TMEM106B and frontotemporal dementia: However, TMEM106B polymorphisms only partially reduce TMEM106B expression [19], so in this study, we crossed Tmem106b+/− mice with Grn+/− mice to test whether partial reduction of Tmem106b would correct the behavioral deficits and lysosomal dysfunction of Grn+/− mice, which model the progranulin haploinsufficiency that causes FTD-GRN [31–33].