Prandial hypoxia in progressive muscular dystrophy]

Progressive muscular dystrophy patients often show progressive body weight loss in early adolescence. This severe body weight loss frequently causes superior mesenteric artery syndrome which may result in a fatal outcome. We performed prandial pulse oximetry and found 12 out of 35 Duchenne muscular dystrophy patients, 1 out of 2 Becker muscular dystrophy patients and 1 out of 3 Limb-Girdle muscular dystrophy patients showed prandial hypoxia with tachycardia. The patients became tired and eating habits were easily interrupted resulting in progressive body weight loss. Nasal administration of 0.2L/min oxygen to 2 Duchenne muscular dystrophy patients, and nasal intermittent positive pressure ventilation to 2 Duchenne muscular dystrophy patients, 1 Becker muscular dystrophy patient and 1 Limb-Girdle muscular dystrophy patient for 15-30 minutes before eating improved the prandial hypoxia and halted the progression of body weight loss. This prandial hypoxia is one of the earliest signs of respiratory failure in progressive muscular dystrophy.     

Rapid and accurate diagnosis of facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is a common muscular disorder, but clinical and genetic complications make its diagnosis difficult. Southern blot analysis detects a smaller sized EcoRI fragment on chromosome 4q35 in most facioscapulohumeral muscular dystrophy patients, that contains integral number of 3.3-kb tandem repeats known as D4Z4. The problems for the genetic diagnosis are that southern blotting for facioscapulohumeral muscular dystrophy is quite laborious and time-consuming, and the D4Z4 number is only estimated from the size of the fragment. We developed a more simplified diagnostic method using a long polymerase chain reaction (PCR) amplification technique. Successful amplification was achieved in all facioscapulohumeral muscular dystrophy patients with an EcoRI fragment size ranging from 10 to 25 kb, and each patient had a specific polymerase chain reaction product which corresponded to the size calculated from the number of D4Z4. Using southern blot analysis, more than 90% of facioscapulohumeral muscular dystrophy patients have a smaller EcoRI fragment than 26kb in our series, and the number of D4Z4 repeats is precisely counted by this polymerase chain reaction method. We conclude that this long polymerase chain reaction method can be used as an accurate genetic screening technique for facioscapulohumeral muscular dystrophy patients.     

Complete allele information in the diagnosis of facioscapulohumeral muscular dystrophy by triple DNA analysis.

Facioscapulohumeral muscular dystrophy is caused by partial deletion of the D4Z4 repeat array on chromosome 4q35. Genetic diagnosis is based on sizing of this repeat array, which is complicated by cross-hybridization of a homologous polymorphic repeat array on chromosome 10 and by the frequent exchanges between these chromosomal regions. The restriction enzyme XapI optimizes the diagnosis of facioscapulohumeral muscular dystrophy by uniquely digesting 4-derived repeat units and leaving 10-derived repeat units undigested, thus complementing BlnI, which uniquely digests 10-derived repeat units. A triple analysis with EcoRI, EcoRI/BlnI, and XapI unequivocally allows characterization of each of the four alleles, whether homogeneous or hybrid. This is particularly useful in the case of identical sized 4-derived and 10-derived arrays, in situations of suspected facioscapulohumeral muscular dystrophy with nonstandard allele configurations, and for assignment of hybrid fragments to their original alleles.     

Facioscapulohumeral muscular dystrophy can be a cause of isolated childhood cognitive dysfunction

Facioscapulohumeral muscular dystrophy is one of the most prevalent muscular dystrophies in the world, resulting from the deletion of tandem repeats on chromosome 4q35. Extramuscular associations include sensorineural hearing loss, mental retardation, and epilepsy. These manifestations are commonly found in those with large deletions and early onset of weakness. A 26-year-old patient with a long-standing history of hearing loss, learning disabilities, and epilepsy presented with new-onset weakness and an elevated serum creatinine kinase level. Genetic testing confirmed sporadic facioscapulohumeral muscular dystrophy with a fragment length of 12 kilobases (normal > 35 kilobases). This unique presentation suggests that facioscapulohumeral muscular dystrophy should be considered in the differential diagnosis of children with cognitive impairment, seizures, and hearing loss.     

Dystrophin and nebulin in the muscular dystrophies

Skeletal muscle from patients with 5 different forms of muscular dystrophy and from 6 fetuses at high risk (95%) for Duchenne muscular dystrophy (DMD) were probed with specific antibodies for the presence of dystrophin and nebulin. Dystrophin was absent in all 5 patients with DMD and 4 of 6 fetuses at high risk for DMD and present in trace amounts in the remaining two. Dystrophin was also undetectable in one borderline DMD/Becker muscular dystrophy (BMD) case and reduced in 2 of 4 cases of BMD. In contrast, dystrophin was present in all 16 biopsies from 4 other types of muscular dystrophy (congenital, limb girdle, Emery-Dreifuss and facioscapulohumeral). Nebulin profiles varied with the type, severity and duration of the dystrophic process. Nebulin was present in 5 of 6 DMD fetal samples but vastly reduced or absent in all samples of clinically manifest DMD.     

Quadriceps myopathy: forme fruste of Becker muscular dystrophy

We examined dystrophin, the protein product of the Duchenne muscular dystrophy gene, in muscle biopsy specimens from 4 male patients with quadriceps myopathy, all of whom showed a mild and slowly progressive myopathy confined to the quadriceps muscles. All 4 patients had clear abnormalities of dystrophin, and were diagnosed as having Becker muscular dystrophy by both immunofluorescence and immunoblot examinations; that is, dystrophin of an abnormal molecular mass was visualized in muscle cryosections as "patchy" or discontinuous immunostaining at the surface membrane of the muscle fibers. One patient had a brother who showed widespread myopathic changes consistent with typical Becker muscular dystrophy. We conclude that the syndrome called quadriceps myopathy includes a group of forme fruste Becker muscular dystrophy.     

Primary adhalin deficiency as a cause of muscular dystrophy in patients with normal dystrophin

In our experience, more than half of muscular dystrophy patients show a primary dystrophinopathy. The underlying cause of muscular dystrophy in the vast majority of patients with normal dystrophin is unknown. Recently, a French family with 4 young siblings showing a muscular dystrophy of unknown progression was shown to have a primary deficiency of ?adhalin,”? the 50-kd dystrophin-associated protein. Here we report the screening of the entire adhalin coding sequence in muscle biopsy specimens from 30 muscular dystrophy patients to (1) determine whether adhalin deficiency is restricted to the French population, (2) determine the incidence of adhalin deficiency in muscular dystrophy patients, and (3) characterize the clinical features and mutations in adhalin-deficient patients. We identified a single African-American girl with childhood-onset muscular dystrophy and adhalin gene mutations. We found her to be a compound heterozygote for two different mutations of the same amino acid (Arg98Cys; Arg98His), one of which was previously identified in the French family. Our results suggest that primary adhalin deficiency in patients with muscular dystrophy but normal dystrophin is relatively infrequent, and that adhalin-deficient patients are not restricted to the French population.     

Decreased creatine kinase activity in cultured Duchenne dystrophic muscle cells

Muscle cells were cultured from six patients with Duchenne muscular dystrophy and nine normal subjects. Protein and myosin content and pyruvate kinase (PK) activity were similar in normal and Duchenne muscular dystrophy cultures. Creatine kinase (CK) activity was lower in Duchenne muscular dystrophy cultures and the isoenzyme distribution indicated MB-CK was significantly lower, while BB-CK was significantly higher in later Duchenne muscular dystrophy cultures. This abnormal isoenzyme pattern suggested aberrant or impaired maturation of Duchenne muscular dystrophy myotubes in vitro.     

The cranial sartorius muscle undergoes true hypertrophy in dogs with golden retriever muscular dystrophy

The degree of atrophy or hypertrophy of selected pelvic limb muscles was determined in the canine homologue of Duchenne muscular dystrophy. While most muscles were atrophied, the caudal and cranial sartorius were hypertrophied. Cranial sartorius weights were corrected for body weight and endomysial space to determine true muscle weights (g/kg; mean+/-SD) in three golden retriever muscular dystrophy age groups, 4-10 (Group 1; n=15), 13-26 (Group 2; n=4), and 33-66 (Group 3; n=4) months and grouped normal dogs (6-20 months; n=12). Group 1 golden retriever muscular dystrophy weights (2.2063+/-0.6884) were greater than those of normal dogs (1.2699+/-0.1966), indicating that young golden retriever muscular dystrophy dogs have true cranial sartorius muscle hypertrophy. Values of Group 2 (1.3758+/-0.5078) and Group 3 (0.5720+/-0.2423) golden retriever muscular dystrophy dogs were less than those of Group 1, suggesting that the cranial sartorius muscle atrophies over time. Given that cranial sartorius muscle weight correlated with tarsal joint angle in affected dogs (r=-0.817), the hypertrophied muscle may play a role analogous to iliotibial band tightness in Duchenne muscular dystrophy.     

Psychological parameters impact health-related quality of life in mental and physical domains in adults with muscular dystrophy

The impacts of potentially treatable psychological parameters on quality of life are relatively unreported in adults with Facioscapulohumeral, Becker and Limb-girdle muscular dystrophy. The purpose of this study was to compare quality of life, psychological parameters, and physical function between adults with muscular dystrophy and controls, and to examine relationships among these parameters in muscular dystrophy. Twenty-one adults with muscular dystrophy (n = 7 Becker, n = 8 Facioscapulohumeral, n = 6 Limb-girdle) and ten age-matched controls participated. Outcome measures were health-related quality of life, depressive symptoms, trait anxiety, self-esteem, physical self-worth and six-minute walk distance. Quality of life scores were lower in the muscular dystrophy groups than the control (p < .05). Depressive symptoms had the greatest association with quality of life in the Mental Health domain (r= ?0.89, p < .001). Depressive symptoms also had the most associations with quality of life (7 of 10 domains), followed by trait anxiety (6 of 10 domains), physical self-worth (5 of 10 domains), self-esteem (4 of 10 domains) and six-minute walk distance (3 of 10 domains). Psychological parameters and, to a lesser extent, physical function impact quality of life in muscular dystrophy. This study provides a rationale to include psychological assessment and treatment within muscular dystrophy healthcare.     

Are Males With Duchenne Muscular Dystrophy at Risk for Reading Disabilities?

Males with Duchenne muscular dystrophy have sub-average cognitive capacities and may manifest more specifically language-related deficits. In the current study, the information-processing capacity, reading performance, and behavioral functioning of 25 Dutch males with Duchenne muscular dystrophy (mean age 10.1 years) were systematically assessed. This study relied on the use of a new battery of tests to explore more precisely reading disabilities in males with Duchenne muscular dystrophy. Five of the males had serious reading problems and another five had moderate reading problems, which indicates that reading problems are significantly more common in males with Duchenne muscular dystrophy than in males from a normal population. These reading problems were independent of the level of information processing and behavioral functioning. Implications of these findings and possible directions for future research are discussed, especially with regard to the early detection and treatment of reading problems in males with Duchenne muscular dystrophy.     

Efficacy and tolerance of gastrostomy feeding in Japanese muscular dystrophy patients

Although muscular dystrophy patients often have feeding difficulty and need long-term enteral nutrition, only a few reports have described gastrostomy feeding in these patients. This study was designed to evaluate the efficacy and tolerance of gastrostomy feeding in patients with muscular dystrophy. We performed a retrospective, multicenter study on 144 patients with muscular dystrophy who received gastrostomy feeding between 2007 and 2009 in 25 neuromuscular centers in Japan. There were 77 Duchenne muscular dystrophy (median age at gastrostomy placement 26 years, range 13-47 years), 40 myotonic dystrophy (median age 54.5 years, range 13-70 years), 11 Fukuyama congenital muscular dystrophy (median age 22 years, range 13-29 years), 5 limb girdle muscular dystrophy (median age 62 years, range 43-78 years), and 5 facioscapulohumeral muscular dystrophy (median age 52 years, range 28-67 years) patients. Many benefits including amelioration of malnutrition, swallowing difficulty and respiratory status were observed after the introduction of gastrostomy feeding. Especially in patients with Duchenne muscular dystrophy, mean body weight significantly increased after gastrostomy placement. Although most complications, which are commonly observed in other populations, were tolerable, respiratory failure and peritonitis were important concerns. These findings suggest that gastrostomy placement at an appropriate time is advisable in patients with muscular dystrophy.     

Corticosteroids in Duchenne muscular dystrophy: a reappraisal

Duchenne muscular dystrophy is the most common and most severe form of childhood muscular dystrophies, resulting in early loss of ambulation between the ages of 7 and 13 years and death in the teens and twenties. Despite the phenomenal advances made in the understanding of the molecular genetics of the disease, no definitive cure has been found. Of all of the therapeutic drugs studied in Duchenne muscular dystrophy, only prednisone seems to have the potential for providing interim functional improvement for boys with Duchenne muscular dystrophy while they wait for a cure with gene or cell therapy. There is still no consensus regarding recommending corticosteroids as standard therapy for boys. This is an evidence-based review of all of the studies of corticosteroids (prednisone, deflazacort, and oxandrolone) in Duchenne muscular dystrophy. From this review, it is clear that until a definitive treatment for Duchenne muscular dystrophy is available, the use of deflazacort and prednisone with judicious dietary control and close clinical monitoring for side effects seems the best intervention for interim preservation of function in such a common devastating disorder of young growing boys.     

Immunocytochemical localisation of complement components C8 and C9 in human diseased muscle. The role of complement in muscle fibre damage

The localisation of the complement components C8 and C9 was studied immunocytochemically in human diseased muscle to determine the role of complement in muscle fibre damage. Monoclonal antibodies to 2 epitopes of C9 and a monoclonal antibody to the alpha subunit of C8 were applied to frozen sections of muscle biopsies from 9 cases of dermatomyositis, 5 cases of polymyositis, 7 cases of Duchenne muscular dystrophy and 4 cases of Becker muscular dystrophy. These were compared with 6 control biopsies which were morphologically normal. In all cases of inflammatory myopathies several non-necrotic fibres showed discrete peripheral patches of C9 and to a lesser extent C8. In the muscular dystrophies peripheral C9 was observed on a few non-necrotic fibres and basophilic fibres showed C9 between the fibres as well as at the periphery. In all cases necrotic fibres labelled intensely with C9 and C8 but intensities varied with the different monoclonal antibodies. This was thought to result from differences in the polymerisation of the C9 molecule in the membrane attack complex. Complement C8 and C9 were also localised to blood vessels in 3 cases of muscular dystrophy, 2 cases of polymyositis and all cases of juvenile dermatomyositis. No complement was observed in the control samples. Our results provide evidence for the sublytic formation of the membrane attack complex (MAC) on non-necrotic fibres in inflammatory myopathies and muscular dystrophy. This sublytic formation of the MAC may induce sublethal metabolic damage, mediated by calcium, and suggests a primary role of complement in muscle damage not only in inflammatory disorders but also muscular dystrophy.     

Selenium metabolism and supplementation in patients with muscular dystrophy

We studied selenium metabolism in patients with Duchenne muscular dystrophy and in contrast to previous reports found no significant abnormalities in these patients. Supplementation of muscular dystrophy patients and control subjects with sodium selenite (1 mg selenium/day) induced a variable rise in the activity of the selenium-dependent enzyme glutathione peroxidase in plasma and red cells, but no significant change in muscle glutathione peroxidase activities. There was no effect of selenium supplementation on disease activity in the patients with muscular dystrophy. Thiobarbituric acid-reacting substances (an index of free radical-mediated lipid peroxidation) were elevated in the muscle of patients with Duchenne muscular dystrophy in contrast to patients with other forms of muscular dystrophy and control subjects. This elevation was unaffected by selenium supplementation.     

Cognitive and psychological profile of males with Becker muscular dystrophy

Duchenne and Becker muscular dystrophy are allelic X-linked disorders causing progressive muscle weakness in males. Duchenne muscular dystrophy is caused by absence of dystrophin in muscle and brain; boys with Duchenne muscular dystrophy have a static cognitive impairment with mean Full Scale IQ approximately 1 standard deviation below the mean. Less is known of the cognitive profile of males with Becker muscular dystrophy, which is associated with variable alterations in the amount or size of the dystrophin protein. The aim of this study was to describe the cognitive and psychological profile of males with Becker muscular dystrophy. This was a prospective cohort study. Clinical data collected included age at diagnosis and assessment, socioeconomic status, serum creatine kinase level, and site of gene deletion/mutation (by exon number). The following psychological tests were used to assess general intellectual functioning, academic achievement, incidence and nature of behavioral problems: The Wechsler Intelligence Scales, The Wide Range Achievement Test-Revised, The Developmental Test of Visual-Motor Integration, The Child Behavior Checklist, and The Conner's Parent Rating Scale. Twenty-four males were enrolled. The Wechsler Full Scale IQ was normally distributed with a mean of 95.6 (SD 23.3), which did not differ significantly from the population mean. The frequency of learning difficulties for reading was 21%, for spelling was 32%, and for arithmetic was 26%, significantly higher than the frequency in the general population. The frequency of total behavioral problems in the clinical range was 67%, and the frequency of autism was 8.3%. Patients with Becker muscular dystrophy demonstrate a less homogeneous cognitive phenotype than that seen in Duchenne muscular dystrophy. Males with Becker muscular dystrophy have a high incidence of learning difficulties. Autism and behavioral and attention problems are also more common in Becker muscular dystrophy than in the general population.     

Nuclear proteins and cell death in inherited neuromuscular disease

X-linked Emery-Dreifuss muscular dystrophy is caused by mutations in emerin, a novel nuclear membrane protein. Other major inherited neuromuscular diseases have now also been shown to involve proteins which localize and function at least partly in the cell nucleus. These include lamin A/C in autosomal dominant Emery-Dreifuss muscular dystrophy, SMN in spinal muscular atrophy, SIX5 in myotonic dystrophy, calpain3 in type 2A limb-girdle muscular dystrophy, PABP2 in oculopharyngeal dystrophy, androgen receptor in spinal and bulbar muscular atrophy and the ataxins in hereditary ataxias. This review compares the molecular basis for these various disorders and considers the role of cell death, including apoptosis, in their pathogenesis.     

Therapeutic advances in muscular dystrophy

The muscular dystrophies comprise a heterogeneous group of genetic disorders that produce progressive skeletal muscle weakness and wasting. There has been rapid growth and change in our understanding of these disorders in recent years, and advances in basic science are being translated into increasing numbers of clinical trials. This review will discuss therapeutic developments in 3 of the most common forms of muscular dystrophy: Duchenne muscular dystrophy, facioscapulohumeral muscular dystrophy, and myotonic dystrophy. Each of these disorders represents a different class of genetic disease (monogenic, epigenetic, and repeat expansion disorders), and the approach to therapy addresses the diverse and complex molecular mechanisms involved in these diseases. The large number of novel pharmacologic agents in development with good biologic rationale and strong proof of concept suggests there will be an improved quality of life for individuals with muscular dystrophy. Ann Neurol 2013;74:404–411     

Genetic treatments in muscular dystrophies

PURPOSE OF REVIEW: The search for a cure for Duchenne muscular dystrophy and other muscular dystrophies is progressing rapidly despite significant challenges posed by some genes and the complexity of targeting all skeletal muscles. This review focuses on three areas in which experimental clinical studies are in progress. RECENT FINDINGS: Two Phase I/IIa gene-therapy trials using adeno-associated viral vectors have recently started, one in limb-girdle muscular dystrophy and one in Duchenne muscular dystrophy. They will assess the safety of the intramuscular administration of the relevant adeno-associated viral vectors, and local efficacy. Two more Phase I/IIa studies are underway in Duchenne muscular dystrophy, focused on the intramuscular administration of antisense oligonucleotides to induce exon skipping. A third study is evaluating efficacy and tolerability of a drug which induces read-through of stop codons in Duchenne muscular dystrophy patients carrying nonsense mutations. SUMMARY: These studies should provide proof of principle of these experimental approaches in humans. It is likely that further refinement will be required before extending their use to the wider community of patients with muscular dystrophy. In the meantime it is important to prepare accurate registries of molecularly characterized patients to facilitate their recruitment in future studies.