Ptosis and ophthalmoplegia can have numerous causes. Once acquired causes are excluded, genetic conditions should be considered.

Pathogenic variants in the POLG gene are one of the most common causes of primary mitochondrial disease. Patients may present with differing features, depending on the age of onset.

Myoclonic epilepsy with ragged red fibres is a relatively common cause of myoclonic epilepsy, especially when associated with maternal inheritance.

Mitochondrial encephalopathy lactic acidosis and stroke-like episodes is a common genetic diagnosis in patients with a suspected mitochondrial condition.