The Registry and Natural History Study for Progressive Myoclonus Epilepsy Type 1 (EPM1) is focused on gathering longitudinal clinical data as well as biological samples (blood and/or urine) from male and female patients, of all ages, who have a molecular diagnosis of EPM1or CSTB-null-related disease. Currently, there are no therapies that halt disease progression in any CSTB-related diseases, highlighting the urgency for translational research into this condition. The primary objective of the registry is to determine the natural history and genotype-phenotype correlations of disease-causing variants in EPM1 and CSTB-null-related disease.