U of S Study Finds Genetic Mutation Linked to Multiple Births
Posted September 11, 2000
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2000-09-08-MED
EMBARGOED UNTIL 5 P.M. CENTRAL STANDARD TIME FRIDAY, SEPT. 8/2000
U of S Study Finds Genetic Mutation Linked to Multiple Births
In a study published Sept. 9 in the prestigious British medical journal The
Lancet, University of Saskatchewan researchers report they have found a
genetic mutation potentially responsible for twins and other multiple birth
pregnancies.
Though the study involves just one family with a history of multiple births,
a Lancet reviewer says the research paper "could be a breakthrough" in the
search for the gene responsible for twinning or other multiple births.
"This is the first genetic explanation for the phenomenon of twinning in
humans," says principal investigator Dr. Ayman Al-Hendy, a resident doctor
at the time of the study who conducted the research with his supervisor Dr.
Valter Feyles and colleagues Oksana Moshynska and Dr. Anurag Saxena.
The findings could pave the way for a simple DNA test to identify women at
higher risk for multiple birth pregnancies. Multiple birth pregnancies are
one of the undesired effects of infertility treatments and pose a higher
risk for complications both to the babies and the mother. Women undergoing
fertility treatment who test positive for the twinning mutation could then
have their ovulation medication doses adjusted, thereby reducing the risk of
multiple births.
Such a test could also lead to earlier diagnosis of twins in pregnant women,
resulting in improved pre-natal care and reduced risk of complications.
But Al-Hendy cautions further research is needed. "We now have to do further
studies on at least a dozen more families with a strong familial history of
spontaneous (without the use of fertility medications) twinning," he said.
"We also need to do further lab studies to determine the mechanism for these
genetic mutations."
It?s long been known that spontaneous twins and triplets run in families.
But no specific gene has been associated with this phenomenon.
Research has focused on the hormone FSH (follicular-stimulating hormone)
that stimulates the ovaries to mature and produce eggs. Scientists have
wondered whether women with spontaneous twins or other multiple pregnancies
have higher levels of FSH circulating in their blood, but studies have not
found this to be the case in all women with twins.
U of S researchers think the answer lies with the specific sites or
receptors where FSH binds on the ovaries. They hypothesized that if these
FSH receptors are normal, then the ovaries will
respond with normal ovulation, producing one egg every month. But if the FSH
receptor is too sensitive to the hormone due to a genetic mutation, then
that could lead to maturation and release of several eggs at a time, causing
multiple pregnancies.
The team narrowed the search to three FSH receptor gene suspects. They
conducted DNA tests on blood samples from a woman who had given birth to two
sets of twins and who had a family history of multiple pregnancies over two
previous generations. They also took blood samples from other members of her
family and from a control group of 34 women with one baby per pregnancy and
no family history of twinning.
Al-Hendy?s team found two linked mutations in DNA from the blood sample from
the patient who?d given birth to two sets of twins. There were no mutations
in the blood samples of the women from the control group. The mutations were
found in just one of the three FSH receptor gene suspects.
"We suggest that the two mutations together produce a presumably more
sensitive FSH receptor," he said.
He noted this research may also improve our understanding of other
conditions and diseases (such as ovarian cancer and infertility) in which
the FSH receptors are thought to play a role.
"It?s important knowing how these receptors work so that the search and
progress for a solution to several women's health problems can continue," he
said.
The study was funded by a U of S College of Medicine clinical teaching and
research grant obtained by Feyles, former director of the U of S In Vitro
Fertilization Program and now an associate professor at McMaster University.
Dr. Al-Hendy has recently taken up a position with the University of Texas
Medical Branch in Galveston, Texas.
For more information contact:
Dr. Ayman Al-Hendy
Assistant Professor
Division of Gynecology
Department of Obstetrics and Gynecology
University of Texas Medical Branch
Galveston, Texas
Tel. (409) 772-8599
(409) 7726804
(409) 772-3510
Pager (409) 643-1304
Fax (409) 747-0366
E. mail: Ayalhend@UTMB.edu
Dr. Valter Feyles
Associate Professor, McMaster University
Department of Obstetrics and Gynecology
(905) 525-9140 ext: 22228
FAX: (905) 524-2911
E-mail: feylesv@fhs.mcmaster.ca
Kathryn Warden
Research Communications Officer
Office of the Vice-President Research
University of Saskatchewan
(306) 966-2506
