Since June 2021, the safety and tolerability of IT, single-ascending, and multiple-ascending doses of WVE-004 in adult patients with C9orf72-associated ALS or FTD are being evaluated in a randomized phase 1b/2a double-blind, placebo-controlled trial called FOCUS-C9 (NCT04931862). This evidence concerns the gene C9orf72 and frontotemporal dementia.