| Summary: | 碩士 === 臺北醫學大學 === 生物醫學技術研究所 === 92 === Down’s syndrome is the most common disease of chromosomal aberration on cytogenetics. The major form of chromosomal aberration is trisomy 21, an extra chromosome of chromosome 21. There are many studies in Down’s syndrome including clinical pathology, cytogenetics and molecular genetics. It is distinct why the germ cells are susceptible to trisomy formation at meiosis or mitosis stage. Recently, some researches reported that oxidative stress might play some roles in the formation of trisomy. Mitochondria are the major organelles that produce reactive oxygen species. In this study, we hypothesized the mitochondrial dysfunction might be contributed to the pathogenesis of Down’s syndrome. We investigated on mitochondria DNA (mtDNA) copy number, mtDNA deletion and oxidative damages in amniotic cells of Down’s syndrome patient. Decreased copy numbers of mtDNA were found in the patients of Down’s syndrome. Moreover, a novel 5335 bp mtDNA deletion was identified in amniotic cells from Down’s syndrome patient. Analysis of nucleotide sequences flanking the breakpoints of this deletion revealed a 10 nucleotides direct repeat “CCTATAGCAC” flanking the junction site of the 5335 bp deletion at nucleotide position 8263-8272 and 13598-13607. Increased ROS generation and oxidative damages were revealed in Down’s amniotic cells. Taken these data together, we suggested that the dysfunctional mitochondria might play a role in the pathogenesis of Down’s syndrome.
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