Some morbidly obese missing genes that could affect weight: study

THE CANADIAN PRESS


MONTREAL - Researchers have discovered that a small proportion of morbidly obese people are missing a chunk of their DNA, and that genetic deletion may be dramatically affecting their weight.


In a study published in this week's issue of the journal Nature, the international team of scientists suggests that about seven in every 1,000 morbidly obese people are missing the 30-gene section of DNA. The genetic variation was not found in people of normal weight.



About two per cent of North Americans are morbidly obese, with a Body Mass Index over 40. (A healthy BMI, a mathematical ratio of weight and height, is between 18.5 and 24.9.) In about five per cent of cases, excessive weight gain is believed to be linked to genetic causes, including mutations and missing DNA.



"In the past three years, we have made fantastic progress in learning how common genetic changes can lead to chronic diseases like diabetes, as well as to small differences in people's weight and height," said co-author Dr. Robert Sladek of McGill University in Montreal.



"The genetic change identified in this study is much less common, but leads to much more substantial changes in the body weight of the individuals that it affects," Sladek said Wednesday in a release.



Previous research has identified several genetic variations that appear to contribute to obesity, most of them single mutations that change the function of a gene.



While the Nature study authors do not know all the functions of the 30 missing genes, mutations in some of them have been linked to delayed development, autism and schizophrenia.



They suggest there may be other genetic deletions, besides the ones they identified, that increase a person's risk of becoming obese.

"It is becoming increasingly clear that for some morbidly obese people, their weight gain has an underlying genetic cause," said lead author Philippe Froguel, a professor in the School of Public Health at Imperial College London.


"If we can identify these individuals through genetic testing, we can then offer them appropriate support and medical interventions, such as the option of weight-loss surgery, to improve their long-term health."