APP and rheumatoid arthritis: Examination of the abstracts led to the exclusion of 26 studies; 1 regarded rheumatoid arthritis (15); 3 studied macular degeneration (16–18); 2 investigated the placenta (7,19); 1 addressed tuberous sclerosis complex 2 (20); 3 were animal studies (21–23); 1 assessed amyloid precursor protein (4); 2 evaluated other biomarkers (24,25); 6 were exclusively in vitro studies (1;26–30); and 7 were reviews (2,31–36), thus leaving 21 studies.