Martínez Francisco, León Ana María, Monfort Sandra, Oltra Silvestre, Roselló Mónica, Orellana Carmen
Unidad de Genética y Diagnóstico Prenatal, Hospital Universitario La Fe, Valencia, Spain.
Genet Test. 2006 Fall;10(3):174-7. doi: 10.1089/gte.2006.10.174.
We present a new method for differential diagnosis of Prader-Willi (PWS) and Angelman syndromes (AS) that requires only a small amount of DNA including that obtained from amniocentesis specimens. This method not only proved to be robust and rapid, but, most importantly, it can be dosage sensitive, supplying additional information useful for genetic counselling. After methylation-dependent digestion of DNA with HpaII or McrBC, exon 1 of the SNRPN gene is amplified together with a sequence in the CpG island of the H19 gene. Given the similarities in sequence composition and methylation status between the amplified sequences, their co-amplification under semiquantitative conditions allows an easy discrimination between single dosage (present in deletions or chromosomal translocations) and a double-dosage state (uniparental disomy or imprinting error), when the appropriate controls are included. The method we have developed in combination with standard cytogenetic studies and segregation analysis of microsatellite markers offers a rapid and easy procedure to resolve most suspected cases of PWS and AS, and consequently to provide accurate genetic counselling.
我们提出了一种用于鉴别普拉德-威利综合征（PWS）和安吉尔曼综合征（AS）的新方法，该方法仅需要少量DNA，包括从羊膜穿刺术标本中获取的DNA。这种方法不仅被证明是可靠且快速的，而且最重要的是，它具有剂量敏感性，能提供对遗传咨询有用的额外信息。在用HpaII或McrBC对DNA进行甲基化依赖性消化后，SNRPN基因的外显子1与H19基因的CpG岛中的一个序列一起被扩增。鉴于扩增序列之间在序列组成和甲基化状态上的相似性，当纳入适当对照时，它们在半定量条件下的共扩增使得能够轻松区分单剂量状态（存在于缺失或染色体易位中）和双剂量状态（单亲二体或印记错误）。我们开发的这种方法与标准细胞遗传学研究及微卫星标记的分离分析相结合，提供了一种快速且简便的程序来解决大多数疑似PWS和AS病例，从而提供准确的遗传咨询。
