Nyström Anna-Maja, Ekvall Sara, Thuresson Ann-Charlotte, Denayer Ellen, Legius Eric, Kamali-Moghaddam Masood, Westermark Bengt, Annerén Göran, Bondeson Marie-Louise
Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Dag Hammarskjölds väg 20, SE-751 85 Uppsala, Sweden.
Eur J Med Genet. 2010 May-Jun;53(3):117-21. doi: 10.1016/j.ejmg.2010.03.001. Epub 2010 Mar 17.
The RAS-MAPK syndromes are a group of clinically and genetically related disorders caused by dysregulation of the RAS-MAPK pathway. A member of this group of disorders, Noonan syndrome (NS), is associated with several different genes within the RAS-MAPK pathway. To date, mutations in PTPN11, SOS1, KRAS, RAF1 and SHOC2 are known to cause NS and a small group of patients harbour mutations in BRAF, MEK1 or NRAS. The majority of the mutations are predicted to cause an up-regulation of the pathway; hence they are gain-of-function mutations. Despite recent advances in gene identification in NS, the genetic aetiology is still unknown in about 1/4 of patients. To investigate the contribution of gene dosage imbalances of RAS-MAPK-related genes to the pathogenesis of NS, a multiplex ligation-dependent probe amplification (MLPA) assay was developed. Two probe sets were designed for seven RAS-MAPK-syndrome-related candidate genes: PTPN11, SOS1, RAF1, KRAS, BRAF, MEK1 and MEK2. The probe sets were validated in 15 healthy control individuals and in glioma tumour cell lines. Subsequently, 44 NS patients negative for mutations in known NS-associated genes were screened using the two probe sets. The MLPA results for the patients revealed no gene dosage imbalances. In conclusion, the present results exclude copy number variation of PTPN11, SOS1, RAF1, KRAS, BRAF, MEK1 and MEK2 as a common pathogenic mechanism of NS. The validated and optimised RAS-MAPK probe sets presented here enable rapid high throughput screening of further patients with RAS-MAPK syndromes.
RAS-MAPK综合征是一组由RAS-MAPK信号通路失调引起的临床和遗传相关疾病。该组疾病中的一种，努南综合征（NS），与RAS-MAPK信号通路中的几个不同基因相关。迄今为止，已知PTPN11、SOS1、KRAS、RAF1和SHOC2中的突变可导致NS，一小部分患者在BRAF、MEK1或NRAS中存在突变。大多数突变预计会导致该信号通路的上调；因此它们是功能获得性突变。尽管NS在基因鉴定方面最近取得了进展，但约四分之一的患者的遗传病因仍然未知。为了研究RAS-MAPK相关基因的基因剂量失衡对NS发病机制的影响，开发了一种多重连接依赖探针扩增（MLPA）检测方法。针对七个与RAS-MAPK综合征相关的候选基因设计了两个探针组：PTPN11、SOS1、RAF1、KRAS、BRAF、MEK1和MEK2。这些探针组在15名健康对照个体和胶质瘤肿瘤细胞系中进行了验证。随后，使用这两个探针组对44名已知NS相关基因突变阴性的NS患者进行了筛查。患者的MLPA结果显示没有基因剂量失衡。总之，目前的结果排除了PTPN11、SOS1、RAF1、KRAS、BRAF、MEK1和MEK2的拷贝数变异作为NS常见致病机制的可能性。本文介绍的经过验证和优化的RAS-MAPK探针组能够对更多RAS-MAPK综合征患者进行快速高通量筛查。
