The Ageing Human Egg
On Wednesday 6 May Professor Keith Jones, Chair of Human Physiology at the University of Newcastle, travelled to Greenslopes Private Hospital to give a seminar on “the effects of ageing on female fertility”. The seminar organised by Assisted Conception Australia, gave doctors from around Brisbane the chance to learn about this exciting research and how this might impact on fertility treatment for older women.
It is already known that a woman’s fertility declines with age and there is an associated risk of chromosome abnormalities in her offspring, for example, Down Syndrome that is caused by an extra copy of chromosome 21.However, what causes abnormal numbers of chromosomes (a phenomenon called aneuploidy) to occur in a woman’s eggs, is still a mystery.
In women, all eggs are present by birth, and these are ovulated one by one each month over several decades from puberty onwards. Researchers, however, have shown that women over 35 years of age have a significant increase in the number of eggs that have abnormal numbers of chromosomes - with 33% of eggs affected in women over 40 years of age.
Professor Jones and his team are investigating how abnormal chromosome numbers may arise in the eggs of older women. They believe this is caused by two errors within the eggs; the first is a chromosomal error that occurs during early development before birth, the second is a failure to detect and correct this error at a later stage during maturation of the egg just prior to ovulation.
Out of several proteins known to be necessary for an egg to mature, before it is released at ovulation, Professor Jones and his team have identified one protein that is linked to abnormalities in chromosome number. If the amount of this protein is reduced, eggs with these types of chromosome anomalies are produced.
Professor Jones now intends toinvestigate whether this protein is responsible for the chromosome anomalies in human eggs from women undergoing fertility treatment, in collaboration with Dr Steven Fleming, Scientific Director at ACA.He says, “Understanding how this protein might cause aneuploidy is important for the development of future treatments; to allow older women to achieve a successful healthy pregnancy.”
This seminar was generously sponsored by Schering Plough.