GENETICS OF FAMILIAL FOCAL SEGMENTAL GLOMERULOSCLEROSIS

局灶节段性肾小球硬化（FSGS）是一种病因不明的进行性肾脏疾病，可导致蛋白尿和终末期肾病（ESRD）。目前，我们对节段性肾小球硬化发生的分子机制了解有限。在目前的应用中，我们建议通过应用定位克隆策略来确定家族性FSGS常染色体显性形式的遗传缺陷。我们已经确定了FSGS作为高外显率的孟德尔性状遗传的家庭。到目前为止，我们已经收集了50个多代家庭，其中包括219名受影响的个体，并对这些家庭成员中的543名进行了DNA存储，其中包括114名受影响的受试者。在初步研究中，我们建立了与染色体11q21-22的连锁关系，并证明家族性FSGS具有遗传异质性。我们计划采用系统的方法来研究家族性FSGS，包括：(1)扩大现有家族性FSGS并收集其他家族性FSGS，(2)对非连锁家族进行全基因组定位以确定遗传异质性的全谱，(3)使用重组和单倍型分析缩小最小候选区域（MCR），以及(4)确定突变的FSGS基因。最初，我们将缩小已经建立连锁的11号染色体上的MCR，然后将类似的范例应用于其他FSGS位点。我们已经在染色体11q21-22上发现了一个横跨MCR的YAC序列，这将为该区域表达序列标签位点（est）、微卫星和基因的定位提供一个框架。一旦这个框架建立，PAC/BAC序列将被构建，这将作为产生新的多态标记和候选基因的资源，以识别FSGS缺陷。新的候选基因将通过直接选择从非嵌合的YACs或pac中鉴定出来。定位到MCR的候选基因将被充分识别并筛选受影响个体的突变。这些研究对我们了解FFSGS的分子基础至关重要。从FFSGS获得的知识也将有助于更好地了解非遗传性FSGS的发病机制，并可能为更常见的散发形式的该病的治疗提供见解。

Focal Segmental Glomerulosclerosis (FSGS) is a progressive disorder of the kidney of unknown etiology that results in proteinuria and End Stage Renal Disease (ESRD). Currently, we have limited insights into the molecular mechanism(s) underlying the development of segmental glomerulosclerosis. In the current application, we propose to determine the genetic defects underlying autosomal dominant forms of familial FSGS by applying positional cloning strategies. We have identified families in which FSGS is inherited as a Mendelian trait with high penetrance. To date, we have collected 50 multiplex, multi-generational families containing 219 affected individuals and banked DNA on 543 of these family members including 114 affected subjects. In preliminary studies, we established linkage to chromosome 11q21-22 and demonstrated that familial FSGS is genetically heterogeneous. We plan to take a systematic approach to study familial FSGS that includes: (1) expanding existing and collecting additional families with familial FSGS, (2) genome wide mapping of unlinked families to define the full spectrum of genetic heterogeneity, (3) narrowing the minimal candidate region (MCR) using recombinant and haplotype analysis, and (4) identifying the mutant FSGS gene. Initially, we will narrow the MCR on chromosome 11 where we have established linkage and later apply a similar paradigm to other FSGS loci. We have identified a YAC contig spanning the MCR on chromosome 11q21-22, which will be verified to provide a framework for mapping of Expressed Sequence Tag Sites (ESTs), microsatellites and genes in the region. Once this framework is established, a PAC/BAC contig will be constructed that will serve as a resource for generating new polymorphic markers and candidate genes to identify the FSGS defect. New candidate genes will be identified using direct selection from non-chimeric YACs or PACs. Candidate gene mapped to the MCR will be fully identified and screened for mutations in affected individuals. These investigations are critical to our understanding of the molecular basis of FFSGS. Knowledge derived from FFSGS will also allow a better understanding of pathogenesis of non-hereditary forms FSGS and may provide insights regarding management of the more common sporadic forms of this disorder.