Genes Dictate Age of Menopause
Excerpt By Patricia Reaney, Reuters Health

LONDON (Reuters) - Women wanting to know how much time they have left on their biological clock should consult their mothers, because the age at which menopause occurs is largely dictated by genes, Dutch doctors said on Thursday.

Scientists at the Diakonessen Hospital in Utrecht and Wageningen University, who carried out a study of the genetic factors involved in menopause, said it was 85% determined by genes. So a woman is likely to follow the same pattern as her mother or sisters.

``A woman with one or more first-degree relatives with a history of early menopause is liable to experience earlier menopause herself,'' said Dr. Jan-Peter de Bruin of Diakonessen Hospital, who led the research team.

``This same woman is also expected to start becoming less fertile and to be completely infertile at an earlier age.''

Most women experience menopause around the age of 50, but it can occur a decade or more earlier or later.

With many women postponing having children until their mid-30s or 40s, the findings could have important implications because sub-fertility and infertility can begin years before menopause.

``If our hypothesis is correct, it would be sensible for a woman to make herself aware of the age which her female relatives have reached menopause. If she wants a family it could help her decide whether it is wise to postpone motherhood too long,'' de Bruin said.

But he added that even if a woman has a family history of late menopause it may not be safe to postpone starting a family.

Women are generally thought to be most fertile between the ages of 20 and 25. Fertility begins to decline after 30.

FINDING THE GENES

The scientists studied data on 243 sisters from 118 families who took part in a breast cancer screening project that began in the 1970s, as well as information from 22 non-identical and 37 identical sets of twins. Their research is reported in the journal Human Reproduction.

De Bruin and his team found that the age at which non-twin sisters reached menopause was 85% to 87% due to genetic factors. In twin sisters, genetics accounted for up to 71%.

Other factors such as smoking, having children and the birth control pill may also influence the age at the onset of menopause, which is caused by the depletion of a woman's eggs.

``Probably the onset of decreasing fertility and the end of fertility is also triggered by earlier thresholds in the number of eggs, so the genetic factors that determine the age of menopause are likely to be the same factors that determine the rate at which the eggs decrease,'' de Bruin explained.

The scientists are now trying to isolate the genes that control menopause. In the future de Bruin said women may be able to take a DNA test that could predict the age at which they could expect menopause to begin.

A better understanding of the genetic factors influencing the decline of female fertility could also lead to the development of treatments that may slow down the process, according to researchers.

SOURCE: Human Reproduction 2001;16:2014-2018.

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