Wendy S. Meschino, MD, CCFP, FRCPC, FCCMG
North York General Hospital,
"My mother has Alzheimer disease. Can I be tested to see if I carry the gene?" Such questions from patients are likely to be a familiar refrain to many physicians. While there is a great deal of discussion regarding the potential hereditary aspects of Alzheimer disease (AD), genetic testing is not appropriate for the vast majority of patients or their unaffected relatives. Genetic testing is possible only in selected situations where there is a significant family history of early-onset disease. In this article, we will explore how to take a family history of Alzheimer disease, how to recognize when genetic testing is appropriate, the critical issues to be discussed in genetic counselling and a brief review of the genes identified to date which are associated with familial Alzheimer disease (FAD).
In taking a family history, it is important to inquire about affected and unaffected relatives on both sides of the family. Details of the family history may be recorded in pictorial form as a pedigree (Figure 1). A minimum of three generations should be noted including siblings, parents, aunts, uncles, cousins and grandparents.