Beckwith Wiedemann syndrome and Uniparental Disomy 11p: Fine mapping of the recombination breakpoints and evaluation of several techniques.

Pablo Lapunzina (1) , Valeria Romanelli (1) , Heloisa Meneses (1) , Luis Fernández (1) , Victor Martínez-Glez (1) , Ricardo Gracia-Bouthelier (1) , Mario Fraga (1) , Encarna Guillén-Navarro (1) , Julián Nevado (1) , Esther Gean (1) , Loreto Martorell (1) , Victoria Esteban Marfil (1) , Sixto García-Miñaur (1)

1 INGEMM, Institute of Medical and Molecular Genetics

Beckwith-Wiedemann syndrome (BWS) is a phenotypically and genotypically heterogeneous overgrowth syndrome characterized by somatic overgrowth, macroglossia and abdominal wall defects. Other usual findings are hemihyperplasia, embryonal tumors, adrenocortical cytomegaly, ear anomalies, visceromegaly, renal abnormalities, neonatal hypoglycaemia, cleft palate, polydactyly and a positive family history. BWS is a complex, multigenic disorder associated, in up to 90% of patients, with alteration in the expression or function of one or more genes in the 11p15.5 imprinted gene cluster. There are several molecular anomalies associated with BWS and the large proportion of cases, about 85%, is sporadic and karyotypically normal. One of the mayor categories of BWS molecular alteration (10-20% of cases) is represented by mosaic paternal uniparental disomy (pUPD11), namely patients with two paternally derived copies of chromosome 11p15 and no maternal contribution for that. In these patients, in addition to the effects of IGF2 overexpression, a decreased level of the maternally expressed gene CDKN1C may contribute to the BWS phenotype. In this paper, we reviewed a series of 9 patients with BWS due to pUPD11 using several methods with the aim to evaluate the percentage of mosaicism, the methylation status at both loci, the extension of the pUPD11 at the short arm and the breakpoints of recombination. Fine mapping of mitotic recombination breakpoints by SNP-array in individuals with UPD and fine estimation of epigenetic defects will provide a basis for understanding the aetiology of BWS, allowing more accurate prognostic predictions and facilitating management and surveillance of individuals with this disorder.

Mots clés: Beckwith-Wiedemann syndrome; uniparental disomy; breakpoint

Pablo Lapunzina, Valeria Romanelli, Heloisa Meneses, Luis Fernández, Victor Martínez-Glez, et al.. Beckwith Wiedemann syndrome and Uniparental Disomy 11p: Fine mapping of the recombination breakpoints and evaluation of several techniques.. European Journal of Human Genetics, 2011, ⟨10.1038/ejhg.2010.236⟩. ⟨hal-00609411⟩