“Thriving infant” genes increase risk of obesity

Press release issued: 26 May 2010

Scientists using data from the University of Bristol's ALSPAC study have discovered a genetic link between obesity and rapid weight gain in babies as young as six weeks old. The research is published in PLoS Medicine.

Scientists at the Medical Research Council (MRC) have discovered a genetic link between obesity and rapid weight gain in babies as young as six weeks old. The genes, known to cause obesity, also provided babies with greater protection against ‘failure to thrive’ – a potentially harmful condition of very slow weight gain. This genetic protection in early life could explain why many people are prone to being overweight as adults.

The research conducted by the MRC Epidemiology Unit in Cambridge followed more than 7,000 children from the ALSPAC, the Avon Longitudinal Study of Parents and Children (also known as Children of the 90s) study, at the University of Bristol.

The study analysed the weights and heights of children aged 0-11 years. Measurements routinely collected at birth and by health visitors at six weeks, nine months, 1.5 years and 3.5 years old were used, while children between 7 and 11 years old were weighed and measured by the ALSPAC clinics.

Children with just one extra copy of an obesity gene were 17 per cent more likely to be obese in childhood, while their risk of ‘failure to thrive’ was reduced by 8 per cent, compared to those with fewer of the genetic variants. However, children with multiple copies of the genes would be at even greater risk of obesity.

Lead author Cathy Elks from the MRC said: “We know that the ability to put on sufficient weight during the first few weeks of life could have major advantages during this vulnerable period. What we’ve found is that the genes which help infants to thrive and put on weight could be one reason why some people are more prone to obesity later in life.”

Dr Ken Ong, a Paediatric Endocrinologist at the MRC Epidemiology Unit, and co-author of the study said: “Babies and children who gain weight rapidly during the first year of life are at increased risk of obesity, and while the influence may be genetic, parents should be mindful of this when considering their child’s diet and other environmental factors like exercise, to ensure they’re not placed at even greater risk.

“Adult and childhood obesity are among the biggest public health challenges in the UK today, which is why the MRC funds research like ours to understand why it happens and hopefully prevent it. It’s very interesting to find that genetic factors play a key role, both in helping infants to thrive and mapping out our likelihood of obesity, and this new information should ultimately take us closer to finding safe, effective ways to predict and prevent obesity.”

The research was in collaboration with the MRC, the University of Bristol, Addenbrooke’s Hospital in Cambridge and the University of Cambridge.

The paper, Genetic markers of adult obesity risk are associated with greater early infancy weight gain and growth is published in PLoS Medicine today.

Further information

Rapid weight gain and failure to thrive is shown on infant growth charts, which are provided to all parents to record their child’s growth progress. Failure to thrive was identified when the infant’s weight crossed downwards through more than two lines on their growth chart in the first 6 weeks of life. Rapid weight gain was indicated by the child’s weight rising up though two or more lines on the chart. For example a newborn weighing 3.5kg rising to over 6kg at 6 weeks. There is a wide range of healthy shapes and sizes among children and weight gain or loss cannot be quantified in the same way as adult weight gain or loss, e.g. using BMI or just weight.

For almost 100 years the Medical Research Council has improved the health of people in the UK and around the world by supporting the highest quality science. The MRC invests in world-class scientists. It has produced 29 Nobel Prize winners and sustains a flourishing environment for internationally recognised research. The MRC focuses on making an impact and provides the financial muscle and scientific expertise behind medical breakthroughs, including one of the first antibiotics penicillin, the structure of DNA and the lethal link between smoking and cancer. Today MRC funded scientists tackle research into the major health challenges of the 21st century.

ALSPAC, the Avon Longitudinal Study of Parents and Children (also known as Children of the 90s), is a unique ongoing research project based in the University of Bristol. It enrolled 14,000 mothers during pregnancy in 1991-2 and has followed most of the children and parents in minute detail ever since. Funding for ALSPAC is provided by the MRC, Wellcome Trust and University of Bristol.

Please contact Joanne Fryer for further information.