Epimutation of the telomeric imprinting center region on chromosome 11p15 in Silver-Russell syndrome

Christine Gicquel¹, Sylvie Rossignol¹, Sylvie Cabrol¹, Muriel Houang¹, Virginie Steunou¹, Véronique Barbu², Fabienne Danton¹, Nathalie Thibaud¹, Martine Le Merrer³, Lydie Burglen⁴, Anne-Marie Bertrand⁵, Irène Netchine¹ & Yves Le Bouc¹

¹  Laboratoire d'Explorations Fonctionnelles Endocriniennes, Inserm U515 et UPMC Paris 6, Hôpital Armand Trousseau, AP-HP, 26 avenue Arnold Netter, 75012 Paris, France.

²  Inserm U680, Faculté Saint-Antoine, 27 rue Chaligny 75012 Paris, France.

³  Département de Génétique, Hôpital Necker-Enfants Malades, 149 rue de Sèvres, 75015 Paris, France.

⁴  Unité de Génétique, Hôpital Armand Trousseau, 26 avenue Arnold Netter, 75012 Paris, France.

⁵  Service d'Endocrinologie Pédiatrique, Hôpital de Besançon, 2 Place Saint-Jacques, 25030 Besançon, France.

Silver-Russell syndrome (SRS, OMIM 180860) is a congenital disorder characterized by severe intrauterine and postnatal growth retardation, dysmorphic facial features and body asymmetry. SRS is genetically heterogenous with maternal uniparental disomy with respect to chromosome 7 occurring in 10% of affected individuals. Given the crucial role of the 11p15 imprinted region in the control of fetal growth, we hypothesized that dysregulation of genes at 11p15 might be involved in syndromic intrauterine growth retardation. We identified an epimutation (demethylation) in the telomeric imprinting center region ICR1 of the 11p15 region in several individuals with clinically typical SRS. This epigenetic defect is associated with, and probably responsible for, relaxation of imprinting and biallelic expression of H19 and downregulation of IGF2. These findings provide new insight into the pathogenesis of SRS and strongly suggest that the 11p15 imprinted region, in addition to those of 7p11.2-p13 and 7q31-qter, is involved in SRS.

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