Chorea-acanthocytosis without chorea: Expanding the clinical phenotype

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.

Chorea-acanthocytosis: Time-dependent changes of symptoms and imaging findings

BACKGROUND AND PURPOSE

Chorea-acanthocytosis, a rare neurodegenerative disease, affects both the striatum and the medial temporal lobe which may cause involuntary movements and epilepsy, respectively. We examined the imaging changes of the hippocampus/amygdala and the striatum as well as clinical symptoms.

MATERIALS AND METHODS

We retrospectively reviewed 29 MRI and 13 SPECT studies and the clinical findings of seven genetically confirmed chorea-acanthocytosis patients. We evaluated the time-dependent imaging changes of the hippocampus/amygdala and striatum and examined the relationships among these images and symptoms.

RESULTS

The initial symptom was epilepsy in four patients and involuntary movements in three patients. These symptoms were eventually noted in five and all seven patients, respectively. On MRI, most patients showed striatum atrophy before a hippocampus/amygdala abnormality emerged, but one patient showed a hippocampus/amygdala abnormality before striatum atrophy. Abnormal MRI findings of hippocampus/amygdala were noted in five patients and atrophy of striatum in all seven patients. SPECT demonstrated hypoperfusion of hippocampus/amygdala in three patients and that of striatum in all five available patients. Four patients demonstrated hypoperfusion of striatum earlier than that of hippocampus/amygdala and one patient showed hypoperfusion of both simultaneously. Many imaging abnormal lesions were accompanied by their corresponding symptoms, but not always so.

CONCLUSION

Striatum abnormalities were the initial imaging findings in many chorea-acanthocytosis patients, but epilepsy or hippocampus/amygdala imaging abnormalities may be the only findings at the early stage. It is important to understand the detailed clinical and imaging time courses for the diagnosis of chorea-acanthocytosis.

Chorea-Acanthocytosis Presenting as Autosomal Recessive Epilepsy in a Family With a Novel VPS13A Mutation

Chorea-acanthocytosis (ChAc) is a rare, adult-onset disease usually characterized by, hence the name, a movement disorder and acanthocytosis in the blood. It is caused by mutations of the VPS13A gene with an autosomal recessive transmission. We report a consanguineous Turkish family with a different and informative clinical and diagnostic course. Three siblings developed seizures and the index patient had been diagnosed with bilateral temporal lobe epilepsy. A key finding, however, was the basal ganglia involvement in neuroimaging although no movement disorder was present. [¹⁸F]FDG-PET showed a prominent decline in striatal glucose metabolism at 31 years of age and [¹²³I]FP-CIT-SPECT revealed a moderate loss of striatal dopamine transporter availability. The family was referred for genetic testing and exome sequencing detected a homozygous novel truncating mutation c.4326 T>A (p.Tyr1442^*) in VPS13A in all affected siblings. With this case, we present autosomal recessive epilepsy as the predominant phenotype of ChAc with a new homozygous VPS13A mutation and provide pathological structural and molecular neuroimaging findings.

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.