Although this long-standing belief is currently in a state of controversy, we previously confirmed that there were altered levels of amyloidogenic degenerative markers in plasma isolated from IBM patients (including BACE-1 and PS-1 [31]) and decided to evaluate the presence of Aβ1–42 (associated with β- and ɣ-secretase enzymes) in a fluid that was easily accessible, i.e., saliva, for which samples isolated from IBM patients vs. CTLs were compared. The gene discussed is BACE1; the disease is inclusion body myositis.