SNP Shot: Genomic Insights

Ataxia-telangiectasia (A-T) is a rare, inherited disease affecting the nervous, immune, and other bodily systems. A key feature of A-T is progressive difficulty with movement coordination (ataxia), typically starting in early childhood, before age 5. Children with A-T usually experience problems with walking, balance, and hand coordination, along with involuntary jerking movements (chorea), muscle twitches (myoclonus), and nerve function issues (neuropathy). These movement difficulties often lead to the need for wheelchair assistance by adolescence. Individuals with A-T may also have slurred speech and difficulty moving their eyes from side to side (oculomotor apraxia). Another characteristic sign is the presence of telangiectases, which are small clusters of enlarged blood vessels visible in the eyes and on the skin's surface.

Individuals with A-T tend to have abnormally high levels of alpha-fetoprotein (AFP) in their blood. AFP levels are typically elevated in pregnant women, but the reason for increased AFP in A-T and its effects are not fully understood.

A weakened immune system is common in individuals with A-T, leading to frequent chronic lung infections. They also face a heightened risk of developing certain cancers, particularly leukemia (cancer of blood-forming cells) and lymphoma (cancer of immune system cells). Importantly, people with A-T are exceptionally sensitive to radiation exposure, including that from medical x-rays.

Currently, there is no cure for ataxia-telangiectasia. However, various treatments, such as physical and speech therapy, and interventions to improve immune system function and nutrition, can help manage some symptoms. The life expectancy for individuals with A-T varies considerably, but most live into early adulthood.

Inheritance:

Ataxia-telangiectasia follows an autosomal recessive inheritance pattern. This means that both copies of the ATM gene in each cell must carry a mutation for the condition to develop. Parents of a child with an autosomal recessive disorder usually each carry one copy of the mutated gene but do not exhibit any signs or symptoms of A-T. Approximately 1% of the U.S. population are carriers, meaning they have one altered copy and one normal copy of the ATM gene. While carriers do not have A-T, they may have an increased risk of developing cancer, with female carriers facing a higher risk of breast cancer. Carriers of an ATM gene variant might also have a greater risk of heart disease.