采用全外显子组测序技术识别鉴定甲状腺功能亢进伴周期性麻痹的致病基因和致病位点

Thyrotoxic hypokalemic periodic paralysis (TPP) is a potentially life-threatening complication of thyrotoxicosis, triggered by thyrotoxicosis and environmental factors. The pathogenesis of TPP is still a conundrum, although a few risk factors have been identified using candidate strategy and genome-wide association study. In this study, to identify the causal variant(s)/gene(s) of TPP, firstly we carried out the exome sequencing for the Graves' disease patients without hypokalemic periodic paralysis as the negative control and excluded its causal genes from the potential TPP causal genes based on the exome sequencing results in three TPP trios and 31 TPP individuals. Next, we performed the extended confirmation study for the above-identified TPP candidate genes in approximately 500 Graves’ disease patients with TPP, Also, to investigate the specific causal genes of TPP, we performed the association study for the loci with the highly mutated variants between the Graves’ disease patients with TPP and the normal healthy controls. Finally, we would use the functional experiments and bioinformatics to verify the mechanisms how the variants or genes can trigger TPP attacks. Take together, this study can confirm whether TPP is a specific molecular subtype of Graves’ disease, thus providing insights into the prevention and treatment of TPP.

甲状腺功能亢进伴周期性麻痹（TPP）是一种甲状腺功能亢进伴发的威胁患者生命的严重疾病状态。尽管前期的候选基因策略和全基因组关联分析策略识别了一些TPP的易感或候选基因，然而TPP发病的分子遗传学特点及其致病机制仍不明确。课题组在前期对3个TPP三联家系和31例TPP散发病例进行全外显子组测序及信息生物学分析的基础上，通过选择特殊不伴有低钾周期性麻痹的Graves病患者作为阴性对照进行二代测序，排除其突变，并对可能的TPP候选致病基因在超过500例的大样本TPP人群中验证，用以识别TPP的频发突变位点和突变基因；并通过与正常对照人群的关联分析等，找到TPP的特异突变位点和突变基因；同时，采用一系列生物学信息分析和功能实验，找到这些突变位点和突变基因引起TPP发病的分子机制，阐明TPP是否为一种具有特殊遗传背景型别的Graves病，进而为这种疾病的防治提供全新的思路。

该项目进展顺利，取得了一些新的成果，并产生了重要的可继续深入的研究的新的领域。以甲状腺功能亢进合并低钾周期性麻痹为切入点，通过全外显子组测序技术和全基因组关联分析策略，明确了甲状腺功能亢进合并低钾周期性麻痹的致病易感基因和易感位点，包括3个区段是甲状腺功能亢进合并低钾周期性麻痹的特异性致病易感区段，其中17号染色体和4号染色体上的两个相关性最强的甲状腺功能亢进合并低钾周期性麻痹特异性易感位点和甲状腺功能亢进合并低钾周期性麻痹相关性的比值比高达2.08和1.58，同时甲状腺功能亢进合并低钾周期性麻痹和甲亢共享HLA和Xq21.1区段；且临床资料表明：甲状腺功能亢进合并低钾周期性麻痹的抗促甲状腺激素自身抗体持续阳性率远高于不合并低钾周期性麻痹的甲亢患者。提示：甲状腺功能亢进合并低钾周期性麻痹是一种特殊类型的甲亢。我们采用甲状腺功能亢进合并低钾周期性麻痹的特异性致病易感位点，可以很好的从总甲亢人群中预测处甲状腺功能亢进合并低钾周期性麻痹的这一种严重甲亢亚型，进一步验证甲亢分子亚型学说，明确是否不同分子亚型有不同的临床预后和转归，是否不同亚型需要采用不同的临床治疗方案，加深人们对甲亢发生分子机制的理解和认识，为甲亢临床治疗方案的选择和预后评估提供新思路。在该项目的资助下，已发表SCI收录论文7篇。