PSEN1 and Alzheimer disease: We recently examined the ganglioside composition of the brains of a double-Tg (transgenic) mouse model [APP (amyloid precursor protein)/PSEN1 (presenilin-1)] of AD that co-expresses mouse/human chimeric APP with the Swedish double-mutation and human PSEN1 with a deletion of exon 9 (Ariga et al., 2010).