A recent study has revealed that of the analysis of mutations, such as ATM Serine/Threonine Kinase (ATM) and Breast Cancer 1/2 (BRCA1/2), or the expression of specific genes can indicate the risk, metastatic potential, or radio sensitivity of PC [100,101]; however, investigations regarding metastatic PC through molecular diagnosis are limited. Here, MARK2 is linked to pachyonychia congenita.