We found staining for beta amyloid in neurons of MEC of MPS IIIB mice by using antibodies raised against the 14 N-terminal amino acids, against the N-terminus of the amyloid precursor protein (APP), and against Abeta peptides 1–40 and 1–42; such staining was not found in the control region or unaffected mouse brain (Fig. 5). This evidence concerns the gene APP and mucopolysaccharidosis type 3B.