Australasian Science: Australia's authority on science since 1938

Genes Raise Chance of Twins

Gene variants that increase a woman’s chance of giving birth to non-identical twins by 29% have been identified by researchers from Queensland, Iceland, The Netherlands and the US.

A/Prof Dale Nyholt of the Queensland University of Technology Institute of Health and Biomedical Innovation said the identification of the two DNA variants associated with a higher chance of non-identical twins also shed light on female fertility by identifying key mechanisms controlling ovarian function.

“We found one variant is close to the gene coding for the secretion of the hormone that stimulates ovarian follicles to release an egg, and the second variant is in a location likely to be involved in the ovaries’ response to follicle-stimulating hormone,” he said. “When both variants are present, a woman has a 29% greater chance of having non-identical twins.”

Nyholt said one of the gene variants also had significant effects on other fertility measures, including the age of a girl’s first period, age at menopause, number of children, and the age at first and last child. “It also affects the genes behind polycystic ovary syndrome, which is a major cause of female infertility,” he said.

“This discovery will help research on the response to hormone stimulation for assisted reproduction such as IVF.”

While there are more genes to be found that influence non-identical twin birth, Nyholt said that a simple gene test could be developed to identify women at risk of a strong response to hormonal treatment that could prevent the serious complication of ovarian hyperstimulation syndrome.

The research has been published in the American Journal of Human Genetics (http://tinyurl.com/jho9vru).