12 Mar 1997

An enormous extended family living in a rural community in Colombia could provide new insights into environmental and genetic factors contributing to Alzheimer’s disease. All family members who were diagnosed with the disease carried an identical genetic mutation in the presenilin-1 gene, previously shown to cause an inherited, early onset form of Alzheimer’s disease. Of the nearly 3,000 individuals surveyed in the study, 128 were diagnosed with Alzheimer’s, and they carried the gene mutation (glutamic acid-to-alanine at codon 280). However, the age at onset ranged from 34 to 62, suggesting that other factors play an important role as well. Because the family members share a similar genetic makeup and environment, they offer an unprecedented opportunity for winnowing out environmental and genetic factors that influence the development of the disease. The findings were reported today in the Journal of the American Medical Society.—June Kinoshita