Newswise – The same complex genetics that contribute to a higher risk of type 2 diabetes may also increase the risk of developing diabetes during pregnancy among women of South Asian descent, a study published today in and Life Shows.
The finding could lead to new ways to identify women who would benefit from interventions to prevent diabetes during pregnancy.
People of South Asian descent have a high risk of developing type 2 diabetes. Women in this group are also twice as likely to develop a condition called gestational diabetes during pregnancy compared to women of European descent. But why South Asians are at greater risk for these two conditions is currently unclear.
“Only a handful of studies have examined how genetic and environmental factors interact in gestational diabetes in South Asian women,” says lead author Amel Lamri, a research associate at McMaster University and the Population Health Research Institute ( PHRI) in Ontario, Canada. “No one has examined how genes associated with type 2 diabetes may interact with environmental factors to contribute to gestational diabetes in South Asian women.”
To fill this gap, Lamri and colleagues evaluated the relationship between genes associated with type 2 diabetes, environmental factors, and gestational diabetes. They examined whether the presence of genetic signatures linked to type 2 diabetes risk was also linked to gestational diabetes in 837 and 4,372 South Asian women who participated in the SouTh Asian BiRth CohorT (START) study and the Born in Bradford study, respectively (BiB).
The team measured the genetic risk of type 2 diabetes using a polygenic risk score, which estimates an individual’s inherited risk of developing a disease based on the number of risk alleles they have. The researchers found that South Asian women with higher type 2 diabetes polygenic risk scores also had a higher risk of gestational diabetes; each incremental increase in score was associated with a 45% increase in the risk of developing this condition.
When the scientists studied gestational diabetes risk at the population level, they found that having a polygenic risk score in the highest third explained 12.5 percent of the risk of developing this condition in South Asian women. When they combined a family history of type 2 diabetes and a polygenic risk score in the top third, it explained 25% of the risk of developing gestational diabetes.
“These results show that a higher polygenic risk score for type 2 diabetes and a family history of diabetes are strongly and independently associated with gestational diabetes in women of South Asian descent,” explains Lamri.
The scientists also examined whether environmental factors modulated these genetic risk factors. Most of the environmental factors considered (with the possible exception of body mass index and diet quality) did not significantly alter the risk of diabetes during pregnancy in either study. But the authors note that the studies may not have been large enough to detect more modest environmental effects, and that more studies are needed to confirm the observed modulatory effects.
“Our findings support the notion that type 2 diabetes and gestational diabetes share a common genetic background,” concludes senior author Sonia Anand, Michael G. DeGroote Chair in Population Health and senior scientist at PHRI, McMaster University and Hamilton Health Sciences. “If future studies confirm our findings, this information could help identify which women would benefit most from interventions to help prevent diabetes during pregnancy.”
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