GRN and frontotemporal dementia: Defects in ganglioside breakdown cause neurological diseases, for example, upon loss of the hexosaminidase HEXA that converts GM2 to GM3 (Tay-Sachs disease), or upon loss of GRN, where decreased BMP levels result in increased GM2 and other sialyated gangliosides (Frontotemporal dementia, FTD)7.