Genetic factors are strongly associated with the development of gestational diabetes (GDM) among women of South Asian ancestry, Hamilton-led research has found.

This risk is independent of other risk factors for GDM such as maternal age, body mass index, diet quality, and parental history of diabetes. This is an important finding as women of South Asian ancestry have amongst the highest rates of gestational diabetes world-wide. For example, the incidence of GDM among South Asians in the Peel Region of Ontario is 36 per cent.

The study by Canadian and U.K. researchers is the first time a Type 2 diabetes-derived polygenic risk score (PRS) along with other GDM risk factors (such as age, BMI, diet quality, birth country, education, and the number of times a woman has given birth) has been tested to see how these factors and their interactions may place an expectant mother at risk for GDM.

The study was published today by the journal eLife.

Researchers analyzed the DNA of more than 5,000 pregnant South Asian women from participants included in the study led by researchers of the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences and from a U.K. study.  

The PHRI study is known as the South Asian Birth Cohort (START), and the U.K. study is known as Born in Bradford. Combining information from both studies, the researchers showed that combining genetic variants known for their T2D-increasing effect in a single score is also associated with a higher risk of GDM.

"A type 2 diabetes-derived polygenic risk score is predictive of GDM," said senior author Sonia Anand.

She is a McMaster professor of medicine, the Canada Research Chair in Ethnicity and Cardiovascular Disease as well as the Michael G DeGroote Heart and Stroke Foundation Chair in Population Health and a PHRI senior scientist. She is also a vascular medicine specialist at Hamilton Health Sciences.

“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 family history each partially convey independent information about GDM is a significant finding of our research, said the publication's first author Amel Lamri, a research associate at McMaster University working with Anand.

Anand added that 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 GDM.”

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