A set of four proteins was also identified in three selected studies as differentially expressed in BD patients, namely serotransferrin, TRFE [50,66,71], complement C1q subcomponent subunit C, C1QC [33,49,67], complement C4-A, CO4A [32,49,70], and retinol-binding protein 4, RET4 [33,64,67]. The gene discussed is C4A; the disease is Behcet disease.