Ataxia-telangiectasia: A review of movement disorders, clinical features, and genotype correlations.

Ataxia-telangiectasia is an autosomal recessive neurodegenerative disorder that was initially thought to present exclusively in childhood. With the discovery of the ATM gene, the phenotypic spectrum of the condition has expanded. This review elaborates the expanded phenomenology, including oculomotor apraxia and immunodeficiency, and estimates the presence of each movement disorder feature from previously reported literature. Initial manifestations of Ataxia-telangiectasia include cerebellar symptoms (67%), dystonia (18%), choreoathetosis (10%), and tremor (4%), with parkinsonism and myoclonus not reported as initial features. The prevalence of movement disorders during the course of the disease includes cerebellar symptoms (96%), dystonia (89%), parkinsonism (41%), choreoathetosis (89%), myoclonus (92%), and tremor (74%). Phenomenology and age of onset is modulated by presence of residual ATM kinase activity, with genotypes heavily truncating the ATM protein associated with the most severe phenotypes. Ataxia-telangiectasia commonly results in a spectrum of movement disorders beyond ataxia and telangiectasias.