NPC1 and renal hypoplasia: Consequently, Dnmt1 deletion resulted in a remarkable reduction in nephron numbers, as well as renal hypoplasia at birth, suggesting that Dnmt1 regulates NPC self‐renewal.13 Further analyses indicated that global DNA hypomethylation promotes ectopic expression of germline‐related genes and activation of endogenous retroviral elements, potentially leading to an interferon response and cell cycle inhibition, eventually interfering the NPC progenitor cell regulatory network.