Role of a BHLHB9 polymorphism in the etiology of a developmental disorder

BHLHB9 多态性在发育障碍病因学中的作用

• 批准号: 8877869
• 负责人: Peter G Smith
• 金额: $ 20.39万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8877869
• 关键词: 10 year old; Affect; Alleles; Apoptosis; Award; Axon; Behavior assessment; Behavioral; Behavioral Assay; Biochemical; Biological; Biological Assay; Brain; Categories; Cell Death; Cell model; Cell physiology; Cells; Cessation of life; Childhood; Clinical; Code; Cognitive; Cognitive deficits; Communication; Data; Development; Disease; Drug Formulations; Etiology; Exhibits; Functional disorder; G Protein-Coupled Receptor Genes; G-Protein-Coupled Receptors; Gene Targeting; Genes; Genetic; Genetic Engineering; Genetic Polymorphism; Genetic Screening; Genome; Genomics; Goals; Histology; Human; Image; Impaired cognition; In Vitro; Intellectual functioning disability; Kansas; Lead; Link; Literature; Magnetic Resonance Imaging; Mental Retardation and Developmental Disabilities Research Centers; Missense Mutation; Modeling; Modification; Motor; Mus; Mutation; Nature; Neonatal; Nervous System Physiology; Nervous system structure; Neuronal Differentiation; Neurons; Nucleotides; Parents; Pathology; Patients; Peripheral Nervous System Diseases; Pharmaceutical Preparations; Phenotype; Point Mutation; Proteins; Rare Diseases; Research Project Grants; Resources; Rodent; Role; Safety; Sensory; Small Interfering RNA; Symptoms; Technology; Testing; Therapeutic; Transgenic Mice; Translating; United States National Institutes of Health; Variant; X Chromosome; base; brain volume; cellular pathology; cerebral atrophy; clinical phenotype; deep sequencing; developmental disease; disability; disease phenotype; genetic variant; high throughput screening; in vitro Assay; in vivo; induced pluripotent stem cell; insight; knock-down; loss of function; male; member; model development; motor disorder; mouse model; mutant mouse model; myelination; nerve stem cell; neuron apoptosis; neuron loss; neuronal survival; novel; null mutation; prevent; proband; programs; public health relevance; relating to nervous system; repaired; screening; skills; therapeutic target; tool

 DESCRIPTION (provided by applicant): High-throughput genome screening of patients provides hope for identifying biological mechanisms in rare, undiagnosed disorders, and may provide broader insight into more common disease categories. However, variant identification is only a first step; a cause-effect relationship between variant and phenotype must be established, and therapeutic strategy formulation requires a thorough understanding of cellular and protein pathologies. The NIH Undiagnosed Disease Program recently characterized a male patient, UDP1757 with neonatal onset of motor dysfunction, cognitive deficiencies, low brain volume, and peripheral neuropathy, worsening at 15 months, and who died at 10 years of age. Genetic screening showed a hemizygous single point mutation in the BHLHB9 locus (C318R) located on the X chromosome. BHLHB9 has been shown to prevent apoptosis and to promote neuronal differentiation and axonogenesis. We hypothesize that C318R results in a loss- or reduction-of-function mutation that results in increased neuronal cell death and reduced axon outgrowth, hence leading to cortical atrophy and broad-spectrum neural dysfunction. The objective of this proposal is to establish a role of the C318R mutation in abnormal neuronal death and reduced neuronal differentiation and axonogenesis. To do so, we propose in vitro assays involving modifications of the BHLHB9 gene in mouse neural stem cells and patient-derived, neutrally differentiated iPS cells in order to define cellular pathologies. We will additionally use mouse models in which Bhlhb9 mutations are introduced, behavioral phenotype determined, and CNS impact defined anatomically. We anticipate that the mouse will recapitulate the clinical phenotype of UDP1757, and that both cell assays and anatomical imaging will yield data consistent with our hypothesis that BHLHB9 C318R is a loss- or reduction-of-function mutation. A strength is a team of experts with complementary skills in pediatric genetics and rare diseases, genetic engineering, transgenic mouse and iPS cell technologies, rodent behavioral assessment, and neuronal culture and quantitation. Additionally, the proposal draws on the rich core resources of the Kansas Intellectual and Developmental Disabilities Research Center. This Exploratory/Developmental Research Grant Award will make significant contributions by establishing cellular processes responsible for an uncharacterized clinical phenotype, and will provide a basis for subsequent studies using the in vitro and in vivo tools developed in this study to formulate, screen and test therapeutic strategies to ameliorate this and related devastating developmental disorders.

 描述（由申请人提供）：患者的高通量基因组筛查为确定罕见、未诊断疾病的生物学机制提供了希望，并可能为更常见的疾病类别提供更广泛的见解。然而，变异鉴定只是第一步;必须建立变异和表型之间的因果关系，并且治疗策略的制定需要对细胞和蛋白质病理学的透彻理解。美国国立卫生研究院未诊断疾病项目最近描述了一名男性患者UDP 1757，其新生儿发作运动功能障碍、认知缺陷、脑容量减少和周围神经病变，在15个月时恶化，并在10岁时死亡。遗传学筛查显示，位于X染色体上的BHLHB 9位点（C318 R）存在半合子单点突变。BHLHB 9已被证明可以防止细胞凋亡并促进神经元分化和轴突生成。我们假设C318 R导致功能丧失或功能降低突变，导致神经元细胞死亡增加和轴突生长减少，从而导致皮质萎缩和广谱神经功能障碍。本提案的目的是确定C318 R突变在异常神经元死亡和减少神经元分化和轴突发生中的作用。为此，我们提出了体外试验，涉及小鼠神经干细胞和患者来源的中性分化iPS细胞中BHLHB 9基因的修饰，以确定细胞病理学。我们将另外使用其中引入Bhlhb 9突变、确定行为表型和解剖学上定义的CNS影响的小鼠模型。我们预期小鼠将重现UDP 1757的临床表型，并且细胞测定和解剖成像将产生与我们的假设一致的数据，即BHLHB 9 C318 R是功能丧失或功能降低突变。优势是一个专家团队，他们在儿科遗传学和罕见疾病、基因工程、转基因小鼠和iPS细胞技术、啮齿动物行为评估以及神经元培养和定量方面具有互补技能。此外，该提案还利用了堪萨斯智力和发育障碍研究中心丰富的核心资源。该探索性/发展性研究资助奖将通过建立负责未表征临床表型的细胞过程做出重大贡献，并将为后续研究提供基础，这些研究使用本研究中开发的体外和体内工具来制定，筛选和测试治疗策略，以改善这种和相关的破坏性发育障碍。