Based on clonal relations of driver mutations, Omori et al. classified IPMN development into three types: a sequential subtype featuring less diversity in incipient foci with frequent GNAS mutations; a branch-off subtype featuring identical KRAS mutations with different GNAS mutations; and a de novo subtype harboring driver mutations absent from concurrent IPMNs13. The gene discussed is KRAS; the disease is pancreatic intraductal papillary-mucinous neoplasm.