Pediatric patients with classical AT may present dystonia as the main manifestation, or even a first symptom, besides typical cerebellar ataxia, bulbar conjunctive telangiectasia, etc. Crucially, we also found three novel pathogenic ATM gene variants (c.437_440delTCAA, c.2482A>T, and c.5495_5496+2delAAGT), expanding the ATM pathogenic gene mutation spectrum. This evidence concerns the gene ATM and cerebellar ataxia.