GRN and early-onset autosomal dominant Alzheimer disease: Homozygous GRN mutation carriers develop the lysosomal storage disorder NCL [2, 31, 59], and heterozygous carriers typically develop dominantly inherited FTD [5, 16], though some develop other disorders such as Alzheimer’s disease, Parkinson’s disease (PD), or DLB [10, 32, 56, 68].