Children with Down
syndrome are more likely than their unaffected siblings to have higher
levels of a hormone associated with obesity, according to pediatric
researchers. The hormone, leptin, may contribute to the known higher risk
of obesity among children and adults with Down syndrome.
A research team from The Children's Hospital of Philadelphia and the
University of Pennsylvania School of Medicine published their study online
today in the Journal of Pediatrics.
The researchers studied 35 children with Down syndrome and 33 of their
siblings. All of the children were between the ages of four and 10, and
were from the Philadelphia area. The researchers intentionally did not
include severely obese children in the study, in order to focus on risk
factors for obesity before obesity occurred.
The children with Down syndrome had significantly higher body mass
index, a higher percentage of body fat, and higher levels of leptin
compared to their siblings. The higher leptin levels persisted even when
the researchers adjusted for the effect of percentages of body fat,
suggesting that differences in body composition did not account for the
difference in leptin levels.
"The normal role of leptin is to suppress appetite and regulate body
weight," said senior author Nicolas Stettler, M.D., MSCE, a pediatric
nutrition specialist at The Children's Hospital of Philadelphia. "In
general, obese people have higher levels of leptin, which suggests that
they have some leptin resistance--their bodies do not respond to the
hormone properly. Because Down syndrome is a chromosome disorder, children
with Down syndrome may have a genetic predisposition to more severe leptin
resistance."
Sheela N. Magge, M.D., M.S.C.E., a pediatric endocrinologist at
Children's Hospital, the first author of the study, stressed that more
research remains to be done on this question, as the reasons are yet
uncertain why patients with Down syndrome are at higher risk of obesity.
"Although the study had an advantage in including siblings as a control
group, because this decreases the influence of different environments on
children with or without Down syndrome, the sample size was limited, so
larger studies are necessary. However, our findings may point to a useful
approach to understanding why obesity often occurs in Down syndrome."
The National Institutes of Health, the Penn-Cheyney Export Center, the
National Down Syndrome Society, the Juvenile Diabetes Research Foundation,
and the Lawson Wilkins Pediatric Endocrinology Society all provided support
for this study. Dr. Stettler and Dr. Magge's co-authors were Virginia A.
Stallings, M.D., and Kristen O'Neill, M.S., of Children's Hospital; and
Justine Shults, Ph.D., of the University of Pennsylvania School of
Medicine. Stettler, Magge, and Stallings also have appointments at the Penn
School of Medicine.
About The Children's Hospital of Philadelphia: The Children's Hospital
of Philadelphia was founded in 1855 as the nation's first pediatric
hospital. Through its long-standing commitment to providing exceptional
patient care, training new generations of pediatric healthcare
professionals and pioneering major research initiatives, Children's
Hospital has fostered many discoveries that have benefited children
worldwide. Its pediatric research program is among the largest in the
country, ranking third in National Institutes of Health funding. In
addition, its unique family-centered care and public service programs have
brought the 430-bed hospital recognition as a leading advocate for children
and adolescents. For more information, visit chop.edu.
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