Steve Hayes wrote: > On Wed, 06 Feb 2008 12:42:26 GMT, David Harper <devnull@obliquity.u-net.com> > wrote: > >> The three people involved contributed DNA as follows: >> >> Mother: 23 chromosomes, around 3 billion DNA "letters" >> Father: 23 chromosomes, around 3 billion DNA "letters" >> Egg donor woman: mitochondrial DNA, about 16,000 DNA "letters" >> [SNIP] >> The purpose of the research that was reported this week is to help such >> women to have healthy children. The donor woman would be someone >> without a defect in the mitochondrial DNA. >> >> I hope this helps to clarify things. > > Thank you, yes it does help to clarify them. > > But, if I understand you correctly, even if the children were healthy, they > would still pass on defective mitochondrial DNA to *their* children? The children would inherit healthy mitochondrial DNA from the egg donor, instead of the defective mitochondrial DNA from their mother. The daughters would then pass on the egg donor's healthy mitochondrial DNA to all of their children. The mother is the only person to have defective mitochondrial DNA in this scenario. David Harper Cambridge, England