Scientific Reports, 2021, 11 (1), 5736

Genetic dissection of down syndrome-associated alterations in APP/amyloid-β biology using mouse models

Justin L Tosh, Elena R Rhymes, Paige Mumford, Heather T Whittaker, Laura J Pulford, Sue J Noy, Karen Cleverley, Matthew C Walker, Victor L J Tybulewicz, Rob C Wykes, Elizabeth M C Fisher, Frances K Wiseman, LonDownS Consortium

Individuals who have Down syndrome (caused by trisomy of chromosome 21), have a greatly elevated risk of early-onset Alzheimer’s disease, in which amyloid-β accumulates in the brain. Amyloid-β is a product of the chromosome 21 gene APP (amyloid precursor protein) and the extra copy or ‘dose’ of APP is thought to be the cause of this early-onset Alzheimer’s disease. However, other chromosome 21 genes likely modulate disease when in three-copies in people with Down syndrome. Here we show that an extra copy of chromosome 21 genes, other than APP, influences APP/Aβ biology. We crossed Down syndrome mouse models with partial trisomies, to an APP transgenic model and found that extra copies of subgroups of chromosome 21 gene(s) modulate amyloid-β aggregation and APP transgene-associated mortality, independently of changing amyloid precursor protein abundance. Thus, genes on chromosome 21, other than APP, likely modulate Alzheimer’s disease in people who have Down syndrome.