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Natural history study of mouse models for limb girdle muscular dystrophy, types 2D and 2F
S234
Abstracts / Neuromuscular Disorders 25 (2015) S184–S316
Limb girdle muscular dystrophy (LGMD) type 2D, a subgroup of autosomal-recessive inherited LGMD, is caused by the mutations in the SGCA gene, encoding α-sarcoglycan (SG). α-SG forms heterotetramer with other SGs in sarcolemma, composing dystrophin–glycoprotein complex. The clinical phenotype is thus overlapped with that seen in the dystrophinopathy. However, it is relatively rarer than dystrophinopathy and so far only a few patients were reported in Asia. We identified four patients with the same homozygous mutation c.101G > T (p.Arg34Leu) in SGCA from a big aboriginal family in Taiwan by clinical, pathological and molecular analyses. Intrafamilial variety of clinical phenotype was observed. Surprisingly, both the parents of the index patient carry the heterozygous mutation, c.101G > T, who are not consanguineous and are from two different aboriginal tribes, originally living in different geographic regions in Taiwan. In this family, ten asymptomatic carriers among whom some are from two different tribes and some are mixed were also identified. The results suggest that the carrier rate of c.101G > T in SGCA may be high in the aboriginal population in Taiwan regardless of the tribes. It is thus important to further investigate the prevalence of LGMD 2D in Taiwan, especially in aboriginal tribes for early diagnosis and genetic consultation. http://dx.doi.org/10.1016/j.nmd.2015.06.178
G.P.164 Natural history study of mouse models for limb girdle muscular dystrophy, types 2D and 2F M. van Putten *, C. Tanganyika-de Winter, J. van der Meulen, L. van Vliet, J. Plomp, A. Aartsma-Rus Leiden University Medical Center, Leiden, The Netherlands There is no cure available for the autosomal recessive limb girdle muscular dystrophies (LGMD) types 2D and 2F. The pre-clinical development of therapies is ongoing, but would be catalyzed by the availability of detailed knowledge on the natural disease history and standardized (functional) outcome measures. To facilitate this, we assessed functional performance in 4 weeks old male (n = 6) and female (n = 6) SGCA-null (LGMD2D), SGCD-null (LGMD2F) and C57BL/6 (wild type) mice twice monthly for a duration of 34 weeks. The functional test regime consisted of four-limb grip strength, rotarod running, wire and grid hanging tests and beam walking. Similar sized sedentary groups of both dystrophic strains were taken along to assess whether the tests were detrimental to the phenotype. Respiratory function was measured twice during the study duration (age 15 and 34 weeks). Mice aged 34 weeks were subjected to muscle physiology testing of the tibialis anterior, consisting of force frequency and eccentric (lengthening) contraction protocols. In all functional tests, C57BL/6 mice outperformed both dystrophic strains, while SGCA-null mice performed worse than SGCD-null mice. Interestingly, for the SGCD-null strain, females outperformed males in both hanging tests, whereas no gender differences were found for SGCA-null mice. Creatine kinase levels measured twice monthly were elevated in both LGMD strains, but did not differ between genders. Strength of the tibialis anterior was affected in both LGMD strains. Eccentric contractions provoked a large force drop in SGCA-null and SGCD-null mice, while C57BL/6 mice were resistant. Post-mortem analyses of several skeletal muscles and heart are pending. Our study offers a comprehensive natural history data set which will be useful in the design of standardized tests and future pre-clinical studies in LGMD2D and 2F mice. http://dx.doi.org/10.1016/j.nmd.2015.06.179
G.P.165 Discovery of biomarkers for LGMD2I R. Heredia 1, Y. Hathout 1, S. Moore 2, M. Katherine 3, S. Cirak *,4 1 Research Center for Genetic Medicine, Children’s National Medical Center, Washington DC, USA; 2 Department of Pathology, University of Iowa, Iowa City, USA; 3 Department of Paediatrics, University of Iowa, Iowa City, USA;
4
Institute of Human Genetics, University Hospital Cologne, 50935, Germany
Limb-girdle muscular dystrophy 2I (LGMD2I) is one of the most common LGMDs in the Caucasian population. Surrogate biomarkers are needed to monitor disease progression and predict outcomes to guide clinical trials. Serum proteome profiling has become important as a minimally invasive method that can give an early read-out of disease progression or potential drug efficacy. We have recently described serum biomarkers for Duchenne Muscular Dystrophy (DMD). Myofibrillar proteins, glycolytic enzymes, extracellular matrix and other muscle specific proteins were significantly elevated in mdx mice and decayed along age. Many of these proteins were validated in sera of DMD patients by combined proteomics approaches. We hypothesize that there are common biomarkers between DMD and LGMD2I reflecting the overlapping dystrophic changes in skeletal muscle of all muscular dystrophies. Label free proteome profiling was performed with high precision mass spectrometry on sera sample from LGDMD2I patients from different age groups and agematched healthy volunteers as well as age-matched pathological controls (other muscular dystrophies). Initial results showed several DMD associated biomarkers to be also modulated in LGMD2I patients versus healthy controls. These included (a) myofibrillar proteins, (b) glycolytic enzymes, (c) extracellular matrix and (d) other muscle specific proteins. Some of the discovered serological proteins were increased in the youngest LGMD2I patients (6–15 years old) compared to age-matched healthy controls. Using samples with different age groups demonstrated age dependent changes in the level of some of these biomarkers. In this regard, we found an age-dependent modulation of Matrix metalloproteinase 9 (MMP-9). We observed an age dependent decay of serum biomarker concentrations similar as we had observed in DMD. http://dx.doi.org/10.1016/j.nmd.2015.06.180
G.P.166 Muscle strength relative to cross-sectional area in hypertrophic calf muscles of patients affected by limb girdle type 2I and Becker muscular dystrophies N. Løkken *,1, G. Hedermann 1, C. Thomsen 2, J. Vissing 1 1 Rigshospitalet, Copenhagen Neuromuscular Center, Copenhagen, Denmark; 2 Rigshospitalet, Department of Clinical Neurology, Copenhagen, Denmark The aim of this study was to investigate whether the relationship between muscle strength and muscle cross-sectional area (CSA) is preserved in calf muscles of patients with muscular dystrophies. In healthy persons, there is a linear relationship between muscle strength and muscle CSA. We wanted to investigate whether this relationship is disrupted in patients with muscular dystrophies. We studied 14 patients with Becker muscular dystrophy (BMD) and 11 with limb-girdle muscular dystrophy type 2I patients (LGMD2I). The Dixon MRI technique was used to quantify fat and measure CSA of calf muscles. Maximal isokinetic muscle strength was determined using the Biodex System 3 PRO dynamometer. Findings were compared with those in 23 agedmatched controls. The results showed a significantly higher fat fraction in calf muscles in BMD and LGMD2I patients compared to controls. Maximal strength (peak torque, Nm) of plantarflexors and dorsiflexors was significantly lower in BMD (46.1 Nm/18.7 Nm) and in LGMD2I (59.1 Nm/19.3 Nm) compared with controls (94.4 Nm/31.6 Nm). Muscle peak torque relative to CSA was significantly lower in BMD and LGMD2I compared to controls. When taking the fat fraction into account, the strength/CSA relationship was still severely disrupted in patients with BMD, while the relationship normalized in patients with LGMD2I. Despite hypertrophic calves, muscle strength is significantly reduced in BMD and LGMD2I compared to healthy. When correcting for fat infiltration, the force CSA relationship was intact in LGMD2I, but severely disrupted in BMD. This indicates that weakness in BMD is not solely related to fatty replacement of muscle, but also an intrinsic impairment of contractile properties in remaining muscles. http://dx.doi.org/10.1016/j.nmd.2015.06.181
Abstracts / Neuromuscular Disorders 25 (2015) S184–S316
Limb girdle muscular dystrophy (LGMD) type 2D, a subgroup of autosomal-recessive inherited LGMD, is caused by the mutations in the SGCA gene, encoding α-sarcoglycan (SG). α-SG forms heterotetramer with other SGs in sarcolemma, composing dystrophin–glycoprotein complex. The clinical phenotype is thus overlapped with that seen in the dystrophinopathy. However, it is relatively rarer than dystrophinopathy and so far only a few patients were reported in Asia. We identified four patients with the same homozygous mutation c.101G > T (p.Arg34Leu) in SGCA from a big aboriginal family in Taiwan by clinical, pathological and molecular analyses. Intrafamilial variety of clinical phenotype was observed. Surprisingly, both the parents of the index patient carry the heterozygous mutation, c.101G > T, who are not consanguineous and are from two different aboriginal tribes, originally living in different geographic regions in Taiwan. In this family, ten asymptomatic carriers among whom some are from two different tribes and some are mixed were also identified. The results suggest that the carrier rate of c.101G > T in SGCA may be high in the aboriginal population in Taiwan regardless of the tribes. It is thus important to further investigate the prevalence of LGMD 2D in Taiwan, especially in aboriginal tribes for early diagnosis and genetic consultation. http://dx.doi.org/10.1016/j.nmd.2015.06.178
G.P.164 Natural history study of mouse models for limb girdle muscular dystrophy, types 2D and 2F M. van Putten *, C. Tanganyika-de Winter, J. van der Meulen, L. van Vliet, J. Plomp, A. Aartsma-Rus Leiden University Medical Center, Leiden, The Netherlands There is no cure available for the autosomal recessive limb girdle muscular dystrophies (LGMD) types 2D and 2F. The pre-clinical development of therapies is ongoing, but would be catalyzed by the availability of detailed knowledge on the natural disease history and standardized (functional) outcome measures. To facilitate this, we assessed functional performance in 4 weeks old male (n = 6) and female (n = 6) SGCA-null (LGMD2D), SGCD-null (LGMD2F) and C57BL/6 (wild type) mice twice monthly for a duration of 34 weeks. The functional test regime consisted of four-limb grip strength, rotarod running, wire and grid hanging tests and beam walking. Similar sized sedentary groups of both dystrophic strains were taken along to assess whether the tests were detrimental to the phenotype. Respiratory function was measured twice during the study duration (age 15 and 34 weeks). Mice aged 34 weeks were subjected to muscle physiology testing of the tibialis anterior, consisting of force frequency and eccentric (lengthening) contraction protocols. In all functional tests, C57BL/6 mice outperformed both dystrophic strains, while SGCA-null mice performed worse than SGCD-null mice. Interestingly, for the SGCD-null strain, females outperformed males in both hanging tests, whereas no gender differences were found for SGCA-null mice. Creatine kinase levels measured twice monthly were elevated in both LGMD strains, but did not differ between genders. Strength of the tibialis anterior was affected in both LGMD strains. Eccentric contractions provoked a large force drop in SGCA-null and SGCD-null mice, while C57BL/6 mice were resistant. Post-mortem analyses of several skeletal muscles and heart are pending. Our study offers a comprehensive natural history data set which will be useful in the design of standardized tests and future pre-clinical studies in LGMD2D and 2F mice. http://dx.doi.org/10.1016/j.nmd.2015.06.179
G.P.165 Discovery of biomarkers for LGMD2I R. Heredia 1, Y. Hathout 1, S. Moore 2, M. Katherine 3, S. Cirak *,4 1 Research Center for Genetic Medicine, Children’s National Medical Center, Washington DC, USA; 2 Department of Pathology, University of Iowa, Iowa City, USA; 3 Department of Paediatrics, University of Iowa, Iowa City, USA;
4
Institute of Human Genetics, University Hospital Cologne, 50935, Germany
Limb-girdle muscular dystrophy 2I (LGMD2I) is one of the most common LGMDs in the Caucasian population. Surrogate biomarkers are needed to monitor disease progression and predict outcomes to guide clinical trials. Serum proteome profiling has become important as a minimally invasive method that can give an early read-out of disease progression or potential drug efficacy. We have recently described serum biomarkers for Duchenne Muscular Dystrophy (DMD). Myofibrillar proteins, glycolytic enzymes, extracellular matrix and other muscle specific proteins were significantly elevated in mdx mice and decayed along age. Many of these proteins were validated in sera of DMD patients by combined proteomics approaches. We hypothesize that there are common biomarkers between DMD and LGMD2I reflecting the overlapping dystrophic changes in skeletal muscle of all muscular dystrophies. Label free proteome profiling was performed with high precision mass spectrometry on sera sample from LGDMD2I patients from different age groups and agematched healthy volunteers as well as age-matched pathological controls (other muscular dystrophies). Initial results showed several DMD associated biomarkers to be also modulated in LGMD2I patients versus healthy controls. These included (a) myofibrillar proteins, (b) glycolytic enzymes, (c) extracellular matrix and (d) other muscle specific proteins. Some of the discovered serological proteins were increased in the youngest LGMD2I patients (6–15 years old) compared to age-matched healthy controls. Using samples with different age groups demonstrated age dependent changes in the level of some of these biomarkers. In this regard, we found an age-dependent modulation of Matrix metalloproteinase 9 (MMP-9). We observed an age dependent decay of serum biomarker concentrations similar as we had observed in DMD. http://dx.doi.org/10.1016/j.nmd.2015.06.180
G.P.166 Muscle strength relative to cross-sectional area in hypertrophic calf muscles of patients affected by limb girdle type 2I and Becker muscular dystrophies N. Løkken *,1, G. Hedermann 1, C. Thomsen 2, J. Vissing 1 1 Rigshospitalet, Copenhagen Neuromuscular Center, Copenhagen, Denmark; 2 Rigshospitalet, Department of Clinical Neurology, Copenhagen, Denmark The aim of this study was to investigate whether the relationship between muscle strength and muscle cross-sectional area (CSA) is preserved in calf muscles of patients with muscular dystrophies. In healthy persons, there is a linear relationship between muscle strength and muscle CSA. We wanted to investigate whether this relationship is disrupted in patients with muscular dystrophies. We studied 14 patients with Becker muscular dystrophy (BMD) and 11 with limb-girdle muscular dystrophy type 2I patients (LGMD2I). The Dixon MRI technique was used to quantify fat and measure CSA of calf muscles. Maximal isokinetic muscle strength was determined using the Biodex System 3 PRO dynamometer. Findings were compared with those in 23 agedmatched controls. The results showed a significantly higher fat fraction in calf muscles in BMD and LGMD2I patients compared to controls. Maximal strength (peak torque, Nm) of plantarflexors and dorsiflexors was significantly lower in BMD (46.1 Nm/18.7 Nm) and in LGMD2I (59.1 Nm/19.3 Nm) compared with controls (94.4 Nm/31.6 Nm). Muscle peak torque relative to CSA was significantly lower in BMD and LGMD2I compared to controls. When taking the fat fraction into account, the strength/CSA relationship was still severely disrupted in patients with BMD, while the relationship normalized in patients with LGMD2I. Despite hypertrophic calves, muscle strength is significantly reduced in BMD and LGMD2I compared to healthy. When correcting for fat infiltration, the force CSA relationship was intact in LGMD2I, but severely disrupted in BMD. This indicates that weakness in BMD is not solely related to fatty replacement of muscle, but also an intrinsic impairment of contractile properties in remaining muscles. http://dx.doi.org/10.1016/j.nmd.2015.06.181