Investigations of Methylmalonic Acidemia and Related Disorders

甲基丙二酸血症及相关疾病的调查

• 批准号: 8948366
• 负责人: Charles P Venditti
• 金额: $ 148.49万
• 依托单位: NATIONAL HUMAN GENOME RESEARCH INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8948366
• 关键词: Adult; Affect; Aftercare; Animal Model; Basal Ganglia; Binding; Biochemical; Biochemistry; Biological Markers; Book Chapters; Branched-Chain Amino Acids; Cell model; Cells; Characteristics; Chickens; Chronic Kidney Failure; Citrullinemia; Clinic; Clinical; Clinical Protocols; Clinical Research; Cobalamin; Collaborations; Complex; Control Groups; Data; Defect; Developmental Delay Disorders; Diabetes Mellitus; Diagnosis; Dideoxy Chain Termination DNA Sequencing; Diet; Disease; Effectiveness; Electron Transport; Employee Strikes; End stage renal failure; Environment; Extramural Activities; Functional disorder; Funding; Gene Transduction Agent; Gene Transfer Techniques; Genes; Genetic; Genetic Transcription; Genomics; Globulins; Globus Pallidus; Goals; Grant; Growth; Hemodialysis; Human; Hyperhomocysteinemia; Impairment; Inborn Errors of Metabolism; Individual; Infarction; Inherited; International; Investigation; Kidney; Kidney Diseases; Kidney Transplantation; Laboratories; Lead; Life; Link; Liver; Magnetic Resonance Imaging; Manuscripts; Medical; Metabolic; Metabolic Diseases; Metabolism; Modeling; Mus; Mutation; National Human Genome Research Institute; Natural History; Neonatal; Nephrons; Newborn Infant; Obesity; Organ; Organ Transplantation; Osteoporosis; Pancreas; Pancreatitis; Pathology; Pathway interactions; Patient Care; Patients; Phenotype; Preparation; Primary carcinoma of the liver cells; Property; Proteins; Proteomics; Publications; Regulation; Resources; Role; Safety; Serotyping; Solid; Stroke; Syndrome; Testing; Therapeutic Intervention; Thyroid Gland; Transcobalamins; Transcriptional Regulation; Translating; Translational Research; Viral; Viral Genes; Vitamin B 12 Deficiency; adeno-associated viral vector; base; bench to bedside; beta Actin; boys; cohort; exome sequencing; gene therapy; genotoxicity; host cell factor C1; improved; insight; male; medical schools; member; metabolic abnormality assessment; metabolomics; methylmalonic aciduria; mouse model; mutant; novel; pre-clinical; programs; promoter; response; screening; stable isotope; vector

The clinical characterization of patients with methylmalonic acidemia (MMA) and related disorders, via a dedicated natural history study, NHGRI protocol Clinical and Basic Investigations of Methylmalonic Acidemia and Related Disorders (ClinicalTrials.gov Identifier: NCT00078078) has continued. Through our clinical protocol, we have continued to accrue patients with MMA and cobalamin metabolic disorders and have evaluated > 160 affected individuals; this is the largest single center cohort of such patients in the world. In the past year, we have continued to focus on the clinical characterization of patients with previously undefined forms of MMA as well as studies that expand our understanding of the natural history of well-recognized forms of MMA. One collaborative effort has led to the identification of a new inborn error of metabolism caused by mutations in a transcriptional co-regulator, HCFC1. This gene product participates in the regulation of transcription at many cellular promoters and had been previously identified and studied by others for more than a decade for its role in transcriptional co-regulation. As part of a multicenter approach to characterize a subset of severely affected males who were previously diagnosed with cblC or cblD deficiency by cellular biochemistry but lacked mutations in the respective genes, we determined the genetic basis of a novel, X-linked form of combined methylmalonic acidemia and hyperhomocysteinemia called cobalamin X deficiency (cblX). These severely affected males were previously diagnosed with cblC or cblD deficiency by cellular biochemistry but lacked mutations in the respective genes. Reassessment of these boys, first using exome sequencing and then traditional Sanger sequencing, revealed pathogenic mutations in HCFC1, an X-linked transcriptional co-regulator, in 14 patients, establishing the first human metabolic disorder caused by aberrant transcription Reference 1. These studies demonstrate the novel insights into intermediary metabolism that can be achieved through the study of rare metabolic disorders and highlights the rapid and comprehensive advances that can be achieved in the diverse and highly collaborative NHGRI IRP environment. Our group also participated in the further delineation of the pathology underlying MMA associated kidney disease. As part of a collaboration with a group at Harvard Medical School, we helped establish that megamitochondrion formation in the proximal tubule, associated with a functional electron transport chain defect, characterizes ultrastructure of affected nephrons Reference 2. We also contributed to a large, retrospective, international study that described the natural history of transcobalamin 2 deficiency Reference 3 and to a manscript detailing the response of a patient with MMA to hemodialysis and combined liver-kidney transplantation Reference 4. Lastly, a comprehensive book chapter on the topic of branched chain amino acid disorders was contributed Reference 5. A manuscript describing the neuroradiographic manifestations in patients with MMA who have suffered from metabolic strokes of the basal ganglia has recently been accepted for publication (Baker EH, Sloan JL, Hauser N, Gropman AL, et al. MRI Characteristics of Globus Pallidus Infarcts in Isolated Methylmalonic Acidemia, Am J of Neuroradiology, accepted 6/2014, in press). Active efforts include clinical and CNS neuroradiographic characterization of our cohort using MRI, MRS and DTI analyses, , analyses of the spectroscopic properties of MMA, a description of the state of MMA post solid organ transplantation, delineation of the natural history and ophthalmological phenotypes in patients with MUT MMA and cblC deficiency, renal phenotyping, and a critical reappraisal of the formula composition and dietary management of patients with MMA. A collaborative intra- and extramural Bench to Bedside grant with Dr Mendel Tuchman (CNMC) to fund our studies using stable isotopes in MMA patients ended this year. A publication describing the results from stable isotopic metabolic studies in MMA patients is in preparation. Laboratory investigations have continued to focus on generating and characterizing mouse models of methylmalonic acidemia and gene therapy studies. We propose to use transgenesis to enable the examination of the effects of organ and/or cell specific correction on the biochemical and pathological phenotype of Mut -/- mice, a strategy that is supported by our natural history observations of MMA patients with various forms of solid organ transplantation. In the next year, we will continue to characterize murine models that have an physiologically apparent intermediate or inducible phenotype yet are robust to allow the assessment of gene therapy approaches and the exploration of pathophysiological mechanisms. We will then characterize the disease state using genomic, proteomic and metabolomic approaches to define mechanisms and identify biomarkers that might be translated to patient care. We have studied viral gene therapy as treatment for MMA, using preclinical cellular and animal models to gather efficacy and safety data. We had previously developed and tested adeno-associated viral (AAV) vectors to transfer the Mut gene into mice and used vectors of serotypes 2, 8 and 9 that express the Mut or MUT gene under the control of a the enhanced, chicken beta-actin promoter (CBA) or the liver-specific, thyroid-binding globulin promoter (TBG) and had delivered them to Mut-/- mice in the neonatal period. The results in the all the prior studies were striking: while the untreated Mut-/- mice uniformly perish in early life, the treated Mut-/- mice had near normal long-term survival, behaved normally, displayed an ameliorated metabolic phenotype and demonstrated enzymatic activity as long as two years after treatment with an AAV8 or AAV9 vector. During the last cycle, we noted that many AAV treated mice, in both mutant and control groups, developed hepatocellular carcinoma (HCC). Over the past year, in collaboration with Dr Shawn Burgess of the NHGRI IRP, we have defined the genotoxicity of AAV in mice. These efforts have defined new safety considerations for AAV and helped direct the construction of new vectors with improved safety. We are preparing a manuscript describing our results as we develop AAV vectors with ameliorated genotoxicity. Such vectors will lead to the creation of an optimal vector for use in humans, affording an opportunity to pursue an IND submission to the FDA as a step toward translating gene therapy to the clinic. We have also served as a resource for other groups in the NHGRI who strive to develop gene therapy vectors, including a study members of the section led on AAV gene therapy for citrullinemia Reference 6.

甲基丙二酸血症（MMA）和相关疾病患者的临床特征，通过一项专门的自然历史研究，NHGRI方案甲基丙二酸血症和相关疾病的临床和基础调查（ClinicalTrials.gov标识符：NCT00078078）继续进行。通过我们的临床方案，我们继续积累MMA和钴胺素代谢紊乱患者，并评估了160名受影响的个体；这是世界上最大的此类患者单中心队列研究。在过去的一年里，我们继续关注先前未定义形式的MMA患者的临床特征，以及扩大我们对公认形式的MMA自然史的理解的研究。一项合作研究发现了一种由转录共调节因子HCFC1突变引起的新的先天性代谢错误。该基因产物参与了许多细胞启动子的转录调控，并且已经被其他人发现和研究了十多年，因为它在转录共调控中的作用。作为多中心方法的一部分，我们确定了一种新的、X连锁的甲基丙二酸血症和高同型半胱氨酸血症合并形式（称为钴胺素X缺乏症（cblX））的遗传基础，这些严重影响的男性以前被细胞生物化学诊断为cblC或cblD缺乏症，但各自的基因缺乏突变。这些严重受影响的男性先前被细胞生物化学诊断为cblC或cblD缺乏症，但各自的基因缺乏突变。对这些男孩的重新评估，首先使用外显子组测序，然后使用传统的Sanger测序，在14例患者中发现了x连锁转录共调节因子HCFC1的致病性突变，建立了第一个由异常转录引起的人类代谢紊乱。这些研究展示了通过对罕见代谢疾病的研究可以实现对中间代谢的新见解，并突出了在多样化和高度协作的NHGRI IRP环境中可以实现的快速和全面的进展。