MOLECULAR MECHANISMS LEADING TO RETT SYNDROME

描述：(逐字摘自申请者摘要)Rett综合征(RTT)是一种 儿童早期起病的神经性障碍，其特征是 随着言语和有目的使用手的丧失而发展倒退， 小头畸形和癫痫。RTT通常是零星的，是深层次疾病的常见原因 智力低下，每10-15,000名女性中就有一人受到影响。罕见家族性疾病的研究 病例，包括一名受严重影响的男性，提供了压倒性的证据 RTT是由于一种基因的X连锁显性突变从头开始发生 受到X-失活的影响。家族性病例的多态标记分型 允许排除X染色体的大部分区域，并集中搜索 Xq28带上的RTT基因。将确定更多的RTT系列，并 研究进一步划定候选区域。拟议的研究将 使用系统的方法和新技术来识别基因 对这一疾病负责，并确定其在 神经系统；发现突变机制并确定 突变对神经元发育或生存的影响。这个 假设RTT是由Xq28中的微缺失引起的，将通过一项 利用序列标签位点聚合酶链式反应和脉冲场凝胶进行系统缺失搜索 用覆盖Xq28区域的探针进行的电泳分析。假说 基因组重排导致女性Xq28的两个从头突变 RTT和另一种X连锁显性疾病--色素性失禁(IP) 对雄性的致命性，将通过基因组方法和荧光检测 原位杂交。RTT突变导致差异基因的假说 表达将通过抑制消减杂交方法进行评估 用含rtt基因的细胞系的cDNA进行比较杂交 并将对照与基因表达微阵列相匹配。确定候选基因 通过上述任何一种映射到Xq28的方法，都将在 无血缘关系的RTT个人。定位基因的差异表达模式 基因组的其他部分可能揭示了受RTT影响的途径 基恩的功能。此外，人类基因图谱和测序数据库 在候选区域中包含大量基因。其中19个已经成为 优先进行突变分析。一旦RTT基因被鉴定出来， 分子诊断将在疾病的早期阶段成为可能。 新生儿筛查程序可以确定症状前突变携带者。一 致病的遗传机制是已知的，对病理生理的理解 可能导致早期治疗干预。

DESCRIPTION: (Verbatim from the Applicant's Abstract) Rett Syndrome (RTT) is a neurological disorder of early childhood onset that is characterized by developmental regression with loss of speech an of purposeful hand use, microcephaly and seizures. Usually sporadic, RTT is a common cause of profound mental retardation, affecting 1 in 10-15,000 females. Studies of rare familial cases, including a severely affected male, provide overwhelming evidence that RTT is due to de novo occurrence of X-linked dominant mutations of a gene that is subject to X-inactivation. Polymorphic marker typing of familial cases allowed exclusion of most regions of the X chromosome and focused the search for the RTT gene on band Xq28. Additional RTT families will be identified and studied to further delineate the candidate region. The proposed research will use a systematic approach and novel technologies to identify the gene responsible for this disorder and to determine its normal function in the nervous system; to discover the mutational mechanisms and to determine the consequences of the mutations for neuronal development or survival. The hypothesis that RTT is due to microdeletions in Xq28 will be tested by a systematic deletion search using sequence-tagged-sites PCR and pulsed-field-gel electrophoresis analyses with probes covering the Xq28 region. The hypothesis tat a genomic rearrangement causes two de novo mutations in Xq28 in a female with RTT and Incontinentia Pigmenti (IP), another X-linked dominant disorder lethal in males, will be tested by genomic approaches and by fluorescence in situ hybridization. The hypothesis that RTT mutations lead to differential gene expression will be evaluated by suppression subtractive hybridization methods and by comparative hybridization of cDNA from RTT-gene containing cell lines and matched controls to Gene Expression Microarrays. Candidate genes identified by any of the above approaches that map to Xq28 will be tested for mutation in unrelated RTT individuals. Differential expression patterns of genes located elsewhere in the genome may reveal pathways that are influenced by the RTT gene's function. In addition, human gene mapping and sequencing databases contain numerous genes in the candidate region. Nineteen of them have been prioritized for mutation analysis. Once the RTT gene has been identified, Molecular diagnosis will become possible at early stages of the disorder. Newborn screening programs could identify presymptomatic mutation carriers. One the causative genetic mechanism is known, understanding of the pathophysiology may lead to early therapeutic intervention.