In addition, the green cluster included several proteins mainly produced in the liver, such as apolipoprotein A1 (APOA1) and inter-alpha-trypsin inhibitor heavy chain 1 (ITIH1) while the yellow cluster contained proteins known to be altered in AD, including the Aβ peptides, t-tau, p-tau, NRGN and neuromodulin/growth associated protein 43 (GAP43). Here, NRGN is linked to Alzheimer disease.