Clinical and molecular features of encephalomyopathy due to the A3302G mutation in the mitochondrial tRNA(Leu(UUR)) gene.
BACKGROUND
The mitochondrial DNA mutation A3302G in the tRNA(Leu(UUR)) gene causes respiratory chain complex I deficiency. The main clinical feature appears to be a progressive mitochondrial myopathy with proximal muscle weakness.


OBJECTIVE
To report on clinical and molecular features in 4 novel patients with the A3302G mutation.


METHODS
Case reports.


METHODS
Four patients (3 of whom are from the same family) with a myopathy caused by the A3302G mitochondrial DNA mutation.


METHODS
Identification of the A3302G mutation by DNA sequencing.


RESULTS
All 4 patients had an adult-onset progressive mitochondrial myopathy with proximal muscle weakness, resulting in exercise intolerance. In 2 unrelated patients, upper limb reflexes were absent with preservation of at least some lower limb reflexes. Other features including hearing loss, recurrent headaches, ptosis, progressive external ophthalmoplegia, and depression were present.


CONCLUSIONS
While the dominant clinical features of the A3302G mutation were exercise intolerance and proximal muscle weakness, other features of mitochondrial encephalomyopathies, previously not described for this mutation, were present.
Hutchison
Wendy M
WM
Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.
Thyagarajan
Dominic
D
Poulton
Joanna
J
Marchington
David R
DR
Kirby
Denise M
DM
Manji
Shehnaaz S M
SS
Dahl
Hans-Henrik M
HH
D000328:Adult; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D004252:DNA Mutational Analysis; D003866:Depressive Disorder / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D004579:Electron Transport / Q000235:genetics; D017079:Exercise Tolerance / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D006261:Headache / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D034381:Hearing Loss / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D008297:Male; D017237:Mitochondrial Encephalomyopathies / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009154:Mutation / Q000235:genetics*; D015835:Ocular Motility Disorders / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D012313:RNA / Q000235:genetics*; D000077278:RNA, Mitochondrial; D012356:RNA, Transfer, Leu / Q000235:genetics*; D012021:Reflex, Abnormal / Q000235:genetics
D000077278:RNA, Mitochondrial; D012356:RNA, Transfer, Leu; D012313:RNA