In a new study scientists have found that particular genetic variations are linked to early menopause before the age of 45. They compared the DNA of more than 2,000 women who had experienced early menopause with that of women who had menopause later than 45 years. The researchers found that four particular genetic variations might account for part, but not all, of the risk of early menopause. They say further research is also needed to determine how the presence of these variations affects the function of the surrounding DNA. Nevertheless, this research is a useful early step in developing tools for predicting early menopause.
The study was conducted at the Peninsula Medical School and funded by The Institute of Cancer research. The study was published in the peer-reviewed medical journal Human Molecular Genetics.
Experts say that at least 5% women experience menopause before 45 and women become infertile approximately 10 years before menopause, which can occur at any age between 40 and 60 years of age. This is important for women who want to put off their pregnancy till later. They said that current methods for predicting menopause can only do so just prior to the onset of menopause. The researchers were interested in seeing whether it was possible to make an earlier prediction of when a woman would be likely to experience menopause, providing her with an estimate of when she would be most likely to be fertile and able to have a child.
They studied four regions of DNA that had been associated with early menopause in earlier studies. The researchers looked at four regions of DNA on chromosome 20, 6, 19 and 5 to look for differences in the sequences of DNA (called single-nucleotide polymorphisms SNPs) between the participants of the study. The participants were included in the Breakthrough Generations Study (BGS) - a separate prospective cohort study launched in September 2004, which investigated the environmental, behavioral, hormonal genome wide association studies of early menopause. Blood samples of each of these women were collected and they were asked to fill questionnaires related to their menstrual histories. Natural menopause was defined as absent menstruation for at least six months without known cause.
The results of the study showed that there were common genetic variants of the sequence on chromosome 19 and 20 affected the age of menopause in all of the women. A genetic variation (SNP) on chromosome 19 was associated with a reduction in menopause age of three months, whereas a SNP on chromosome 20 was associated with a rise in menopausal age of 11 months. Women with early menopause were more likely to possess each of the risk SNPs. The likelihood was between 13-85% greater than in the women who had menopause after 45.
According to Dr Anna Murray, from the University of Exeter the ability to predict time of menopause could be crucial to decisions made many years earlier. She added, “It is estimated that a woman's ability to conceive decreases on average 10 years before she starts the menopause…Therefore, those who are destined to have an early menopause and delay childbearing until their 30s are more likely to have problems conceiving…These findings are the first stage in developing an easy and relatively inexpensive genetic test which could help the one in 20 women who may be affected.”
According to Professor Anthony Swerdlow, from the Institute of Cancer Research this study was a “valuable step.” “This may in turn allow them to make informed decisions about their future fertility,” he said.
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