KCNJ11 and congenital isolated hyperinsulinism: Moreover, two unclassified patients possibly had histologically atypical CHI, one with a possible low-grade somatic mosaic CHI mutation without germline representation, the other with the possibility of a novel variant of focal CHI: A paternal KCNJ11 germline mutation plus a second somatic hit of low-grade mosaic pUPD11p15 in an area with clear focal 18F-DOPA uptake, but absence of a distinct focal lesion by surgery and histology; more simply named “low-grade mosaic focal CHI”.