Retinal manifestations in mitochondrial diseases associated with mitochondrial DNA mutation.
OBJECTIVE
To scrutinize retinal involvement associated with distinct mitochondrial DNA (mtDNA) defects, we reviewed the records of a consecutive series of patients with various mitochondrial diseases.


METHODS
Clinical, laboratory and mtDNA studies were performed in: five patients with Kearns-Sayre syndrome (KSS); six patients with chronic progressive external ophthalmoplegia (CPEO); three patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode (MELAS); three patients with myoclonic epilepsy and ragged-red fibers (MERRF); 20 patients with Leber's hereditary optic neuropathy (LHON); 30 patients with simple diabetes mellitus.


RESULTS
All KSS patients with neurologic and cardiac symptoms associated with a deletion of mtDNA in muscle biopsy specimens showed widespread retinal pigmentary changes characterized by salt- and pepper-like appearance of the fundus. Three of six patients with CPEO, a mild variant of KSS, showed subtle defects at the level of retinal pigment epithelium of the posterior pole, although mtDNA deletion was similar to that in KSS. Of three patients with MELAS syndrome, one patient showed juvenile cataract and mild retinal pigmentary defect in the posterior pole. Of three patients with MERRF syndrome associated with a mtDNA mutation at nucleotide position (np) 8344, one patient showed mild pigment disorder in the posterior pole in addition to optic neuropathy. Two of 20 patients with LHON associated with a mtDNA mutation at np 11778 showed mild pigmentary defect in the macula together with typical optic neuropathy. In addition, two of 30 patients with isolated diabetes mellitus showed a mtDNA mutation at np 3243 (MELAS mutation), but they did not present with any other neurologic or multisystem disorder.


CONCLUSIONS
The retina, in particular the retinal pigment epithelium, is highly vulnerable to be involved by mtDNA defect, and the retinopathy is phenotypically variable and frequently subclinical, depending to some extent on the type or site of mtDNA defect.
Isashiki
Y
Y
Department of Ophthalmology, Center for Chronic Viral Disease, Kagoshima University Faculty of Medicine, Japan.
Nakagawa
M
M
Ohba
N
N
Kamimura
K
K
Sakoda
Y
Y
Higuchi
I
I
Izumo
S
S
Osame
M
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D004272:DNA, Mitochondrial / Q000235:genetics*; D004596:Electroretinography; D005260:Female; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D017353:Gene Deletion; D006801:Humans; D007625:Kearns-Sayre Syndrome; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000235:genetics / Q000473:pathology*; D017237:Mitochondrial Encephalomyopathies / Q000150:complications* / Q000235:genetics; D010857:Pigment Epithelium of Eye / Q000473:pathology; D017354:Point Mutation; D012164:Retinal Diseases / Q000209:etiology* / Q000473:pathology
D004272:DNA, Mitochondrial