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Ataxia telangiectatica (Louis-Bar syndrome)
Last reviewed: 05.07.2025
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Ataxia telangiectatica (syn.: Louis-Bar syndrome) is a rare systemic disease characterized by cerebellar ataxia, which is the earliest symptom, telangiectasias appearing later, usually at 4 years of age, chromosomal instability, immunodeficiency leading to frequent infections, mainly of the upper respiratory tract, and a tendency to develop tumors, mostly lymphoreticular.
[ Causes and pathogenesis
It is inherited in an autosomal recessive manner, gene locus - Ilq22-q23. There is a point of view that the disease is a hereditary disorder of the ability to respond to damage caused by ionizing radiation. The possibility of a defect in DNA reparation in some genetic variants is also allowed. It is assumed that thymus hypoplasia and changes in the nervous system can be caused by vascular anomalies due to a mesodermal defect, or autoimmune reactions to an antigen common to thymocytes and nerve cells. A connection is indicated between T-cell tumors in patients with telangiectatic ataxia and a chromosomal break, mainly 14qll.
In the epidermis, histologically, mild hyper- and parakeratosis and significant melanin deposition are detected. In the upper third of the dermis, there is diffuse vascular dilation.
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