Background Biallelic pathogenic variants in the ANO10 gene cause autosomal recessive progressive ataxia (ATX‐ANO10). Methods Following the MDSGene protocol, we systematically investigated genotype–phenotype relationships in ATX‐ANO10 based on the clinical and genetic data from 82 published and 12 newly identified patients. Results Most patients (>80%) had loss‐of‐function (LOF) variants. The most common variant was c.1150_1151del, found in all 29 patients of Romani ancestry, who had a 14‐year earlier mean age at onset than patients homozygous for other LOF variants. We identified previously undescribed clinical features of ATX‐ANO10 (e.g., facial muscle involvement and strabismus) suggesting the involvement of brainstem pathology, and we propose a diagnostic algorithm that may aid clinical ATX‐ANO10 diagnosis. Conclusions The early disease onset in patients with c.1150_1151del may indicate the existence of genetic/environmental disease‐modifying factors in the Romani population. Our findings will inform patient counseling and may improve our understanding of the disease mechanism. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.