Alzheimer’s Gene Has Only Limited Role

A gene once thought to be involved in about two-thirds of Alzheimer’s disease cases has been found in a large statistical study to be a primary factor in only about 10 percent of patients with the brain-killing disorder.

In a study of 310 families, researchers at Massachusetts General Hospital found that the Alzheimer’s gene, called apoE-4, is a risk factor only among patients who develop the disease before the age of 70.

“Since the majority of the approximately 4 million Americans who have AD become afflicted over the age of 70, the main genetic causes for the disease have yet to be identified,” said Rudolph E. Tanzi, principal author of the study.

Tanzi said the study shows that any Alzheimer’s screening test based on the presence of the apoE-4 gene, he said, is of only “very limited value.”