
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: FRIDAY, August 18, 1995                   TAG: 9508180062
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A1   EDITION: METRO 
SOURCE: ASSOCIATED PRESS|
DATELINE: WASHINGTON                                 LENGTH: Medium

ALZHEIMER'S SECRET UNLOCKED

A mutation found only among some German-Russian immigrants has been identified as the third gene to cause inherited Alzheimer's disease. Scientists say the discovery may speed development of drugs to combat the brain-destroying disorder.

Researchers isolated the gene by probing the chromosomes of a group known as Volga Germans, who have a very high incidence of Alzheimer's before age 65. The mutated gene was found on chromosome 1 and linked directly to causing the disease.

+r Two reports on the discovery will be published today in Science, the journal of the American Association for the Advancement of Science.

Rudolph Tanzi of Massachusetts General Hospital, a principal collaborator in the research, said the new Alzheimer's gene makes a protein that is closely related to protein produced by an Alzheimer's gene his team found earlier on chromosome 14.

This similarity, said Tanzi, puts researchers on a fast track for understanding what causes formation in the brain of amyloid-beta, a gluelike substance that is toxic to brain cells and is a primary feature of Alzheimer's. He said the two proteins may have common functions even though they are produced from different genes.

Once the proteins' function is found, he said, researchers can develop a drug to block the disease.

``This is an incredibly important discovery,'' said Marcelle Morrison-Bogorad, a professor of neurology at the University of Texas, Southwestern Medical School in Dallas. ``This means that genetics has pretty much solved the mystery of early-onset [Alzheimer's] and it clears a path for scientific research that wasn't there before.''

With three Alzheimer's genes identified, she said, researchers are free to focus on specific molecular processes.

``The body makes about 100,000 proteins,'' said Morrison-Bogorad. ``Now instead of having to study 100,000, we can concentrate on the three proteins [made] by these genes.''

Tanzi and his team in 1987 found the first Alzheimer's gene on chromosome 21. They isolated the chromosome 14 gene in June.

People who inherit one of these three rare mutations develop Alzheimer's before the age of 65 and sometimes as young as 40.

About 4 million Americans have Alzheimer's. It is the fourth-leading cause of death, killing about 100,000 annually.

by CNB