Ocular Telangiectasia and Cerebellar Atrophy in Ataxia-Telangiectasia (Louis-Bar Syndrome).

Background: Ataxia-telangiectasia (Louis-Bar syndrome) is a rare genetic disorder characterized by progressive ataxia, ocular telangiectasias, immunodeficiency and increased cancer risk due to impaired DNA repair.

Phenomenology shown: Thorough clinical and subsequently radiological examination in a 19-year-old woman with a history of previously undiagnosed, progressive gait ataxia since early childhood, diffuse large B-cell lymphoma and severe combined immunodeficiency revealed the eponymous features of the disease, ocular telangiectasias and cerebellar atrophy, enabling targeted genetic testing.

Educational value: Ocular telangiectasias represent an important clue for a diagnosis of ataxia-telangiectasia in young patients with progressive ataxia, implicating awareness of increased malignancy risk and treatment of immunodeficiency.

Highlights: Ataxia-telangiectasia is a rare genetic disorder characterized by its eponymous features, progressive cerebellar ataxia and ocular telangiectasias. These signs can help in establishing an early diagnosis, hence preventing, or addressing secondary complications of the disease caused by impaired DNA repair, such as malignancies, immunodeficiency, and increased radiation sensitivity.