Using known phenotypic associations captured within OMIM and HPO23 showed that childhood-onset ataxia genes had the highest mean number of associated HPO terms per gene (Fig. 2A) and affected a significantly larger number of distinct body systems compared with adult-onset (Wilcoxon rank sum P = 5.400 × 10−4) and overlap-onset genes (P = 1.800 × 10−4) (Fig. 2B and Supplementary Fig. 1C). This evidence concerns the gene GFER and cerebellar ataxia.