Ataxia Telangiectasia Flashcards
What is Ataxia-telangiectasia?
rare inherited disorder that affects the nervous system, immune system, and other body systems
What is the disorder characterised by?
progressive difficulty with coordinating movements (ataxia) beginning in early childhood, usually before age 5
cerebellar degeneration, immunodeficiency, radiosensitivity (sensitivity to radiant energy, such as x-ray), and a predisposition to cancer
What are the signs of AT?
typically develop difficulty walking, problems with balance and hand coordination, involuntary jerking movements (chorea), muscle twitches (myoclonus), and disturbances in nerve function (neuropathy)
slurred speech and trouble moving their eyes to look side-to-side (oculomotor apraxia)
Small clusters of enlarged blood vessels called telangiectases, which occur in the eyes and on the surface of the skin
What indicates AT in the blood?
high amounts of a protein called alpha-fetoprotein (AFP) in their blood. The level of this protein is normally increased in the bloodstream of pregnant women, but it is unknown why individuals with ataxia-telangiectasia have elevated AFP or what effects it has in these individuals.
What medical issues are patients with AT susceptible too?
weakened immune system, and many develop chronic lung infections. They also have an increased risk of developing cancer, particularly cancer of blood-forming cells (leukemia) and cancer of immune system cells (lymphoma). Affected individuals are very sensitive to the effects of radiation exposure, including medical x-rays
What is the life expectancy of AT?
varies greatly, but affected individuals typically live into early adulthood
Which gene has mutations in AT?
ATM gene
What is the purpose of the ATM gene?
provides instructions for making a protein that helps control cell division and is involved in DNA repair. This protein plays an important role in the normal development and activity of several body systems, including the nervous system and immune system. The ATM protein assists cells in recognizing damaged or broken DNA strands and coordinates DNA repair by activating enzymes that fix the broken strands. Efficient repair of damaged DNA strands helps maintain the stability of the cell’s genetic information.
What occurs as a result of mutations in the ATM gene?
Cells in the part of the brain involved in coordinating movements (the cerebellum) are particularly affected by loss of the ATM protein. The loss of these brain cells causes some of the movement problems characteristic of ataxia-telangiectasia. Mutations in the ATM gene also prevent cells from responding correctly to DNA damage, which allows breaks in DNA strands to accumulate and can lead to the formation of cancerous tumors.
What is the inheritance of AT?
Autosomal recessive
Although ATM mutation carriers do not have ataxia-telangiectasia, they are more likely than people without an ATM mutation to develop cancer; female carriers are particularly at risk for developing breast cancer. Carriers of a mutation in the ATM gene also may have an increased risk of heart disease.
When do the first signs of AT usually appear?
second year of life as a lack of balance and slurred speech
