Mitochondrial Encephalomyopathy Associated with a Novel Mutation in the Mitochondrial tRNAleu(UUR)Gene (A3243T)

• Published in: Biochemical and biophysical research communications Vol. 233; no. 3; pp. 637 - 639
• Main Authors: Shaag, Avraham, Saada, Ann, Steinberg, Abraham, Navon, Pnina, Elpeleg, Orly N.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 28.04.1997
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1997.6496

We report a new mutation, an A→T transition at nt 3243 in the mitochondrial tRNAleu(UUR)gene, in a 9-year-old girl who presented with muscle weakness of 3 years duration complicated by rapidly progressive encephalopathy. In muscle, the activity of the mitochondrial respiratory chain complexes I, III, and IV was markedly reduced. The mutation, involving a highly conserved base pair in the dihydrouridine loop, was heteroplasmic in muscle (81.4%), skin (69.3%), and blood (13.8%) and was not present in blood of 50 healthy individuals. The mitochondrial 3243 base is a “hot spot” for mutations; an A→G transition at this position is found in a high proportion in most MELAS patients. Since the A→T transtion creates a new recognition site for the restriction enzyme TspRI, both ApaI and TspRI should be used to exclude a mutation at nt 3243.