High Throughput Genotyping and DNA Sequencing for Studying the Genetic Contributions to Human Disease: Genetics of Dental Enamel Formation (Hu)

遗传性牙釉质畸形是由牙釉质形成所必需的基因缺陷引起的，被统称为无釉质发育不全症（AI）。人工智能是一种严重的疾病，可能与身体其他部位的健康问题有关。由于牙齿的毁容，AI患者通常会有自我意识。他们的自尊心较低，认为自己的生活质量较差。他们不吃冷的食物和饮料。有些人接受了广泛的牙齿康复治疗，但大多数人只是受到这种疾病的影响。人工智能有很多种形式，每种都是由不同基因的缺陷引起的。在综合征型AI中，牙釉质畸形伴有严重的、有时是隐藏的系统性问题，如失明、肾钙化、免疫缺陷或皮肤起泡。临床上往往无法区分孤立型和综合征型的AI，因此通过基因检测识别致病的遗传缺陷，可以建立诊断，并辨别除牙釉质外是否有其他组织或器官受到影响。更好地了解人工智能的病因为改进人工智能疾病的诊断、预后评估、治疗和治愈提供了希望。一些突变会导致蛋白质合成过早停止，这可能会被“读出”分子治疗。其他基因缺陷引起的细胞病理与蛋白质错误折叠有关，而不是与蛋白质功能丧失有关。化学伴侣可以防止由突变引起的细胞病理，这些突变导致分泌蛋白或膜蛋白折叠不当。在本研究中，我们检验了以下三个假设：1)全外显子组分析可以在已证实的AI候选基因中识别出牙釉质缺陷的因果突变，也可以识别出新的AI致病基因和突变。2) AI类中发现的新基因缺陷的因果关系可以通过相应敲除（KO）小鼠的牙釉质畸形来支持。3)一些人工智能是由潜在可逆的病理机制引起的。为了验证这些假设，我们提出以下两个具体目标：SA 1：确定导致AI类遗传性牙釉质缺陷的新基因和突变。SA 2：确定人工智能引起的翻译过早终止或内质网应激是否可逆。意义：识别导致遗传性牙釉质缺陷的基因将使基因检测能够诊断AI，改善对患者预后的评估，并识别可以用化学伴侣或读通分子治疗的突变，以促进遗传背景有缺陷的患者的正常牙齿发育。

Inherited enamel malformations are caused by defects in genes essential for dental enamel formation and are grouped together under the collective designation of Amelogenesis Imperfecta, or AI. AI is a serious condition and may be associated with health problems in other parts of the body. AI patients are often self- conscious because of the disfiguring appearance of their teeth. They have lower self-esteem and perceive themselves as having an inferior quality of life. They avoid cold food and drinks. Some undergo extensive dental rehabilitation procedures, but the majority simply suffer the effects of the disease. There are numerous forms of AI, each caused by defects in a different gene. In syndromic forms of AI, enamel malformations are accompanied by serious, sometimes hidden systemic problems, like blindness, kidney calcifications, immunodeficiency, or skin blistering. Isolated and syndromic forms of AI often cannot be distinguished clinically, so genetic testing that identifies the causative genetic defect would establish the diagnosis and discern whether or not other tissues or organs besides enamel are affected. Better understanding of the causes of AI provides hope for improvements in the diagnosis, assessment of prognosis, treatment, and cure of AI diseases. Some mutations cause synthesis of a protein to stop prematurely, which can potentially be treated with "readthrough" molecules. Other gene defects cause cell pathology related to protein misfolding rather than to a protein's loss of function. Chemical chaperones can prevent cell pathology resulting from mutations that cause secreted or membrane proteins to fold improperly. In this study we test the following three Hypotheses: 1) Whole-exome analyses can identify causal mutation(s) in kindreds with enamel defects in proven AI candidate genes, and also identify novel AI-causing genes and mutations. 2) Causality of novel gene defects identified in AI kindreds can be supported by the demonstration of enamel malformations in the corresponding knockout (KO) mice. 3) Some AI is caused by potentially reversible pathological mechanisms. To test these hypotheses we propose the following two Specific Aims: SA 1: Identify novel genes and mutations that cause inherited enamel defects in AI kindreds. SA 2: Determine if AI-causing premature translation termination or ER stress is reversible. Significance: Identifying the genes that cause inherited enamel defects will permit genetic testing to diagnose AI, improve assessment of the patients' prognoses, and recognize mutations that can be treated with chemical chaperones or readthrough molecules to promote normal tooth development in patients with a defective genetic background.