Spinocerebellar ataxia type 2 (SCA2) is a condition characterized by progressive problems with movement. People with this condition initially experience problems with coordination and balance (ataxia). Other early signs and symptoms of SCA2 include additional movement problems, speech and swallowing difficulties, and weakness in the muscles that control eye movement (ophthalmoplegia). Eye muscle weakness leads to involuntary back-and-forth eye movements (nystagmus) and a decreased ability to make rapid eye movements (saccadic slowing).
Mutations in the ATXN2 gene cause SCA2. The ATXN2 gene provides instructions for making a protein called ataxin-2. This protein is found throughout the body, but its function is unknown. Ataxin-2 is found in the fluid inside cells (cytoplasm), where it appears to interact with a cell structure called the endoplasmic reticulum. The endoplasmic reticulum is involved in protein production, processing, and transport. Researchers believe that ataxin-2 may be involved in processing RNA, a chemical cousin of DNA. Ataxin-2 is also thought to play a role in the production of proteins from RNA (translation of DNA's genetic information).
The prevalence of SCA2 is unknown. This condition is estimated to be one of the most common types of spinocerebellar ataxia; however, all types of spinocerebellar ataxia are relatively rare. SCA2 is more common in Cuba, particularly in the Holguín province, where approximately 40 per 100,000 individuals are affected.
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. An affected person usually inherits the altered gene from one affected parent. However, some people with SCA2 do not have a parent with the disorder. Individuals who have an increase in the number of CAG repeats in the ATXN2 gene, but do not develop SCA2, are at risk of having children who will develop the disorder.
Published Date: December 01, 2019Published By: National Institutes of Health