Case reportAdult-onset of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome with hypothyroidism and psychiatric disorders

•We presented an adult MELAS patient with a mutation at A3243G point.•Hypothyroidism and psychiatric disorder were observed as accompanying symptoms.•MRI findings were typical and provided clues to diagnose the underlying MELAS.

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a clinical syndrome associated with mitochondrial disorders (MIDs). This report illustrates a case of MELAS syndrome with hypothyroidism and psychiatric disorders, which is different from the common clinical manifestations of MELAS syndrome, such as exercise intolerance, migraine-like headaches, hearing loss and seizures etc. There are considerable interests in the possibility that mitochondrial dysfunction may play a role in the pathogenesis of endocrine dysfunctions and psychiatric disorders in MELAS syndrome.