UBQLN1 and frontotemporal dementia: We crossed congenic C57BL/6 Tg mouse lines expressing either human UBQLN1 or the P497S ALS/FTD mutant UBQLN2 cDNA with one another and obtained progeny with all four permutations of the two transgenes (Fig. 1b): Non-Tg, single transgenic UBQLN1, single Tg P497S UBQLN2 and double Tg UBQLN1:P497S UBQLN2 mice.