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This comprehensive review explores the physiological and pathophysiological significance of VPS13A, a protein encoded by the VPS13A gene. The VPS13A gene is associated with Chorea-acanthocytosis (ChAc), a rare hereditary neurodegenerative disorder. The review covers essential aspects, beginning with the genetics of VPS13A, highlighting its role in the pathogenesis of ChAc, and addressing the spectrum of genetic variants involved. It delves into the structure and function of the VPS13A protein, emphasizing its presence in various tissues and its potential involvement in protein trafficking and lipid homeostasis. Molecular functions of VPS13A in the brain tissue and other cell types or tissues with respect to their role in cytoskeletal regulation and autophagy are explored. Finally, it explores the intriguing link between VPS13A mutations, lipid imbalances, and neurodegeneration, shedding light on future research directions. Overall, this review serves as a comprehensive resource for understanding the pivotal role of VPS13A in health and disease, particularly in the context of ChAc. Key words: Chorein , Tumor, Actin, Microfilament, Gene expression, Chorea-acanthocytosis.

Herein we report on a patient acutely admitted to the emergency room due to malaise and effort intolerance. A heart ultrasound, a cardiovascular MRI and an endomyocardial biopsy were suggestive of myocarditis. With appropriate medications the ejection fraction (EF) slowly improved but follow-up blood examinations revealed a hyperckemia. A neuromuscular examination revealed bilateral atrophy of medial gastrocnemius muscle and absent deep tendon reflexes at lower limbs . Genetic analysis revealed the presence of the hemizygous novel mutation c.757delT (p.Trp253fs) in XK gene thus confirming the diagnosis of McLeod Syndrome (MLS). In this patient an overlap of two conditions, dilative cardiomyopathy (DCMi) due to myocarditis and MLS, might have occurred. Patients with DCMi and hyperckemia should undergo a careful neuromuscular examination as some subclinical signs (calves-hypotrophy, areflexia) might go overlooked. We therefore suggest including the search for acanthocytes in patients with DCMi and hyperCKemia as it is a quick and cheap test that might unravel the MLS diagnosis., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Chorea acanthocytosis (ChAc), an ultra-rare devastating neurodegenerative disease, is caused by mutations in the VPS13A gene, which encodes for the protein chorein. Affected patients suffer from chorea, orofacial dyskinesia, epilepsy, parkinsonism as well as peripheral neuropathy. Although medium spinal neurons of the striatum are mainly affected, other regions are impaired as well over the course of the disease. Animal studies as well as studies on human erythrocytes suggest Lynkinase inhibition as valuable novel opportunity to treat ChAc. In order to investigate the peripheral neuropathy aspect, we analyzed induced pluripotent stem cell derived midbrain/hindbrain cell cultures from ChAc patients in vitro. We observed dendritic microtubule fragmentation. Furthermore, by using in vitro live cell imaging, we found a reduction in the number of lysosomes and mitochondria, shortened mitochondria, an increase in retrograde transport and hyperpolarization as measured with the fluorescent probe JC-1. Deep phenotyping pointed towards a proximal axonal deterioration as the primary axonal disease phenotype. Interestingly, pharmacological interventions, which proved to be successful in different models of ChAc, were ineffective in treating the observed axonal phenotypes. Our data suggests that treatment of this multifaceted disease might be cell type and/or neuronal subtype specific, and thus necessitates precision medicine in this ultra-rare disease., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Objective: To present five new McLeod Syndrome (MLS) pedigrees with novel XK gene mutations, review the literature of this disorder, and discuss the typical and atypical clinical features noted with these new mutations., Methods: This is a multi-center retrospective review of five MLS cases with novel gene mutations. Genotypic and phenotypic information has been obtained from each center., Results: Five novel mutations are reported in this Case series. New clinical findings include prolonged asymptomatic elevated creatine kinase (CK) levels, vocal tics, presence of obstructive sleep apnea (OSA), and one patient of Vietnamese ethnicity., Conclusions: We expand on the clinical and genetic spectrum of MLS demonstrating the clinical variability of MLS., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Importance: McLeod syndrome, encoded by the gene XK, is a rare and progressive disease that shares important similarities with Huntington disease but has widely varied neurologic, neuromuscular, and cardiologic manifestations. Patients with McLeod syndrome have a distinct hematologic presentation with specific transfusion requirements. Because of its X-linked location, loss of the XK gene or pathogenic variants in this gene are principally associated with the McLeod blood group phenotype in male patients. The clinical manifestation of McLeod syndrome results from allelic variants of the XK gene or as part of a contiguous gene deletion syndrome involving XK and adjacent genes, including those for chronic granulomatous disease, Duchenne muscular dystrophy, and retinitis pigmentosa. McLeod syndrome typically manifests as neurologic and cardiologic symptoms that evolve in individuals beginning at approximately 40 years of age., Observations: Diagnosis of McLeod syndrome encompasses a number of specialties, including neurology and transfusion medicine. However, information regarding the molecular basis of the syndrome is incomplete, and clinical information is difficult to find. The International Society of Blood Transfusion has recently compiled and curated a listing of XK alleles associated with the McLeod phenotype. Of note, McLeod syndrome caused by structural variants as well as those cases diagnosed as part of a contiguous gene deletion syndrome were previously classified under a singular allele designation., Conclusions and Relevance: This review discusses the clinical manifestations and molecular basis of McLeod syndrome and provides a comprehensive listing of alleles with involvement in the syndrome published to date. This review highlights the clinical diversity of McLeod syndrome and discusses the development of molecular tools to elucidate genetic causes of disease. A more precise and systematic genetic classification is the first step toward correlating and understanding the diverse phenotypic manifestations of McLeod syndrome and may guide clinical treatment of patients and support for affected and carrier family members. This review provides a knowledge base for neurologists, hematologists, and clinical geneticists on this rare and debilitating disease.

Neuroacanthocytosis (NA) syndromes are a group of rare diseases characterized by neurological disorders and misshaped spiky red blood cells (acanthocytes) including Chorea-Acanthocytosis (ChAc), McLeod syndrome (MLS), Huntington disease-like 2 (HDL 2), pantothenate kinase-associated neurodegeneration (PKAN), abeta- and hypobetalipoproteinemia and aceruloplasminemia. This clinically and genetically heterogeneous group of diseases shares main clinical features presenting most often as a hyperkinetic movement disorder. Even though these are long noted disease conditions, we still know only little on the underlying disease mechanisms. The current review focuses upon ChAc as the core entity of NA syndromes caused by mutations in the VPS13A gene. The support of patient organizations and the ERA-NET initiative yielded to different multidisciplinary efforts with significant progress on our understanding of ChAc. Disturbances in two pathways are currently considered to be significantly involved in the pathophysiology of ChAc, namely elevated Lyn kinase phosphorylation and decreased signaling via Phosphoinositide 3-kinase (PI3K). These recent developments may reveal potential drugable targets for causative therapies of ChAc., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Chorea-acanthocytosis (Ch-Ac) is an autosomal recessive neurodegenerative disorder characterized by adult-onset chorea, acanthocytes in the peripheral blood, and Huntington's disease-like neuropsychiatric symptoms. Animal studies have shown mutation-related dysregulated cortical gamma-aminobutyric acid (GABA)ergic inhibitory networks in its pathophysiology. Herein we found that in patients with Ch-Ac there is a striking alteration of intracortical inhibitory circuits detected by using paired pulse transcranial magnetic stimulation protocols. Our findings show in vivo the functional disruption of GABA(A)-mediated networks in humans with Ch-Ac supporting the existing data in mice models with this condition., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Chorea is an abnormal movement characterized by a continuous flow of random muscle contractions. This phenomenon has several causes, such as infectious and degenerative processes. Chorea results from basal ganglia dysfunction. As the control of the eye movements is related to the basal ganglia, it is expected, therefore, that is altered in diseases related to chorea. Sydenham's chorea, Huntington's disease and neuroacanthocytosis are described in this review as basal ganglia illnesses that can present with abnormal eye movements. Ocular changes resulting from dysfunction of the basal ganglia are apparent in saccade tasks, slow pursuit, setting a target and anti-saccade tasks. The purpose of this article is to review the main characteristics of eye motion in these three forms of chorea.

Objective: To provide clinical clues to differential diagnosis in patients with chorea and other movement disorders with blood acanthocytes., Methods: We present a long-term video accompanied follow-up of six Caucasian patients with neuroacanthocytosis from several centers, three diagnosed with chorea-acanthocytosis (ChAc): 34-y.o.(no.1), 36-y.o.(no.2), 43-y.o.(no.3), two diagnosed with McLeod Syndrome (MLS): 52-y.o.(no.4), 61-y.o.(no.5) and one 63-y.o.(no.6), a brother of no.5, with clinical suspicion of MLS. Additionally we report pathological findings of the mother of two brothers with MLS reported in our series with acanthocytes on peripheral blood smear, Results: The patients had an unremarkable family history and were asymptomatic until adulthood. Patients no. 1,2,4,5,6 developed generalized chorea and patient no. 3 had predominant bradykinesia. Patients no. 1,2,3 had phonic and motor tics, additionally patients no. 1 and 2 exhibited peculiar oromandibular dystonia with tongue thrusting. In patients no. 2 and 3 dystonic supination of feet was observed, patient no. 3 subsequently developed bilateral foot drop. Patients no. 2 and 4 had signs of muscle atrophy. Tendon reflexes were decreased or absent and electroneurography demonstrated sensorimotor neuropathy in patients no. 1,2,3,4,5, except no. 6. Generalized seizures were seen in patients no. 2,3,5,6 and myoclonic jerks in patient no. 1. Cognitive deterioration was reported in patients no. 1,2,3,5,6. Serum creatine kinase levels were elevated in all six patients., Conclusion: We highlight the variability of clinical presentation of neuroacanthocytosis syndromes and the long time from the onset to diagnosis with the need to screen the blood smears in uncertain cases, however, as in one of our cases acanthocytes may even be not found. Based on our observations and data from the literature we propose several red flags that should raise the suspicion of an NA syndrome in a patient with a movement disorder: severe orofacial dyskinesia with tongue and lip-biting (typical of ChAc), feeding dystonia, psychiatric and cognitive disturbances, seizures, peripheral neuropathy, elevation of creatine kinase, elevation of transaminases, hepatosplenomegaly, cardiomyopathy and arrhythmias, and an X-linked pattern of inheritance (McLeod Syndrome, MLS)., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Chorea-acanthocytosis (ChAc) is an extremely rare autosomal recessive disorder caused by mutations in the VSP13A gene on chromosome 9q21. It is characterized by neurological symptoms, psychiatric manifestations and multisystem involvement resulting in myopathy, axonal neuropathy and presence of spiculated red blood cells or acanthocytes. Rarely, epilepsy may be the early symptom in these patients. This can lead to serious delays in diagnosis. We here report the case of a patient with this disease who had seizures several years before the onset of typical manifestations., Competing Interests: Conflits d’intérêts Les auteurs ne déclarent aucun conflit d’intérêts.

Postoperative encephalopathy with choreoathetosis ("postpump chorea") is a rare complication of open-heart surgery and, in particular, the employment of a cardiopulmonary bypass pump. It almost exclusively occurs in young children. While risk factors and the underlying histopathology have been identified, the pathogenesis of postpump chorea, crucially, remains largely unknown. Transient cerebral hypoperfusion associated with cardiopulmonary bypass is considered a likely candidate mechanism, but the evidence is insufficient and inconclusive. It is hypothesized in this article, that postpump chorea may be caused by mechanical trauma to red blood cells and resulting acanthocytosis. These dysfunctional erythrocytes could then lead to damage to the globus pallidus and disease development akin to that presumed in neuroacanthocytosis. In patients with neuroacanthocytosis an association between acanthocytosis and basal ganglia pathology has been suggested. To test the mechanism hypothesized here, the effects of cardiopulmonary bypass on erythrocyte morphology and function could be systematically tested in children undergoing cardiac surgery. Ideally, the extent of erythrocyte damage could be correlated with the risk of developing postpump chorea. Finally, if the proposed hypothesis is supported by empirical findings, efforts to reduce blood cell damage during extracorporeal circulation in children might prevent this devastating complication., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

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. We previously produced a ChAc model mice encoding a human disease mutation with deletion of exons 60-61 in the VPS13A gene. The behavioral and pathological phenotypes of the model mice varied a good deal from individual to individual, indicating that differences between individuals may be caused by the content of a genetic hybrid 129/Sv and C57BL/6J strain background. To establish the effect of the genetic background on phenotype, we backcrossed the ChAc-model mice to different inbred strains: C57BL/6J and 129S6/Sv. Although no significant difference between ChAc-mutant mice and wild-type mice on the C57BL/6J background was observed, the ChAc-mutant mice on the 129S6/Sv showed abnormal motor function and behavior. Furthermore, we produced ChAc-mutant mice on two different inbred strains: BALB/c and FVB. Significant reduction in weight was observed in ChAc mutant mice on the FVB and 129S6 backgrounds. We found a marked increase in the osmotic fragility of red blood cells in the ChAc mutant mice backcrossed to 129S6/Sv and FVB. The phenotypes varied according to strain, with ChAc mutant mice on the FVB and 129S6 backgrounds showing remarkably abnormal motor function and behavior. These results indicate that there are modifying genetic factors of ChAc symptoms., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Panthothenate kinase-associated neurodegeneration (PKAN) belongs to a group of hereditary neurodegenerative disorders known as neuroacanthocytosis (NA). This genetically heterogeneous group of diseases is characterized by degeneration of neurons in the basal ganglia and by the presence of deformed red blood cells with thorny protrusions, acanthocytes, in the circulation., Objective: The goal of our study is to elucidate the molecular mechanisms underlying this aberrant red cell morphology and the corresponding functional consequences. This could shed light on the etiology of the neurodegeneration., Methods: We performed a qualitative and semi-quantitative morphological, immunofluorescent, biochemical and functional analysis of the red cells of several patients with PKAN and, for the first time, of the red cells of their family members., Results: We show that the blood of patients with PKAN contains not only variable numbers of acanthocytes, but also a wide range of other misshapen red cells. Immunofluorescent and immunoblot analyses suggest an altered membrane organization, rather than quantitative changes in protein expression. Strikingly, these changes are not limited to the red blood cells of PKAN patients, but are also present in the red cells of heterozygous carriers without neurological problems. Furthermore, changes are not only present in acanthocytes, but also in other red cells, including discocytes. The patients' cells, however, are more fragile, as observed in a spleen-mimicking device., Conclusion: These morphological, molecular and functional characteristics of red cells in patients with PKAN and their family members offer new tools for diagnosis and present a window into the pathophysiology of neuroacanthocytosis.

Purpose of Review: This review discusses the mechanisms involved in the generation of thorny red blood cells (RBCs), known as acanthocytes, in patients with neuroacanthocytosis, a heterogenous group of neurodegenerative hereditary disorders that include chorea-acanthocytosis (ChAc) and McLeod syndrome (MLS)., Recent Findings: Although molecular defects associated with neuroacanthocytosis have been identified recently, their pathophysiology and the related RBC abnormalities are largely unknown. Studies in ChAc RBCs have shown an altered association between the cytoskeleton and the integral membrane protein compartment in the absence of major changes in RBC membrane composition. In ChAc RBCs, abnormal Lyn kinase activation in a Syk-independent fashion has been reported recently, resulting in increased band 3 tyrosine phosphorylation and perturbation of the stability of the multiprotein band 3-based complexes bridging the membrane to the spectrin-based membrane skeleton. Similarly, in MLS, the absence of XK-protein, which is associated with the spectrin-actin-4.1 junctional complex, is associated with an abnormal membrane protein phosphorylation state, with destabilization of the membrane skeletal network resulting in generation of acanthocytes., Summary: A novel mechanism in generation of acanthocytes involving abnormal Lyn activation, identified in ChAc, expands the acanthocytosis phenomenon toward protein-protein interactions, controlled by phosphorylation-related abnormal signaling.

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.

Chorea-acanthocythosis (ChAc) is an inherited neurodegenerative disorder characterized by movement disorders, neuropsychiatric disturbances, neuropathy, myopathy, seizures and acanthocytosis accompanied by an elevated serum creatine kinase (CK) level. Its causative gene (VPS13A) produces chorein which is absent in ChAc patients as evaluated by Western blot assay. We report the first three Iranian patients whose disease has been confirmed by chorein Western blot. Our cases presented with heterogeneous courses of ChAc. A high sense of clinical awareness in approaching patients with deteriorating and/or multiple abnormal movements that are accompanied by other neurological signs such as neuropathy, myopathy, seizures and high serum CK level will support an early diagnosis of this disease. We also emphasize on the presence of axial flexion/extension spasms as a good clinical sign for narrowing differential diagnosis.

Chorea-acanthocytosis is an inevitably lethal genetic disease characterized by a progressive hyperkinetic movement disorder and cognitive and behavioral abnormalities as well as acanthocytosis. The disease is caused by loss-of-function mutations of the gene encoding vacuolar protein sorting-associated protein 13A (VPS13A) or chorein, a protein with unknown function expressed in various cell types. How chorein deficiency leads to the pathophysiology of chorea-acanthocytosis remains enigmatic. Here we show decreased phosphoinositide-3-kinase (PI3K)-p85-subunit phosphorylation, ras-related C3 botulinum toxin substrate 1 (Rac1) activity, and p21 protein-activated kinase 1 (PAK1) phosphorylation as well as depolymerized cortical actin in erythrocytes from patients with chorea-acanthocytosis and in K562-erythrocytic cells following chorein silencing. Pharmacological inhibition of PI3K, Rac1, or PAK1 similarly triggered actin depolymerization. Moreover, in K562 cells, both chorein silencing and PAK1 inhibition with IPA-3 decreased phosphorylation of Bad, a Bcl2-associated protein, promoting apoptosis by forming mitochondrial pores, followed by mitochondrial depolarization, DNA fragmentation, and phosphatidylserine exposure at the cell surface, all hallmarks of apoptosis. Our observations reveal chorein as a novel powerful regulator of cytoskeletal architecture and cell survival, thus explaining erythrocyte misshape and possibly neurodegeneration in chorea-acanthocytosis.

We report a 39-year-old woman with chorea-acanthocytosis (ChAc) who was referred with refractory hyperkinetic movement and truncal bending spasm. She was diagnosed with ChAc with clinical features and laboratory findings of acanthocytosis in peripheral blood smear, and genetic studies revealed novel mutations in the VPS13 gene. Because her symptoms did not respond well to medical treatment, she was in a totally dependent state. We decided to perform globus pallidus interna deep brain stimulation (GPi-DBS) for symptom control. After the operation her hyperkinetic movement, bradykinesia, and truncal bending motion were improved, the preoperative total score of the motor section on the Unified Huntington's Disease Rating Scale (UHDRS) was 44, the independence scale was 50, and functional capacity was 1. However, a year after GPi-DBS, the postoperative score on the motor section was 12, the independence scale was 80, functional capacity was 9, and she had become capable of independent daily life. Although there is currently no curative treatment for ChAc, GPi-DBS represents a promising option for symptomatic control., (Copyright © 2012 S. Karger AG, Basel.)

Neuroacanthocytosis (NA) syndromes are a group of genetically defined diseases characterized by the association of red blood cell acanthocytosis and progressive degeneration of the basal ganglia. NA syndromes are exceptionally rare with an estimated prevalence of less than 1 to 5 per 1'000'000 inhabitants for each disorder. The core NA syndromes include autosomal recessive chorea-acanthocytosis and X-linked McLeod syndrome which have a Huntington's disease-like phenotype consisting of a choreatic movement disorder, psychiatric manifestations and cognitive decline, and additional multi-system features including myopathy and axonal neuropathy. In addition, cardiomyopathy may occur in McLeod syndrome. Acanthocytes are also found in a proportion of patients with autosomal dominant Huntington's disease-like 2, autosomal recessive pantothenate kinase-associated neurodegeneration and several inherited disorders of lipoprotein metabolism, namely abetalipoproteinemia (Bassen-Kornzweig syndrome) and hypobetalipoproteinemia leading to vitamin E malabsorption. The latter disorders are characterized by a peripheral neuropathy and sensory ataxia due to dorsal column degeneration, but movement disorders and cognitive impairment are not present. NA syndromes are caused by disease-specific genetic mutations. The mechanism by which these mutations cause neurodegeneration is not known. The association of the acanthocytic membrane abnormality with selective degeneration of the basal ganglia, however, suggests a common pathogenetic pathway. Laboratory tests include blood smears to detect acanthocytosis and determination of serum creatine kinase. Cerebral magnetic resonance imaging may demonstrate striatal atrophy. Kell and Kx blood group antigens are reduced or absent in McLeod syndrome. Western blot for chorein demonstrates absence of this protein in red blood cells of chorea-acanthocytosis patients. Specific genetic testing is possible in all NA syndromes. Differential diagnoses include Huntington disease and other causes of progressive hyperkinetic movement disorders. There are no curative therapies for NA syndromes. Regular cardiologic studies and avoidance of transfusion complications are mandatory in McLeod syndrome. The hyperkinetic movement disorder may be treated as in Huntington disease. Other symptoms including psychiatric manifestations should be managed in a symptom-oriented manner. NA syndromes have a relentlessly progressive course usually over two to three decades.

Chorea-acanthocytosis (ChAc) is an uncommon basal ganglia disorder, in which the movement disorder element may be obscured by the predominance of seizures. We report a pertinent case of a patient who had undergone extensive evaluation for epilepsy, including intracranial EEG before finally the diagnosis of ChAc was made and confirmed by Western blot. We suggest that in patients with epilepsy, particularly of temporal lobe origin and with onset in the third decade with inconclusive findings on clinical examination and neuroimaging such as dyskinesias, dystonia and basal ganglia involvement, ChAc should be considered., (Copyright © 2010 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.)

Neuroacanthocytosis is an inclusive term for a genetically heterogeneous group of disorders characterized by the association of neurological abnormalities with red cell acanthocytosis. In the late 1960s, Levine et al. reported a family with a syndrome of neurological deficits such as choreiform involuntary movements, epileptic seizures, intellectual impairment, and paranoid ideation along with acanthocytosis without any disturbance in either alpha- or beta-lipoproteins nor retinitis pigmentosa. Critchley et al. also reported familial cases with acanthocytosis and neurological disorders without beta-lipoproteinemia. These cases have been classified as the Levine-Critchley syndrome of neuroacanthocytosis. Cases of neuroacanthocytosis have been classified into 2 groups depending on the presence or absence of movement disorders such as chorea. One group comprises the core neuroacanthocytosis syndromes in which neurodegeneration occurs primarily in the basal ganglia, specifically the striatum, causing movement disorders. The core neuroacanthocytosis syndromes mainly comprise of the two diseases, chorea-acanthocytosis and the McLeod syndrome. Huntington's disease-like 2, and pantothenate kinase-associated neurodegeneration (PKAN) are very rare but these diseases can also be included in this group of syndromes. Advances in molecular genetics have enabled us to distinguish between these diseases. Recently, the hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa and pallidal degeneration syndrome (HARP syndrome) has been genetically shown to be an allelic form of PKAN. The second group of neuroacanthocytosis syndromes includes abetalipoproteinemia (Bassen-Kornzweig disease) and hypobetalipoproteinemia that are characterized by the abnormal decay of lipoprotein with the intestinal malabsorption of fat leading to neurological abnormalities and acanthocytosis. In this type of neuroacanthocytosis shows a progressive spinocerebellar ataxia with peripheral neuropathy and retinitis pigmentosa are observed, but movement disorders are not seen.

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.

The X-linked McLeod syndrome is defined by absent Kx red blood cell antigen and weak expression of Kell antigens, and this constellation may be accidentally detected in routine screening of apparently healthy blood donors. Most carriers of this McLeod blood group phenotype have acanthocytosis and elevated serum creatine kinase levels and are prone to develop a severe neurological disorder resembling Huntington's disease. Onset of neurological symptoms ranges between 25 and 60 years, and the penetrance of the disorder appears to be high. Additional symptoms of the McLeod neuroacanthocytosis syndrome that warrant therapeutic and diagnostic considerations include generalized seizures, neuromuscular symptoms leading to weakness and atrophy, and cardiopathy mainly manifesting with atrial fibrillation, malignant arrhythmias and dilated cardiomyopathy. Therefore, asymptomatic carriers of the McLeod blood group phenotype should have a careful genetic counseling, neurological examination and a cardiologic evaluation for the presence of a treatable cardiomyopathy.

Two sisters aged 28 and 26, suffering from neuroacanthocytosis (NA), had hypothyroidism and showed a flat growth hormone (GH) response to the insulin tolerance test. GH-releasing hormone (GHRH) administration resulted in a normal GH response in the older sister and a partial GH response in the younger sister. A pathological process--attributable to NA--can be suggested, leading to impaired hypothalamic function, but sparing the pituitary.