FKBP5 and Behcet disease: Pyrophosphate sequencing verified that cg03546163, cg25114611, cg23261343, and cg142905764 CpG sites with abnormal methylation status can be used as diagnostic markers of BD, in which the hypomethylation of FKBP5 promoter is the most significant, while the expression of FKBP5 gene is high.