請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/59160
標題: | 偽副甲狀腺功能低下症之基因檢測 Genetic Testing for Pseudohypoparathyroidism |
作者: | You-Mei Chen 陳幼玫 |
指導教授: | 楊偉勛(Wei-Shiung Yang) |
共同指導教授: | 陳沛隆(Pei-Lung Chen) |
關鍵字: | 偽副甲狀腺功能低下症,次世代定序,甲基化, Pseudohypoparathyroidism,Next-generation sequencing,methylation, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 由於副甲狀腺素受體下游包括刺激型G蛋白的α次單元之GNAS基因發生異常,導致細胞受體經副甲狀腺素的刺激後,無法將訊號正常傳遞,而引起偽副甲狀腺功能低下症(pseudohypoparathyroidism, PHP)。GNAS是個高複雜性的印記基因(imprinted gene),可透過不同的選擇性啟動子(alternative promoters)及選擇性剪接(alternative splicing)產生不同的轉錄產物(transcripts),其中最具有特色的轉錄產物就是由GNAS基因產生的Gsα,在大部份的組織中GNAS基因會同時以兩個對偶基因來表現Gsα,但少部份的組織(例如:近端腎小管)則是只表現母系那條對偶基因的Gsα。
偽副甲狀腺功能低下症1a型是由於母系GNAS對偶基因的外顯子發生突變,使近端腎小管對副甲狀腺素有阻抗性,但大部份的組織中,其具有功能之Gsα蛋白單倍劑量不足(haploinsufficiency),而造成遺傳性骨發育不全(Albright hereditary osteodystrophy, AHO)的臨床表徵。偽假性副甲狀腺功能低下症是由於父系GNAS對偶基因的外顯子發生突變性,患者雖不會會副甲狀腺素有抗性,但其仍會有遺傳性骨發育不全的臨床症狀。而偽副甲狀腺功能低下症1b型患者是由於GNAS基因差異甲基化區域的甲基化情形發生異常而造成患者的腎近端小管對副甲狀腺素有阻抗性,其臨床表現少有遺傳性骨發育不全特徵。 目前臺大醫院陳沛隆醫師實驗室已經建立以聚合酶連鎖反應(polymerase chain reaction, PCR)及桑格定序(Sanger sequencing)來檢測分析GNAS基因13個外顯子之序列。但這個流程費時又費力,故我們將利用探針捕獲(probe capture)待測區域及次世代定序(next-generation sequencing)一次將GNAS基因13個外顯子進行分析,以減緩臨床檢測時效性的壓力,且能提高檢測的精準度。另外,在臺灣偽副甲狀腺功能低下症1b型的基因檢測方式仍尚未建立,故我們將建立藉由解析度高的次世代定序方法來檢測GNAS基因之差異甲基化區域的甲基化情況,以提供臨床上疑似偽副甲狀腺功能低下症1b型患者進行分子診斷確診,目前我們看到在偽副甲狀腺功能低下症1b型患者患者之差異甲基化區域(exon A/B)的甲基化情況有別於未生病的正常控制組,其甲基化情況與我們預期偽副甲狀腺功能低下症1b型皆無甲基化相符合。除此之外,亦建立以探針捕獲差異甲基化區域的方法檢測偽副甲狀腺功能低下症1b型。 Pseudohypoparathyroidism (PHP) is caused by pathogenic variants and/or epigenetic changes at the complex GNAS locus on chromosome 20q13.3. GNAS encodes for the alpha-subunit of the stimulatory G protein (Gsα) and several other alternative splicing products. GNAS is paternally imprinted in certain tissues, which means that Gsα expression of the paternal allele is absent in those tissues (including proximal renal tubules). Consequently, in the presence of an inactivating mutation in the maternal GNAS gene, there is little or no Gsα protein, leading to PTH-resistant hypocalcemia and hyperphosphatemia. The inactivating variant in the maternal GNAS gene causes PHP1a, while the paternal GNAS pathogenic variant ends up in pseudo-PHP (PPHP). And loss of methylation at a differentially methylated region (DMR) of the GNAS locus, exon A/B, has been observed in patients with PHP1b. Patients with PHP1a often present with additional hormonal resistance and show characteristic physical features that are collectively termed Albright’s hereditary osteodystrophy (AHO). These features are also present in PPHP, but patients affected by this disorder do not show hormone resistance. Patients with PHP1b have hypocalcemia and hyperphosphatemia due to renal PTH-resistance, but lack physical features of AHO. In Taiwan, genetic testing of PHP1b has not yet been established, so we established a testing method using next-generation sequencing (NGS) for diagnosis of PHP1b. Furthermore, we also successfully applied the NGS-based methods for the genetic diagnosis of all types of PHPs. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/59160 |
DOI: | 10.6342/NTU201701518 |
全文授權: | 有償授權 |
顯示於系所單位: | 分子醫學研究所 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-106-1.pdf 目前未授權公開取用 | 7.11 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。