ZFAND4 and oral cavity squamous cell carcinoma: For example, ZFAND4 encodes zinc finger AN1-type-containing 4 and serves as a marker to predict metastasis and prognosis in oral squamous cell carcinoma [49], while ZFAND4 was strictly expressed in the testis; its paralogous copy ZFAND5 is a ubiquitously expressed gene and was highly expressed in other tissues such as the brain, lung, and testis (Figure 4b), indicating the genes not under positive selection harbor wide tissue and positive selection may eliminate the tissues ubiquity of ZFAND4. In the remaining 13 gene pairs, non-PSGs had higher tissue specificity than PSGs.