Showing papers by "Douglas C. Wallace published in 1989"

Spontaneous Kearns-Sayre/chronic external ophthalmoplegia plus syndrome associated with a mitochondrial DNA deletion: a slip-replication model and metabolic therapy

Abstract: The muscle mitochondria of a patient with Kearns-Sayre/chronic external ophthalmoplegia plus syndrome were found to be completely deficient in respiratory complex I activity and partially deficient in complex IV and V activities. Treatment of the patient with coenzyme Q10 and succinate resulted in clinical improvement of respiratory function, consistent with the respiratory deficiencies. Restriction enzyme analysis of the muscle mtDNA revealed a 4.9-kilobase deletion in 50% of the mtDNA molecules. Polymerase chain reaction analysis demonstrated that the deletion was present in the patient's muscle but not in her lymphocytes or platelets. Furthermore, the deletion was not present in the muscle or platelets of two sisters. Hence, the mutation probably occurred in the patient's somatic cells. Direct sequencing of polymerase chain reaction-amplified DNA revealed a 4977-base-pair deletion removing four genes for subunits of complex I, one gene for complex IV, two genes for complex V, and five genes for tRNAs, which paralleled the respiratory enzymes affected in the disease. A 13-base-pair direct repeat was observed upstream from both breakpoints. Relative to the direction of heavy-strand replication, the first repeat was retained and the second repeat was deleted, suggesting a slip-replication mechanism. Sequence analysis of the human mtDNA revealed many direct repeats of 10 base pairs or greater, indicating that this mechanism could account for other reported deletions. We postulate that the prevalence of direct repeats in the mtDNA is a consequence of the guanine-cytosine bias of the heavy and light strands.

A Mitochondrial DNA Mutation as a Cause of Leber's Hereditary Optic Neuropathy

Abstract: Leber's hereditary optic neuropathy is a maternally inherited disease associated with the late onset of bilateral loss of central vision and cardiac dysrhythmias. The maternal inheritance is explained by the mitochondrial origin of the disease. Analysis of the sequence of a mitochondrial DNA has indicated that a single nucleotide change at position 11778 is associated with this disease. This mutation converts the 340th amino acid of NADH dehydrogenase subunit 4 from an arginine to a histidine and eliminates an SfaNI endonuclease restriction site. A survey of restriction-fragment-length polymorphisms in the mitochondrial DNA of three independent families with this disease (an American black and two white European families) and 10 controls confirmed that this SfaNI site is associated with the disease. A phylogenetic tree for mitochondrial DNA polymorphism and sequence variants from three probands with Leber's disease and four controls was constructed, and the mutation at position 11778 was found to be associated with two mitochondrial DNA backgrounds--an American black mitochondrial DNA and a European mitochondrial DNA. Thus, this mutation must have arisen twice independently. Since the mutation correlated with symptoms of Leber's disease in both cases, these findings indicate that the mutation is a cause of the disease. This genetic analysis has identified the specific point mutation in the mitochondrial DNA that results in Leber's hereditary optic neuropathy.

Evidence in a lethal infantile mitochondrial disease for a nuclear mutation affecting respiratory complexes I and IV

Abstract: A child died at 4 months of age of a lethal infantile mitochondrial disease associated with cardiomyopathy. Detailed pathologic evaluation of this patient revealed abnormalities in the striated muscle, smooth muscle, heart, and liver, but not the central nervous system. Biochemical analysis revealed a combined complex I and IV deficiency in skeletal muscle, heart, and liver, but not in kidney and brain. Analysis of mitochondrial translation products and mitochondrial DNA failed to detect any abnormality. Parallel studies on both parents were uniformly normal. These data support the hypothesis that this disease was the result of a nuclear DNA mutation in a developmental stage-specific and tissue-specific oxidative phosphorylation-gene.

Genetic test for hereditary neuromuscular disease

Abstract: The present invention relates a method and manufacture for detecting neuromuscular disease, particularly Leber's hereditary optic neuropathy, by ascertaining whether a point mutation has occurred at the 11778 nucleotide position in the mitochondrial DNA of a patient. The invention provides methods to detect this mutation including digestion of the patient's mtDNA with restriction endonucleases followed by analysis of the resulting fragments, differential hybridization of oligonucleotides procedures, and differential PCR techniques.