Alzheimer-Down syndrome bond tightens.

Alzheimer/Down syndrome bond tightens

The latest in a series of reports suggesting a common geneticdefect for Alzheimer's disease and Down syndrome comes from an international corps of scientists in Paris and the National Institutes of Health (NIH). According to a report in the March 13 SCIENCE, there is an extra copy of a gene--responsible for the production of the protein amyloid--in cells from both Alzheimer's and Down patients. Abnormal deposition of the protein in brain tissue is characteristic of the two diseases, and the extra gene could lead to excessive amyloid production.

Earlier studies had localized the amyloid gene on chromosome21, known for years to be abnormal in people with Down syndrome. Also, the gene was found near a genetic defect responsible for an inherited from of Alzheimer's. After observing that similar abnormalities are found in brain tissue from both Alzheimer's patients and older Down syndrome patients, researchers had begun searching for the link between the two disorders (SN: 1/25/86, p.60).

Last fall, scientists from NIH announced their characterizationof a gene on chromosome 21 that codes for the protein amyloid (SN: 11/22/86, p.327). That announcement was followed several months later by a flurry of published reports dealing with the amyloid-coding gene and its possible role in both diseases. Although the growing amount of data implicating the amyloid gene does not prove that the genetic aberration is the sole or even primary cause of either condition, it strongly suggests a genetic defect in Alzheimer's disease.