A2M and thromboangiitis obliterans: The MS data of GD patients vs. healthy controls and TAO patients with healthy controls exposed some identical downregulated proteins, such as α‐2 macroglobulin (A2M) and cerebellin‐4 (CBLN4), which was similar to downregulated β2‐microglobulin based on proteomics of tear fluid in TAO patients [9].