Ab in Lens in Down Syndrome Figure 6. Increased Ab expression in Down syndrome lens and brain. (A-D) Anti-Ab ELISA analysis of human lens (A) and brain (B) fractionated by Ab isoform. (A) Lens homogenates demonstrate elevated lens Ab in subjects with Down syndrome (n = 8; p = 0.027) compared to normal controls (n = 15). (B) Brain homogenates demonstrate elevated Ab in subjects with Down syndrome (n = 8; p = 0.007) and Alzheimer’s disease (n = 6; p = 0.026) compared to normal controls (n = 6). (C) Immunoblot analysis of Down syndrome lens and brain homogenates reveals an intense Ab- immunoreactive band that migrated with an apparent molecular weight of ,4kDa corresponding to synthetic human Ab monomer (arrow). Note strong band corresponding to Ab monomer in the 2-year-old Down syndrome lens (lane 7) and apparent shift from lower- to higher-order oligomeric Ab in Down syndrome lenses with advancing age (lanes 7–9). Protein loading was normalized in each lane. doi:10.1371/journal.pone.0010659.g006 PLoS ONE | www.plosone.org 9 May 2010 | Volume 5 | Issue 5 | e10659