Although it was demonstrated that altered lysosomal acidity (a reliable indicator of lysosomal health) was observed upon GPNMB knock-down in GRN-FTD patient monocytes, it was not possible to confirm lysosomal dysfunction with an orthogonal assay (such as BMV109 or DQ-BSA) as was done here in murine macrophages due to a limited supply of cryopreserved cells available. The gene discussed is GPNMB; the disease is frontotemporal dementia.