Walking Capacity in Children With Ataxia Telangiectasia From the Global Ataxia Telangiectasia Family Data Platform.

OBJECTIVE: Walking capacity declines prematurely in individuals with ataxia telangiectasia. However, granular data on walking capacity loss in ataxia telangiectasia are scarce. In this large cross-sectional cohort, we describe age-related walking capacity loss reported by participants and compare categories of a subjective walking capacity scale with the International Cooperative Ataxia Rating Scale (ICARS) walking categories. METHODS: Children with ataxia telangiectasia who presented with neurological symptoms at 5 years of age or younger and were 18 years of age or younger at the time of walking capacity reporting were included. Descriptive statistics, Spearman's rank correlations, and simple linear regression of score versus age were used to analyze the data. RESULTS: Mean walking capacity scores from 372 participants remained stable until age 5, followed by progressive worsening between ages 5 and 14, with persistently high scores thereafter. Categories from the subjective walking capacity scale were mapped to ICARS and its abbreviated, more functional version, Rescored modified ICARS (RmICARS) walking categories. Correlation with age was similar across all three scales (Spearman's rho: 0.711, 0.713, and 0.714). Linear regression in participants aged 5-14 years (N = 220) showed consistent R² values (~0.45) across all scales and confirmed a statistically significant relationship between age and diminished walking capacity (p < 0.001). CONCLUSIONS: Although age-related loss of ambulation was statistically significant, it accounted for just under half of the variability in walking capacity progression. Controlling for disease severity, i.e., classical or the mild variant of ataxia telangiectasia, and capturing more granular data on walking with assistance may improve the prediction of age-associated walking capacity loss.