The Role of Genetics in Ataxia Telangiectasia
Ataxia telangiectasia is a recessive genetic condition, which means that in order for a child to have the disease, he or she will need to have two copies of the affected gene -- one from each parent.
Research on ataxia telangiectasia shows that:
- A protein kinase called ATM responds to DNA damage by chemically modifying and triggering the accumulation of a molecular or tumor suppressor called p53.
- The p53 tumor suppressor is defective in about half of all human cancers and is the master control switch for a process that normally prevents cells from dividing.
- In people with ataxia telangiectasia, the ATM protein is missing or defective. This delays the accumulation of p53, allowing cells to divide without their damaged DNA being repaired. This increases the risk of cancer.
A carrier is a person with one normal gene and one altered copy of a gene that is linked to a particular disease. These individuals usually do not realize they are carriers because the disease is not present or its signs and symptoms are mild. People who have one normal copy and one altered copy of the ATM gene are carriers of ataxia telangiectasia.
An estimated 1 percent of the U.S. population, or about 2.5 million people, may be carriers. Ataxia telangiectasia has no racial, economic, geographic, or educational barriers, and males and females are equally affected. It is believed that many children with this condition -- particularly those who die at a young age -- are never properly diagnosed. Therefore, ataxia telangiectasia may actually be much more common than estimated.
In the past, carriers were identified mainly because they were parents of a child with the disease. However, with the cloning of the ATM gene, doctors or cancer genetics professionals can now do genetic testing by analyzing a person's DNA to look for mutations in the ATM gene. It is important to note that genetic testing is complex and difficult, and definitive results may not be possible.