It is a recessively inherited disease, which means that two copies of the defective gene must be inherited in order to produce symptoms. Genes occur in pairs on their respective chromosome pairs, with half of each pair inherited from the mother and half from the father. Several other forms of ataxia exhibit dominant inheritance, which means that only a single defective gene is needed to produce symptoms, allowing the disease itself to be passed from parent to child. In order to develop effective disease treatments, scientists are trying to understand more and more precisely, on a molecular level in fact, how disease affects the body's tissues, such as muscle, bone, or nerve tissue. In the biological scheme of things, our tissues are made up of groups of similar cells.
Cells contain the chromosomes which consist of long strands of DNA on which the genes are arranged.
Genes are sets of instructions that tell the cells how to build the proteins which enable the cells to carry out their various functions. Although the majority of our cells contain our complete gene set, the only genes active in any group of cells are those required for the specific function of the tissue. As in any good mystery adventure, the protagonists of this story encountered unexpected findings. It is known that a dominant form of ataxia called SCA1 is associated with expanded CAG repeats. The location of the repeat in a supposedly silent portion of the gene, called an intron, was also an unexpected finding, and raised many questions about how it causes malfunctioning of the gene.