β-Amyloid (1-40), England mutation, is a biologically active peptide with a histidine (His) to arginine (Arg) substitution at position 6, known to enhance oligomerization kinetics that serve as fibril seeds and increase neurotoxicity in cultured neurons. This alteration is one of several mutations in the beta-amyloid precursor gene implicated in autosomal dominant Alzheimer's Disease across multiple kindreds.