PSEN1 genetic mutation analysis is used to screen asymptomatic or symptomatic adults who have a strong family history of early onset Alzheimer’s Disease, especially when a PSEN1 mutation has been identified in other family members. It may be used to aid in the differential diagnosis of early onset Alzheimer’s Disease (versus some other form of early onset dementia) but usually only in those with a family history of AD3. PSEN1 is also occasionally used prenatally and, where appropriate, with genetic counseling to assess the risk of having and passing on a PSEN1 mutation.

The test is usually ordered for asymptomatic or symptomatic adults with a strong family history of early onset Alzheimer’s Disease, especially when there are multiple family members in multiple generations (preferably three generations) who have had AD3. It is NOT useful as a screen for the general population or for those who have late onset AD.

If you have one of the PSEN1 mutations, it is highly likely that you will eventually develop AD3, usually at a similar age to other affected family members. The penetrance of the gene (symptoms, severity, and rate of progression), however, can vary from individual to individual. Since it is a dominant gene, if you have a PSEN1 mutation, each of your children will have a 50% chance of having the PSEN1 mutation.

It should be remembered that the PSEN1 genetic mutation analysis, in its current form, is only capable of picking up 30-60% of PSEN1-caused AD3. If your test is negative, there is still a chance that you have an unidentified PSEN1 mutation.

PSEN1 genetic mutation is almost exclusively family-related and is not associated with late onset AD. A few cases of PSEN1 genetic mutation will show up without a strong family history because of “alternate” paternity, new mutations, or because a parent died before symptoms developed so this element of the family history was unknown.

The PSEN1 test is a new, relatively expensive test that has limited use and is still rarely ordered. It is performed in only a few laboratories in the world, so if your doctor recommends the test, your blood sample will need to be sent to a reference lab and results may take longer to return.