MC1R and Behcet disease: Several genes associated with hypoxic adaptability appeared to be targets of positive selection, including melanocortin 1 receptor (MC1R) in HZ, excision repair cross-complementing 2 (ERCC2) in HZ, transcription factor 25 (TCF25) in BD and OL, itchy E3 ubiquitin protein ligase (ITCH) in HZ and BD, tyrosinase (TYR) in GY, ZK and SG1, RALY heterogeneous nuclear ribonucleoprotein (RALY) in OL, and KIT proto-oncogene receptor tyrosine kinase (KIT) in ZK.