APP and Alzheimer disease: While the amounts of APP were similar in all genotypes (Fig. 8a, b) the amounts of Aβ protein (Fig. 8a, c), including the most neurotoxic Aβ(1–42) form (Fig. 8d), were significantly lower in the C73A brains compared to the 3xTg-AD and 4xTg-WT brains.