Progress in Neuroacanthocytosis Syndromes and Related Diseases Including other Bulk Lipid Transfer Disorders

VPS13A disease (formerly chorea-acanthocytosis; due to bi-allelic mutations in VPS13A) and XK disease (formerly McLeod syndrome; due to mutations of XK) are rare neurodegenerative diseases, classified together as “neuroacanthocytosis syndromes”. In addition to neurological features, deformed red blood cells in the peripheral blood, known as acanthocytes, give the syndrome its name. Progressive neuronal degeneration of the basal ganglia, especially the caudate nucleus, is seen in neuroimaging and neuropathology. The clinical picture can resemble Huntington's disease and additionally can involve a broad spectrum of different movement disorders, including chorea, tics, dystonia, and parkinsonism. Other typical features are seizures, peripheral neuromyopathy, cognitive decline, and behavioral changes. Disease onset is typically in young-mid adulthood (VPS13A disease) or middle age (XK disease). Both diseases are chronic and progressive, resulting in dependence on activities of daily living and shortened life expectancy. Preliminary studies of post-mortem human brain tissue suggest lipid metabolism dysfunction at the subcellular level.

The related proteins, VPS13A and XK, are involved in bulk lipid transfer at membrane contact sites. They closely interact forming a protein complex at the contact sites between the endoplasmic reticulum and the cellular membrane system. VPS13A and the other VPS13 proteins (B-D) belongs to the newly-acknowledged superfamily of bridge-like lipid transfer proteins (BLTPs). Mutations of the other VPS13 genes cause either neurodegenerative (VPS13C, D) or neurodevelopmental (VPS13B) disorders. While the underlying pathophysiology is not yet known, it is possible that VPS13A and XK diseases, as well as the related conditions, are part of a new group of disorders with a common mechanism of impaired bulk lipid transport.

This Research Topic accompanies the 11th International Meeting on Neuroacanthocytosis Syndromes in Homburg/Saar in September 2023 with the goal of scientific exchange on the molecular understanding of the diseases, new diagnostic procedures, and new treatment concepts. The aim is to connect basic research scientists with clinicians and foster the interdisciplinary approach required for the understanding and management of the syndromes and to find starting points for new treatments and possibly for the healing of these neurodegenerative diseases.

The Research Topic covers all aspects of neuroacanthocytosis syndromes and related diseases, from molecular mechanisms to clinical considerations. This includes but is not limited to:

• the newly acknowledged protein superfamily of Bridge Like Transfer Proteins (BLTP);

• bulk lipid transfer disorders – new clinical developments;

• disease insight from model organisms;

• the broader exploration of the XK-VPS13A-complex;

• Cellular models and erythrocyte remodeling;

• Role of these proteins in the brain;

• New animal models of disease

We welcome all article types including research reports, method papers, reviews and perspectives. All conference participants are strongly encouraged to submit their work to the Research Topic; however, the Topic is also open to non-conference attendees who would be interested.