Researchers looked at the genetic make-up of 2,480 children
with severe obesity and compared them with 7,370 healthy children. The study found nine genes which were strongly
linked to early weight gain. Five of these genes had been previously linked to obesity
whilst four were new.
importance of genetics in obesity is debated, lead author Dr Eleanor Wheeler, of
the Wellcome Trust Sanger Institute, says that scientists have 'known for a long time that
changes to our genes can increase our risk of obesity. For example, the gene
FTO has been unequivocally associated with BMI [Body Mass Index], obesity
and other obesity-related traits'.
Two of the four new genes - PRKCH and RMST - appear to have
a similar or stronger effect on obesity than the FTO gene.
Another of the new genes, LEPR, has several variants
associated with an increased risk of obesity, with a common form found in six
percent of the population. Rarer variations are thought to contribute strongly to
a severe form of early-onset obesity.
A total of 29 genetic changes were more frequent in obese
children than healthy children. Rare structural variations were identified which
effectively delete sections of DNA important in maintaining proteins
involved in weight control.
The study has brought the total number of genetic variants
linked to obesity to 50 and suggests that there are different genetic
influences on adult and child obesity.
Study co-author Professor Sadaf Farooqi, from the
University of Cambridge, said that research indicates that 'some children will
be obese because they have severe mutations'. Other children, she says, 'may
have a combination of severe mutations and milder acting variants that in
combination contribute to their obesity'.
Speaking to The Independent, Professor Farooqi added
that a person's environment would also influence a child's risk of becoming obese. 'There have always been' heavily overweight children, she said, but
now, 'because of the environment they are growing up in, we are seeing many more
children in this category'.
The study was published in Nature Genetics and was funded by
the Wellcome Trust. It is part of a wider project investigating genetics in obesity called UK10K.