Approach to Progressive Myoclonic Epilepsies: Clinical Clues for Genetic Testing.

This article focuses on the diagnostic challenges of progressive myoclonic epilepsy (PME), a group of genetically heterogeneous disorders characterized by drug-resistant seizures, cognitive decline, and ataxia. It presents a case of an adult with PME symptoms since age 17 who remained undiagnosed for four years due to inappropriate genetic testing; ultimately, polymerase chain reaction testing of the ATN1 gene confirmed dentatorubral-pallidoluysian atrophy (DRPLA), an autosomal dominant trinucleotide repeat disorder. The report emphasizes the importance of integrating detailed clinical evaluation, family history, and inheritance patterns to guide the selection of appropriate genetic tests, as whole-exome sequencing may miss repeat expansions like those in DRPLA. A diagnostic flowchart is proposed to assist clinicians in narrowing differential diagnoses and improving testing strategies for PME.