GAA Repeat Expansions and Frataxin.(ataxia genetics)

I will talk a little about genetics and move onto Friedreich ataxia (FA), in particular the GAA repeat, and Frataxin. The human genome refers to all of the genetic material that is in the nucleus of most of our cells. We estimate that there are 80,000 to 120,000 genes. But we don't know exactly how many there are going to be. Within the cell's nucleus there are structures referred to as chromosomes which contain the DNA. The bases or nucleotides that make up the DNA are the C's, A's, G's, and T's. They come in pairs, C's pair with G's and A's pair with T's. The goal of the Human Genome Project is to determine the sequence of all of the C's, A's, G's, and T's that make up our genome. How many are there? There are three billion bases of nucleotides in the genome. How big is that? It you type 300 letters a minute it would take you 10 hours a day, 360 days a year, for 40 years to type out all of the C's, A's, G's, and T's. In another way, if you have a set of books, 6,000 letters a page, 500 pages to a book, the complete sequence would fill 1,000 books. The Human Genome Project is a huge undertaking. Humans have 23 pairs of chromosomes, one inherited from your mother, the other from your father. All of our DNA is stored in the nucleus of a cell on the chromosomes.

The gene for FA (the GAA ataxia) is on chromosome 9. It is a minute portion of all of the DNA in our cells. What do we know about this gene? We know that within the gene is what we refer to as a GAA repeat. If you have a large number of these repeats, you will have FA (if you inherit a copy from your mother and father that both have a …