Gene Hunting

Alzheimer's disease tends to run in families, but if one member does have Alzheimer's disease it does not necessarily mean that all family members will get the disease, just as not having Alzheimer's disease in your family does not mean that you won't get it. As with most diseases, both environmental factors and genes play a role in the development of Alzheimer's disease.

There are two basic types of Alzheimer's disease (AD): familial and sporadic.

Familial Alzheimer's disease (FAD), which runs in families, is a rare form of the disease, affecting less than 10% of AD patients.

Familial Alzheimer's disease occurs more frequently in younger people (usually before age 60) than sporadic AD. It is the result of a certain inheritance pattern called autosomal dominance, in which all offspring in the same generation have a 50/50 chance of developing Alzheimer's disease if one of their parents has it.

Known Causes of Familial Alzheimer's disease

To date, mutations in three genes have been identified as causing FAD:

the amyloid precursor protein (APP) gene on chromosome 21
the presenilin-1 (PS1) gene on chromosome 14
the presenilin-2 (PS2) gene on chromosome 1

Ultimately, all three genes appear to influence whether an abnormal protein, known as beta amyloid, is deposited in the brain to cause Alzheimer's disease.

The McCusker Foundation has identified many of the mutations in these genes in Australian families, thus offering the next generation a better chance of more effective treatment due to early diagnosis in those families.

Current Research

While the identification of these three genes has helped considerably in advancing our understanding of the disease, studies over the last few years suggest that other genes may play an important role in Alzheimer's disease.

Researchers in the McCusker laboratory are hunting for new genes that will provide the potential for improved diagnosis as well as better understanding of the mechanisms causing the disease.

Over the last 10 years, a number of families have been interviewed and blood samples collected in order to identify the genes that lead to Alzheimer's disease in these families. Sufficient families have been recruited and the team has commenced work to identify these genes.