Sonia Anand with South Asian patient

Genetic factors are strongly associated with the development of gestational diabetes (GDM) among women of South Asian ancestry – independent of other risk factors for GDM such as maternal age, body mass index, diet quality, and parental history of diabetes – an analysis published in eLife today has shown.

This is an important finding, as women of South Asian ancestry have amongst the highest rates of GDM world-wide. For example, the incidence of GDM among South Asians in the Peel Region of Ontario is 36 per cent, says the study’s principal investigator, PHRI Senior Scientist Sonia Anand.

The analysis was the first time a type 2 diabetes-derived polygenic risk score (PRS) – interacting with other GDM risk factors (such as age, BMI, diet quality) – has been tested to see how the combination might put an expectant mother at risk for GDM. A PRS measures genetic variants a person has that increases her risk of developing a particular disease.

Researchers analyzed the DNA of more than 5,000 pregnant South Asian women in PHRI’s study, South Asian Birth Cohort (START), and the UK study, Born in Bradford (BiB). Combining information from both studies they showed that many – but not all – genetic variants associated with type 2 diabetes (T2D) are also associated with GDM.

Amel Lamri

“A type 2 diabetes derived polygenic risk score is predictive of GDM,” says Anand, senior author of the publication in eLife. “However, having a family history of diabetes, low diet quality, elevated maternal weight, and lower height” are also predictive. There is a signal which requires future confirmation that an expectant mother’s risk of GDM is increased when they have a strong genetic predisposition and a low diet quality.”

Showing that “polygenic risk score and a family history partially convey independent information about GDM is a significant finding of our study,” says the publication’s first author, Amel Lamri, a research associate at McMaster University working with Anand.

Further research “should focus on deriving and estimating the predictive value of a composite score which combines the GDM/T2D genetic factors, family history of diabetes, prior GDM status, and diet quality score in order to improve the identification of women at higher risk of developing T2D,” says Anand.

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