Synonym: Louis-Bar Syndrome
Ataxia-Telangiectasia (A-T) is an autosomal recessive disease and a rare inherited disorder caused by the inactivation of the ATM gene. It can affect many body systems, but the defects are mainly found in the nervous system and the immune system. The ATM gene is important because it encodes a kinase protein, which plays a key role in repairing DNA breakage (1). If the ATM gene is inactivated, there will not be enough ATM protein and DNA damage will accumulate, which eventually causes the dead of many cells, especially central nervous cells (1)(3)(4). The inability to repair DNA breakage also affects the recombination process of T-cell receptors and Ig genes, which then results in the abnormal humoral and cell-mediated immunity.
Individuals …show more content…
Indeed, most patients with A-T show the severe depletion of intracellular ATM protein, in which about 90% of them have no detectable ATM protein, about 10% have trace amounts of ATM protein, and only 1% have a normal amount of ATM protein, but no kinase activity (3). The measurement of the alpha fetoprotein level in the blood is another important lab test needed for the diagnosis of A-T because more than 95% of individuals with A-T have serum alpha-fetoprotein concentration elevated above 10 ng/mL (6).
Gene analysis can be also performed to look for mutations in the ATM gene (2). A karyotype of A-T patients is characterized by t7;14 translocations and leukemic clones (3). Healthcare faculty should also need to look for serum immunoglobulin levels (IgE, IgA, IgG/IgM), and B/T cell levels of the patient. Low levels of these components indicate defects in humoral and cellular immunity. Other tests such as radiosensitivity assay, MRI of cerebellum, chest x-ray can be obtained if necessary (3).