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Hereditary Ataxia
Hereditary ataxias are caused by changes in genes that can be passed through families. Genes are chemical blueprints for our body. Changes in these genetic blueprints can cause ataxia in some families. Ataxias can be inherited in several different patterns: - Autosomal dominant-Autosomal means that both males and females are affected. Dominant means that each child of an affected individual has a 50% chance of inheriting the genetic change that causes ataxia. The dominant ataxias are labeled as spinocerebellar ataxias (SCA) and they are numbered in order of their discovery (i.e. SCA1 was the first dominant ataxia discovered and SCA32 is the most recent ataxia discovered in 2010).
- Autosomal recessive-Autosomal means that both males and females can be affected. Recessive means that in order to have the disease, a person must inherit a genetic change (mutation) from both of their parents. While affected individuals have two mutations, other family members may carry one copy of the mutation but are unaffected. These family members are called “carriers” of the disease. These carriers could potentially have children with ataxia only if they have children with another carrier. The most common recessive ataxias are Friedreich ataxia, AOA1, and AOA2.
- X-linked-X-linked conditions are caused by genetic changes that are found on the sex chromosomes. Sex chromosomes determine if we are male or female. Males usually have one X-chromosome and Y-chromosome, while females have two X-chromosomes. X-linked conditions tend to affect males more often than females. The most common X-linked form of ataxia is Fragile X tremor ataxia syndrome (FXTAS).
- Mitochondrial-Mitochondria are small structure found inside the cells. Mitochondria are the energy factories of our bodies. Mitochondria have their own set of genetic blueprints. Some types of ataxia may be caused by changes in the genes found in the mitochondria. These types of ataxias are usually passed to all children by females, but they are not passed to any children by males. Mitochondrial diseases can also be transmitted by autosomal dominant, autosomal recessive, or X-linked patterns of inheritance.
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