[Ataxia telangiectasia. A prototype of neurological involvement in primary immune deficiencies].

The number of primary immune deficiencies exceeds 350, approximately a quarter of them having neurological implications. Severe central nervous system infections may occur in an even higher proportion. Beyond listing in a table of all diseases with a neurological impact, the author gives detailed analysis of one typical disorder. Ataxia telangiectasia is caused by biallelic mutation of the ATM gene resulting in genomic instability, increased cancer risk, immune deficiency and a predominantly cerebellar neurodegeneration. The most common classic form is characterized by gait and limb ataxia, oculomotor apraxia, choreoathetosis, disturbance of speech and swallowing, less often by other movement disorders. There is no remarkable cognitive deficit. Telangiectasia of the conjunctivae and skin usually appears after 6 years of age. Frequent, especially severe sino-pulmonary infections may indicate the immune deficiency present in 60 to 80% of patients, who are also prone to malignancies. The clinical course is sometimes atypical or has a late onset which results in diagnostic difficulties. Serum alpha-fetoprotein level is elevated in nearly all patients. Brain MRI shows progressive cerebellar atrophy starting at the age of 7-8 years. DNA testing of the ATM gene is necessary for the diagnosis. The detected biallelic pathogenic variants provide help for family planning and for possible gene therapies in the future. Ataxia telangiectasia has to be differentiated from a number of other disorders, some of which also belong to primary immune deficiencies. The disorder has no causal treatment at present, the patients live until their young adult ages. Orv Hetil. 2018; 159(49): 2057-2064.