Spinocerebellar Ataxia

Excerpt

Ataxia is the absence of voluntary muscle coordination and loss of control of movement that affects gait stability, eye movement, and speech. Spinocerebellar ataxia (SCA) is an inherited (autosomal dominant), progressive, neurodegenerative, and heterogeneous disease that mainly affects the cerebellum. SCA is a subset of hereditary cerebellar ataxia and is a rare disease. To date, more than 40 distinct genetic SCAs have been identified which are classified according to the genetic loci in order of identification. SCA1 was the first SCA described and then further subtypes are identified sequentially. SCA doesn't compulsorily mean that it is restricted to the cerebellum and spinal cord. It may involve the other parts of the central nervous system as well, such as pontine nuclei, spinal cord, peripheral nerves, cortex, basal ganglia, etc. SCA6 is restricted to the cerebellum whereas SCA2 spares cerebellum. Well defined and common types are SCA1, SCA2, SCA3, and SCA6 which accounts for more than half of cases and other rare variants constitute the remaining cases. SCA is very complex to understand both genotypically and phenotypically and very difficult to describe all variants at one time.