In line with the Aβ-induced impairment of reelin-signalling found in cultured cells, the amounts of these ApoER2-fragments drop by about 50% in cerebrospinal fluid of Alzheimer’s disease-subjects, even though levels of ApoER2 messenger RNA as well as full-length ApoER2 remain unaltered.51,89 This provides convincing corroborative evidence that an interaction between reelin and Aβ occurs in the brain of Alzheimer’s disease-subjects, and that this impairs the reelin-signalling cascade. The gene discussed is RELN; the disease is early-onset autosomal dominant Alzheimer disease.