Zeschnigk Michael, Albrecht Beate, Buiting Karin, Kanber Deniz, Eggermann Thomas, Binder Gerhard, Gromoll Jörg, Prott Eva-Christina, Seland Saskia, Horsthemke Bernhard
Institut für Humangenetik, Universitätsklinikum Essen, Essen, Germany.
Eur J Hum Genet. 2008 Mar;16(3):328-34. doi: 10.1038/sj.ejhg.5201974. Epub 2008 Jan 9.
Silver-Russell syndrome (SRS) is a clinically and genetically heterogeneous syndrome characterized by severe pre and postnatal growth retardation, body asymmetry and a typical facial phenotype with a triangular face and relative macrocephaly. In 30% of patients, the differentially methylated IGF2/H19 imprinting center region (ICR1) on chromosome 11p15 was found to be hypomethylated, as determined by Southern blot analysis of an HpaII restriction site close to the third CTCF-binding site (CTS3) within ICR1. Using bisulfite treatment and a real-time PCR-based methylation assay (QAMA), we analyzed the third and sixth CTCF-binding sites (CTS3, CTS6) in 5 patients with CTS3 hypomethylation, in 14 patients who were suspected to have SRS but were normal by Southern blot analysis, and in 1 patient with body asymmetry without any other features of SRS or Beckwith-Wiedemann syndrome (BWS). In all 5 patients with CTS3 hypomethylation, in 5 of 14 patients who were judged to be normal at CTS3 by Southern blot analysis and in the patient with isolated body asymmetry, we found CTS3 and CTS6 hypomethylation by QAMA. Using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), we obtained similar results at four additional ICR1 sites in the CTS6 region. These results show that ICR1 hypomethylation occurs more often in SRS patients than as previously thought as well as in isolated hemihypoplasia. Furthermore, we show that methylation analysis by QAMA and MLPA is more sensitive in detecting ICR1 hypomethylation than Southern blot analysis of CTS3.
Silver-Russell综合征（SRS）是一种临床和遗传异质性综合征，其特征为严重的产前和产后生长迟缓、身体不对称以及具有三角形脸和相对巨头畸形的典型面部表型。在30%的患者中，通过对11号染色体p15上靠近ICR1内第三个CTCF结合位点（CTS3）的HpaII限制性位点进行Southern印迹分析，发现差异甲基化的IGF2/H19印记中心区域（ICR1）发生低甲基化。我们使用亚硫酸氢盐处理和基于实时PCR的甲基化检测方法（QAMA），分析了5例CTS3低甲基化患者、14例疑似患有SRS但Southern印迹分析正常的患者以及1例仅有身体不对称而无SRS或Beckwith-Wiedemann综合征（BWS）其他特征的患者的第三个和第六个CTCF结合位点（CTS3、CTS6）。在所有5例CTS3低甲基化患者、14例Southern印迹分析判定CTS3正常的患者中的5例以及仅有身体不对称的患者中，我们通过QAMA发现CTS3和CTS6均发生低甲基化。使用甲基化特异性多重连接依赖性探针扩增（MS-MLPA），我们在CTS6区域的另外四个ICR1位点获得了相似结果。这些结果表明，ICR1低甲基化在SRS患者中比之前认为的更为常见，在孤立性半侧发育不全中也较为常见。此外，我们还表明，与对CTS3进行Southern印迹分析相比，QAMA和MLPA进行的甲基化分析在检测ICR1低甲基化方面更为敏感。
