APP and early-onset autosomal dominant Alzheimer disease: While it would be interesting to test whether prion disease is delayed in Neu1 knockout mice, these mice, unfortunately, do not have a sufficient lifespan, as they suffer from sialidosis, muscle degeneration and Alzheimer’s disease-like amyloidogenic processing of an oversialylated amyloid precursor protein in lysosomes [60, 63, 64].