Obese Child Offers Genetic Link
By BRIGITTE GREENBERG
05:01 PM ET 09/15/99
For the first time, injections of the hormone leptin have been shown to curb
appetite and induce weight loss in a human, a new study says. Scientists caused a
stir four years ago when they announced that leptin could evoke weight loss in mice, but
until now, a direct role in human obesity had not been confirmed.
The findings by doctors at Addenbrooke's Hospital in Cambridge, England, provide
important clues as researchers try to decipher the genetic and environmental factors in
obesity. The work could lead to medical treatments for some forms of the condition. Leptin
is a protein produced by fat cells. It is supposed to signal the brain to stop eating, but
the signal does not get through properly in some overweight people.
The study published in Thursday's edition of The New England Journal of Medicine
involved a severely overweight 9-year-old girl who suffered from a rare genetic defect in
which her body produced virtually no leptin.
While the girl's condition is uncommon, the researchers, led by Dr. I Sadaf
Farooqi, believe the findings have implications for the general population.
At the age of 6, the girl was so overweight that doctors performed liposuction
on her legs to increase her mobility. She was constantly hungry and became disruptive when
denied food. In 1997, when the girl was 9 and weighed 208 pounds, doctors began
administering daily injections of leptin.
Within a week of treatment, the girl's appetite had diminished significantly.
After a year of injections, she had lost 36 pounds, and 95 percent of that weight was fat.
She also began to show signs of early puberty - an interesting side effect since
other people with this congenital defect also have experienced stunted reproductive
development.
In an accompanying editorial in the journal, Drs. Michael Rosenbaum and Rudolph
L. Leibel of the Columbia University College of Physicians and Surgeons wrote that many
factors besides leptin affect weight, and people should not conclude that leptin
injections would make losing weight easy.
If anything, leptin might help some people stick to a diet by curbing their
hunger and aid in keeping the weight off, Rosenbaum said.
``The only thing that we know is that it decreases appetite in this child and in
a mouse,'' Rosenbaum said. ``It's not the be-all and the end-all to promote effortless
weight loss.''
Leptin is being tested in ordinary fat people as an appetite suppressant.
Preliminary findings from one study indicate that it isn't a miracle cure, but shows some
promise when combined with diet and exercise.
Dr. Richard A. Dickey, President of the American Association of Clinical
Endocrinologists, called the study ``a great start,'' adding that although doctors
generally believe many factors are involved in human obesity, leptin is clearly important.
``It's very possible that this child is a clue to appetite control and weight
gain across a large portion of the population,'' he said. ``I think that everybody's
excited about the role of leptin.''
