucial link between caspase activation and PS externalization, which triggers phagocytosis of apoptotic cells.

Facial cellulitis revealing choreo-acanthocytosis: a case report

We report a 62 year-old-man with facial cellulitis revealing choreo-acanthocytosis (ChAc). He showed chorea that started 20 years ago. The orofacial dyskinisia with tongue and cheek biting resulted in facial cellulitis. The peripheral blood smear revealed acanthocytosis of 25%. The overall of chorea, orofacial dyskinetic disorder, peripheral neuropathy, disturbed behavior, acanthocytosis and the atrophy of caudate nuclei was suggestive of a diagnosis of ChAc. To our knowledge no similar cases of facial cellulitis revealing choreo-acanthocytosis (ChAc) were found in a review of the literature.

Short and long term outcome of bilateral pallidal stimulation in chorea-acanthocytosis

Background

Chorea-acanthocytosis (ChAc) is a neuroacanthocytosis syndrome presenting with severe movement disorders poorly responsive to drug therapy. Case reports suggest that bilateral deep brain stimulation (DBS) of the ventro-postero-lateral internal globus pallidus (GPi) may benefit these patients. To explore this issue, the present multicentre (n=12) retrospective study collected the short and long term outcome of 15 patients who underwent DBS.

Methods

Data were collected in a standardized way 2-6 months preoperatively, 1-5 months (early) and 6 months or more (late) after surgery at the last follow-up visit (mean follow-up: 29.5 months).

Results

Motor severity, assessed by the Unified Huntington’s Disease Rating Scale-Motor Score, UHDRS-MS), was significantly reduced at both early and late post-surgery time points (mean improvement 54.3% and 44.1%, respectively). Functional capacity (UHDRS-Functional Capacity Score) was also significantly improved at both post-surgery time points (mean 75.5% and 73.3%, respectively), whereas incapacity (UHDRS-Independence Score) improvement reached significance at early post-surgery only (mean 37.3%). Long term significant improvement of motor symptom severity (≥20 % from baseline) was observed in 61.5 % of the patients. Chorea and dystonia improved, whereas effects on dysarthria and swallowing were variable. Parkinsonism did not improve. Linear regression analysis showed that preoperative motor severity predicted motor improvement at both post-surgery time points. The most serious adverse event was device infection and cerebral abscess, and one patient died suddenly of unclear cause, 4 years after surgery.

Conclusion

This study shows that bilateral DBS of the GPi effectively reduces the severity of drug-resistant hyperkinetic movement disorders such as present in ChAc.

Chorein, the protein responsible for chorea-acanthocytosis, interacts with β-adducin and β-actin

Chorea-acanthocytosis (ChAc) is an autosomal, recessive hereditary disease characterized by striatal neurodegeneration and acanthocytosis, and caused by loss of function mutations in the vacuolar protein sorting 13 homolog A (VPS13A) gene. VPS13A encodes chorein whose physiological function at the molecular level is poorly understood. In this study, we show that chorein interacts with β-adducin and β-actin. We first compare protein expression in human erythrocyte membranes using proteomic analysis. Protein levels of β-adducin isoform 1 and β-actin are markedly decreased in erythrocyte membranes from a ChAc patient. Subsequent co-immunoprecipitation (co-IP) and reverse co-IP assays using extracts from chorein-overexpressing human embryonic kidney 293 (HEK293) cells, shows that β-adducin (isoforms 1 and 2) and β-actin interact with chorein. Immunocytochemical analysis using chorein-overexpressing HEK293 cells demonstrates co-localization of chorein with β-adducin and β-actin. In addition, immunoreactivity of β-adducin isoform 1 is significantly decreased in the striatum of gene-targeted ChAc-model mice. Adducin and actin are membrane cytoskeletal proteins, involved in synaptic function. Expression of β-adducin is restricted to the brain and hematopoietic tissues, corresponding to the main pathological lesions of ChAc, and thereby implicating β-adducin and β-actin in ChAc pathogenesis.

Clinical and molecular research of neuroacanthocytosis

Neuroacanthocytosis is an autosomal recessive or dominant inherited disease characterized by widespread, non-specific nervous system symptoms, or spiculated "acanthocytic" red blood cells. The clinical manifestations typically involve chorea and dystonia, or a range of other movement disorders. Psychiatric and cognitive symptoms may also be present. The two core neuroacanthocytosis syndromes, in which acanthocytosis is atypical, are autosomal recessive chorea-acanthocytosis and X-linked McLeod syndrome. Acanthocytes are found in a smaller proportion of patients with Huntington's disease-like 2 and pantothenate kinase-associated neurodegeneration. Because the clinical manifestations are diverse and complicated, in this review we present features of inheritance, age of onset, neuroimaging and laboratory findings, as well as the spectrum of central and peripheral neurological abnormalities and extraneuronal involvement to help distinguish the four specific syndromes.

Striatal activity in borderline personality disorder with comorbid intermittent explosive disorder: sex differences

Borderline Personality Disorder (BPD) is associated with behavioral and emotional dysregulation, particularly in social contexts; however, the underlying pathophysiology at the level of brain function is not well understood. Previous studies found abnormalities in frontal cortical and limbic areas suggestive of poor frontal regulation of downstream brain regions. However, the striatum, which is closely connected with the medial frontal cortices and plays an important role in motivated behaviors and processing of rewarding stimuli, has been understudied in BPD. Here we hypothesized that, in addition to frontal dysfunction, BPD patients may show abnormal striatal function. In this study, 38 BPD patients with intermittent explosive disorder (BPD-IED) and 36 healthy controls (HC) participated in the Point Subtraction Aggression Paradigm (PSAP), a computer game played with a fictitious other player. (18)Fluoro-deoxyglucose positron emission tomography (FDG-PET) measured relative glucose metabolism (rGMR) within caudate and putamen in response to aggression-provoking and non-provoking versions of the PSAP. Male BPD-IED patients had significantly lower striatal rGMR than all other groups during both conditions, although male and female BPD-IED patients did not differ in clinical or behavioral measures. These sex differences suggest differential involvement of frontal-striatal circuits in BPD-IED, and are discussed in relation to striatal involvement in affective learning and social decision-making.

Computational identification of phospho-tyrosine sub-networks related to acanthocyte generation in neuroacanthocytosis

Acanthocytes, abnormal thorny red blood cells (RBC), are one of the biological hallmarks of neuroacanthocytosis syndromes (NA), a group of rare hereditary neurodegenerative disorders. Since RBCs are easily accessible, the study of acanthocytes in NA may provide insights into potential mechanisms of neurodegeneration. Previous studies have shown that changes in RBC membrane protein phosphorylation state affect RBC membrane mechanical stability and morphology. Here, we coupled tyrosine-phosphoproteomic analysis to topological network analysis. We aimed to predict signaling sub-networks possibly involved in the generation of acanthocytes in patients affected by the two core NA disorders, namely McLeod syndrome (MLS, XK-related, Xk protein) and chorea-acanthocytosis (ChAc, VPS13A-related, chorein protein). The experimentally determined phosphoproteomic data-sets allowed us to relate the subsequent network analysis to the pathogenetic background. To reduce the network complexity, we combined several algorithms of topological network analysis including cluster determination by shortest path analysis, protein categorization based on centrality indexes, along with annotation-based node filtering. We first identified XK- and VPS13A-related protein-protein interaction networks by identifying all the interactomic shortest paths linking Xk and chorein to the corresponding set of proteins whose tyrosine phosphorylation was altered in patients. These networks include the most likely paths of functional influence of Xk and chorein on phosphorylated proteins. We further refined the analysis by extracting restricted sets of highly interacting signaling proteins representing a common molecular background bridging the generation of acanthocytes in MLS and ChAc. The final analysis pointed to a novel, very restricted, signaling module of 14 highly interconnected kinases, whose alteration is possibly involved in generation of acanthocytes in MLS and ChAc.

Erythrocyte membrane changes of chorea-acanthocytosis are the result of altered Lyn kinase activity

Acanthocytic RBCs are a peculiar diagnostic feature of chorea-acanthocytosis (ChAc), a rare autosomal recessive neurodegenerative disorder. Although recent years have witnessed some progress in the molecular characterization of ChAc, the mechanism(s) responsible for generation of acanthocytes in ChAc is largely unknown. As the membrane protein composition of ChAc RBCs is similar to that of normal RBCs, we evaluated the tyrosine (Tyr)-phosphorylation profile of RBCs using comparative proteomics. Increased Tyr phosphorylation state of several membrane proteins, including band 3, β-spectrin, and adducin, was noted in ChAc RBCs. In particular, band 3 was highly phosphorylated on the Tyr-904 residue, a functional target of Lyn, but not on Tyr-8, a functional target of Syk. In ChAc RBCs, band 3 Tyr phosphorylation by Lyn was independent of the canonical Syk-mediated pathway. The ChAc-associated alterations in RBC membrane protein organization appear to be the result of increased Tyr phosphorylation leading to altered linkage of band 3 to the junctional complexes involved in anchoring the membrane to the cytoskeleton as supported by coimmunoprecipitation of β-adducin with band 3 only in ChAc RBC-membrane treated with the Lyn-inhibitor PP2. We propose this altered association between membrane skeleton and membrane proteins as novel mechanism in the generation of acanthocytes in ChAc.

Shape alterations in the striatum in chorea-acanthocytosis

Chorea-acanthocytosis (ChAc) is an uncommon autosomal recessive disorder due to mutations of the VPS13A gene, which encodes for the membrane protein chorein. ChAc presents with progressive limb and orobuccal chorea, but there is often a marked dysexecutive syndrome. ChAc may first present with neuropsychiatric disturbance such as obsessive-compulsive disorder (OCD), suggesting a particular role for disruption to striatal structures involved in non-motor frontostriatal loops, such as the head of the caudate nucleus. Two previous studies have suggested a marked reduction in volume in the caudate nucleus and putamen, but did not examine morphometric change. We investigated morphometric change in 13 patients with genetically or biochemically confirmed ChAc and 26 age- and gender-matched controls. Subjects underwent magnetic resonance imaging and manual segmentation of the caudate nucleus and putamen, and shape analysis using a non-parametric spherical harmonic technique. Both structures showed significant and marked reductions in volume compared with controls, with reduction greatest in the caudate nucleus. Both structures showed significant shape differences, particularly in the head of the caudate nucleus. No significant correlation was shown between duration of illness and striatal volume or shape, suggesting that much structural change may have already taken place at the time of symptom onset. Our results suggest that striatal neuron loss may occur early in the disease process, and follows a dorsal-ventral gradient that may correlate with early neuropsychiatric and cognitive presentations of the disease.

Comprehensive analysis of the genes responsible for neuroacanthocytosis in mood disorder and schizophrenia

Neuroacanthocytosis syndromes are mainly comprised of two diseases: chorea-acanthocytosis (ChAc) and McLeod syndrome (MLS). There is a high incidence of psychiatric disorders such as mood disorder and schizophrenia among neuroacanthocytosis patients. We hypothesized that neuroacanthocytosis-related-genes might be associated with susceptibility to these psychiatric disorders. We performed a comprehensive mutation screen of VPS13A and XK, the gene responsible for ChAc and MLS, respectively, in 85 mood disorder subjects and XK in 86 schizophrenia subjects and compared the variants to 100 or more control alleles. We also performed copy number variation (CNV) analysis in 72 mood disorder subjects and 86 schizophrenia subjects. We identified three non-synonymous, two synonymous and six intron variants in mood disorder subjects and a novel GAT triplet repeat polymorphism in VPS13A. By CNV analysis, we identified a heterozygous exon 60-61 deletion in VPS13A in one mood disorder subject. We identified one non-synonymous and one intron variant in mood disorder and schizophrenia subjects, respectively, in XK. The presence of a pathogenic mutation or a potentially functional variant in mood disorder or schizophrenia subjects suggests that neuroacanthocytosis-related-genes might be involved in the pathogenesis of these psychiatric disorders.

The first case report of neuroacanthocytosis in Thailand: utilization of a peripheral blood smear technique for detecting acanthocytes

BACKGROUND

Neuroacanthocytosis (NA) is a heterogeneous group of hereditary syndromes characterized by the association of neurological abnormalities with acanthocytosis. Among those, chorea-acanthocytosis (ChAc) is the most frequent form, manifested by predominant orofacial dyskinesias associated with marked dysarthria and dysphagia.

PURPOSE

To describe the first known case of ChAc in Thailand.

METHODS AND RESULTS

A 40-year-old man presented with "core features" of NA which led to a high level of suspicion of this syndrome. An initial dry blood smear did not reveal acanthocytes but by utilizing diluted blood combined with a wet blood smear, which is accepted as the clinical gold standard when combined with an examination, acanthocytes were detected.

CONCLUSION

Diagnosis of NA is possible without molecular diagnostics by relying on a high degree of clinical suspicion of characteristic clinical features and a standardized wet blood smear method of peripheral blood examination for acanthocytes.

[Chorea-acanthocytosis without acanthocytes]

INTRODUCTION

Chorea-acanthocytosis (ChAc) is one of the neuroacanthocytosis syndromes which form a group of disorders characterized by the association of neurological abnormalities and spiculated red blood cells called acanthocytes. ChAc patients exhibit involuntary movements, psychiatric abnormalities and progressive cognitive deterioration. We report a case of ChAc in which blood smears failed to demonstrate acanthocytes.

CASE REPORT

A 26-year-old man presented since two years with hyperkinetic movements. The family history was non contributive, parents were consanguineous. Neurological examination revealed choreatic hyperkinesia and dystonia, predominant in the orofacial region. Mild cognitive decline and behavior abnormalities were noted with repetitive activities. Brain MRI showed striatal atrophy. Molecular testing for Huntington's disease was negative. Routine biological screening was normal except for elevated CPK and LDH. Copper and ceruloplasmin blood levels were normal, as well as purine metabolism and lipoproteins. Further screening for metabolic diseases showed no significant abnormality. Expression of Kell antigens was normal. In several blood smears no acanthocytes were seen. Electromyographic studies showed slight neuropathic changes. Despite the absence of acanthocytes, chorein western blot was performed on blood samples which revealed an absent or markedly reduced level of chorein in erythrocyte membranes. A mutation of the ChAc gene was thus likely so the diagnosis of ChAc was retained. Genetic studies for VPS13A are pending.

DISCUSSION

ChAc is an autosomal recessive disorder due to mutations of the VPS13A gene coding for chorein. Absence or late appearance of acanthocytes in ChAc has been described in a few case reports. In conclusion ChAc is a rare disorder in which the presence of acanthocytes is not mandatory. In case of doubt, chorein western blot can be useful.

A neuropathological study of autosomal-dominant chorea-acanthocytosis with a mutation of VPS13A

We report the first autopsy case of genetically confirmed, autosomal-dominant chorea-acanthocytosis (AD-ChAc), showing a heterozygous mutation (G-A) at nucleotide position 8,295 in exon 57 of VPS13A. The patient was a 36-year-old Japanese man and the duration of his illness was 11 years. Neuropathologically, the patient showed marked atrophy and neuronal loss, particularly small and medium-sized neurons, with astrocytic gliosis in the caudate nucleus, putamen and globus pallidus. These findings were similar to previous autopsy reports of autosomal-recessive ChAc (AR-ChAc) with mutations of VPS13A. The broad distribution of atrophic neurons and astrocytosis throughout the whole brain was unique in our AD-ChAc patient and has not been described in AR-ChAc. The neuronal density of the dorsal caudate nucleus was lower than that of the ventral side in this patient as well as in three Huntington's disease (HD) patients. The neuronal densities in both the rostral and caudal sides were lower than that in the middle region at the anterior commissure level, while in the three HD patients, the neuronal densities of the caudate nucleus were more decreased in the caudal side. This ChAc patient showed faint immunoreactivity in the caudate nucleus and globus pallidus with antibodies against the striatal neurotransmitters, methionine-enkephalin, leucine-enkephalin and substance P. The difference in patterns of neuronal vulnerability could reflect those in the mechanisms of neurodegeneration between ChAc and HD.

Demonstration of cerebellar atrophy in neuroacanthocytosis of 2 siblings

SUMMARY

Neuroacanthocytosis is a rare hereditary disorder characterized by involuntary choreiform movements and erythrocytic acanthocytosis in the peripheral blood. Clinical manifestations of this disorder resemble those of Huntington disease (HD). Neuroimaging features of neuroacanthocytosis are atrophy and signal intensity change of the striata on MR imaging, as in HD. We report herein the cases of 2 siblings with neuroacanthocytosis showing cerebellar atrophy as well as atrophy and signal intensity changes of striata.

The McLeod syndrome without acanthocytes

A 45-year-old man developed chorea, behavioural changes, moderate amyotrophy and polyneuropathy. Hypertrophic cardiomyopathy and increased serum lactate dehydrogenase and creatine kinase (CK) were found. Acanthocytes were not detected. The absence of XK protein and faintly expressed Kell antigens on erythrocytes were found. Genetic test revealed a R133X mutation of the XK gene, confirming the McLeod syndrome. After 7 years he suddenly developed delirium followed by severe hypoglycaemia, hyperthermia, rhabdomyolysis, hepatic and renal failure. Malignant arrhythmia caused death.

Clinical and molecular genetic assessment of a chorea-acanthocytosis pedigree

BACKGROUND

Chorea-acanthocytosis (ChAc) is an autosomal recessive hereditary disease characterized by neurodegeneration in the striatum and acanthocytosis that is caused by mutations in the VPS13A gene. There are only few reports that studied clinical status of the obligate carriers of ChAc. Clinical courses with follow-up neuroradiological and neuropsychological evaluations in individuals with ChAc have been rarely reported.

METHODS

We followed an index patient with ChAc and evaluated the clinical features of the pedigree members. Genetic analyses of VPS13A and genes responsible for other neuroacanthocytotic and neurodegenerative diseases were performed.

CONCLUSIONS

The index patient was homozygous for a 3889C>T nonsense mutation in the VPS13A gene and presented with a typical ChAc phenotype. Neuropsychological evaluation with brain imaging in the patient over 3 years revealed atrophy and a decrease in blood flow at the basal ganglia and frontal lobe, and impairment in cognitive function reflecting frontal lobe dysfunction in progressive manners. Four out of five heterozygous mutation carriers in the pedigree showed signs or symptoms potentially attributable to a heterozygous VPS13A mutation.

Primary skeletal muscle involvement in chorea-acanthocytosis

Chorea-acanthocytosis (ChAc) is a hereditary disease characterized by involuntary movements and amyotrophy with elevation of serum creatine kinase. Although skeletal muscle involvement in ChAc has been suggested, the mechanism remains unclear. To investigate chorein abnormalities of the skeletal muscles of ChAc patients with an apparently heterozygous VPS13A mutation compared with those of other hereditary choreic diseases, we performed histological and immunohistochemical studies of the skeletal muscles from 3 ChAc, 1 Huntington's disease (HD), 1 McLeod syndrome (MLS), and 1 normal control (NC) with 2 originally generated anti-chorein antibodies. Chorein immunoreactivities in HD, MLS, and NC were found linearly along the sarcolemma and appeared as speckles in the sarcoplasma, but those in ChAc were uneven and discontinuous along the sarcolemmas and increased in the sarcoplasma especially in type I fibers. This histological observation suggests chorein abnormalities of skeletal muscles might be associated with primary involvement of skeletal muscles in this disorder.

The Kell and XK proteins of the Kell blood group are not co-expressed in the central nervous system

The Kell blood group is constituted by two covalently linked antigens at the surface of red blood cells, Kell and Kx. Whereas Kell is a metalloprotease with demonstrated in vitro enzymatic activity, the role of Kx thereon, and/or alone, remains unknown, although its absence is linked to the McLeod syndrome, a neuroacanthocytosis. In the central nervous system, the expression of Kell and XK has been suggested, but their expression patterns remain uncharacterized, as are the post-translational pathogenic mechanisms involved in the development of the McLeod syndrome. The distributions of Kell and XK were thus studied by in situ hybridization as well as immunohistochemistry in rodent and human brain. The results reveal an independent localization of the two constituents of the Kell blood group, XK (Kx) being expressed throughout this tissue, whereas Kell expression is restricted to red blood cells in cerebral vessels. The XK protein is shown to be neuronal, located mainly in intracellular compartments, suggesting a cell specific trafficking pattern, possibly associated with specific physiological functions.

Head of the caudate nucleus is most vulnerable in chorea-acanthocytosis: a voxel-based morphometry study

Chorea-acanthocytosis (ChAc; OMIM 200150) is a rare autosomal recessive disease with dysfunction of the erythrocyte membrane, presenting with acanthocytes and neurological manifestations characterized by progressive hyperkinesias (chorea, dystonia) and neuropsychological impairment. Damage to the basal ganglia was described previously in neuropathological and neuroimaging investigations. We analyzed high-resolution MRI of six ChAc patients with mutations in the VPS13A gene (median age, 37 years; mean time since clinical onset, 13 years) with respect to regional atrophy by use of the observer-independent technique of voxel-based morphometry in comparison to 15 age-matched healthy controls. Additionally, global brain atrophy was determined using the standardized brain parenchymal fraction (BPF) method. A robust regional reduction of gray matter density was observed in the head of the caudate nucleus bilaterally and was nearly symmetrical (P < 0.001, corrected for small volumes). No additional gray matter changes were found. In the BPF analysis, there was no significant global brain atrophy. The predilection of atrophy in the head of the caudate nucleus, as suggested by our results, argues for a particular vulnerability of this part of the striatum in ChAc and is in agreement with pronounced neuropsychological disturbances that are thought to rely on these regions.

Geriatric Chorea

The differential diagnosis, diagnostic evaluation, and treatment of late-onset chorea are reviewed. Late-onset chorea is rare and has a heterogeneous causation. A systematic approach to geriatric chorea greatly enhances a correct diagnosis. An accurate diagnosis is important because many causes of chorea are treatable or or, when heritable, may have significant implications for subsequent generations. Most late-onset chorea is either nonlimiting, requiring no treatment, has a spontaneous remission, or responds to medication. In a minority of patients, chorea is medically refractory or manifestation of an untreatable disorder.

Developments in neuroacanthocytosis: Expanding the spectrum of choreatic syndromes

As with other neurodegenerative disorders, research into the group of diseases known under the umbrella term of "neuroacanthocytosis" has greatly benefited from the identification of causative genes. The distinct and unifying aspect of these disorders is the presence of thorny deformations of circulating erythrocytes. This may be due to abnormal properties of red cell membranes, which could lead to insights into mechanisms of neurodegeneration. Research approaches in this field, in addition to examining functions and protein interactions of the affected proteins with particular respect to neurons, have also drawn upon the expertise of hematologists and red cell membrane biologists. In this article, recent developments in the field are presented.

Seminar on choreas

Chorea is one of the major types of involuntary movement disorders originating from dysfunctional neuronal networks interconnecting the basal ganglia and frontal cortical motor areas. The syndrome is characterised by a continuous flow of random, brief, involuntary muscle contractions and can result from a wide variety of causes. Diagnostic work-up can be straightforward in patients with a positive family history of Huntington's disease or acute-onset hemichorea in patients with lacunar stroke, but it can be a challenging and complex task in rare autoimmune or genetic choreas. Principles of management focus on establishing an aetiological classification and, if possible, removal of the cause. Preventive strategies may be possible in Huntington's disease where genetic counselling plays a major part. In this review we summarise the current understanding of the neuroanatomy and pathophysiology of chorea, its major aetiological classes, and principles of diagnostic work-up and management.

Identification of a VPS13A founder mutation in French Canadian families with chorea-acanthocytosis

Mutations in VPS13A cause chorea-acanthocytosis (ChAc), an autosomal recessive neurodegenerative disorder. VPS13A is located in a tail-to-tail arrangement with GNA14 on chromosome 9q21. ChAc shows substantial allelic heterogeneity, with no single VPS13A mutation causing the majority of cases. We examined 11 patients in four French Canadian ChAc pedigrees for mutations in VPS13A. Affected members of three families were homozygous for a 37-kb deletion of the four terminal exons of VPS13A (EX70_EX73del). This deletion also encompasses the two terminal exons of GNA14. Two affected females in family 4 were homozygous for the splicing mutation 4242+1G>T. Remarkably, the affected males in this highly consanguineous pedigree were compound heterozygotes for EX70_EX73del and 4242+1G>T. PCR analysis of the deletion breakpoint junction revealed that an additional patient with French Canadian ancestry was heterozygous for the EX70_EX73del allele. The identification of a common 9q21 haplotype associated with EX70_EX73del in at least four apparently unrelated ChAc families implies that ChAc shows a founder effect in French Canadians, and that routine testing for EX70_EX73del in suspected ChAc cases may therefore be worthwhile in this population. The deletion breakpoint PCR described here will enable rapid identification of both homozygous and heterozygous carriers of EX70_EX73del.

Neuroacanthocytosis

PURPOSE OF REVIEW

The term neuroacanthocytosis describes a group of phenotypically and genetically heterogeneous disorders, and thus has long been a source of confusion and diagnostic imprecision. It is vital to distinguish between the lipoprotein deficiency disorders which affect gait, but do not cause movement disorders or neuropsychiatric problems, and the diseases described here, of which these are characteristic features. This review summarizes the current state of knowledge regarding this group of diseases in order to facilitate clinical recognition, accurate diagnosis and appropriate management.

RECENT FINDINGS

Advances in molecular medicine have enabled us to distinguish precisely among the disorders described under the label of neuroacanthocytosis, most notably between autosomal recessive chorea-acanthocytosis and the X-linked McLeod syndrome. This has facilitated appreciation of the range of phenotypes in each of the various conditions. Acanthocytosis is also found in a smaller percentage of cases with pantothenate kinase-associated neurodegeneration (PKAN) and Huntington's disease-like 2 (HDL2). An improved method of determination of acanthocytosis has been described, which if adopted as standard practice may facilitate detection of these conditions.

SUMMARY

Genetic testing has led to increased diagnostic accuracy of the neuroacanthocytosis syndromes, which is essential to extend recognition of these disorders, as well as to improve understanding of the disease process. Most importantly, given the absence of a cure, it is vital for appropriate genetic counselling. Treatments, as in other neurodegenerative conditions, are at present limited to symptomatic therapies.