Different methylation patterns in BWS/SRS cases clarified by MS-MLPA Mihaela Lukova • Albena Todorova • Tihomir Todorov • Vanyo Mitev Received: 11 April 2012 / Accepted: 3 October 2012 / Published online: 20 October 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract Molecular abnormalities in the 11p15.5 imprin- ted gene cluster lead to two different growth diseases: Beckwith-Wiedemann syndrome (BWS) and Silver–Russell syndrome (SRS). They are mainly caused by epigenetic alterations in one of the two imprinting 11p15 control regions (ICR1 and ICR2). These CpG-rich regions are differentially methylated on the maternally and paternally derived chro- mosomes. We report four different methylation patterns along the BWS/SRS critical region, clarified by methylation- specific multiplex ligation-dependent probe amplification. The mathematical processing of the data provides informa- tion about alterations in the methylation status: from hypo- to almost complete demethylation of KvDMR, hypo- and hy- permethylation of H19DMR and combined results from both regions provide information on paternal uniparental disomy (patUPD). The study concerns two BWS cases with KvDMR hypomethylation and almost complete loss of methylation, respectively; two patUPD11p15 cases with H19DMR hypermethylation/KvDMR hypomethylation, and one SRS case with H19DMR demethylation. In some cases KvDMR hypomethylation in patUPD11p15 can be difficult to assess, which requires combination with STR analysis or alternative method. The STR analysis provides also information on complete or segmental coverage and iso- or heterodisomy. Following this systematic approach, the precise diagnosis can be clarified in a few days and different methylation patterns could be detected. Keywords MS-MLPA Á Beckwith-Wiedemann syndrome (BWS) Á Silver–Russell syndrome (SRS) Á 11p15 Á KvDMR Á H19DMR Introduction Beckwith-Wiedemann syndrome (BWS, MIM#130650) is an overgrowth disorder involving developmental abnor- malities [1]. It is characterized by macrosomia, macroglos- sia, visceromegaly, abdominal wall defects as omphalocele and umbilical hernia, hemihyperplasia, kidney abnormali- ties, neonatal hypoglycemia, ear creases/pits, renal abnor- malities and an increased frequency of embryonic (Wilms) tumors [2–5]. Silver–Russell syndrome (SRS, MIM#180860) is a clinically and genetically heterogeneous disorder. The main features of SRS are severe intrauterine and postnatal growth retardation, relative macrocephaly and a charac- teristic small, triangular face [6]. The disease is associated with additional dysmorphic features including fifth finger clinodactyly and hemihypoplasia [6]. The majority of BWS and SRS cases show molecular abnormalities in the 11p15.5 imprinted gene cluster [7]. There are maternally expressed CDKN1C, KCNQ1, and H19 genes and the paternally expressed IGF2 and KCNQ1OT genes from chromosome 11p15.5, which have been implicated in the pathogenesis of BWS and SRS [8]. Most of BWS and SRS cases are sporadic and are mainly caused by epigenetic alterations in one of the two Mihaela Lukova and Albena Todorova contributed equally to the present study. M. Lukova (&) Á A. Todorova Á V. Mitev Department of Medical Chemistry and Biochemistry, Medical University Sofia, 2 ‘‘Zdrave’’ Street, 1431 Sofia, Bulgaria e-mail: lukova@abv.bg M. Lukova Á A. Todorova Á T. Todorov Genetic Medico-Diagnostic Laboratory ‘‘Genica’’, Sofia, Bulgaria 123 Mol Biol Rep (2013) 40:263–268 DOI 10.1007/s11033-012-2057-2