Complex Tissue-Specific Epigenotypes in Russell-Silver Syndrome Associated with 11p15 ICR1 Hypomethylation

Russell Silver Syndrome (RSS) is a p natal and postnatal growth retardation syndrome caused mainly by 11p15 ICR1 hypomethylat on. Clinical presentation is heterogeneous in RSS patients with 11p15 ICR1 hypornethylation. We previously identified a subset of RSS patients with 11p15 ICRI and multilocus bypomethylation. Here, we examine the relationships be tw en IGF2 expression, 11p15 ICR1 rnethylation, and multilocus imprinting defects in various cell types from 39RSS patients with 11p15 ICR1 hypomethylation in eu k ocyte DNA. 11p15 ICItl hypomethylation was more pronounced in leukocytes than in buccal mucosa cells. Skin fibroblast IGF2 expression was correlated with the degree of ICR1 hypomethylation. Different tissue-specific rnultilocus naethylation defects coexisted in 3896 of cases, with some loci hypomethylated and others hypermethyfated within the same cell type in some cases. Our new results suggest that tissue-specific epigenotypes may lead to clinical heterogeneity in RSS. (C) 2014 wiley periodicals Inc.