MOLECULAR AND CYTOGENETIC DELINEATIONS OF 22Q11 DELETIONS

VCFS和22q11.-&gt；11.23的高危患者群体为 非常大。因此，一种基于DNA的快速筛查方法来检测 删除的风险很高的个人将被要求。我们建议 建立和应用基于多重聚合酶链式反应的筛选方法 多态DNA标记。面临删除风险的个人将是 利用荧光原位杂交(FISH)进一步筛选 22q11.2-跨越VCFS关键区域并位于其两侧的特定粘粒克隆 区域。利用多个探针同时杂交的方法 间期核将帮助我们估计缺失的程度 精选的个体。我们将检验这一假设，即 缺失的大小、位置、父母或来源以及病因 22q11解释了在受影响的 家庭成员可能是由于继承的 减数分裂过程中的缺失。为了检验这一假设，我们将关联 缺失的大小和位置与临床结果(核心A)， 发现的基因(项目1)及其表达模式(项目1 2)。我们将比较多个受影响家庭中缺失的大小 成员，并通过确定父级来测试印记效果 起源于患者的缺失。最后，我们建议22q11可以 通过与其他顶着丝粒染色体的着丝粒交换进行重排。 我们将把这种“隐秘的移位”作为一种 与22q11.2缺失相关的机制。最后，我们建议 VCFS表型的孤立特征，特别是腭裂和/或 VIP，可能是由于VCFS中单个基因的异常-缺失所致 区域。为了验证这一假设，我们将测试一组孤立的唇裂 对腭裂患者是否存在缺失及证据进行检查 对于22q11.21-&gt；22q11.23中存在的腭裂基因 检查腭裂患者或家庭中的基因座关联。

The population of patients at-risk for VCFS and 22q11.->11.23 is extremely large. Therefore, a rapid DNA-based screening method to detect individuals at high risk for deletions will be required. We propose to develop and apply a multiplex PCR-based screening assay using highly polymorphic DNA markers. Individuals at risk for deletions will be further screened by fluorescence in situ hybridization (FISH) utilizing 22q11.2-specific cosmid clones which span and flank the VCFS critical region. Utilization of simultaneous hybridization of multiple probes to interphase nuclei will help us to estimate the extent of deletions for selected individuals. We will test the hypothesis that difference in the size, location, parent or origin, and etiology of the deletions within 22q11 account for the phenotypic variability observed between affected members of families may result from change in the size of an inherited deletion during meiosis. To test this hypothesis, we will correlate the size and location of the deletions with the clinical findings (Core A), the genes discovered (Project 1) and their expression pattern (Project 2). We will compare the size of deletions in multiple affected family members and test for imprinting effects by determining the parent of origin in patients with deletions. Finally, we propose that 22q11 may rearrange by centromeric exchange with other acrocentric chromosomes. We will examine the prevalence of such "cryptic translocation" as a mechanism associated with 22q11.2 deletions. Finally, we propose that isolated features of the VCFS phenotype, especially cleft palate and/or VIP, may be caused by abnormalities of a single gene in the VCFS-deletion region. To test this hypothesis we will test a cohort of isolated cleft palate patients for the presence of deletions and examine the evidence for the presence of a cleft palate locus in 22q11.21->22q11.23 by examining locus associations in cleft palate patients or families.