Choreo-acanthocytosis (hAc) is an autosomal-recessive, neurodegenerative disorder, often presenting as movement disorder, seizures and behavioural changes. This case report describes a male patient who presented with progressive movement disorder, long-standing seizures and cognitive impairment. Neurological examination and neuroimaging revealed features suspicious for basal ganglia degeneration. Routine metabolic and infectious investigations were negative. Genetic testing identified a likely pathogenic VPS13A variant (c.799C>T, p.Arg267Ter), a rare genetic mutation associated with ChAc. This report highlights the complexities of diagnosis, differential considerations, the importance of genetic testing in atypical movement disorders, therapeutic strategies,and the detrimental impact of the VPS13A gene mutation on the patient's quality of life. This case also tries to expand the known mutational spectrum of the VPS13A gene and its varied clinical presentation.

Neuroacanthocytosis syndromes are rare inherited neurodegenerative disorders, characterized by the presence of acanthocytes. Among them, Choreoacanthocytosis and McLeod syndrome stand out, sharing similarities with Huntington's disease, including choreic movement disorders, psychiatric symptoms, and cognitive decline. The case described involves a 36-year-old patient with cognitive deficits, involuntary movements, and ataxic gait. Cranial computed tomography revealed accentuation of cortical sulci and cisterns and atrophy of the caudate nucleus with ex-vacuo dilatation of the anterior horns of the lateral ventricles. Magnetic resonance imaging confirmed these findings and showed putamen atrophy and hypointensity in the basal nuclei. Diagnosis included peripheral blood smear, which revealed numerous acanthocytes, culminating in neuroacanthocytosis, specifically choreoacanthocytosis.

Choreoacanthocytosis, one of the forms of neuroacanthocytosis, is caused by mutations in vacuolar protein sorting-associated protein A (VPS13A), and is often misdiagnosed with other form of neuroacanthocytosis with discrete genetic defects. The phenotypic variations among the patients with VPS13A mutations significantly obfuscates the understanding of the disease and treatment strategies. In this study, two unrelated cases were identified, exhibiting the core phenotype of neuroacanthocytosis but with considerable clinical heterogeneity. Case 1 presented with an additional Parkinsonism phenotype, whereas seizures were evident in case 2. To decipher the genetic basis, whole exome sequencing followed by validation with Sanger sequencing was performed. A known homozygous pathogenic nonsense mutation (c.799C > T; p.R267X) in exon 11 of the VPS13A gene was identified in case 1 that resulted in a truncated protein. A novel missense mutation (c.9263T > G; p.M3088R) in exon 69 of VPS13A identified in case 2 was predicted as pathogenic. In silico analysis of the p.M3088R mutation at the C-terminus of VPS13A suggests a loss of interaction with TOMM40 and may disrupt mitochondrial localization. We also observed an increase in mitochondrial DNA copy numbers in case 2. Mutation analysis revealed benign heterozygous variants in interacting partners of VPS13A such as VAPA in case 1. Our study confirmed the cases as ChAc and identified the novel homozygous variant of VPS13A (c.9263T > G; p.M3088R) within the mutation spectrum of VPS13A-associated ChAc. Furthermore, mutations in VPS13A and co-mutations in its potential interacting partner(s) might contribute to the diverse clinical manifestations of ChAc, which requires further study. VPS13A disease, caused by VPS13A loss-of-function pathogenic variants, is characterized by a spectrum of movement disorders (chorea, dystonia, tics, sometimes parkinsonism); predominant orofacial choreic and dystonic movements and tics (with involuntary tongue protrusion on attempted swallowing, habitual tongue and lip biting resulting in self-mutilation, involuntary vocalizations); dysarthria and dysphagia; psychiatric, cognitive, and behavioral changes ("frontal lobe type"); seizures; and progressive neuromuscular involvement. Huntingtonism (triad of progressive movement disorder and cognitive and behavioral alterations) is a typical presentation. Phenotypic variability is considerable even within the same family, including for monozygotic twins. Mean age of onset is about 30 years. VPS13A disease runs a chronic progressive course and may lead to major disability within a few years. Some affected individuals are bedridden or wheelchair dependent by the third decade. Age at death ranges from 28 to 61 years; several instances of sudden unexplained death or death during epileptic seizures have been reported. The diagnosis of VPS13A disease is established in a proband with suggestive findings and biallelic pathogenic variants in VPS13A identified by molecular genetic testing. Treatment of manifestations: There is no cure for VPS13A disease. Supportive treatment to improve quality of life, maximize function, and reduce complications is recommended. This ideally involves multidisciplinary care by specialists in relevant fields of neurology, psychiatry, physiatry, physical therapy (PT), occupational therapy (OT), speech-language therapy, feeding, neuropsychology, and medical genetics. Pharmacotherapy for movement disorders may include dopamine antagonists/depleters such as atypical neuroleptics or tetrabenazine (or its derivatives) for limb and trunk dystonia and orofaciolingual dystonia (which may also benefit from botulinum toxin). Issues with mobility, activities of daily living, and need for assistive devices can be addressed by physiatry, PT, and OT. In persons with dysphagia, feeding assistance can include speech therapy and gastrostomy tube placement as needed to reduce weight loss and/or risk of aspiration. For dysarthria or mutism, therapy can include the use of technical means for augmentative and alternative communication, such as speech-generating devices. Seizure management can include use of phenytoin, clobazam, valproate, and levetiracetam. For psychiatric/behavioral issues, antidepressant or antipsychotic medications are used per conventional approaches. Surveillance: Regular monitoring of existing manifestations, the individual's response to pharmacotherapy and other supportive care, and the emergence of new manifestations is recommended per the multidisciplinary treating specialists. Agents/circumstances to avoid: Seizure-provoking circumstances (e.g., sleep deprivation, alcohol intake) and anticonvulsants that may worsen involuntary movements (e.g., carbamazepine, lamotrigine). VPS13A disease is inherited in an autosomal recessive manner. If both parents are known to be heterozygous for a VPS13A pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Once the VPS13A pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives, prenatal testing for a pregnancy at increased risk, and preimplantation genetic testing are possible.

There are reports of different clinical statuses in carriers of intermediate alleles (IAs) of CAG trinucleotide repeats in the HTT gene, from individuals affected by a clinical picture indistinguishable from Huntington's disease (HD) to those without manifestations. Therefore, the possible clinical significance of these alleles has been widely debated. The aim of this study was to describe general and clinical features and discard HD phenocopies by molecular assessment in a case series of IA carriers on the HTT gene of a laboratory sample from a neurological center in Mexico. We selected individuals who had previously been tested for the HTT gene expansion, which resulted in IAs. Clinical information was obtained from medical records, and molecular analysis of the JPH3, PRNP, and TBP genes was performed only in IA carriers with clinical manifestations. In addition, two patients with IA and acanthocytes were evaluated by whole-exome sequencing. The scientific and ethical committees of the National Institute of Neurology and Neurosurgery Manuel Velasco Suárez (NINNMVS) approved this study. From 1994 to 2019, the Genetics Department of the NINNMVS confirmed 34 individuals with IAs, 15 of whom belonged to 11 families with HD (IA-HD) and 19 of whom had no family history of HD (IA-non-HD). We found a high proportion of manifestations of the HD phenotypic spectrum in the IA-non-HD subgroup. In addition, among the 20 samples of IA carriers with manifestations molecularly evaluated, we identified two unrelated subjects with CAG/CTG repeat expansions on the JPH3 gene, confirming HD-like 2 (HDL2), and one patient with the homozygous pathogenic c.3232G>T variant (p.Glu1078Ter) in the VPS13A gene, demonstrating choreoacanthocytosis. Our results show the most extensive series of subjects with IAs and clinical manifestations. In addition, we identify three HD phenocopies, two HDL2 cases, and one choreoacanthocytosis case. Therefore, we emphasize evaluating other HD phenocopies in IA carriers with clinical manifestations whose family background is not associated with HD.

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. 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. 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.