CD55 and achalasia-alacrima syndrome: Phosphatidylinositol-glycan-specific phospholipase D (GPLD1), an enzyme that hydrolyzes glycosylphosphatidylinositol (GPI) anchors on plasma membranes, has previously been found to be upregulated in plasma from AAA patients analyzed by mass spectrometry [60].GPLD1 plays an important role in inflammation due to GPLD1’s ability to hydrolyze the GPI anchors of several inflammatory membrane proteins, such as CD55 and CD59, which have previously been shown to be connected to AAAs [61,62].