Pharmacological interventions for lipid transport disorders.

The recent discovery that defects in inter-organelle lipid transport are at the heart of several neurological and neurodegenerative disorders raises the challenge of identifying therapeutic strategies to correct lipid transport defects. This perspective highlights two potential strategies suggested by the study of lipid transport in budding yeast. In the first approach, small molecules are proposed that enhance the lipid transfer activity of VPS13 proteins and thereby compensate for reduced transport. In the second approach, molecules that act as inter-organelle tethers could be used to create artificial contact sites and bypass the loss of endogenous contacts.

Novel heterozygous VPS13A pathogenic variants in chorea-neuroacanthocytosis: a case report.

BACKGROUND: Chorea-acanthocytosis (ChAc) is a rare hereditary autosomal recessive neurodegenerative disorder caused by pathogenic variants of the Vacuolar Protein Sorting 13 homolog A (VPS13A) gene. The variant spectrum of VPS13A has not been completely elucidated. This study reports two novel heterozygous VPS13A pathogenic variants in ChAc that expand the variant spectrum of VPS13A. CASE PRESENTATION: We described a case of a 29-year-old man with typical clinical manifestations of ChAc, including chorea, orofacial lingual dyskinesia, vocal tics, elevated serum biochemical indicators, increased acanthocytes in peripheral blood, and caudate nucleus atrophy. Next-generation sequencing revealed two heterozygous variants of VPS13A: a nonsense variant (NM_033305.2: c.8215G > T, p. Glu2739Ter) and a deletion variant in the exons 25-31. CONCLUSION: The identified nonsense variant gives rise to premature translation termination, while the deletion variant is expected to cause a significant in-frame deletion of amino acid residues in the encoded protein. Both variants are considered to be pathogenic and result in loss-of-function proteins. These findings have implications for the genetic counseling of patients with VPS13A variants.

An Autopsy Series of Seven Cases of VPS13A Disease (Chorea-Acanthocytosis).

BACKGROUND: Vacuolar protein sorting 13 homolog A (VPS13A) disease, historically known as chorea-acanthocytosis, is a rare neurodegenerative disorder caused by biallelic mutations in VPS13A, usually resulting in reduced or absent levels of its protein product, VPS13A. VPS13A localizes to contact sites between subcellular organelles, consistent with its recently identified role in lipid transfer between membranes. Mutations are associated with neuronal loss in the striatum, most prominently in the caudate nucleus, and associated marked astrogliosis. There are no other known disease-specific cellular changes (eg, protein aggregation), but autopsy reports to date have been limited, often lacking genetic or biochemical diagnostic confirmation. OBJECTIVE: The goal of this study was to characterize neuropathological findings in the brains of seven patients with VPS13A disease (chorea-acanthocytosis). METHODS: In this study, we collected brain tissues and clinical data from seven cases of VPS13A for neuropathological analysis. The clinical diagnosis was confirmed by the presence of VPS13A mutations and/or immunoblot showing the loss or reduction of VPS13A protein. Tissues underwent routine, special, and immunohistochemical staining focused on neurodegeneration. Electron microscopy was performed in one case. RESULTS: Gross examination showed severe striatal atrophy. Microscopically, there was neuronal loss and astrogliosis in affected regions. Luxol fast blue staining showed variable lipid accumulation with diverse morphology, which was further characterized by electron microscopy. In some cases, rare degenerating p62- and ubiquitin-positive cells were present in affected regions. Calcifications were present in four cases, being extensive in one. CONCLUSIONS: We present the largest autopsy series of biochemically and genetically confirmed VPS13A disease and identify novel histopathological findings implicating abnormal lipid accumulation. © 2023 International Parkinson and Movement Disorder Society.

Acupuncture for treating symptoms associated with chorea-acanthocytosis: A CARE-compliant case report.

BACKGROUND: Chorea-acanthocytosis (ChAc) is the most common type of neuroacanthocytosis syndromes. Characteristic movement disorders of ChAc are choreiform movements affecting both trunk and extremities. Acanthocytosis in peripheral blood smear, elevated serum creatine kinase, atrophy of heads of caudate nuclei and dilation of the anterior horn of the lateral ventricles in magnetic resonance imaging could assist the diagnosis of ChAc. OBJECTIVE: We aimed to report on the use of acupuncture to successfully improve ChAc symptoms. METHOD: A patient with definite ChAc was admitted, who had suffered from involuntary tongue protrusion for about 10 years. Acupuncture treatment was administrated for 3 times a week for 2 months. The chorea tremor control area, Baihui (GV20), Sishencong (EX-HN1), Shenting (GV24), Benshen (GB13, bilateral), Yintang (GV29), Neiguan (PC6, bilateral), Tongli (HT5, bilateral), Zusanli (ST36, bilateral), Sanyinjiao (SP6, bilateral), Dicang (ST4, bilateral), Chengjiang (CV24), Lianquan (CV23), Jinjin (EX-HN12) and Yuye (EX-HN13) were selected as acupunture points. RESULTS: Previous drug dosage was reduced and the frequency of involuntary tongue protrusion was significantly reduced. Other clinical symptoms were also well controlled. Peripheral blood smear still indicated an increased proportion of red lineage, but blood analyses revealed improvement at follow-up. CONCLUSIONS: For patients who do not response well to conventional medical treatments, acupuncture might be used as an alternative treatment for symptoms related to ChAc.

The XK plasma membrane scramblase and the VPS13A cytosolic lipid transporter for ATP-induced cell death.

Extracellular ATP released from necrotic cells in inflamed tissues activates the P2X7 receptor, stimulates the exposure of phosphatidylserine, and causes cell lysis. Recent findings indicated that XK, a paralogue of XKR8 lipid scramblase, forms a complex with VPS13A at the plasma membrane of T cells. Upon engagement by ATP, an unidentified signal(s) from the P2X7 receptor activates the XK-VPS13A complex to scramble phospholipids, followed by necrotic cell death. P2X7 is expressed highly in CD25+ CD4+ T cells but weakly in CD8+ T cells, suggesting a role of this system in the activation of the immune system to prevent infection. On the other hand, a loss-of-function mutation in XK or VPS13A causes neuroacanthocytosis, indicating the crucial involvement of XK-VPS13A-mediated phospholipid scrambling at plasma membranes in the maintenance of homeostasis in the nervous and red blood cell systems.

Interaction between VPS13A and the XK scramblase is important for VPS13A function in humans.

VPS13 family proteins form conduits between the membranes of different organelles through which lipids are transferred. In humans, there are four VPS13 paralogs, and mutations in the genes encoding each of them are associated with different inherited disorders. VPS13 proteins contain multiple conserved domains. The Vps13 adaptor-binding (VAB) domain binds to adaptor proteins that recruit VPS13 to specific membrane contact sites. This work demonstrates the importance of a different domain in VPS13A function. The pleckstrin homology (PH) domain at the C-terminal region of VPS13A is required to form a complex with the XK scramblase and for the co-localization of VPS13A with XK within the cell. Alphafold modeling was used to predict an interaction surface between VPS13A and XK. Mutations in this region disrupt both complex formation and co-localization of the two proteins. Mutant VPS13A alleles found in patients with VPS13A disease truncate the PH domain. The phenotypic similarities between VPS13A disease and McLeod syndrome caused by mutations in VPS13A and XK, respectively, argue that loss of the VPS13A-XK complex is the basis of both diseases.

Erysense, a Lab-on-a-Chip-Based Point-of-Care Device to Evaluate Red Blood Cell Flow Properties With Multiple Clinical Applications.

In many medical disciplines, red blood cells are discovered to be biomarkers since they "experience" various conditions in basically all organs of the body. Classical examples are diabetes and hypercholesterolemia. However, recently the red blood cell distribution width (RDW), is often referred to, as an unspecific parameter/marker (e.g., for cardiac events or in oncological studies). The measurement of RDW requires venous blood samples to perform the complete blood cell count (CBC). Here, we introduce Erysense, a lab-on-a-chip-based point-of-care device, to evaluate red blood cell flow properties. The capillary chip technology in combination with algorithms based on artificial neural networks allows the detection of very subtle changes in the red blood cell morphology. This flow-based method closely resembles in vivo conditions and blood sample volumes in the sub-microliter range are sufficient. We provide clinical examples for potential applications of Erysense as a diagnostic tool [here: neuroacanthocytosis syndromes (NAS)] and as cellular quality control for red blood cells [here: hemodiafiltration (HDF) and erythrocyte concentrate (EC) storage]. Due to the wide range of the applicable flow velocities (0.1-10 mm/s) different mechanical properties of the red blood cells can be addressed with Erysense providing the opportunity for differential diagnosis/judgments. Due to these versatile properties, we anticipate the value of Erysense for further diagnostic, prognostic, and theragnostic applications including but not limited to diabetes, iron deficiency, COVID-19, rheumatism, various red blood cell disorders and anemia, as well as inflammation-based diseases including sepsis.

XK-Associated McLeod Syndrome: Nonhematological Manifestations and Relation to VPS13A Disease.

BACKGROUND: McLeod syndrome (MLS) is an X-linked multisystemic progressive disorder caused by loss of function mutations in the XK gene. The rare blood group phenotype of MLS patients with absent Kx antigen requires the support of specialized transfusion institutions because of the risk of transfusion complications. Acanthocytosis of red blood cells occurs in almost all patients. Nonhematological manifestations of MLS are very similar to those of VPS13A disease (chorea-acanthocytosis), an autosomal-recessive condition. Their shared phenotype apart from acanthocytosis includes movement disorders such as chorea and dystonia, epilepsy, peripheral neuropathy, and muscle involvement, typically with creatine kinase (CK) elevation, cardiomyopathy included. SUMMARY: In this review, we describe the nonhematological manifestations of MLS in comparison with those of VPS13A disease. While there are many similarities, differences such as mode of inheritance, sex distribution, age at manifestation, severity of heart involvement, frequency of feeding dystonia or of involuntary head drops may help to distinguish these disorders in the clinic. Immunohematological demonstration of the McLeod-Kell phenotype or detection of pathogenic mutations of XK (or VPS13A, respectively) is the gold standard for distinction. "Neuroacanthocytosis" was often used as an overarching term, but is potentially misleading, as the term does not refer to a defined disease entity. Its use, if continued, must not prevent clinicians to seek a final diagnosis on the basis of molecular findings. The clinical similarity of MLS and VPS13A disease has long suggested some shared pathophysiology. Evidence for molecular interaction between XK, the McLeod protein, and chorein, the VPS13A gene product, has recently been put forward: XK forms a complex with chorein/VPS13A, a bulk lipid transporter located at various membrane contact sites. The exact role of XK in this complex needs to be further elucidated. Impairment of bulk lipid transport appears as the common denominator of both MLS and VPS13A disease. A variety of further conditions may in time be added to the "bulk lipid transport diseases," such as the recently recognized disorders caused by mutations in the VPS13B, VPS13C, and VPS13D genes. KEY MESSAGES: (1) Patients diagnosed with the rare red cell McLeod phenotype (McLeod syndrome, MLS) require interdisciplinary collaboration of transfusion medicine specialists, neurologists, and cardiologists for both their hematological and nonhematological disease manifestations. (2) The phenotypical similarity of MLS and VPS13A disease, often leading to either confusion or insufficient diagnostic depth (under the label of "neuroacanthocytosis"), is based on interaction of the respective proteins, XK and chorein, within the cellular machinery for bulk lipid transport. (3) Overall, the term "bulk lipid transport diseases" seems useful for further research on a group of conditions that may not only share pathophysiology, but may also share treatment approaches.

Compound Heterozygous VPS13A Variants in a Patient with Neuroacanthocytosis: A Case Report and Review of the Literature.

Chorea-acanthocytosis (ChAc) is a rare autosomal recessive neurodegenerative disorder caused by pathogenic variants of the vacuolar protein sorting 13A (VPS13A). Only a few patients with ChAc have been reported to date, and the variant spectrum of VPS13A has not been completely elucidated. We describe the case of a 36-year-old woman who had been experiencing orofacial dyskinesia since age 30 years. In a genetic study using next-generation sequencing, 2 variants of VPS13A, the nonsense variant c.4411C>T (p.Arg1471Ter) and the splicing variant c.145-2A>T, were identified. The splicing variant c.145-2A>T was newly classified as a pathogenic variant through a literature review. Consequently, the patient was diagnosed with ChAc based on the typical clinical manifestations, laboratory findings, and imaging results.

Clinical, neuroimaging and gene mutation characteristics of McLeod syndrome and literature review / 中华神经科杂志

Objective:To study the characteristics of clinical, laboratory, imaging, genetic and differential diagnosis of McLeod syndrome.Methods:The clinical characteristics of 2 cases of McLeod syndrome confirmed by gene detection in Qilu Hospital (Qingdao) on June 27, 2018 and in Qilu Hospital of Shandong University on September 11, 2019 were analyzed retrospectively. And the characteristics of patients of McLeod syndrome reported in China were analyzed in combination with literature review.Results:Both of the 2 patients were adult male, aged 57 and 61 years, respectively, with a slowly progressive course, beginning with gradually involuntary movement of trunk and extremities, involving involuntary biting of the tongue and dysphagia. Two patients had mild cognitive impairment; one patient had emotional agitation. Imaging study showed atrophy of caput nuclei caudate. Neuroelectrophysiological examination of case 1 showed sensory axon neuropathy in both upper limbs with severe damage to the left ulnar nerve. Creatine kinase (CK) was mildly elevated in 2 patients. The peripheral blood smear of 1 patient showed increased acanthocytes, accounting for 13%, the other patient showed no increased acanthocyte. McLeod syndrome related gene was tested in the 2 patients, case 1 with deletion mutation of exon 2 of XK gene, and case 2 with hemizygotic mutation of XK gene c.898delC p.L300 *. Conclusions:The clinical manifestations of McLeod syndrome are various and the differential diagnosis is crucial. For elderly male with cephalic facial chorea, elevated CK level and neuromuscular diseases, the possibility of McLeod syndrome should be screened.

[Case-report of neuroacanthocytosis associated with a compound mutation in the VPS13A gene]. / Sluchai neiroakantotsitoza, svyazannyi s mutatsiei VPS13A.

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.

Heterozygous VPS13A and PARK2 Mutations in a Patient with Parkinsonism and Seizures.

Neuroacanthocytosis (NA) is a diverse group of disorders in which nervous system abnormalities co-occur with irregularly shaped red blood cells called acanthocytes. Chorea-acanthocytosis is the most common of these syndromes and is an autosomal recessive disease caused by mutations in the vacuolar protein sorting 13A (VPS13A) gene. We report a case of early onset parkinsonism and seizures in a 43-year-old male with a family history of NA. Neurologic examinations showed cognitive impairment and marked parkinsonian signs. MRI showed bilateral basal ganglia gliosis. He was found to have a novel heterozygous mutation in the VPS13A gene, in addition a heterozygous mutation in the PARK2 gene. His clinical picture was atypical for typical chorea-acanthocytosis (ChAc). The compound heterozygous mutations of VPS13A and PARK2 provide the most plausible explanation for this patient's clinical symptoms. This case adds to the phenotypic diversity of ChAc. More research is needed to fully understand the roles of epistatic interactions on phenotypic expression of neurodegenerative diseases.

Targeting Lyn Kinase in Chorea-Acanthocytosis: A Translational Treatment Approach in a Rare Disease.

Chorea-acanthocytosis (ChAc) is a neurodegenerative disease caused by mutations in the VPS13A gene. It is characterized by several neurological symptoms and the appearance of acanthocytes. Elevated tyrosine kinase Lyn activity has been recently identified as one of the key pathophysiological mechanisms in this disease, and therefore represents a promising drug target. Methods: We evaluated an individual off-label treatment with the tyrosine kinase inhibitor dasatinib (100 mg/d, 25.8-50.4 weeks) of three ChAc patients. Alongside thorough safety monitoring, we assessed motor and non-motor scales (e.g., MDS-UPDRS, UHDRS, quality of life) as well as routine and experimental laboratory parameters (e.g., serum neurofilament, Lyn kinase activity, actin cytoskeleton in red blood cells). Results: Dasatinib appeared to be reasonably safe. The clinical parameters remained stable without significant improvement or deterioration. Regain of deep tendon reflexes was observed in one patient. Creatine kinase, serum neurofilament levels, and acanthocyte count did not reveal consistent effects. However, a reduction of initially elevated Lyn kinase activity and accumulated autophagy markers, as well as a partial restoration of the actin cytoskeleton, was found in red blood cells. Conclusions: We report on the first treatment approach with disease-modifying intention in ChAc. The experimental parameters indicate target engagement in red blood cells, while clinical effects on the central nervous system could not be proven within a rather short treatment time. Limited knowledge on the natural history of ChAc and the lack of appropriate biomarkers remain major barriers for "clinical trial readiness". We suggest a panel of outcome parameters for future clinical trials in ChAc.

Proceedings of the Tenth International Meeting on Neuroacanthocytosis Syndromes.

The 10th International Meeting on Neuroacanthocytosis Syndromes was held online on March 10th12th, 2021. The COVID19 pandemic situation made our planned meeting in Barcelona on March 2020 to be suspended by one year, and finally took place online. The meeting followed the previous nine international symposia, the last of which was held in Dresden, Germany in March, 2018. The setting of the meeting encouraged interactions, exchange of ideas and networking opportunities among the high number of participants from around the globe, including scientists, neurologists and specially patients and caregivers. A total of 27 oral communications were distributed in 8 sessions with topics ranging from molecular and cellular functions of VPS13 genes and proteins, their involvement in Neuroacanthocytosis Syndromes and finally clinical aspects and patients care. In addition, 5 posters were presented. Altogether, scientists and neurologists discussed recent advances and set the bases for next steps, action points, and future studies in close collaboration with the patients associations, which are always actively involved in the whole process.