[Asn23] β-Amyloid (1-40), Iowa mutation, is a biologically active peptide associated with autosomal dominant Alzheimer's Disease in multiple families. This specific mutation involves the substitution of Asp 23 with Asn, leading to severe cerebral amyloid beta-protein angiopathy (CAA). Individuals with this mutation exhibit a missense alteration in the APP gene at position 694, which results in the mutated β-amyloid peptide aggregating more quickly and forming toxic fibrils.