PTPN11 and large congenital melanocytic nevus: Specifically, nevus spilus can also be caused by variants in HRAS (Sarin et al., 2013), but HRAS is a rare driver of melanoma (Chin et al., 2006; Forbes et al., 2015) and is less frequently found mutated in melanoma than PTPN11 (Forbes et al., 2015).