A major cause of an imprinting disorder, Silver-Russell syndrome (SRS), is the loss of DNA methylation (LOM) of imprinting control region 1 (ICR1) within the IGF2/H19 domain. ICR1-LOM on the paternal allele reduces IGF2 repression and makes H19 express biallelically. Majority of the patients showed consistent hypomethylation of ICR1; however, one exhibited LOM at the centromeric block of ICR1 but normal methylation at the telomeric block. This clearly refines our understanding of the IGF2/H19 imprinting mechanisms for the control of IGF2 and H19 expression and a molecular diagnosis. (By Dr. Hidenobu Soejima, https://jmg.bmj.com/content/early/2020/05/23/jmedgenet-2020-106907 )