For the smaller diabetes study, at least three children and both parents from each of the 98 families were evaluated. Scientists at the four field centers measured their abdominal visceral fat using computed tomography, an X-ray imaging technique that distinguishes between the two types of belly fat. They determined insulin resistance by measuring the fasting blood level of the hormone. Then Hong and his colleagues created family trees to determine which family members shared the two traits being evaluated and how closely they shared the traits.
A gene that plays a role in a disease will pass from the parent with the gene to some of the couple's children. By evaluating how often parents and children share a trait such as insulin resistance, researchers estimate the likelihood that genes underlie the trait.
The pattern of insulin resistance in the families suggested that 21 percent of the factors determining the likelihood of developing diabetes are inherited. And 40 percent of the likelihood for developing abdominal visceral fat appeared to result from genes. These findings agree with previous studies.
But what about susceptibility to abdominal fat and diabetes? To determine this likelihood, the investigators looked at how often a parent with insulin resistance had a child with extra belly fat and vice versa. If the same genetic factors favor two traits, one trait should appear more often than by chance in children of a parent bearing the other. In the study, 6 percent of the genetic factors associated with insulin resistance also influenced the accumulation of abdominal visceral fat.
This means that about one-third of the genetic factors that predispose people to
insulin resistance also ma
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Contact: Barbra Rodriguez
rodrigub@medicine.wustl.edu
314-286-0122
Washington University in St. Louis
24-Feb-1999