Directly repeated sequences associated with pathogenic mitochondrial DNA deletions.
We determined the nucleotide sequences of junctional regions associated with large deletions of mitochondrial DNA found in four unrelated individuals with a phenotype of chronic progressive external ophthalmoplegia. In each patient, the deletion breakpoint occurred within a directly repeated sequence of 13-18 base pairs, present in different regions of the normal mitochondrial genome-separated by 4.5-7.7 kilobases. In two patients, the deletions were identical. When all four repeated sequences are compared, a consensus sequence of 11 nucleotides emerges, similar to putative recombination signals, suggesting the involvement of a recombinational event. Partially deleted and normal mitochondrial DNAs were found in all tissues examined, but in very different proportions, indicating that these mutations originated before the primary cell layers diverged.
Johns
D R
DR
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Rutledge
S L
SL
Stine
O C
OC
Hurko
O
O
D001483:Base Sequence; D001706:Biopsy; D015139:Blotting, Southern; D002872:Chromosome Deletion; D004272:DNA, Mitochondrial / Q000235:genetics*; D005784:Gene Amplification; D006801:Humans; D008931:Mitochondria, Muscle / Q000032:analysis; D008969:Molecular Sequence Data; D009132:Muscles / Q000473:pathology*; D009886:Ophthalmoplegia / Q000235:genetics* / Q000473:pathology; D012091:Repetitive Sequences, Nucleic Acid
D004272:DNA, Mitochondrial