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Unexplained infertility could be down to genetics

Around 10% of all infertile couples have no explanation for their infertility - everything looks normal, including the woman's ovulation cycles and hormone levels.

Signe Altmäe. Photo: Uppsala Universitet

Knowing more about the reasons for infertility would perhaps mean that we could help more of these couples. Signe Altmäe, PhD student at the Department of Clinical Science, Intervention and Technology, and her colleagues are researching whether some cases could be down to genetic factors.

How can studying genetics increase our knowledge of previously unexplained infertility?

"Infertility can have many different causes, but in some women with unexplained infertility the lining of the womb looks different at the time of egg implantation compared to fertile women, even though their hormone levels are normal. So we're looking at whether this could be down to altered gene expression of the substances needed for the lining of the womb to receive the fertilised egg."

Which genes are proving most interesting?

"We've seen that the gene expression of several substances is different in infertile and fertile women, including leukaemia inhibitory factor, tissue factor and hyaluronan binding protein 2. These factors all play some role in the process that makes the lining of the womb receptive to the fertilised egg."

You've also studied total gene expression in the lining of the womb when the fertilised egg is implanted. What have you found?

"There's a clear difference between the infertile women and the controls, with completely different genes active in the infertile women. It's interesting that the difference is so marked, and we hope to find out more about what this means for infertility.

What are the implications of differences in gene expression?

"It doesn't necessarily mean that totally different proteins are formed, as there can also be adjustments further down the track from gene to finished protein. One explanation could be that there is a gene-related imbalance in infertile women in the proteins needed when the lining of the womb thickens."

Text: Cecilia Odlind, Published in "Medical Science" no 4, 2010