MITOCHONDRIAL-DNA DELETION IN HUMAN OOCYTES AND EMBRYOS

Mitochondrial DNA (mtDNA) deletions are present in both human oocytes and embryos. It has been found that these tissues contain a mtDNA muta tion which is present in high amounts in patients with Kearns-Sayre sy ndrome (KSS) and progressive external ophthalmoplegia. In the present study, the frequency of this KSS deletion was investigated in human oo cytes and embryos. Using a nested primer polymerase chain chian reacti on (PCR) strategy, the frequency of the KSS deletion in 74 human oocyt es and 137 embryos was found to be 32.8 and 8.0% respectively. Using a 'long PCR-short PCR' nested primer strategy, the frequency of the KSS deletion in 181 human oocytes and 104 embryos was found to be 47.0 an d 20.2% respectively. There was no statistical correlation between the age of the patients at the time of oocyte retrieval and the presence of the deleted molecules. There was a statistical difference between t he presence of the deleted molecules in oocytes versus embryos using e ither technique (P< 0.0001). The relevance of these findings to the ac cumulation of low levels of deleted mtDNA in both oocytes and embryos is discussed in this study.