Mutations in the presenilin (PS) genes are linked to the development of early-onset Alzheimer's disease by a gain-of-function mechanism that alters proteolytic processing of the amyloid precursor protein (APP).
Familial forms of CAA are because of mutations in the gene encoding the beta-amyloid precursor protein (APP) and duplications of this gene can cause early-onset Alzheimer's disease associated with CAA.
Mutations in amyloid precursor protein (APP) and presenilin (PSEN) genes are known to cause familial early-onset Alzheimer's disease (AD), which account for around 5% of AD cases.
A subset of early-onset Alzheimer's disease is inherited as an autosomal-dominant trait and is associated with mutations in the genes encoding β-amyloid precursor protein, presenilin 1, or presenilin 2.
To determine the spectrum of mutations in a group consisting of 40 Polish patients with clinically diagnosed familial EOAD and 1 patient with mild cognitive impairment (MCI) and family history of AD, we performed a screening for mutations in the presenilin 1 (PSEN1), presenilin 2 (PSEN2) and amyloid precursor protein (APP) genes.
We have found a significantly lower frequency of the presenilin-1 (PS-1) intronic polymorphism 2/2 genotype in early-onset Alzheimer's disease (AD) patients without APOE epsilon4 alleles (2/2 = 0.054; P = 0.009) as compared to age matched non-epsilon4 controls (2/2 = 0.227).
To clarify the respective contribution of the amyloid precursor protein and PSEN mutations to autosomal dominant AD and to determine its contribution to sporadic and familial nonautosomal dominant early-onset AD and familial late-onset AD in a referral-based Spanish population.
Pathogenic variants in the autosomal dominant genes PSEN1, PSEN2, or APP, APOE4 alleles, and rare variants within TREM2, SORL1, and ABCA7 contribute to early-onset Alzheimer's disease (EOAD).
Four mutations involving amino acid substitutions in exons 16 and 17 of the amyloid precursor protein (APP) gene, have been identified which co-segregate with the disease in some families multiply affected by early onset Alzheimer's disease.
A guanine-to-adenine transition in exon 17 of the APP gene resulting in a valine-to-isoleucine substitution at codon 717 was detected in 14 subjects including 6 patients with EOAD.
Direct sequencing of exons 16 and 17 of the beta-amyloid precursor protein gene in 14 families with familial early onset Alzheimer's disease without the known pathogenic mutation (APP717) failed to reveal other mutations within the beta-amyloid sequence in this form of the disorder.