Recurrent Stroke-Like Episodes in FBXL4-Associated Early-Onset Mitochondrial Encephalomyopathy

Mutations in the FBXL4 gene have been recently identified as the cause of early-onset mitochondrial encephalomyopathy (EOMEM, OMIM #615471).1,2 Progressive supratentorial and cerebellar atrophy are known manifestations (Figure A); strokelike episodes, although well described in mitochondrial encephalopathy, lactic acidosis, and strokelike episodes (MELAS), however, have not yet been reported with this entity. We document two strokelike episodes in a 13-year-old girl with genetically confirmed FBXL4 (p.[Gln106*]; [Gly568Ala])-associated EOMEM. At age 10 years, she suffered a large right-hemispheric stroke crossing vascular territories and resulting in significant damage with permanent left-sided hemiparesis (Figure B-C). A contralateral left-