To date, autosomal recessive mutations in ADCK3 have only been identified in 22 patients from 13 families, and these mutations have been associated with clinically heterogeneous diseases.9 Patients usually present with a complex neurological phenotype, with cerebellar ataxia as the predominant manifestation.8–11 In this family, cerebellar symptoms were relatively mild compared to the disabling myoclonus and involuntary movements which affected both siblings. Here, COQ8A is linked to cerebellar ataxia.