INHERITANCE OF DOMINANT SCA
Most types of SCA are inherited in an autosomal dominant
pattern. This means each son or daughter of an affected person has a
1 in 2, or 50% chance of inheriting SCA. Spinocerebellar ataxia
affects males and females equally. Each type of SCA is caused by a
change (mutation) in a specific gene that is needed for normal brain
function. (see Table 2)
Genes are the basic units of heredity, and contain the set of
instructions that determine how the body grows and develops.
Genes are composed of DNA (deoxyribonucleic acid). It is estimated
that every cell in a person’s body contains about 30,000
genes. Genes, in turn, are packaged on chromosomes– threadli