Spinocerebellar Ataxia Health Article

Definition

Spinocerebellar ataxia is a genetically inherited disorder characterized by abnormal brain function that represents a varied group of disorders. It is most commonly inherited as a dominant trait, which means that any individual who is a carrier of one of the many different gene mutations is affected. It also means that a carrier will have a 50% percent chance of having an affected offspring, regardless of the genetic background of the reproductive mate. In this group of disorders, the brain and spinal cord degenerate.

Description

Individuals affected with spinocerebellar ataxia develop a degenerative condition that affects a region in the base of the brain called the cerebellum located behind the brainstem. The primary function of the cerebellum is to coordinate the body's ability to move. Loss of this quintessential function leads to a progressive atrophy, or wasting away of muscles. The spine also atrophies and this can lead to spasticity.

Spinocerebellar ataxia can be physically devastating and the progressive loss of the ability to coordinate movements in emotional complications and significant lifestyle changes. The adverse effects involve the legs, hands, and the speech. Currently, there are 11 types of spinocerebellar ataxia. As there are many different genes mutations that cause this disease, there are different names for each type. The different types have numerical assignments as nomenclature. For example, Spinocerebellar ataxia type 1 is also known as SCA1. The numbers span from 1-25 (there is no SCA9) and are designated based on the time at which they were identified and characterized. Spinocerebellar ataxia is the same disease as spinal cerebellar ataxia.

Demographics

There are several gene mutations on different chromosomes that cause Spinocerebellar ataxia and the frequency of these gene within different populations varies considerably. In fact, due to the number of different types it is often difficult to estimate the incidence of a specific type in a specific population. In general, the incidence is thought to be approximately one to five per 100,000 people. There is no known predilection for sex. As with virtually all autosomal dominant disorders, males and females are equally likely to inherit a defective gene.