A first study on nicotinamide riboside treatment of 24 individuals with ataxia telangiectasia with a mean age of 17.5 years showed improved ataxia scores and immunoglobulin levels. We here present the effect of nicotinamide riboside in another individual with ataxia and recurrent infections in whom treatment started as early as at age 3 years and 6 months. During 11 months of follow-up, mean total Scale-for-the-Assessment-and-Rating-of-Ataxia (SARA) decreased from 27 to 9 points and mean total Score for the Gross-Motor-Function-Measure increased from 61 to 78%. Improvement of drawing skills was observed by ICF-based ergotherapeutic examination. Use of antibiotics and frequency of hospitalisations due to infections were reduced by more than 90%. Immunological parameters in blood remained unchanged. No adverse effects occurred...