MT-TL1 and maternally-inherited diabetes and deafness: The most common form of mitochondrial disease is attributed to the pathogenic mtDNA point mutation m.3243A>G in the mt‐tRNA leucine gene (MTTL‐1), estimated to be present in approximately 1 in 400 of the population.3, 4 Clinical syndromes classically associated with the phenotypic expression of the m.3243A>G mutation include mitochondrial encephalomyopathy, lactic acidosis, and stroke‐like episodes (MELAS), maternally inherited deafness and diabetes (MIDD), and chronic progressive external ophthalmoplegia.