Progressive myoclonus epilepsy type 1 (EPM1): Retrospective and prospective study is a part of the project “Rare Diseases of Finnish Disease inheritage, MIRAS, IOSCA, AHS, EPM1 and their disease mechanisms”, which belongs to the New Modalities Ecosystem. The EPM1 study will include new as well as follow-up study visits. Patients will undergo a comprehensive clinical evaluation including video-recorded Unified Myoclonus Rating Scale test panel, Magnetic Resonance Imaging, PET-imaging, Transcranial Navigated Brain Stimulation (TMS), TMS-EEG and polysomnography measurements. The goal is to characterize disease progression and determine possible biomarkers for future personalized prediction of the disease progression and possible treatment effects.