CD4 and Behcet disease: Yu et al. (2015)investigated whether CNVs of apoptosis-related genes, including FAS, caspase8, caspase3, and BCL2, were associated with BD in the Chinese population and showed that BD patients had an increased frequency of high FAS copy number, and BD patients with more than two copies of FAS had an increased mRNA expression of FAS in anti-CD3/CD28 antibody-stimulated CD4+ T cells. Their results provided important evidence that high FAS copy number is involved in the pathogenesis of BD (Yu et al., 2015).