2020–2021 BCSC Basic and Clinical Science Course™
2 Fundamentals and Principles of Ophthalmology
Part III: Genetics
Chapter 5: Molecular Genetics
MELAS and MIDD
Two different disorders—mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS) and maternally inherited diabetes and deafness (MIDD; also called type 2 diabetes mellitus with deafness)—are associated with an mtDNA point mutation (A-to-G change at nucleotide position 3243), which affects an mtDNA-encoded tRNA. Macular retinal pigment epithelial atrophy and this mutation have been described in patients with MELAS.
Isashiki Y, Nakagawa M, Ohba N, et al. Retinal manifestations in mitochondrial diseases associated with mitochondrial DNA mutation. Acta Ophthalmol Scand. 1998;76(1):6–13.
Yu-Wai-Man P, Griffiths PG, Hudson G, Chinnery PF. Inherited mitochondrial optic neuropathies. J Med Genet. 2009;46(3):145–158.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.