FGFR4 and pachyonychia congenita: Many researchers have reported that the FGFR4 rs351855 G>A polymorphism is involved with the development of various types of cancer, including BC (12–14), PC (15, 16), colorectal cancer (CRC) (12, 13, 17), lung cancer (LC) (18–20), hepatocellular carcinoma (HCC) (21, 22), gastric cancer (GC) (23), head and neck squamous cell carcinoma (HNSCC) (24–26), and cervical cancer (27, 28).