Loss of a particular gene's function in humans and mice causes morbid obesity, say researchers.
Research has pointed to the importance of genetic factors in human obesity and has shown that heritability plays a role in 40 percent to 90 percent of cases.
The study of a morbidly obese family provides new insights into the pathways that control body weight and nutritional status, and the results could be useful for designing therapies for obesity and malnutrition.
"Starting with gene discovery in a single family with morbid obesity, these studies led to the identification a gene that seems to be fundamental to regulating nutritional status," one of the senior authors, Dr. John Martignetti of the Icahn School of Medicine at Mount Sinai in New York City, said.
"This gene is shown to be present not only in humans and mice but also in the simplest known single-cell animal. Nature considers this gene so important that it has preserved its structure for more than 700 million years."
Drs. Martignetti and Adel Shalata, of the Ziv Medical Center Safed, Israel, and their team analysed a large Israeli Arab family affected by autosomal-recessive morbid obesity and identified a truncating mutation in the gene that recently was found to encode CEP19, a ciliary protein.
When the investigators deleted the Cep19 gene in mice, the animals became obese and diabetic and had increased appetites, decreased energy expenditure, and impaired fat metabolism.
The study is published in The American Journal of Human Genetics.