This, together with the fact that the phenotype is not modified by deleting App expression, suggests that the neurodegeneration in the γ‐secretase‐deficient mice is not AD related but likely caused by the accumulation of large amounts of hydrophobic protein domains in the neuronal cell membranes and/or the inactivation of crucial γ‐secretase‐dependent pathways. The gene discussed is APP; the disease is Alzheimer disease.