GRN and dementia: In our search for biomarkers that correlate with disease progression, changes in gangliosides and other sphingolipid degradation products were most pronounced in symptomatic subjects with FTD‐GRN mutations, and we found a positive correlation between GlcSph, GM3(d18:1/16:0), Cer(d18:1_23:0), and Cer(d18:1_24:1) levels and FTD severity, as measured by the CDR + NACC FTLD‐SB dementia scoring system.