In humans, loss‐of‐function variants in DOCK3 cause developmental delay, muscle hypotonia, and ataxia.[20] In mice, global Dock3 deficiency induced muscle atrophy and impaired muscle function.[19b] Dock3‐deficient myoblasts show defective myogenic differentiation.[19b] However, in Duchenne muscular dystrophic mice, haploinsufficiency of Dock3 improved dystrophic muscle pathologies. Here, DOCK3 is linked to cerebellar ataxia.