APP and Alzheimer disease: In this shot gun mass spectrometry approach we focused on sphingomyeline, carnitine, phosphatidylcholine-plasmalogens, phosphatidylcholine, lyso-phosphatidylcholine, and triacylglycerides, because these lipids are known to be affected by AD or APP processing or altered in serum samples of patients treated with acitretin21–28.