We found a pathogenic m.5541C>T mutation in the mitochondrial tRNATrp gene in a large MELAS family. This mutation firstly affected the maturation and stability of mitochondrial tRNATrp and impaired mitochondrial respiratory chain complex activities, followed by remarkable mitochondrial dysfunction. Surprisingly, we identified that the supplementation of taurine alone remarkably ameliorated the instability and the translation machinery defect of mutant mitochondrial tRNATrp at the in vitro cell level. Further studies are needed to explore the full potential of taurine supplementation as therapy for patients with this mutation. (By Professor Chuanzhu Yan, https://jmg.bmj.com/content/early/2020/11/17/jmedgenet-2020-107323 )