Genetic etiology of familial RASopathy

• Main Authors: Wei-ChenChang, 張維真
• Other Authors: Peng-Chieh Chen
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/10350717234106432671

碩士 === 國立成功大學 === 臨床醫學研究所 === 104 === RASopathy is a class of developmental disorders caused by germline mutations in genes encoding components of the RAS/MAPK pathway, which occur in familial or sporadic manner. Owing to the common mechanisms of Ras/MAPK pathway dysregulation, RASopathy share chracteristic phenotypes such as short stature, facial dysmorphia, cardiac defects and developmental delay. We have enrolled three familial cases with RASopathy, all carrying no mutations in the known causative genes. In this study, we aim to identify the disease-causing genetic events through exome sequencing on genomic DNA from the patients and their affected parents. In previous study, whole-exome sequencing provide a diagnostic approach for Mendelian disorders (1). In addction, all the known disease-causing mutations for RASopathy are in the protein-coding region of the genome. Hence, we hypothesize that the causative mutation in these familial cases is also in the exonic region and can be identified through WES.Exome sequencing was used to identified genetic variants in familial RASopathy cases. Shared variants between patients and affected parent were filtered. The activation of RAS/MAPK pathway was used to confirm the causative role of each RASopathy-associated mutation. In particular, level of phosphorylated-ERK was assayed in cell expressing wild-type and mutant RASopathy-associated gene.We identified novel mutation in RASIP1 in both the patient and the affected parent in one family. We have generated WT and mutant RASIP1 transient or stable expression system in HEK293T cells and TREx 293T cell respectively. RASIP1R806* lead to dysregulated signaling of RAS/MAPK pathway in response to EGF stimulation when compared with WT. In addition, RASIP1R806* increased Ras-GTP levels in Ras activity assay and changed localization in cells. In previous study, NS patients with PTPN11 mutations are predisposed to juvenile myelomonocytic leukaemia (JMML), and CS is associated with neuroblastoma (NBL) and bladder cancer. Identifying disease-causing genes is important not only for providing accurate diagnosis but also for referring proper treatments. We identified novel mutations in RASIP1 which lead to dysregulated signaling of RAS/MAPK pathway. Key words: RASopathy, RASIP1