The spectrum of evidence for TUDCA ranges from in vitro studies on primary neuronal cultures and neuroblastoma cell lines (either incubated with amyloid-β or expressing genetic mutations of AD-associated genes) to in vivo studies on transgenic AD murine models carrying mutations in the amyloid precursor protein (APP), presenilin 1 (PS1) or presenilin 2 (PS2) genes. The gene discussed is PSEN2; the disease is Alzheimer disease.