Screening for mutations in the open reading frame and promoter of the beta -amyloid precursor protein gene in familial Alzheimer's disease: Identification of a further family with APP717 Val arrow right Ile

Following the identification of mutations in the beta -amyloid precursor protein (APP) gene in familial, early onset Alzheimer's disease (AD), we have developed a screening protocol using single strand conformation analysis (SSCA) to screen exon 17 for the known mutations within APP. In addition, we used this protocol to screen the other seventeen exons of APP and a three hundred and thirty base pair regulatory region of the promoter for new mutations in 9 families with early onset AD. Exons 16 and 17, which encode the deposited beta-amyloid peptide, were screened in a further 10 families. The data suggest that mutations in APP are a rare cause of familial early onset AD (3/21 families tested) and that within APP most, possibly all, mutations which cause AD are in exon 17.