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Use of multiplex ligation‐dependent probe amplification increases the detection rate for 11p15 epigenetic alterations in Silver–Russell syndrome
Author(s) -
Eggermann T,
Schönherr N,
Eggermann K,
Buiting K,
Ranke MB,
Wollmann HA,
Binder G
Publication year - 2008
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.2007.00930.x
Subject(s) - multiplex ligation dependent probe amplification , dna methylation , biology , epigenetics , differentially methylated regions , microbiology and biotechnology , methylation , southern blot , multiplex , genomic imprinting , genetics , western blot , gene , gene expression , exon
Silver–Russell syndrome (SRS) describes a malformation syndrome with severe intrauterine and postnatal growth retardation. Currently, two major (epi)mutations have been described: while approximately 10% of patients carry a maternal uniparental disomy of chromosome 7 (UPD7), 35–60% show a hypomethylation at the H19 differentially methylated regions (DMRs) in 11p15. Until recently, a Southern‐blot based test was routinely used to identify epimutation carriers. Nevertheless, this test was time consuming and hampered by the huge amount of genomic DNA needed. With the methylation‐specific multiplex ligation‐dependent probe amplification assay (MLPA) for SRS, a PCR‐based test is now available, allowing the analysis also of small amounts of DNA. Probes in this assay hybridize to the H19 DMRs but do not cover the genomic target of the Southern‐blot probe. We now screened 72 patients with SRS by MLPA. Hypomethylation of the H19 DMRs was confirmed in all patients analyzed by Southern blot. In addition, we identified six individuals with hypomethylation of the H19 DMR who had previously normal blot results. This discrepancy can be explained by the observed generally lower degree of demethylation in this group, possibly not detectable by the less sensitive Southern‐blot method but also with a varying degree of methylation at different DMRs in the same individual. Apart from hypomethylation in the H19 DMR, we observed a slight demethylation for one of the IGF2 probes. The total detection rate of 11p15 hypomethylation is now increased to >38%. Considering maternal UPD7 and chromosomal aberrations, (epi)genetic alterations now account for more than 50% of SRS patients. In summary, MLPA represents an easy, low cost and reliable system in the molecular diagnostics of SRS.