A mitochondrial tRNA aspartate mutation causing isolated mitochondrial myopathy.
Several mutations in mitochondrial transfer RNA (tRNA) genes can cause mitochondrial myopathy. We describe a young girl who presented with pronounced exercise intolerance. The anaerobic threshold and the maximal oxygen consumption were decreased. She had decreased complex I and IV enzyme activity and ragged red fibers on muscle biopsy. An A to G transition at nucleotide position 7526 in tRNA Aspartate (tRNA(Asp)) gene was heteroplasmic in several of the patient's tissues. We were unable to detect the mutation in muscle tissue from the patient's mother. This case adds a new genetic etiology for mitochondrial myopathy. It also illustrates for patients with combined deficiency of the complex I and IV enzyme activity the value of sequencing in the affected tissue muscle, and not only in blood, all mitochondrial tRNA genes including those not commonly affected, such as in this case mt tRNA(Asp).
Seneca
Sara
S
Center of Medical Genetics, Free University Brussels, Brussels, Belgium.
Goemans
Nathalie
N
Van Coster
Rudy
R
Givron
Patrice
P
Reybrouck
Tony
T
Sciot
Raf
R
Meulemans
Ann
A
Smet
Joel
J
Van Hove
Johan L K
JL
D000328:Adult; D001483:Base Sequence; D001706:Biopsy; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D005260:Female; D006801:Humans; D017240:Mitochondrial Myopathies / Q000235:genetics* / Q000473:pathology; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D009154:Mutation; D017354:Point Mutation; D012349:RNA, Transfer, Asp / Q000235:genetics*
D004272:DNA, Mitochondrial; D012349:RNA, Transfer, Asp