C-terminally cleaved fragments—among which is Aβ1-34, a fragment generated by the action of the matrix metalloproteases MMP-2 and MMP-9 [27] as well as by BACE1 cleavage [41]—have been described as components of the heterogeneous cerebrospinal fluid (CSF) Aβ profile [31, 42, 43] and as constituents of soluble extracts obtained from amyloid brain deposits in AD and various Tg models [38, 39], suggesting their role in clearance mechanisms. The gene discussed is BACE1; the disease is Alzheimer disease.