Amyloid Precursor Protein – mutations or duplications of this gene cause a minority of cases of autosomal dominantly inherited familial Alzheimer’s disease. Age at symptom onset may be slightly older than is seen with Presenilin 1 mutations.
A genetic abnormality occurs when there is a fault (mutation) within a gene. With autosomal dominant inheritance, the abnormal gene only needs to be present in one parent for the disease to be inherited. That parent’s children each have a 50:50 chance of inheriting the genetic mutation. Children who do not inherit the abnormal gene will not develop or pass on the disease.
Familial Alzheimer’s disease (FAD) is caused by genetic mutations that are inherited within families. It probably accounts for less than 1% of cases of Alzheimer’s disease overall and generally affects people at a younger age than the more common sporadic (non-inherited) form of Alzheimer’s disease.
Mutations in this gene are the most common cause of autosomal dominantly inherited familial Alzheimer’s disease. Over 180 different Presenilin 1 mutations have been identified to date.
Mutations in this gene are the rarest cause of autosomal dominantly inherited familial Alzheimer’s disease. Presenilin 2 mutations typically cause symptoms at a slightly later age than mutations in the Presenilin 1 or APP genes.