[Motor Neuron Involvement in RFC1 CANVAS/Spectrum Disorders]

Area of Science:

• Neuroscience
• Genetics
• Neurology

Context:

• Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) presents with ataxia, vestibular deficits, and sensory neuropathy.
• The dorsal root ganglion is implicated in sensory disturbances, suggesting neuronopathy.
• Motor neuron involvement was historically considered uncommon in CANVAS.

Purpose:

• To explore the pathomechanism of peripheral nervous system disorders in CANVAS.
• To investigate the role of RFC1 gene pentanucleotide repeat expansions in CANVAS.
• To analyze the phenotypic diversity and motor neuron involvement in CANVAS patients based on RFC1 repeat types.

Summary:

• CANVAS is caused by homozygous pentanucleotide repeat expansions in the RFC1 gene.
• These expansions lead to varied phenotypes, including upper and lower motor neuron deficits.
• AAGGG repeat expansions are associated with motor neuron involvement, while the frequency in ACAGG repeat expansions requires further elucidation.

Impact:

• Clarifies the genetic etiology of CANVAS and its associated neurological deficits.
• Highlights the potential for motor neuron involvement in CANVAS, expanding the understanding of its clinical spectrum.
• Provides insights into genotype-phenotype correlations, aiding in diagnosis and management of CANVAS.