Genetic analysis of the ciliopathies ARPKD and Meckel syndrome

描述（由申请人提供）：在过去的几年中，人们已经清楚地认识到多囊肾病（PKD）是纤毛相关基因突变引起的纤毛病。在这个建议中，我们将研究两个明显的隐性遗传PKD，常染色体隐性PKD（ARPKD）和梅克尔综合征（MKS）。在ARPKD中，该疾病主要限于肾脏和肝脏，而MKS是一种致命的综合征PKD，其中通常还发现中枢神经系统和手指缺陷ARPKD被认为是由于PKHD 1突变引起的遗传同质性疾病，尽管对具有ARPKD样表型的大群体的研究仅在约一半的个体中发现PKHD 1突变。MKS在遗传上更复杂，鉴定了11个基因，其他基因座的等位基因也被认为起作用;可能的寡基因遗传。虽然表面上这些疾病看起来非常不同，但最近的出版物和我们的初步数据表明遗传重叠。常染色体显性PKD（ADPKD）基因PKD 1的亚型突变已被证明可导致ARPKD样疾病和外显子富集，NGS已在MKS患者中显示PKHD 1和相关PKHDL 1等位基因。本研究的目的是采用尖端的遗传学方法来了解这两种疾病的全部遗传负荷，同时将利用动物模型来确定检测到的变异的意义，以及纤毛病基因之间上位效应的强度。在第一个目标中，总共约100个MKS和约200个ARPKD样家族，这些家族在遗传上尚未解决，将通过纤毛病和其他纤毛基因的外显子富集和下一代测序进行分析，适当时，再加上全外显子组分析。将在Aim 2细胞系统和模式生物C中对变体进行生物信息学评估。elegans和斑马鱼用来评估最有希望的变异的意义。在MKS和一些ARPKD样家族中发现的表型是由于一个以上基因的等位基因，上位性起着核心作用，这一概念将在目标3中使用C.线虫、斑马鱼和纤毛病小鼠模型的杂交。最终的目的将通过开发敲入/敲除小鼠模型来表征与所有转录物的破坏相关的表达和表型，来探索PKHD 1副基因和疑似纤毛基因PKHDL 1的作用。这些研究将为ARPKD样疾病和MKS的病因学提供更清晰的观点，并阐明这些“简单”遗传疾病的真正复杂性。

DESCRIPTION (provided by applicant): In the last few years it has become clear that polycystic kidney diseases (PKDs) are ciliopathies, due to mutations in cilia related genes. In this proposal we will study two apparently recessively inherited PKDs, autosomal recessive PKD (ARPKD) and Meckel syndrome (MKS). In ARPKD, the disease is largely restricted to the kidney and liver, while MKS is a lethal, syndromic PKD in which central nervous system and digital defects are typically also found. ARPKD is considered a genetically homogenous disorder due to PKHD1 mutation, although studies of large populations with an ARPKD-like phenotype have found PKHD1 mutations in only about one half of individuals. MKS is genetically more complex with 11 genes identified and alleles at other loci also thought to play a role; possible oligogenic inheritance. Although on the surface these diseases appear very different, recent publications and our preliminary data suggest genetic overlap. Hypomorphic mutations in the autosomal dominant PKD (ADPKD) gene, PKD1, have been shown to cause an ARPKD-like disease and exon enrichment and NGS has shown PKHD1, and the related PKHDL1, alleles in MKS patients. The purpose of this study is to employ cutting-edge genetic methods to understand the full genetic load in these two disorders, while animal models will be utilized to determine the significance of detected variants, plus the strength of epistatic effects between ciliopathy genes. In the first aim a total of ~100 MKS and ~200 ARPKD-like families, that are genetically unresolved, will be analyzed by exon enrichment and next-generation sequencing of ciliopathy and other ciliogenes, plus, when appropriate, whole exome analysis. Variants will be assessed bioinformatically and in Aim 2 cellular systems and the model organisms C. elegans and zebrafish employed to assess the significance of the most promising variants. The concept that the phenotype found in MKS and some ARPKD-like families is due to alleles at more than one gene, that epistasis plays a central role, will be tested in Aim 3 employing C. elegans, zebrafish and interbreeding of mouse models of ciliopathies. The final aim will explore the role of the PKHD1 paralog and suspected ciliogene, PKHDL1, by developing knock- in/out mouse models to characterize expression and the phenotype associated with disruption of all transcripts. Together these studies will provide a much clearer view of the etiology of ARPKD-like disease and MKS and clarify the true complexity of these "simple" genetic diseases.