Objective:

Mitochondrial encephalopathy, lactic acidosis, and stroke like episodes (MELAS) is a mitochondrial disorder presenting most commonly between 2 to 40 years of age, with 75% of cases before age 20. Rare cases have been reported past age 60. We report on a case of a family presenting with late onset MELAS in the same year.

Background:

A 66-year-old female with a past medical history of sensorineural hearing loss, type 2 diabetes, hypertension and hyperlipidemia presented with word finding difficulty and right sided neglect. MRI demonstrated a DWI lesion in the left temporal lobe consistent with infarct. Vessel imaging, echocardiogram, and cardiac monitor were unremarkable, and she was discharged on clopidogrel. She returned 11 days later with worsening aphasia and MRI revealed extension of her stroke into the left occipital lobe and right cerebellum. It was then discovered her previously healthy 33-year-old son had been diagnosed with MELAS three months prior. The son had presented with subtle speech difficulties and was found to have a right temporal DWI and T2 hyperintense lesion on MRI. CSF and serum studies were unremarkable for infectious and autoimmune causes. He was discharged following improvement of symptoms but returned the following day after having generalized seizure. MRI revealed expansion of the lesion into the right parietal lobe. MR Spectroscopy showed an elevated lactate peak leading to a presumptive diagnosis of MELAS. He was started on L-Arginine and CoQ10. In both cases, genetic testing revealed a pathogenic MT-TL1 m.3243A>G variant consistent with MELAS (9.7% heteroplasmy in mother and 31% heteroplasmy in son).  

Design/Methods:

NA

Results:

NA

Conclusions:

This case demonstrates low heteroplasmy can lead to a later presentation of MELAS requiring MELAS to be on the differential even in people older than 60.