Abnormal birth weight is often caused by genetic factors, according to a recent study. The same genetic factors also increase the risk of type 2 diabetes and cardiovascular diseases later in life. This observation may open new avenues for the prevention and treatment of these diseases. The findings from the extensive, international study were published in Nature.
The study analysed genetic differences throughout the genomes of nearly 154,000 people. The researchers are members of the Early Growth Genetics (EGG) Consortium and represent 17 countries. From the University of Eastern Finland, the Physical Activity and Nutrition in Children (PANIC) Study, carried out at the Institute of Biomedicine and involving approximately 450 children in the Kuopio region, participated in the study.
By linking the genetic profiles of the study participants to information on birth weight, the researchers could identify 60 regions of the genome that were clearly driving differences in birth weight. Many of these regions are the same that have earlier been linked to increased risk of type 2 diabetes and cardiovascular diseases.
The results indicate that a substantial proportion -- at least one-sixth -- of the differences in birth weight is explained by genetic differences between babies. This is seven to eight times more variation than can be explained by environmental factors already known to influence birth weight, such as the mother smoking during pregnancy or her body mass index before pregnancy.
Earlier research has shown that babies whose birth weight is well below, or well above, average have a markedly increased risk of type 2 diabetes later in life. Researchers have assumed that this link reflects the long-term impact of the nutritional environment in which the fetus develops: in other words, events in early life can "set up" an individual's body in ways that makes it more prone to diseases in later life.
The study published now shows that the genes regulating both birth weight and the risk of type 2 diabetes and cardiovascular diseases are partially located in the same genetic regions. Most of this overlap involves the baby's genetic profile, but the mother's genes also played an important role in influencing her baby's birth weight According to the researchers, this is most likely through the ways in which the mother's genes alter the baby's environment during pregnancy.
"Our findings show that genetic factors play an important role in explaining abnormal birth weight and the related increased risk of diseases later in life. This highlights the importance of healthy lifestyle habits in children who have an abnormal birth weight. Lifestyle interventions carried out in maternity clinics and within school health care are crucial in preventing chronic diseases," says Professor Timo Lakka, Director of the Physical Activity and Nutrition in Children Study.
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