Chinese researchers have identified genetic mutations that cause infertility in a small number of women.
Mutations in the TUBB8 gene appear to cause defects that prevent the women's eggs from maturing properly. Scientists are not certain how many women are affected by infertility caused by persistent immature eggs, but it is thought to be rare – it has been reported to be as low as 0.1 percent of women who seek fertility treatment in China.
The researchers looked at women with egg-maturation problems from 24 families who were referred from the Reproductive Medicine Center at Ninth Hospital in Shanghai. They found that women from seven of the families had mutations in the TUBB8 gene.
In five of the families the mutation was was inherited from the father. The other two families had mutations that occurred spontaneously and were not inherited.
Experiments using cell culture and mice confirmed that the eggs failed to mature because of the TUBB8 mutation, confirming that the gene is essential for fertility.
The findings were described as an 'important step forward' by Dr Jurrien Dean, chief of the cellular and developmental biology lab at the US National Institute of Diabetes and Digestive and Kidney Diseases, who wrote an accompanying editorial in the New England Journal of Medicine.
Dr Dean thinks that this knowledge could be useful for developing fertility treatments in the future. For now, testing for TUBB8 mutations could help women with mutations in this gene avoid fertility treatments that would have little or no chance of working for them, such as IVF using their own eggs.
'There would be no point in doing those procedures,' said Dr Dean. 'That's incredibly useful information because it allows patients to move forward and consider other options for having a family – such as using a surrogate, or adoption.'