Meta-analysis of FTD-ALS spectrum disorders versus controls using standard mean difference found an effect estimate of 0.55 (95% CI: 0.01–1.09) and a Z-score of 2.0 (p < 0.05) demonstrating a significant increase in detectable TDP-43 in the CSF of patients with FTD or ALS compared to controls. This evidence concerns the gene TARDBP and frontotemporal dementia.