Expression of APP isoforms in platelets of sporadic AD patients, Met239Val mutated subjects and controls. (A) Reverse transcription-polymerase chain reaction (RT-PCR) analysis of amyloid precursor protein (APP) 770/751/695 in platelets obtained from presenilin 2 (PS2)-mutated subjects (PS2 Met239Val), sporadic Alzheimer’s disease patients (ADsp) and control subjects (C). APP 777/751/695 were amplified in 28 PCR cycles. No difference in the relative expression of APP forms was observed in Met239Val-mutated subjects, compared with both control and sporadic AD patients. The presence or absence of the mutation is indicated in each family member. Markers of DNA fragments are in the left lane. (B) Box plot of the density ratio of APP 770 and APP 751 in platelets of Met239Valmutated patients, sporadic AD patients (ADsp) and control subjects (C). The optical density of APP 777 and 751 DNA fragments was quantified from EtBr-stained gels after 28 cycles of PCR amplification by means of computer-assisted imaging. Data were normalized for GAPDH expression. No difference in the relative expression of APP770/APP751 was observed between the experimental groups analyzed.