Low incidence of limb-girdle muscular dystrophy type 2C revealed by a mutation study in Japanese patients clinically diagnosed with DMD

<p>Abstract</p> <p>Background</p> <p>Limb-girdle muscular dystrophy type 2C (LGMD2C) is an autosomal recessive muscle dystrophy that resembles Duchenne muscular dystrophy (DMD). Although DMD is known to affect one in every 3500 males regardless of race, a widespread founder mutation causing LGMD2C has been described in North Africa. However, the incidence of LGMD2C in Japanese has been unknown because the genetic background remains uncharacterized in many patients clinically diagnosed with DMD.</p> <p>Methods</p> <p>We enrolled 324 patients referred to the Kobe University Hospital with suspected DMD. Mutations in the dystrophin or the SGCG genes were analyzed using not only genomic DNA but also cDNA.</p> <p>Results</p> <p>In 322 of the 324 patients, responsible mutations in the dystrophin were successfully revealed, confirming DMD diagnosis. The remaining two patients had normal dystrophin expression but absence of γ-sarcoglycan in skeletal muscle. Mutation analysis of the SGCG gene revealed homozygous deletion of exon 6 in one patient, while the other had a novel single nucleotide insertion in exon 7 in one allele and deletion of exon 6 in the other allele. These mutations created a stop codon that led to a γ-sarcoglycan deficiency, and we therefore diagnosed these two patients as having LGMD2C. Thus, the relative incidence of LGMD2C among Japanese DMD-like patients can be calculated as 1 in 161 patients suspected to have DMD (2 of 324 patients = 0.6%). Taking into consideration the DMD incidence for the overall population (1/3,500 males), the incidence of LGMD2C can be estimated as 1 per 560,000 or 1.8 per million.</p> <p>Conclusions</p> <p>To the best of our knowledge, this is the first study to demonstrate a low incidence of LGMD2C in the Japanese population.</p

Living with muscular dystrophy: health related quality of life consequences for children and adults

<p>Abstract</p> <p>Background</p> <p>Muscular dystrophies are chronic diseases manifesting with progressive muscle weakness leading to decreasing activities and participation. To understand the impact on daily life, it is important to determine patients' quality of life.</p> <p>Objective</p> <p>To investigate Health Related Quality of Life (HRQoL) of children and adults with muscular dystrophy (MD), and to study the influence of type and severity of MD on HRQoL in adult patients.</p> <p>Methods</p> <p>Age-related HRQoL questionnaires were administered to 40 children (8–17 years), and 67 adult patients with muscular dystrophies.</p> <p>Results</p> <p>Significant differences in HRQoL were found in children and adults with MD compared to healthy controls. Patients with Becker muscular dystrophy reported a better HRQoL on the several scales compared to patients with other MDs. Severity was associated with worse fine motor functioning and social functioning in adult patients.</p> <p>Conclusion</p> <p>This is one of the first studies describing HRQoL of patients with MD using validated instruments in different age groups. The results indicate that having MD negatively influences the HRQoL on several domains.</p

Are mice good models for human neuromuscular disease? Comparing muscle excursions in walking between mice and humans

The mouse is one of the most widely used animal models to study neuromuscular diseases and test new therapeutic strategies. However, findings from successful pre-clinical studies using mouse models frequently fail to translate to humans due to various factors. Differences in muscle function between the two species could be crucial but often have been overlooked. The purpose of this study was to evaluate and compare muscle excursions in walking between mice and humans

Dystrophic heart failure blocked by membrane sealant poloxamer

Dystrophin deficiency causes Duchenne muscular dystrophy (DMD) in humans, an inherited and progressive disease of striated muscle deterioration that frequently involves pronounced cardiomyopathy(1). Heart failure is the second leading cause of fatalities in DMD1,2. Progress towards defining the molecular basis of disease in DMD has mostly come from studies on skeletal muscle, with comparatively little attention directed to cardiac muscle. The pathophysiological mechanisms involved in cardiac myocytes may differ significantly from skeletal myofibres; this is underscored by the presence of significant cardiac disease in patients with truncated or reduced levels of dystrophin but without skeletal muscle disease(3). Here we show that intact, isolated dystrophin-deficient cardiac myocytes have reduced compliance and increased susceptibility to stretch-mediated calcium overload, leading to cell contracture and death, and that application of the membrane sealant poloxamer 188 corrects these defects in vitro. In vivo administration of poloxamer 188 to dystrophic mice instantly improved ventricular geometry and blocked the development of acute cardiac failure during a dobutamine-mediated stress protocol. Once issues relating to optimal dosing and long-term effects of poloxamer 188 in humans have been resolved, chemical-based membrane sealants could represent a new therapeutic approach for preventing or reversing the progression of cardiomyopathy and heart failure in muscular dystrophy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62706/1/nature03844.pd

Deflazacort for the treatment of Duchenne Dystrophy: A systematic review

BACKGROUND: To complete a systematic review and meta-analysis based on the clinical question: Is Deflazacort (DFZ), a prednisolone derivative, an effective therapy for improving strength, with acceptable side effects, in children with Duchenne Dystrophy (DD)? METHODS: MEDLINE, EMBASE, Current Contents, Dissertation Abstracts, Health Star, PsychINFO and Cochrane, were searched using the following inclusion criteria: 1) A randomized controlled trial comparing DFZ with placebo or another therapy; 2) Male participants age 2–18 years with DD; 3) Outcomes of (a) any form of strength or functional testing, or (b) any form of side effect. RESULTS: Fifteen studies of potential relevance were identified, with five meeting the inclusion criteria. These five studies included 291 children and were published in English language journals between 1994 and 2000. Two studies compared DFZ versus placebo, two studies compared DFZ with prednisone and one study had both placebo and prednisone comparisions. Two large trials were identified that have not been published in article format. Due to the heterogeneity in outcome measures and the inconsistent reporting of summary statistics a meta-analytic approach could not be taken. CONCLUSIONS: Examining individual studies it appears that DFZ improves strength and functional outcomes compared to placebo, but it remains unclear if it has a benefit over prednisone on similar outcomes. Two trials found that DFZ causes less weight gain than prednisone

Rare single gene disorders:estimating baseline prevalence and outcomes worldwide

As child mortality rates overall are decreasing, non-communicable conditions, such as genetic disorders, constitute an increasing proportion of child mortality, morbidity and disability. To date, policy and public health programmes have focused on common genetic disorders. Rare single gene disorders are an important source of morbidity and premature mortality for affected families. When considered collectively, they account for an important public health burden, which is frequently under-recognised. To document the collective frequency and health burden of rare single gene disorders, it is necessary to aggregate them into large manageable groupings and take account of their family implications, effective interventions and service needs. Here, we present an approach to estimate the burden of these conditions up to 5 years of age in settings without empirical data. This approaches uses population-level demographic data, combined with assumptions based on empirical data from settings with data available, to provide population-level estimates which programmes and policy-makers when planning services can use

Dystrophin deficiency in canine X-linked muscular dystrophy in Japan (CXMDJ) alters myosin heavy chain expression profiles in the diaphragm more markedly than in the tibialis cranialis muscle

<p>Abstract</p> <p>Background</p> <p>Skeletal muscles are composed of heterogeneous collections of muscle fiber types, the arrangement of which contributes to a variety of functional capabilities in many muscle types. Furthermore, skeletal muscles can adapt individual myofibers under various circumstances, such as disease and exercise, by changing fiber types. This study was performed to examine the influence of dystrophin deficiency on fiber type composition of skeletal muscles in canine X-linked muscular dystrophy in Japan (CXMD_J), a large animal model for Duchenne muscular dystrophy.</p> <p>Methods</p> <p>We used tibialis cranialis (TC) muscles and diaphragms of normal dogs and those with CXMD_Jat various ages from 1 month to 3 years old. For classification of fiber types, muscle sections were immunostained with antibodies against fast, slow, or developmental myosin heavy chain (MHC), and the number and size of these fibers were analyzed. In addition, MHC isoforms were detected by gel electrophoresis.</p> <p>Results</p> <p>In comparison with TC muscles of CXMD_J, the number of fibers expressing slow MHC increased markedly and the number of fibers expressing fast MHC decreased with growth in the affected diaphragm. In populations of muscle fibers expressing fast and/or slow MHC(s) but not developmental MHC of CXMD_Jmuscles, slow MHC fibers were predominant in number and showed selective enlargement. Especially, in CXMD_Jdiaphragms, the proportions of slow MHC fibers were significantly larger in populations of myofibers with non-expression of developmental MHC. Analyses of MHC isoforms also indicated a marked increase of type I and decrease of type IIA isoforms in the affected diaphragm at ages over 6 months. In addition, expression of developmental (embryonic and/or neonatal) MHC decreased in the CXMD_Jdiaphragm in adults, in contrast to continuous high-level expression in affected TC muscle.</p> <p>Conclusion</p> <p>The CXMD_Jdiaphragm showed marked changes in fiber type composition unlike TC muscles, suggesting that the affected diaphragm may be effectively adapted toward dystrophic stress by switching to predominantly slow fibers. Furthermore, the MHC expression profile in the CXMD_Jdiaphragm was markedly different from that in <it>mdx </it>mice, indicating that the dystrophic dog is a more appropriate model than a murine one, to investigate the mechanisms of respiratory failure in DMD.</p

The Shortest Isoform of Dystrophin (Dp40) Interacts with a Group of Presynaptic Proteins to Form a Presumptive Novel Complex in the Mouse Brain

Duchenne muscular dystrophy (DMD) causes cognitive impairment in one third of the patients, although the underlying mechanisms remain to be elucidated. Recent studies showed that mutations in the distal part of the dystrophin gene correlate well with the cognitive impairment in DMD patients, which is attributed to Dp71. The study on the expression of the shortest isoform, Dp40, has not been possible due to the lack of an isoform specific antibody. Dp40 has the same promoter as that found in Dp71 and lacks the normal C-terminal end of Dp427. In the present study, we have raised polyclonal antibody against the N-terminal sequence common to short isoforms of dystrophin, including Dp40, and investigated the expression pattern of Dp40 in the mouse brain. Affinity chromatography with this antibody and the consecutive LC-MS/MS analysis on the interacting proteins revealed that Dp40 was abundantly expressed in synaptic vesicles and interacted with a group of presynaptic proteins, including syntaxin1A and SNAP25, which are involved in exocytosis of synaptic vesicles in neurons. We thus suggest that Dp40 may form a novel protein complex and play a crucial role in presynaptic function. Further studies on these aspects of Dp40 function might provide more insight into the molecular mechanisms of cognitive impairment found in patients with DMD

Communication and information-giving in high-risk breast cancer consultations: influence on patient outcomes

This longitudinal study aimed to document (i) the information-giving and patient-communication styles of clinical geneticists and genetic counsellors (consultants) in familial breast cancer clinics and (ii) assess the effect of these styles on women`s knowledge, whether their expectations were met, satisfaction, risk perception and psychological status. A total of 158 women from high-risk breast cancer families completed self-report questionnaires at 2 weeks preconsultation and 4 weeks postconsultation. The consultations were audiotaped, transcribed and coded. Multivariate logistic regressions showed that discussing prophylactic mastectomy (P = 0.00) and oophorectomy (P = 0.01) led to women having significantly more expectations met; discussing genetic testing significantly decreased anxiety (P = 0.03) and facilitating understanding significantly decreased depression (P = 0,05). Receiving a summary letter of the consultation significantly lowered anxiety (P = 0.01) and significantly increased the accuracy of perceived risk (P = 0.02). Women whose consultant used more supportive communications experienced significantly more anxiety about breast cancer at the 4 weeks follow-up (P=0.00), These women were not significantly more anxious before genetic counselling. In conclusion, this study found that consultants vary in the amount of information they give and the way they communicate; and this variation can result in better or worse psychosocial outcomes. Greater use of supportive and counselling communications appeared to increase anxiety about breast cancer. Identifying methods to assist consultants to address emotional issues effectively may be helpful