Journal Article

Extensive investigation of the <i>IGF2/H19</i> imprinting control region reveals novel OCT4/SOX2 binding site defects associated with specific methylation patterns in Beckwith-Wiedemann syndrome

Walid Abi Habib, Salah Azzi, Frédéric Brioude, Virginie Steunou, Nathalie Thibaud, Cristina Das Neves, Marilyne Le Jule, Sandra Chantot-Bastaraud, Boris Keren, Stanislas Lyonnet, Caroline Michot, Massimiliano Rossi, Laurent Pasquier, Christine Gicquel, Sylvie Rossignol, Yves Le Bouc and Irène Netchine

in Human Molecular Genetics

Volume 23, issue 21, pages 5763-5773
Published in print November 2014 | ISSN: 0964-6906
Published online June 2014 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddu290
Extensive investigation of the IGF2/H19 imprinting control region reveals novel OCT4/SOX2 binding site defects associated with specific methylation patterns in Beckwith-Wiedemann syndrome

Show Summary Details

Preview

Isolated gain of methylation (GOM) at the IGF2/H19 imprinting control region 1 (ICR1) accounts for about 10% of patients with BWS. A subset of these patients have genetic defects within ICR1, but the frequency of these defects has not yet been established in a large cohort of BWS patients with isolated ICR1 GOM. Here, we carried out a genetic analysis in a large cohort of 57 BWS patients with isolated ICR1 GOM and analyzed the methylation status of the entire domain. We found a new point mutation in two unrelated families and a 21 bp deletion in another unrelated child, both of which were maternally inherited and affected the OCT4/SOX2 binding site in the A2 repeat of ICR1. Based on data from this and previous studies, we estimate that cis genetic defects account for about 20% of BWS patients with isolated ICR1 GOM. Methylation analysis at eight loci of the IGF2/H19 domain revealed that sites surrounding OCT4/SOX2 binding site mutations were fully methylated and methylation indexes declined as a function of distance from these sites. This was not the case in BWS patients without genetic defects identified. Thus, GOM does not spread uniformly across the IGF2/H19 domain, suggesting that OCT4/SOX2 protects against methylation at local sites. These findings add new insights to the mechanism of the regulation of the ICR1 domain. Our data show that mutations and deletions within ICR1 are relatively common. Systematic identification is therefore necessary to establish appropriate genetic counseling for BWS patients with isolated ICR1 GOM.

Journal Article.  7040 words.  Illustrated.

Subjects: Genetics and Genomics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.