International audienceThis study was an investigation of 79 patients referred to the Wessex Regional Genetics Laboratory with suspected Russell-Silver Syndrome or unexplained short stature/intra uterine growth restriction, warranting genetic investigation. Methylation status was analysed at target sequences within eleven imprinted loci (PLAGL1, IGF2R, PEG10, MEST1, GRB10, KCNQ1OT1, H19, IGF2P0, DLK1, PEG3, NESPAS). 37% (29/79) of samples were demonstrated to have a methylation abnormality. The commonest finding was a loss of methylation at H19 (23/29), as previously reported in Russell-Silver Syndrome. In addition, four of these patients had methylation anomalies at other loci, of whom two show hypomethylation of multiple imprinted loci, and two showed a complete gain of methylation at IGF2R. This latter finding was also present in five further patients who did not have demonstrable changes at H19. In total, 7/79 patients showed a gain of methylation at IGF2R and this was significantly different from a normal control population of 267 individuals (p=0.002). This study demonstrates the importance of widening the epigenetic investigation to include multiple imprinted loci and highlights potential involvement of the IGF2R locus in growth restriction

We suggest that patUPD20 should be considered in the evaluation of patients with sporadic PHP1b.

Silver-Russell syndrome (SRS) is a clinically heterogeneous disorder characterised mainly by intrauterine and postnatal growth retardation. While maternal uniparental disomy of chromosome 7 is found in 5-10% of SRS patients, recently genetic and epigenetic mutations affecting the imprinting centres on chromosome 11p15 have been reported in up to 64% of patients. Chromosome 11p15 abnormalities reported in SRS include methylation defects in the imprinting centre 1 (ICR1) and maternally inherited duplications involving all or part of the imprinted region of 11p15. Here we report the first published case of SRS with mosaic maternal uniparental disomy of chromosome 11.

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