What are the types of SCAs and their histological features?

SCAs are classified based on their genetic mutations, and several types have been identified, each with unique histological characteristics. For example:

- SCA1: Characterized by a significant loss of Purkinje cells and Bergmann glia proliferation. The cerebellar cortex shows extensive gliosis.
- SCA2: Marked by Purkinje cell loss, as well as degeneration in the pontine nuclei and substantia nigra.
- SCA3: Also known as Machado-Joseph disease, involves widespread neuronal loss in the dentate nucleus, pontine nuclei, and basal ganglia.
- SCA6: Primarily affects Purkinje cells but spares other brain regions, making it somewhat unique among SCAs.