Given these premises, in a large cohort of patients with FTLD‐associated syndromes, we aimed to (1) assess the ability of plasma biological markers, such as NfL, GFAP, BD‐tau, p‐tau217, and Aβ42/Aβ40 ratio, to predict survival probability; (2) develop a survival probability risk score at the individual patient level, considering identified biological markers and clinical variables; and (3) determine which are the brain correlates of the developed survival probability risk score. Here, GFAP is linked to Down syndrome.