Spinocerebellar ataxia type 6 (SCA6) 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 SCA6 include speech difficulties, involuntary eye movements (nystagmus), and double vision. Over time, individuals with SCA6 may develop loss of coordination in their arms, tremors, and uncontrolled muscle tensing (dystonia).

Variants (also known as mutations) in the CACNA1A gene cause SCA6. The CACNA1A gene provides instructions for making a protein that forms a part of some calcium channels. These channels transport positively charged calcium atoms (calcium ions) across cell membranes. The movement of these ions is critical for normal signaling between nerve cells (neurons) in the brain and other parts of the nervous system. The CACNA1A gene provides instructions for making one part (the alpha-1 subunit) of a calcium channel called CaV2.1. CaV2.1 channels play an essential role in communication between neurons in the brain.

The worldwide prevalence of SCA6 is estimated to be less than 1 in 100,000 individuals.

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. In most cases, an affected person has one parent with the condition.

Published Date: July 29, 2022
Published By: National Institutes of Health