Mitochondrial encephalomyopathy associated with a novel mutation in the mitochondrial tRNA(leu)(UUR) gene (A3243T).

Abstract

We report a new mutation, an A-->T transition at nt 3243 in the mitochondrial tRNA(leu)(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 transition creates a new recognition site for the restriction enzyme TspRI, both ApaI and TspRI should be used to exclude a mutation at nt 3243.

• Authors: A Shaag, A Saada, A Steinberg, P Navon, O N Elpeleg
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 233 Issue 3 Pg. 637-9 (Apr 28 1997) ISSN: 0006-291X [Print] United States
• PMID: 9168904 (Publication Type: Case Reports, Comparative Study, Journal Article)

Chemical References

• DNA, Mitochondrial
• RNA, Transfer, Leu
• DNA Restriction Enzymes
• Deoxyribonucleases, Type II Site-Specific
• GGGCCC-specific type II deoxyribonucleases

Topics

• Base Sequence
• Child
• DNA Restriction Enzymes
• DNA, Mitochondrial (genetics)
• Deoxyribonucleases, Type II Site-Specific
• Electron Transport
• Female
• Humans
• MELAS Syndrome (diagnosis, genetics)
• Mitochondria, Muscle (metabolism)
• Mitochondrial Encephalomyopathies (diagnosis, genetics, metabolism)
• Point Mutation
• RNA, Transfer, Leu (genetics)