These authors then tested if elevated HYAL1 could influence disease progression by injecting a lentivirus carrying the HYAL1 gene into the dentate gyrus of 6- to 7-month-old 3xTg-AD mice that bear three human genes associated with familial AD: APPKM670/671ML (Swedish), MAPTP301L, and PSEN1M146V. This evidence concerns the gene HYAL1 and Alzheimer disease.