Five individuals from 2 unrelated pedigrees in our cohort carry the biallelic E149Kfs*18 frameshift and R495W substitution and manifest an early onset, progressive myoclonus epilepsy (PME) and ataxia, therefore, expanding the neurological phenotypes associated with ATP6V0A1 variants beyond the more severe developmental and epileptic encephalopathy observed in the de novo cases. This evidence concerns the gene ATP6V0A1 and developmental and epileptic encephalopathy.