been identified as a risk or susceptibility factor. Genetic testing for Alzheimer's is controversial due to the complex nature of the disease. Genetic counselling and testing guidelines for the disease have recently been published by the American College of Medical Genetics and the National Society of Genetic Counsellors. The guidelines are similar to those for Huntington's disease and involve extensive multidisciplinary consultation with the patient and their family. They recommend against the use of direct to consumer tests, testing in children and APOE testing. For patients, genetic testing may provide a definitive diagnosis and allow for resolution of matters pertaining to care, family and finances. It also allows interested family members to undergo predictive testing. But the complex genetics of Alzheimer's are not completely understood; only an estimated 18% of families with a history of early-onset Alzheimer's carry an unidentified genetic mutation. Whether other genetic mutations and risk factors influence the age of onset for this type of Alzheimer's, and how, are also unknown. So some people using genetic testing may receive a negative result simply because they don't carry a mutation that's been identified and characterised but they may still have the disease. What's more, the lifetime risk for Alzheimer's is around 10% to 12% and one in four people over the age of 85 have dementia; a negative genetic result won't preclude an individual from developing Alzheimer's later in life. As public awareness of predictive genetic testing increases, it's vital that concerned families and individuals have access to