Gene 'profile' linked to extended fertility
Dr. Kirsty Horsey
Progress Educational Trust27 June 2005
BioNews reporting from ESHRE conference, Copenhagen: The ability of some women to conceive naturally after the age of 45 could be down to genetic differences, Israeli researchers say. The team, who presented their findings at the annual meeting of the European Society of Human Reproduction and Embryology (EHSHRE) in Copenhagen, say the work could help develop better treatments for infertility in older patients.
Advances in 'gene chip' technology mean that scientists can study thousands of different genes at the same time, to identify those that are being expressed (switched on) in a particular body tissue. Scientists from Haddassah University in Jerusalem used this technique to study the ageing process in women fertile after the age of 45. Most women do not conceive spontaneously after this age, due to ageing of the ovaries. The researchers initially recruited 250 women over 45 who had conceived naturally. 'Mostly they had had a large number of children and also a low miscarriage rate', said team leader Neri Laufer, adding 'these two factors indicated to us that they had a natural ability to escape the ageing process of the ovaries'.
The scientists used gene chips to look at gene expression in blood samples taken from eight such women, and compared these to samples from six women of the same age who had finished their families by the age of 30. They found that the women fertile after the age of 45 had a unique gene 'profile' - pattern of gene expression - that was not present in the control group of women. The genes involved, fewer than 50, were mainly related to the processes of programmed cell death (apoptosis) and DNA repair. The older fertile women appear to have 'a unique genetic predisposition that protects them from the DNA damage and cellular ageing that helps age the ovary', according to Laufer.
The women in the study were all Ashenazi Jews, but the team say they have preliminary data showing similar results in Bedouin women, and intend to study other ethnic groups. Identifying such women would enable doctors to know which women are still fertile at an advanced age, which could have counselling implications, says Laufer, adding 'the question of motherhood over the age of 45 is a delicate and complex one'. The findings could also help researchers understand why fertility declines sharply in the years leading up to the menopause, and may eventually lead to new treatments for infertility.
Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.