IDENTIFICATION OF VUR GENES BY COMBINED LINKAGE ANALYSIS AND EXOME SEQUENCING

描述（由申请人提供）：原发性膀胱输尿管反流（PVUR），或非综合征性VUR，是最常见的肾脏和尿路先天性异常（CAKUT）类型。在儿童年龄组中，PVUR是肾盂肾炎和肾实质瘢痕形成的最重要的危险因素。由PVUR引起的肾实质瘢痕形成被称为反流肾病，是儿童需要透析和肾移植的终末期肾病的主要原因。PVUR具有家族聚集性；然而，尽管有许多连锁研究，PVUR的具体遗传原因尚不清楚。造成这种情况的原因包括：疾病的可变表达，病例确定的困难，遗传异质性和缺乏可以促进位点鉴定的大谱系。我们已经确定了一个跨越五代的97名成员的PVUR家族。我们对该家族进行了全基因组连锁研究（GWLS），并在6p染色体上获得了3.3的显著全基因组LOD评分。我们对家族中受影响的个体进行了外显子组测序，并确定了tenascin XB （TNXB）突变是家族性VUR的一个原因。拟开展的研究有以下具体目标：a)确定腱素基因在PVUR病因学中的作用；b)鉴定新的PVUR致病基因。我们的具体目标是：(1)在200名家族性和散发性PVUR患者中进行TNXB和其他tenascin的突变分析，并确定基因型/表型相关性。(2)对PVUR家族进行序列全基因组连锁研究（GWLS）和全外显子组/靶向测序。对公众健康的影响：PVUR基因的鉴定可能为PVUR患儿提供一种新的非侵入性诊断工具。此外，本研究将进一步揭示PVUR的发病机制，并进一步阐明肾脏和泌尿生殖系统发育的途径。未来的研究将确定这些基因在其他肾脏和尿路畸形的病因学中的作用，并试图揭示所鉴定的基因导致PVUR和其他肾脏和尿路畸形的机制。

DESCRIPTION (provided by applicant): Primary vesicoureteric reflux (PVUR), or non-syndromic VUR, is the most common type of congenital anomaly of the kidney and the urinary tract (CAKUT). PVUR is the single most important risk factor for pyelonephritis and renal parenchymal scarring in the pediatric age group. Renal parenchymal scarring due to PVUR is referred to as reflux nephropathy and is a major cause of end stage kidney disease requiring dialysis and kidney transplantation in children. PVUR shows familial aggregation; however, the specific genetic cause(s) of PVUR is unknown despite a number of linkage studies. Reasons for this include: variable expression of the disease, difficulty with case ascertainment, genetic heterogeneity and lack of large pedigrees that can facilitate locus identification. We have ascertained a large 97 member PVUR kindred spanning five generations. We performed a genome-wide linkage study (GWLS) on this family and obtained a significant genome-wide LOD score of 3.3 on chromosome 6p. We performed exome sequencing on affected individuals in the family and identified mutations in tenascin XB (TNXB) as a cause of familial VUR. The proposed studies have the following specific objectives: a) to define the role of tenascin genes in the etiology of PVUR and b) to identify new PVUR causative genes. Our specific aims are (1) To perform mutation analysis in TNXB and other tenascins in a cohort of 200 individuals with familial and sporadic PVUR and define genotype/phenotype correlations. (2) To perform sequential genome wide linkage studies (GWLS) and whole exome/targeted sequencing in families with PVUR. Impact on public health: Identification of PVUR genes may provide a novel non-invasive diagnostic tool for a subset of children with PVUR. Furthermore, this research will provide insights into the pathogenesis of PVUR and further elucidate the pathways involved in the development of the kidney and genitourinary tract. Future studies will define the role of the genes in the etiology of other malformations of the kidney and urinary tract and also seek to unravel the mechanisms by which the identified gene causes PVUR and other malformations of the kidney and the urinary tract.