SMAD4 and pachyonychia congenita: The therapeutic modality of gene transfer therapy for PC principally involves the utilisation of diverse strategies and tools for the introduction of tumour suppressor genes (such as p16, p21, p53, Smad4/DPC4, etc.), anti-angiogenic genes (such as endostatin), apoptosis -related genes (such as TRAIL, TNF), and suicide genes [146].