PSEN1 and neuroblastoma: PSEN1 p.Ala396Thr has previously been reported to lead to increased Aβ40 and Aβ42 production without a change in the Aβ42/Aβ40 ratio in mouse neuroblastoma cells, while an independent cell-free assay suggests that PSEN1 p.Ala396Thr leads to reduced Aβ40 yielding an increase in Aβ42/Aβ40; thus, which the mechanism of the effect remains to be resolved the disruption in Aβ processing is consistent [21, 25, 38].