Molecular genetics of Pelizaeus-Merzbacher disease

Pelizaeus-Merzbacher 病的分子遗传学

• 批准号: 7755867
• 负责人: Grace M. Hobson
• 金额: $ 21.9万
• 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 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7755867
• 关键词: Accounting; Animals; Cognitive; 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; Lead; Life; Limb structure; 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; public health relevance; segregation

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: This research is directly relevant to public health because it will lead to a better understanding of genetic disease mechanisms, which will ultimately improve diagnostic and therapeutic approaches for PMD and other disorders that result from complex genomic and genetic mutational events.

描述（由申请人提供）：佩利扎乌斯-梅茨巴赫病（PMD）是一种 X 连锁脑白质营养不良，由编码主要中枢神经系统髓磷脂蛋白的蛋白脂质蛋白 1 基因（PLP1）的遗传缺陷引起。 含有 PLP1 的基因区域重复是 PMD 的最常见原因，占所有病例的 60% 以上。 尽管疾病的严重程度可能存在差异，但即使在一个家庭中，大多数 PLP1 重复的患者也具有相似的表型，在出生后的最初几个月出现眼球震颤和肌张力减退，在出生后的头十年出现肢体和步态共济失调、痉挛性四肢瘫痪以及认知和视力障碍。 大多数患者的运动里程碑和言语也延迟。 基因复制的分子机制和 PMD 临床表型的分子基础都不清楚。 在我们之前对 13 名 PMD 患者的重组连接 DNA 序列进行的研究中，我们发现了与导致基因重复的耦合同源、非同源重组机制一致的数据。 然而，Lupski 及其同事最近通过对两名具有复杂重排的患者的重组连接的分析表明，基于复制的机制也可能参与了这一过程。 在拟议的研究中，我们将使用包括高密度寡核苷酸阵列在内的策略组合来分析更大的基因重复患者群体中重组断点的结构和序列。 此外，为了进一步了解这些复杂的基因重复引起的临床表型的基础，我们将构建含有 X 染色体 PLP1 区域的大而复杂的重复的 PMD 小鼠模型。 含有这种重复的 ES 细胞已经被构建出来，并且含有 X 染色体重排部分的小鼠也正在被制造出来。 然后将分析动物的临床表型、重复编码基因的表达（包括 PLP1）以及髓鞘形成程序中其他基因的表达。 还将在女性携带者中检查 X 染色体重排部分的分离对 X 失活的影响。 总而言之，这些研究将为 PMD 中基因复制的机制以及这种基因复制对基因表达和神经功能的影响提供重要的新信息。 由于我们开发了独特的患者资源以及我们在过去十年致力于 PMD 诊断和研究中获得的专业知识，我们的团队特别做好了开展这些研究的准备。 具体目标是：（1）检验以下假设：PMD 患者的基因组重排经常以复杂的重排形式发生，包括第二个重复区域和删除、三重或倒置区域，与耦合同源、非同源重组机制一致。 (2) 检验以下假设：Plp1 基因座上存在基因重复会改变 Plp1 基因表达，从而导致男性髓磷脂程序破坏和女性 X 染色体失活模式补偿性偏差。 公共健康相关性：这项研究与公共健康直接相关，因为它将有助于更好地了解遗传疾病机制，最终将改善 PMD 和其他由复杂基因组和基因突变事件引起的疾病的诊断和治疗方法。