A. Shaag et al., MITOCHONDRIAL ENCEPHALOMYOPATHY ASSOCIATED WITH A NOVEL MUTATION IN THE MITOCHONDRIAL TRNA(LEU(UUR)) GENE (A3243T), Biochemical and biophysical research communications, 233(3), 1997, pp. 637-639
We report a new mutation, an A-->T transition at nt 3243 in the mitoch
ondrial tRNA(leu(UUR)) gene, in a 9-year-old girl who presented with m
uscle weakness of 3 years duration complicated by rapidly progressive
encephalopathy, In muscle, the activity of the mitochondrial respirato
ry 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 mutatio
n at nt 3243. (C) 1997 Academic Press.