Why do individuals with spinocerebellar ataxia experience loss of muscle control even though the ataxin-1 protein builds up only in the brain and spinal cord?

Answer 1

Individuals with spinocerebellar ataxia experience loss of muscle control due to the degeneration of specific neurons in the cerebellum and brainstem, which are crucial for coordinating movement. The accumulation of ataxin-1 protein disrupts normal cellular functions, leading to neuronal dysfunction and death. This disruption impairs the brain's ability to process and relay motor commands effectively, resulting in the characteristic lack of coordination and balance associated with the disorder. Even though the protein buildup occurs primarily in the brain and spinal cord, its effects cascade throughout the motor control pathways, leading to widespread motor deficits.