New phenotypic diversity associated with the mitochondrial tRNA(SerUCN) gene mutation.
We performed detailed clinical, histopathological, biochemical, in vitro translation and molecular genetic analysis in patients from two unrelated families harbouring the tRNA(SerUCN) 7472C-insertion mutation. Proband 1 developed a progressive neurodegenerative phenotype characterised by myoclonus, epilepsy, cerebellar ataxia and progressive hearing loss. Proband 2 had a comparatively benign phenotype characterised by isolated myopathy with exercise intolerance. Both patients had the 7472C-insertion mutation in identical proportions and they exhibited a similar muscle biochemical and histopathological phenotype. However, proband 2 also had a previously unreported homoplasmic A to C transition at nucleotide position 7472 in the tRNA(SerUCN) gene. This change lengthens further the homopolymeric C run already expanded by the 7472C-insertion. These data extend the phenotypic range associated with the 7472C-insertion to include isolated skeletal myopathy, as well as a MERRF-like phenotype.
Pulkes
T
T
Centre for Neuromuscular Disease, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
Liolitsa
D
D
Eunson
L H
LH
Rose
M
M
Nelson
I P
IP
Rahman
S
S
Poulton
J
J
Marchington
D R
DR
Landon
D N
DN
Debono
A G
AG
Morgan-Hughes
J A
JA
Hanna
M G
MG
D000293:Adolescent; D000328:Adult; D004252:DNA Mutational Analysis / Q000379:methods; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000378:metabolism; D004586:Electrophoresis / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008931:Mitochondria, Muscle / Q000473:pathology; D017237:Mitochondrial Encephalomyopathies / Q000201:enzymology / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D024101:Mitochondrial Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000473:pathology / Q000648:ultrastructure; D009154:Mutation; D009690:Nucleic Acid Conformation; D010641:Phenotype; D012362:RNA, Transfer, Ser / Q000737:chemistry / Q000235:genetics*; D012694:Serine / Q000378:metabolism
D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D012362:RNA, Transfer, Ser; D012694:Serine; D003576:Electron Transport Complex IV