APP and Alzheimer disease: Further, while individual amyloidosis-related models—the TAS line expressing an amyloid precursor protein containing two familial AD mutations and the TPM line expressing a presenilin 1 gene containing a familial AD mutation—do not show meaningful change in module expression over time, their combination in the homozygous state (HO-TASTPM) does show an elevation of both modules that is apparent at 8 months and enhanced at 18 months as pathology accumulates.