Zeroing in on Genetic Link to Hypertension

      Framingham researchers have found that a variation in the ACE (angiotension converting enzyme) gene may be an important contributor to high blood pressure in men.   ACE produces a converting enzyme important in controlling blood pressure.

      No relationship between the gene and high blood pressure in women was found.  Because the gene exerts its impact on men and not women, there is evidence that the ACE gene is sex-specific.

      Scientists, using molecular linkage techniques, examined 1,044 pairs of siblings from the second Framingham Study cohort and found the ACE variant gene in 30 percent of the men and women.  Men with the ACE variant had a 59 percent increased risk for high blood pressure.

      Linkage studies, used in this investigation, are powerful tools scientists use to identify a gene region or locus involved in a specific disease.  Researchers are able to study genetic markers spaced evenly along all the chromosomes in order to assess an association between a chromosomal region and a phenotype -- the manifestation of a particular disorder such as hypertension.

      Although the region containing the ACE gene was implicated for hypertension, the study did not determine whether the ACE or another close-by gene is responsible for raising blood pressure.

      Researchers must now conduct "finer mapping" of the chromosomal region to pinpoint the position of the responsible gene to understand the genetic causes of high blood pressure and ways to develop better treatments, especially for those with a genetic predisposition.

      Two Investigations Point To Locations of Genes Responsible for Decreased Risk and Increased Risk for Heart Disease

      Researchers are working to identify a region of the human genome that appears to contain a gene that protects individuals from developing heart disease.   The gene in this region is related to the production of increased amounts of high density lipoprotein (HDL -- "good cholesterol").

      Individuals who express this gene may have a decreased chance of having a heart attack.   Researchers theorize that further work to understand how this gene functions may lead to the development of new therapies to help those lacking this protective genetic trait.

      In a second effort, researchers are looking for the locations of genes that increase the risk for heart disease. They are concentrating on a region containing a gene that appears to cause high levels of low density lipoprotein (LDL -- "bad cholesterol).

      This gene, unlike the one that produces high HDL, puts individuals at greater risk for heart disease.   Those with this gene may need to consider regimes to modify their diets or other lifestyle habits to reduce their risk of disease.

      The researchers are scanning DNA samples from 52 of the largest Framingham Heart Study families (parents, children, aunts, uncles and cousins) looking for genes controlling the major risk factors for heart disease: hypertension, high levels of cholesterol, diabetes and pulmonary function.  All of these have an important genetic component.