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Characterization of the P448L FKRP Mutant Mouse Model
- Drs. Kanneboyina Nagaraju & Chris Spurney at the Children’s National Medical Center in Washington, DC
- 2013-2015
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Description:
This grant aimed at characterizing the recently-created mouse model by Dr. Qi Long Lu, the P448L model. Cardiac and respiratory parameters as well as muscle histology and grip strength were measured and compared with wild type mice to describe the disease in this research model.
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Outcome:
The P448L mouse model shows muscle impairment. Characteristic dystrophic patterns were observed by histology.
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Articles:
- “Skeletal, cardiac and respiratory muscle function and histopathology in the P448Lneo- mouse model of FKRP deficient muscular dystrophy”. Qing Yu et al. Skeletal Muscle. 2018 in press
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Assessment of Muscle Function in P448L Mouse Model of LGMD2I
- Drs. Dan Rodgers and David Lin in Washington State University in Pullman, WA
- 2014-2016
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Description:
In this grant, as a complement to grant #1, muscle function was to be fully characterized in the P448L mice. Respiratory and cardiac performance, exercise capacity and the contractile properties of whole muscles were assessed. In addition, a gait analysis was performed.
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Outcome:
The P448L mice presented with a smaller number of small myofibers and a higher number of large myofibers in skeletal muscles compared to the non-mutated mice. This difference in myofibers is expected to exist in human dystrophy. In addition, this variation in muscle fibers is responsible for reduced specific twitch and tetanic forces, and thus a much-reduced maximal force of the mutated muscles. The mice had a Trendelenburg-Like Gait triggered by a weakness in the hip abductor muscles, also noted in muscular dystrophy patients. Clear dilated cardiomyopathy was also observed.
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Articles:
- Trendelenburg-Like Gait, Instability and Altered Step Patterns in a Mouse Model for LGMD2I. J.W. Maricelli et al. PLoS ONE 2016 11(9): e0161984.
- Sexually dimorphic skeletal muscle and cardiac dysfunction in a mouse model of LGMD2I. J.W. Maricelli et al. J. Appl. Physiol. 2017 123(5):1126-1138.
- Skeletal muscle contraction dynamics in a novel murine model for LGMD2I. J. Rehwaldt, B.D. Rodgers, D.C. Lin. J. Appl. Physiol. 2017 123(6):1698-1707.
- Demembranated skeletal and cardiac fibers produce less force with altered cross-bridge kinetics in a mouse model for limb-girdle muscular dystrophy 2I. Fenwick AJ, Awinda PO, Yarbrough-Jones JA, Eldridge JA, Rodgers BD, Tanner BCW. Am. J. Physiol. Cell Physiol. 2019 317(2):C226-C234.
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Generation and Characterization of Antibodies to Alpha-Dystroglycan
- Dr. Susan Brown at the Royal Veterinary College in London, UK and Dr. Glenn Morris at the RJAH Orthopaedic Hospital in Oswestry, UK
- 2012-2013
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Description:
The objective of this project was to produce a series of well characterized polyclonal and monoclonal antibodies directed against different glycol-epitopes of a-dystroglycan. Immunolabelling of the 2 antibodies traditionally used to characterize glycosylated a-dystroglycan, IIH6 and V1A4-1, has been shown not to correlate directly with the clinical dystrophic phenotype in a single muscle biopsy. These new antibodies would provide additional diagnostic resources.
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Outcome:
This program was successful and generated 4 antibodies against a-dystroglycan. These antibodies will help to diagnose patients, increase our understanding of the disease process, and improve our ability to interpret the efficacy of future therapeutic intervention by properly measuring the level of glycosylated a-dystroglycan. They are available to the scientific community.
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Articles:
- A new monoclonal antibody DAG-6F4 against human alpha-dystroglycan reveals reduced core protein in some, but not all, dystroglycanopathy patients. E.L. Humphrey et al. Neuromuscular Disorders. 2015 25:32-42
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Evaluation of New Monoclonal Antibodies to a-DG in a Diagnostic Setting
- Dr. Susan Brown at the Royal Veterinary College in London, UK
- 2016-2017
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Description:
This project aimed at assessing the quality of different antibodies to differentiate types of dystroglycanopathies and, in the case of LGMD2I, to differentiate the severity of the disease.
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Outcome:
This preliminary study showed that 3 antibodies developed in the previous grant (DAG -6F4, -IG4, and -IF7) were excellent tools to differentially label different LGMDs on human tissues.
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Generation of a Monoclonal Antibody Against FKRP
- Dr. Isabelle Richard at the Généthon at Evry, France
- 2012; 2019
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Description:
The LGMD2i Research Fund financed the production of a FKRP antibody that would be made available to the research community. Dr. Richard led this challenging project and is now distributing the antibody to LGMD2I researchers on request.
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Personalized Medicine for Childhood Rare Diseases: Development of Dystroglycanopathy Patient Specific Cell-Based Assays for Drug Screening.
- Dr. Anne Bang at the Sanford-Burnham Medical Research Institute in La Jolla, CA
- 2012
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Description:
The aim was to develop assays to assess binding of laminin in relevant cell types from LGMD2I patients in response to drug candidates that increase laminin binding to these cells.
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Outcome:
This program successfully generated a panel of cell lines from patients with dystroglycanopathy. These cell lines were used for drug screening. They are also made available to the scientific community.
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Biomarkers Discovery in LGMD2I
- Drs. Sebahattin Cirak and Yetrib Hathout at the Children’s National Medical Center in Washington, DC
- 2014-2015
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Description:
This grant funded a preliminary search for biomarkers, serum molecules whose concentrations would fluctuate predictably with disease progression.
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Outcome:
Using patients’ samples, Drs. Cirak and Hathout identified several potential biomarkers that could help clinicians follow the progression of disease and measure the impact of novel treatments. These biomarkers need to be clinically validated.
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Development and Characterization of Novel Zebrafish Models of Dystroglycanopathies
- Dr. James Dowling at the University of Michigan in Ann Arbor, MI
- 2012
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Description:
The project was to generate a series of zebrafish with mutations in the FKRP gene using zinc finger nuclease technology.
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Outcome:
The technology used by Dr. Dowling failed to create mutant zebrafish.
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Drug Screening: LGMD2I Zebrafish Characterization
- Dr. Louis Kunkel and Dr. Matthew S. Alexander at the Boston Children’s Hospital in Boston, MA
- 2014-2015
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Description:
The grant focused on the creation of a Zebrafish model for LGMD2I that would enable the screening of therapeutic compounds.
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Outcome:
A zebrafish model with no FKRP expression was created. This model allows the screening of drugs that would bypass the requirement for a functional FKRP to provide normal muscle function. Twenty compounds that ameliorate the overall disease pathology have been identified by screening the Prestwick Drug Library (version 2). Several of these compounds are antibacterial, steroidal, and anti-inflammatory medical drugs. One compound in particular, pentetic acid is an agent that binds to heavy metals like magnesium and calcium and is used to treat heavy meal poisoning. Pentetic acid was able to ameliorate and block the muscle, cardiac, eye, and brain pathological defects in the LGMD2I zebrafish, suggesting that the regulation of metallic ions, specifically calcium, may serve as a means for ameliorating LGMD2I-associated disease pathologies.
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Articles:
- “A limb-girdle muscular dystrophy 2I model of muscular dystrophy identifies corrective drug compounds for dystroglycanopathies”. Peter R. Serafini et al. JCI Insight. 2018 3(18):e120493
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Myomatrix 2012 Conference
- Dr. Anne Rutowski at CureCMD in San Pedro, CA
- 2012
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Description:
This conference focused on three forms of Congenital Muscular Dystrophy (CMD) that span CMD to LGMD: alpha dystroglycan related dystrophies, collagen VI myopathies and laminin alpha 2 related CMD.
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Outcome:
73 international participants discussed the dynamic relationship between muscle and its matrix in the context of muscular dystrophy with a specific focus on congenital muscular dystrophy.
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Articles:
- Report on the Myomatrix Conference April 22-24, 2012, University of Nevada, Reno, Nevada, USA. Rutkowski A et al. Neuromuscul Disord. 2013 23(2):188-91.
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Workshop on Clinical Trial Readiness in FKRP
- Organized by Dr. Isabelle Richard at the Généthon in Évry France, Dr. Jean-Pierre Laurent of the LGMD2i Research Fund, Dr. Sebahattin Cirak at the Center for Molecular Medicine in Cologne, Germany, Dr. John Vissing at the Copenhagen Neuromuscular Center of the University of Copenhagen, Copenhagen, Denmark, and the European NeuroMuscular Centre
- 2016
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Description:
The objectives of the workshop were to review the clinical phenotypes of patients with FKRP-related diseases and evaluate the need for further characterization of natural history, to evaluate the state of patient registries and to discuss other preparatory works needed to enable future clinical trials.
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Articles:
- 216th ENMC international workshop: Clinical readiness in FKRP related myopathies. Richard I, Laurent JP, Cirak S, Vissing J; and the ENMC FKRP Study Group. Neuromuscul Disord. 2016 (26):717-724.
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Workshop on Dystroglycan and the Dystroglycanopathies
- Organized by Dr. Susan Brown at the Royal Veterinary College, London, UK, Pr. Steve Winder at the University of Sheffield in Sheffield UK, and the European NeuroMuscular Centre
- 2016
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Description:
This workshop aimed to create a platform to strengthen discussion between researchers working on the clinical and basic aspects of the post-translational modification of dystroglycan. One of the proteins participating in these post-translational modifications is FKRP, making LGMD2I a dystroglycanopathy. The leaders of this workshop hoped to stimulate novel research hypotheses for the development of therapies for these incurable diseases.
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Articles:
- 220th ENMC workshop: Dystroglycan and the dystroglycanopathies. Brown SC, Winder SJ; and the ENMC DGpathy Study Group. Neuromuscul Disord. 2017 (4):387-395.
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“Into the Clinic” a Translational Gene Therapy Meeting for LGMD2I
- John Herbert Stevenson, MD at the University of Massachusetts Medical School, Boston, MA
- 2018
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Description:
The meeting aims to bring together key clinicians and scientists including pharmaceutical companies to review the current landscape of LGMD2i gene therapy and to initiate ways to move forward into clinical trials.
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LGMD Awareness Scholarship
- LGMD2D Foundation
- 2016
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Description:
This funding is to contribute towards advertisement for the LGMD Awareness Scholarship program, which was designed to reward students who teach others about Limb Girdle Muscular Dystrophies. There are two scholarship categories, merit-based and social media based. A total of four $3000 scholarships will be awarded in 2016.
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Muscular Dystrophy Online Course
- Dr. Rachelle Crosbie-Watson at UCLA in Los Angeles, CA
- 2015-2016
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Description:
We supported the development of an online course “PS121: Disease Mechanisms and Therapies,” to teach translational medicine using muscular dystrophy as a theme. We consider that this course, which has a module on dystroglycanopathies (which includes LGMD2I) and one on gene therapy for muscular dystrophy, is a great tool to increase knowledge and awareness of muscular dystrophies.
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Outcome:
This course is being offered to undergraduates and graduate students at all campuses across the University of California since the beginning of 2016.
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Genetic Correction of Patient-Specific LGMD2I iPS Cells and the Regenerative Potential of their Skeletal Muscle Derivatives (CRISPR-based technology)
- Dr. Rita Perlingeiro at the University of Minnesota in Minneapolis, MN
- 2014-2016
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Description:
This project focused on establishing a genetic protocol to stop LGMD2I by correcting FKRP using the CRISPR-Cas9 gene editing tool in muscle stem cells. FKRP-corrected iPS cells (from patients) would be processed to generate skeletal myogenic progenitors, which could be used to regenerate lost dystrophic muscles with healthy muscles.
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Outcome:
While an LGMD2I patient’s cell line was successfully corrected, its engraftment potential could not be tested because of the weak survival of these cells. Instead, transplantation of healthy stem cells in an LGMD2I mouse model was performed and resulted in engraftment of new cells in the diaphragm. This engraftment correlated with an improved respiratory function. Based on these results, the project received funding from the NIH.
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Stem Cell Therapy in Mouse Model of LGMD2I
- Drs. Casey Childers & David Mack at the University of Washington in Seattle, WA
- 2014-2017
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Description:
The goal of this project was to correct any LGMD2I mutation on the FKRP gene by providing wild-type a FKRP gene through lentiviral transduction. The FKRP-corrected cells (mouse cell line) would be used to test engraftment in a FKRP-deficient mouse model.
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Outcome:
Challenges in the differentiation of the mouse cell lines into myogenic progenitors prevented the team to successfully completing the project.
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Effects of Simvastatin on Systemic Muscle Function in P448L Mice
- Dr. Bert Tanner at Washington State University in Spokane, WA
- 2017-2018
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Description:
The aim of this project was to determine if simvastatin could improve systemic muscle function in the P448L (LGMD2I) mouse. Because this drug was demonstrated to reduce inflammation, oxidative stress and fibrosis, and improve some muscle function in the mdx (Duchenne) mouse, long-term simvastatin supplementation in P448L mice was tested.
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Outcome:
No differences in VO2 max (a measure of fitness) and grip strength were observed before and after simvastatin treatment. Some significant changes in respiratory exchange ratio and Energy Expenditure Rate at VO2 max suggest that simvastatin may produce a sexually-dimorphic response, having greater impact on females than males. However, these differences were small and not always consistent.
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Xenograft Models of FKRP Muscular Dystrophy for AAV (gene) therapy
- Dr. Charles P. Emerson, Jr. at the University of Massachusetts Medical School in Worcester, MA
- 2015-2018
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Description:
During this project, a humanized mouse model of FKRP will be developed and validated. In this model, a group of the leg muscles will be destroyed and replaced by human muscles. A mouse with human muscles may provide a more suitable (and cost effective) disease model for the testing of gene therapies in a human muscle without falling under the FDA regulation for the use of human subjects.
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Outcome:
This pioneering grant proved challenging in particular due to an incomplete destruction of the murine cells at the site of chemical injury, making xenografts only predominantly humanized. Importantly, human engrafted myofibers did not appear to have fused with residual mouse muscle fibers allowing the creation of densely humanized regions.
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Determination of the Dose Effect in FKRP Gene Transfer (gene therapy)
- Dr. Isabelle Richard at the Généthon at Evry, France
- 2015-2018
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Description:
Based on promising results of past experiments on genetic correction by transfer of the wild type FKRP gene, this project focuses on studying the effects of variable therapeutic doses of adeno-associated virus (AAV) vector containing the FKRP gene in an appropriate mouse model.
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Outcome:
Two studies were conducted on mice without any FKRP in muscles, both studies showing that the gene therapy product AAV-FKRP is efficacious at low doses compared to efficacious dosage in other muscular dystrophies. At these low doses, the correction of the dystrophy was observed at the molecular, histological and functional levels.
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Articles:
- AAV-mediated transfer of FKRP shows therapeutic efficacy in a murine model but requires control of gene expression. Gicquel E, Maizonnier N, Foltz SJ, et al. Human Molecular Genetics 2017 26(10):1952–1965.
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A Phase 1b/2, Open-Label, Multiple Ascending Dose Study to Evaluate the Safety, Tolerability, Efficacy, Pharmacokinetics and Pharmacodynamics of PF-06252616 in Ambulatory Participants with LGMD2I
- Dr. Kathryn Wagner at the Kennedy Krieger Institute in Baltimore, MD
- Since 2015
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Description
This study provides the initial clinical assessment of PF-06252616, a novel myostatin inhibitor, following repeat IV doses in adult ambulatory participants with LGMD2I. Reduction in myostatin has been found to improve muscle regeneration and decrease fibrosis in a variety of animal models. This study is a Phase 1b/2, open-label multiple ascending dose escalation study to evaluate the safety, tolerability, efficacy, PK and PD of PF-06252616 in 20 ambulatory adults with LGMD2I.
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Outcome
This study provided the initial clinical assessment of PF-06252616, a novel myostatin inhibitor, in adult ambulatory participants with LGMD2I. Nineteen ambulatory adults were treated for 8 months at 3 different dosages. Because of a trend towards improvement, treatment was continued at the highest dosage for 6 months. No significant improvement in the outcome measures was observed when treatment was stopped.
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Articles:
- Longitudinal outcome measures in Fukutin-related protein limb-girdle muscular dystrophy. Leung D, Bocchieri A, Ahlawat S, et al. Annals of Clinical and Translational Neurology 2020. In Press
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Prednisone Clinical Trial: Protocol for Clinical Development
- The Clinical trial Unit of the University of Freiburg in Freiburg, DE – coordinator Dr. Volker Straub at the Newcastle Upon Tyne University in Newcastle Upon Tyne, UK
- 2012
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Description:
As a first step towards a clinical trial on the effects of prednisone on LGMD2I, the clinical trial unit of the University of Freiburg created a study protocol.
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Outcome:
The project advanced through study design and protocol establishment and was stalled at the fundraising stage due to the lack of engagement of large financial partners. The protocol that was created can now serve as the basis for any future clinical trials in LGMD2I, including the myostatin clinical trial protocol.
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Discovery of Chemical Chaperones for the Treatment of FKRP-Related LGMD2I
- Dr. Sebahattin Cirak at the Children’s National Medical Center in Washington, DC
- 2013-2015
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Description:
Chemical chaperones are small molecules that enter cells and serve as a molecular scaffolding in order to cause otherwise-misfolded mutant proteins to fold and route correctly within the cell. This grant aimed at finding small molecules that could serve as a molecular scaffolding to misfolded FKRP mutants.
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Outcome:
The project was stopped because the production of FKRP was too challenging.
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Development of Soluble Mini-Agrin as a Treatment for Dystroglycanopathies
- Dr. Jasbir Seehra at Achelois Biosciences in Lexington, MA
- 2012
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Description:
The grants tested the hypothesis that the delivery of mini-agrin could improve LGMD2I pathology.
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Outcome:
Delivery of mini-agrin did not improve LGMD2I pathology.
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Study of the Effect of Mini-Agrin Over-Expression in FKRPP448L Mutant Mice
- Dr. Qi Lu at the Carolinas Medical Center in Charlotte, NC
- 2013-2014
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Description:
The grants tested the hypothesis that the overexpression of mini-agrin can improve LGMD2I pathology.
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Outcome:
Overexpression of mini-agrin did not improve LGMD2I pathology.
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Study of the Effect of Mini-Agrin Expression in FKRPP448L Mutant Mice via Crossbreeding with Mini-Agrin Transgenic Mice
- Dr. Qi Lu at the Carolinas Medical Center in Charlotte, NC
- 2014-2016
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Description:
In this grant, a mouse model lacking mini-agrin expression would be created by crossbreeding mini-agrin transgene expressing mice to the LGMD2I P448L mice to test if miniagrin expression could improve LGMD2I pathology.
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Outcome:
The muscle function of the newly created mice (lacking mini-agrin) did not differ from the function of healthy muscles. Results suggest that mini-agrin overexpression does not correct the effects of LGMD2I mutations in FKRP.