Molecular genetics of Pelizaeus-Merzbacher disease

Pelizaeus-Merzbacher 病的分子遗传学

• 批准号: 7913108
• 负责人: Grace M. Hobson
• 金额: $ 3.98万
• 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 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7913108
• 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）：Pelizaeus-Merzbacher病（PMD）是由蛋白脂质蛋白1基因（PLP1）的遗传缺陷引起的X连锁白细胞营养不良，它编码主要中枢神经系统髓神经素蛋白。 包含PLP1的基因区域的重复是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，即使在单个家庭中，大多数PLP1重复的患者在生命的头几个月中都具有相似的表型，而在生命的头几个月中，眼球震颤和肌发作的发作，肢体和步态性共济失调，痉挛性四肢摄取，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。 基因复制的分子机制和PMD中临床表型的分子基础都不能很好地了解。 在我们先前对13例PMD患者重组连接的DNA序列的研究中，我们发现数据与引起基因重复的同源，非同源重组机制一致。 然而，Lupski和同事最近通过对2例复杂重排患者的重组连接处的分析提出，基于复制的机制也可能参与此过程。 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进行基因重复的大量患者中重组断点的结构和序列。 此外，为了进一步了解由这些复杂基因重复引起的临床表型的基础，我们将构建一种pMD的小鼠模型，该模型包含X染色体的PLP1区域的大复杂复制。 已经构建了包含此重复的ES细胞，并且正在制作包含X染色体的重排部分的小鼠。 然后，将分析动物的临床表型，包括复制品（包括PLP1）所编码的基因的表达，以及在髓鞘中的其他基因的表达。 X-染色体重排部分的分离也将在女性载体中检查其对X灭活的影响。 综上所述，这些研究将提供有关PMD基因复制机理的重要新信息，以及该基因重复对基因表达和神经功能的影响。 我们的小组特别准备进行这些研究，因为我们已经开发出了独特的患者资源以及从过去十年来对PMD诊断和研究的承诺中获得的专业知识。 具体目的是：（1）检验以下假设：PMD患者的基因组重排经常作为复杂的重排，包括第二重复的区域，并删除，三分一式三份或倒置区域，与偶联的同源性，非同源重组机制一致。 （2）测试以下假设：PLP1基因座的基因重复的存在会改变PLP1基因的表达，从而导致男性中髓磷脂程序的破坏和女性X染色体灭活模式的补偿性偏斜。 公共卫生相关性：这项研究与公共卫生直接相关，因为它将对遗传疾病机制有更好的了解，这最终将改善PMD和其他由复杂的基因组和遗传突变事件引起的PMD和其他疾病的诊断和治疗方法。