ausblenden:
Schlagwörter:
Child
DNA, Mitochondrial/analysis/*genetics
Female
Heterozygote
Humans
Lipoma/*genetics
MERRF Syndrome/*genetics/metabolism
Mothers
*Mutation
Phosphorylation
RNA, Transfer, Lys/genetics
Zusammenfassung:
Myoclonus epilepsy and ragged-red fibers syndrome (MERRF) is caused by a heteroplasmic mutation at nucleotide 8344 (A8344G) of the tRNA(Lys) gene of mitochondrial DNA (mtDNA). This mutation impairs mitochondrial protein synthesis and causes a respiratory chain dysfunction. The risk for transmission of the A8344G mutation from mother to child is dependent on the levels of mutated mtDNA in the mother and above a threshold level of 35-40% the mutation is transmitted to all children. The progression of symptoms in MERRF can be explained by a gene dosage effect with accumulation over time of mutated mtDNA. High levels of mutated mtDNA, ultrastructurally abnormal mitochondria, and a clonal deletion on chromosome 6 are found in lipomas associated with MERRF. These findings indicate that there is a respiratory chain dysfunction in the lipomas and that lipomas may be a manifestation of the A8344G mutation.
