Molecular genetics of Pelizaeus-Merzbacher disease

Pelizaeus-Merzbacher 病的分子遗传学

• 批准号: 8399018
• 负责人: Grace M. Hobson
• 金额: $ 21.1万
• 依托单位: ALFRED I. DU PONT HOSP FOR CHILDREN
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-15 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8399018
• 关键词: Accounting; Animals; Complex; Coupled; DNA Sequence; DNA Sequence Rearrangement; Data; Diagnostic; Diagnostics Research; Disease; Event; Family; Female; Gait Ataxia; Gene Duplication; Gene Expression; Genes; Genetic; Genetic Predisposition to Disease; Genetic Recombination; Genomics; Impaired cognition; Lead; Life; Limb Ataxia; Link; Molecular; Molecular Genetics; Motor; Mus; Muscle hypotonia; Mutation; Myelin; Myelin Proteins; Nervous System Physiology; Neuraxis; Oligonucleotide Microarrays; Pathologic Nystagmus; Patients; Pattern; Pelizaeus-Merzbacher Disease; Phenotype; Process; Proteins; Proteolipids; Public Health; Quadripareses; Recombinants; Research; Resources; Severity of illness; Spastic; Speech; Structure; Testing; Therapeutic; Visual impairment; X Chromosome; X Inactivation; base; clinical phenotype; cohort; density; embryonic stem cell; improved; leukodystrophy; male; mouse model; myelination; programs; segregation

PROJECT SUMMARY Pelizaeus-Merzbacher disease (PMD) is an X-linked leukodystrophy caused by genetic defects of the proteolipid protein 1 gene (PLP1) that encodes the major central nervous system myelin protein. Duplication of a gene region containing PLP1 is the most common cause of PMD, accounting for over 60% of cases. Although there can be variability in the severity of the disease, even within a single family, most patients with PLP1 duplications have a similar phenotype with onset of nystagmus and hypotonia in the first months of life, and limb and gait ataxia, spastic quadriparesis, and cognitive and visual impairment during the first decade. Motor milestones and speech are also delayed in most patients. Neither the molecular mechanisms of gene duplication nor the molecular basis for the clinical phenotype in PMD is well understood. In our previous studies of the DNA sequences of recombinant junctions in 13 patients with PMD, we have found data consistent with a coupled homologous, nonhomologous recombination mechanism causing the gene duplications. Lupski and co-workers, however, recently suggested from the analysis of recombinant junctions in 2 patients with complex rearrangements that a replication-based mechanism may also be involved in this process. In the proposed studies, we will analyze the structure and sequence of the recombination breakpoints in a larger cohort of patients with gene duplications using a combination of strategies, including high-density oligonucleotide arrays. In addition, to further understand the basis of the clinical phenotype caused by these complex gene duplications, we will construct a mouse model of PMD containing a large, complex duplication of the PLP1 region of the X-chromosome. ES cells containing this duplication have been constructed, and mice containing the rearranged portion of the X-chromosome are being made. Animals will then be analyzed for their clinical phenotype, the expression of genes encoded by the duplication, including PLP1, as well as expression of other genes in the program of myelination. Segregation of the rearranged portion of the X- chromosome will also be examined in female carriers for its effects on X-inactivation. Taken together, these studies will provide important new information on the mechanism of gene duplication in PMD, as well as the effect of this gene duplication on gene expression and neurological function. Our group is particularly well poised to perform these studies because of the unique patient resource we have developed and the expertise we have gained from a commitment to PMD diagnostics and research during the past decade. The specific aims are: (1) To test the hypothesis that genomic rearrangements in PMD patients frequently occur as complex rearrangements, including a second duplicated region and deleted, triplicated or inverted regions, consistent with a coupled homologous, nonhomologous recombination mechanism. (2) To test the hypothesis that the presence of a gene duplication at the Plp1 locus alters Plp1 gene expression leading to disruption of the myelin program in males and compensatory skewing of the X-chromosome inactivation pattern in females.

项目摘要 Pelizaeus-Merzbacher病（PMD）是由X连锁的白细胞营养不良，由遗传缺陷引起 蛋白脂蛋白蛋白1基因（PLP1）编码主要的中枢神经系统髓鞘蛋白。重复 含有PLP1的基因区域是PMD的最常见原因，占病例的60％以上。 尽管该疾病的严重程度可能会差异，即使在一个家庭中，大多数患者 PLP1重复具有类似的表型，在生命的头几个月中，眼球震颤和低调发作， 在头十年中，肢体和步态共济失调，痉挛性四次发育以及认知和视觉障碍。 大多数患者的运动里程碑和语音也会延迟。基因的分子机制既不 众所周知，PMD中临床表型的重复或分子基础。在我们的上一个 对13例PMD患者的重组连接的DNA序列的研究，我们发现了数据 与引起基因的耦合同源，非同源重组机制一致 重复。但是，Lupski和同事最近通过重组连接的分析提出了 在2例具有复杂重排的患者中，基于复制的机制也可能涉及 过程。在拟议的研究中，我们将分析重组断点的结构和序列 在较大的具有基因复制的患者中，包括高密度在内的策略组合 寡核苷酸阵列。此外，进一步了解由这些引起的临床表型的基础 复杂的基因重复，我们将构建一个PMD的小鼠模型，该模型包含大型复杂复制 X染色体的PLP1区域。已经构建了包含此重复的ES细胞，小鼠 正在制作包含X染色体的重排部分。然后将分析动物 它们的临床表型，包括PLP1在内的重复编码的基因的表达以及 其他基因在髓鞘中的表达。 X-重新排列的部分的分离 染色体还将在女性载体中检查其对X灭活的影响。总的来说，这些 研究将提供有关PMD基因复制机制的重要新信息，以及 该基因重复对基因表达和神经功能的影响。我们的小组特别好 由于我们开发了独特的患者资源和专业知识，因此准备进行这些研究 在过去的十年中，我们从对PMD诊断和研究的承诺中获得了收益。具体 目的是：（1）检验以下假设：PMD患者经常发生基因组重排时 重排，包括第二重复区域，并删除，三倍或倒置区域，一致 具有同源，非同源重组机制的耦合。 （2）检验以下假设 PLP1基因座的基因重复的存在会改变PLP1基因表达导致髓磷脂的破坏 男性的计划和女性X染色体灭活模式的补偿性偏斜。