VEGFA and pachyonychia congenita: Many studies have found that the abnormal expression or activation of multiple signaling pathways (e.g. Insulin-Like Growth Factor (IGF) pathway), growth factors (e.g. Vascular Endothelial Growth Factor (VEGF)), oncogenes (e.g. K-ras) and suppressor genes (e.g. DCC) play a role in the occurrence and development of PC [3, 6, 29].