Retinal dystrophy associated with a single-base deletion mutation in mitochondrial DNA 3271 in patient with MELAS syndrome
Mitochondrial encephalopathy with lactic acid and stroke-like episodes (MELAS) is caused by mutations in the mitochondrial DNA. Approximately 80% of MELAS patients have an A > G transition mutation at nucleotide pair 3243 in the mitochondrial DNA, m.3243A > G. There are also MELAS patients with a one-base deletion at nucleotide pair 3271 in the mitochondrial DNA, m.3271delT, but these cases are very rare. We report a case of MELAS with the m.3271delT and describe the retinal structure and electrophysiological alterations.
The retinal structure and function of a 37-year-old woman who was referred to our clinic for of nyctalopia were studied. Standard ophthalmological examinations including the medical history, measurements of the best-corrected visual acuity, intraocular pressures, and slit-lamp biomicroscopy, ophthalmoscopy, fluorescein angiography, fundus autofluorescence, spectral-domain optical coherence tomography (SD-OCT), full-field electroretinography (ERG), and multifocal electroretinography (mfERG) were performed.
Fundus examination showed bilateral hypopigmentary changes of the retinal pigment epithelium which extended from the posterior pole to the equator. Fluorescein angiography showed patchy hyperfluorescence due to window defects at the atrophic areas. Fundus autofluorescence demonstrated mild hyperfluorescent lesions in both eyes. SD-OCT showed that the interdigitation zone was indistinct in both eyes, and the inner nuclear layer was slightly thinner. The amplitudes of the rod, cone, and 30-Hz flicker ERGs were severely reduced, and the implicit times were prolonged. The a- and b-waves of the bright-flash mixed rod–cone ERGs were also reduced. The dark-adapted oscillatory potentials were reduced. The amplitudes of the mfERGs were severely depressed except at the fovea in both eyes.
These findings indicate that the RPE atrophy was wider and the rod dysfunction was more severe affected than that of previously reported MELAS cases with the m.3243A > G mutation.
KeywordsMitochondrial DNA 3271 MELAS M.3271delT Retinopathy
We thank Professor Emeritus Duco Hamasaki of the Bascom Palmer Eye Institute of the University of Miami, FL, for discussions and editing the manuscript. This study was supported partly by Intramural Research Grant (29-4) for Neurological and Psychiatric Disorders of NCNP.
Compliance with ethical standards
Conflict of Interest
All authors declare that he/she has no conflict of interest.
All procedures performed in these studies involving human participants were in accordance with the ethical standards of the Institutional and/or National Research Committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.
Informed consent was obtained from all individual participants included in the study.
- 4.Nesbitt V, Pitceathly RD, Turnbull DM, Taylor RW, Sweeney MG, Mudanohwo EE, Rahman S, Hanna MG, McFarland R (2013) The UK MRC mitochondrial disease patient cohort study: clinical phenotypes associated with the m.3243A > G mutation–implications for diagnosis and management. J Neurol Neurosurg Psychiatry 84(8):936–938. https://doi.org/10.1136/jnnp-2012-303528 CrossRefGoogle Scholar
- 12.Hood DC, Bach M, Brigell M, Keating D, Kondo M, Lyons JS, Marmor MF, McCulloch DL, Palmowski-Wolfe AM (2012) International society for clinical electrophysiology of vision ISCEV standard for clinical multifocal electroretinography (mfERG) (2011 edition). Doc Ophthalmol 124:1–13CrossRefGoogle Scholar
- 14.Massin P, Virally-Monod M, Vialettes B, Paques M, Gin H, Porokhov B, Caillat-Zucman S, Froguel P, Paquis-Fluckinger V, Gaudric A, Guillausseau PJ (1999) Prevalence of macular pattern dystrophy in maternally inherited diabetes and deafness GEDIAM Group. Ophthalmology 106(9):1821–1827CrossRefGoogle Scholar