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[Erythrocyte from Duchenne muscular dystrophy is fragile].

Intermittent indirect hyperbilirubinemia was occasionally observed in Duchenne muscular dystrophy (DMD) patients. We suspected that hyperbilirubinemia might be caused by hemolysis of fragile erythrocytes due to damaged endothelium, which was reported in DMD. To examine the fragility of erythrocytes, we performed osmotic resistance test in 25 DMD, 12 myotonic dystrophy (DM), 12 amyotrophic lateral sclerosis (ALS) and 24 healthy volunteers (male 15, female 9). Minimum resistance (beginning point of hemolysis) of DMD (0.447 +/- 0.016%) was higher than that of age matched male controls (0.425 +/- 0.018%: p = 0.0008) and that of DM (0.440 +/- 0.015%) was also higher than that of total controls (0.423 +/- 0.016%, p = 0.0077). The number of poikilocytes was increased in DMD (35.45 +/- 41.17 per a high magnitude field), however no obvious correlation was detected between the ratio of poikilocytes and resistances. Total bilirubin showed correlation (p = 0.029) to minimum resistance. These findings suggested that erythrocyte membrane is fragile in DMD. Involvement of endothelial damage could not be proven, because all investigated patients showed normal tissue plasminogen activator inhibitor-1. Although the mechanism of fragile erythrocytes in DMD is still unknown, we should pay attention to interpret bilirubin in DMD, because hemolysis due to erythrocyte fragility may influence the value.

Aged↗

[Relations between delayed diagnosis and forms of onset in Duchenne muscular dystrophy].

Duchenne Muscular Dystrophy (DMD) is usually diagnosed several years after the onset of symptoms. The relatives of the patients with DMD frequently consult family physicians when they notice the first symptom. The purpose of this study was to determine the cause that influence the delayed diagnosis of DMD. Twenty-two patients with confirmed diagnosis of DMD were interviewed at two Neurology Centers (Mexican Social Security Institute) in Monterrey, Nuevo León, México. Two forms of onset of DMD: Retarded development and locomotion problems were found, confirming other studies. The mean age of onset of symptoms for 22 patients was 2.4 years. The mean age for DMD diagnosis was 4.9 years. Retarded development occurred in 12 (54.4%) of all cases and the age of diagnosis was between 1 and 6 years of age. In 10 cases of the group with locomotion problems (45.4%) the diagnosis was made between 3 and 11 years of age. The serum Creatine Kinase was increased in all patients and in the early stages these levels were much higher than late stages. Family physicians have opportunities to make early diagnosis of DMD if they are aware of the two forms of onset of the disease: Retarded development and locomotion problems and of the changes in serum CK levels. The findings of this study confirm the importance of family physicians in that respect and also in making recommendations for routine determination of serum Creatine Kinase (CK) as early as possible in a child with symptoms suggestive of DMD.

Adipose Tissue↗

Duchenne and Becker muscular dystrophy prevalence in South Africa and molecular findings in 128 persons affected.

A genetic service for Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) was initiated in Cape Town in 1987. Of the 143 DMD patients diagnosed during the period 1987-1992, 66 had a familial pattern of inheritance and 77 were apparently sporadic. Twenty BMD patients were identified, of whom 12 had other affected relatives and 8 were sporadic. Overall minimum prevalence rates of 1/100,000 for DMD and 1/755,000 for BMD were calculated. A markedly low DMD prevalence in the indigenous black population (1/250,000) contributed to the overall low DMD prevalence in South Africa when compared with that in the UK (1/40,000). By means of molecular methods, the diagnosis in 42% of the affected DMD males was confirmed by detection of deletions in the dystrophin gene. Deletions were identified in 50% of Indian, white and mixed ancestry patients. In contrast, only 22% of blacks had identifiable deletions. DMD appears to be underrepresented in the black population; the low deletion frequency in this group suggests that unique mutations not detectable by methods used in this study may be more frequent in these patients than in the other populations. The increased DMD frequency in Indians corroborates findings reported from the UK.

Chromosome Deletion↗

[Estimation of cardiac function by plasma concentration of brain natriuretic peptide in patients with Duchenne muscular dystrophy].

We investigated the usefulness of the plasma concentration of brain natriuretic peptide (BNP) for evaluating cardiac function in patients with Duchenne muscular dystrophy (DMD). The plasma BNP concentration was measured by immunoradiometric assay in 55 patients with DMD and in 34 healthy subjects. Cardiac function was evaluated by the cardiothoracic ratio (CTR) on chest roentgenogram, left ventricular end-diastolic dimension (LVDd) and fractional shortening (FS) on echocardiogram, and the ratio of ejection time to pre-ejection period (ET/PEP) on mechanocardiogram. The function of skeletal muscle was evaluated in terms of the disability of lower limb function, serum creatine kinase (CK) activity and % vital capacity (% VC). The plasma concentration of BNP was increased in patients with DMD (32.7 +/- 14.8 pg/ml, mean +/- SEM) compared with that in normal subjects (4.3 +/- 0.5 pg/ml). Two of the DMD patients had symptoms of heart failure, with markedly increased plasma BNP concentrations. The other DMD patients with increased plasma BNP concentrations showed abnormal cardiac function but no symptoms of heart failure. In addition, in patients with DMD, the plasma BNP concentration showed significant positive correlations with CTR and LVDd (p < 0.01), and negative correlations with ET/PEP and FS (p < 0.01). In severe DMD patients who had advanced disability and decreased CK activity, the plasma BNP concentration tended to be elevated. There was no significant correlation between the plasma BNP concentration and % VC. These findings suggest that the plasma BNP concentration is useful for evaluating cardiac dysfunction, whether manifest or latent, in patients with DMD, in whom accurate evaluation of cardiac function by conventional methods is difficult due to severe muscle atrophy and deformity of the thorax.

Adolescent↗

Screening of male patients with autosomal recessive Duchenne dystrophy through dystrophin and DNA studies.

Previously we estimated that about 2.5-4% of isolated male patients diagnosed as Duchenne dystrophy (DMD) may have the autosomal recessive form (AR-DMD). Such cases can be distinguished from X-linked DMD through the analysis of dystrophin. Fifty DMD patients from 47 families were investigated for dystrophin and DNA deletions. Based on our results, we estimate that the frequency of AR-DMD may be about 8-12% among male patients diagnosed as DMD in whom X-linked inheritance could not be confirmed through pedigree data, serum enzymes in female relatives or DNA studies. Such an estimate must be confirmed in a larger sample; however, it shows the importance of assessing dystrophin in all patients diagnosed as DMD in whom X-linked inheritance cannot be proved, since the distinction between these 2 forms has implications for genetic counseling.

Consanguinity↗

Alterations in creatine kinase in fresh muscle and cell cultures in Duchenne dystrophy.

Creatine kinase (CK) (total and isoenzymes) was measured in cultures obtained by dissociation and subsequent plating of cells from biopsied quadriceps muscle of 10 patients with Duchenne muscular dystrophy (DMD) and 20 controls. The total cellular CK and CK-MM reached highest values around 21 days in both DMD and control cultures, suggesting that DMD cultures do not show delayed myoblast fusion. There was a significant decrease of total cellular CK in DMD cultures at all stages, but the maximum differences were noted for the peak values. The CK isoenzyme pattern in DMD cultures demonstrated a higher percentage of CK-BB and CK-MB and a lower percentage of CK-MM than was observed in cultures from the controls. Addition of cytosine arabinoside after myoblast fusion to muscle cell cultures did not induce significant changes of CK isoenzyme pattern. There was no difference in the CK levels in culture medium from controls and DMD patients. The alterations of cellular CK were similar in fresh muscle and cell cultures from DMD patients.

Cells, Cultured↗

DGGE-based whole-gene mutation scanning of the dystrophin gene in Duchenne and Becker muscular dystrophy patients.

Duchenne and Becker muscular dystrophy (DMD and BMD) are caused by mutations in the dystrophin gene. Large rearrangements in the gene are found in about two-thirds of DMD patients, with approximately 60% carrying deletions and 5-10% carrying duplications. Most of the remaining 30-35% of patients are expected to have small nucleotide substitutions, insertions, or deletions. To detect these subtle changes within the coding and splice site determining sequences of the dystrophin gene, we established a semiautomated denaturing gradient gel electrophoresis (DGGE) mutation scanning system. The DGGE scan covers the dystrophin gene with 95 amplicons, PCRed either individually or in a multiplex setup. PCR and pooling were performed semiautomatically, using a pipetting robot and 384-well plates, enabling concurrent amplification of DNA of four patients in one run. Amplification of individual fragments was performed using one PCR program. The products were pooled just before gel loading; DGGE requires only a single gel condition. Validation was performed using DNA samples harboring 39 known DMD variants, all of which could be readily detected. DGGE mutation scanning was applied to analyze 135 DMD/BMD patients and potential DMD carriers without large deletions or duplications. In DNA from 25 out of 44 DMD patients (57%) and from 5 out of 39 BMD patients (13%), we identified clear pathogenic changes. All mutations were different, with the exception of one DMD mutation, which occurred twice. In DNA from 10 out of 44 potential DMD carriers, including four obligate carriers, we detected causative changes, including one pathogenic change in every obligate carrier. In addition to these pathogenic changes, we detected 15 unique unclassified variants, i.e., changes for which a pathogenic nature is uncertain.

DNA Mutational Analysis↗

A cell surface abnormality in Duchenne muscular dystrophy: intercellular adhesiveness of skin fibroblasts from patients and carriers.

The intercellular adhesiveness of skin fibroblasts from patients and carriers of Duchenne muscular dystrophy (DMD) and control subjects has been determined using couette viscometers. The values for 12 DMD patients (mean = 1.38, SEM = 0.1, n = 32) were significantly lower than for ten control subjects (mean = 3.17, SEM = 0.2, n = 22). According to the Lyon hypothesis, carriers of DMD should be mosaics of cells expressing the normal and DMD phenotypes, and their cultured skin fibroblasts should have intercellular adhesiveness intermediate between that for normal and DMD cells. Cells from three obligate heterozygotes and five individuals at high risk of being carriers had normal values (in both groups mean = 2.82) in contrast to artificial 1:1 mixtures of normal and DMD cells that had intermediate values (mean = 2.22, SEM = 0.2, n = 15). This unexpected finding is probably the result of "correction" of the DMD cells by normal gene product from the cells expressing the normal gene.

Cell Adhesion↗

Characterization of patients with glycerol kinase deficiency utilizing cDNA probes for the Duchenne muscular dystrophy locus.

Genomic DNA from five previously unreported patients with glycerol kinase deficiency (GKD), dystrophic myopathy, and adrenal insufficiency were studied with genomic probes and cDNA probes for the Duchenne muscular dystrophy (DMD) locus. These individuals, together with those reported by ourselves and others, show that patients with a contiguous gene syndrome involving the DMD, GK, and adrenal hypoplasia congenita (AHC) loci have a broader distribution of microdeletion breakpoints than those observed among patients with classical DMD. This study demonstrates the use of the DMD cDNA probes to delineate the centromeric deletion breakpoints for patients with Xp21 microdeletions extending beyond the DMD locus. It also shows the practical diagnostic application of the DMD cDNA probes when the diagnosis of GKD is entertained in a patient with known DMD and only DNA is available for study.

Adolescent↗

Gene deletions in Japanese patients with Duchenne and Becker muscular dystrophy.

Thirty-eight unrelated Japanese patients with Duchenne and Becker muscular dystrophy (DMD and BMD) have been investigated with the DMD cDNA probes. The 14-kb DMD cDNA was subdivided into 6 subclones and HindIII-digested DNAs were analyzed by Southern blotting. Out of 38 unrelated patients, 14 showed a deletion of one or several of the exon-containing HindIII fragments (36.8%). These corresponded to 50% (9/18) of BMD patients and 25% (5/20) of DMD patients, and the position and extent of deletions were mapped and proved to be more heterogeneous in DMD than in BMD. Both ends of deletions detected in probe 1-2a were common to all six BMD patients without the maintenance of reading frame of messenger RNA, and 5' ends of deletions in probe 5b-7 were also common but maintained in frame in three BMD patients. The phenotypic-specific deletion in Japanese BMD patients has existed in the 5' end of the DMD gene, although its apparently similar deletion produced a wide range of clinical courses (BMD phenotype). There was no tight correlation between clinical severity and presence or absence of deletion in DMD or BMD.

Adolescent↗

Echocardiographic and electrocardiographic findings of cardiomyopathy in Duchenne and Becker-Kiener muscular dystrophies.

We assessed the cardiac findings in Duchenne muscular dystrophy (DMD) and Becker-Kiener muscular dystrophy (BMD) patients in the large outpatient group of our single-center institution. The analysis included the revision of patient records (retrospectively) and current echocardiography, electrocardiogram (ECG), and Holter ECG data (prospectively). Reduced left ventricular fraction shortening (FS) < 25% was found in 24% of all patients (50 DMD, 12.1 +/- 4.7 years: 20 BMD, 17.1 +/- 8.5 years). Median age of onset of FS < 25% was 16.8 +/- 1.0 in DMD and 30.4 +/- 3.4 in BMD; (p < 0.05). Holter ECG in DMD demonstrated sinus tachycardia in 26% deprivation of circadian rhythm in 31%, and reduced heart rate variability in 51%. For these reasons, we recommend carrying out echocardiography annually in DMD and BMD > 10 years. Because the rate of disturbances in the cardiac autonomic nervous system is high in DMD, we also recommend Holter ECG annually. Further investigation should be conducted to determine if treatment with ss-blockers and ACE inhibitors in combination reduces cardiac autonomic nervous imbalance, thus improving patient outcome in DMD.

Adolescent↗

Cardiopulmonary support in duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked, rapidly progressive myopathy affecting the limb muscles, the respiratory muscles, the heart, the intestines, and the brain. Since about 90% of DMD patients die from muscular respiratory failure or cardiomyopathy, early and adequate therapy is essential. Ventilatory failure from muscle weakness requires mechanical support for ventilation and coughing as soon as there is symptomatic nocturnal hypoventilation. Today noninvasive positive-pressure ventilation (NIPPV) is the method of choice for supportive long-term mechanical ventilation in DMD. For assisted coughing, various methods are available, among which the mechanical in-exsufflator is the most widely used device. There is large nonrandomized clinical trial evidence that NIPPV improves quality of life and prolongs the lives of DMD patients if medical, social, economic, and ethical issues, raised by the availability of long-term NIPPV, are adequately addressed. Cardiac involvement in DMD manifests as impulse generation or impulse conduction abnormalities or cardiomyopathy. Cardiac abnormalities in DMD respond well to adequate therapy. Though DMD is ultimately a fatal disease, quality of life and life expectancy can be markedly improved if cardiopulmonary manifestations are adequately treated.

Heart Diseases↗

Studies on the carrier state in X-linked recessive (Duchenne) muscular dystrophy.

Observations in 12 normal women and 12 female carriers of X-linked recessive Duchenne muscular dystrophy (DMD), of whom 4 had symptoms and 8 had none, were compared between all 4 groups and with those in 2 DMD boys, one active and one crippled. Carrier symptoms were readily ascertained by systematic examination. Measurement of both lower legs in all 24 women showed neither calf enlargement nor asymmetry in carriers beyond normal variation. Two DMD carrier daughters were noted of the same DMD carrier mother but by different fathers. Whole body counting showed the biological half-life of previously administered 86Rb to be much reduced in DMD, but no differences were found between normal women and any group of carriers. The test is thus valueless for carrier detection, and reasons are given why it should be so. Simultaneous measurement of total body K+, with subsequent determination by isotope dilution of total body water as 3H2O space and extracellular water as NH4 82Br space, showed increased intracellular water and reduced intracellular K+ concentration in all carriers, as if due to osmotic causes, with actual loss of muscle mass and slight diminution of serum K+ in the 4 symptomatic carriers only. Because of diurnal and other variations, the means and standard deviations for six serum enzymes from six fortnightly assays in all subjects were used to measure precise individual status. Their coefficients of variation were abnormal only in symptomatic carriers and ambulant DMD, easily overtexed by even accustomed exertion. This is shown to support previous propositions on the pathogenesis of DMD and the escape of muscle cell content into the circulation.

Adolescent↗

Proline incorporation by cultured skin fibroblasts from patients with duchenne muscular dystrophy.

The incorporation of proline by cultured skin fibroblasts derived from normal individuals and patients with Duchenne muscular dystrophy (DMD) was analyzed by SDS-gel electrophoresis combined with a double-labeling procedure [Pediatr. Res., 12: 887 (1978)]. DMD fibroblasts showed increased proline incorporation into protein of approximately 130 000 daltons which could be degraded partially by collagenase. This difference was observed only at 7 days after seeding, and may be due to slight differences in growth rate as comparison of cells harvested at 2 and 7 days indicated that increased proline incorporation into high molecular weight protein was associated with day 7 cells, whether normal or DMD. During 14 days in culture normal and DMD strains did not differ in protein content, doubling time or incorporation of [3H]leucine and [14C]proline into cellular protein, although the ratio of [14C]proline to [3H]leucine incorporated was greater for DMD fibroblasts at 7 days. Incorporation of [14C]proline and [3H]leucine into extracellular proteins was greater in DMD fibroblast cultures. These subtle differences support the hypothesis that the DMD gene is expressed in fibroblasts.

Cell Differentiation↗

Optimized genomic editing of a common Duchenne muscular dystrophy mutation in patient-derived muscle cells and a new humanized mouse model.

Duchenne muscular dystrophy (DMD) is a fatal X-linked, recessive disease caused by mutations in the DMD gene encoding dystrophin, a membrane-associated protein necessary for maintaining muscle structure and function. One of the common DMD mutations is the deletion of exon 52 (&#x394;52), which introduces a premature stop codon in exon 53, preventing the expression of functional dystrophin protein. Patients with this mutation could benefit from skipping or reframing exon 53 to restore the dystrophin open reading frame. In this study, we investigated the efficacy of single-cut CRISPR gene editing with Staphylococcus pyogenes Cas9 (SpCas9)-LRVQR to restore dystrophin expression in patient-derived induced pluripotent stem cells (iPSCs) and a newly generated humanized DMD mouse model. We compared two injection routes for adeno-associated virus (AAV) serotype 9 to deliver gene-editing components to neonatal mice: intraperitoneal (IP) and facial vein (FV) injection. We observed efficient restoration of dystrophin protein expression across multiple skeletal muscle groups and the heart. The AAV9-mediated CRISPR single-cut approach ameliorated key DMD hallmarks, including histopathological phenotypes, impaired grip strength, and elevated serum creatine kinase levels. Our optimized strategies for dystrophin restoration in humanized DMD mice with exon 52 deletion represent a promising treatment for DMD.

AAV↗

Glucose, free fatty acid and ketone body metabolism in Duchenne muscular dystrophy.

We examined how the substances, especially glucose, free fatty acids (FFA) and ketone bodies, and hormones associated with energy metabolism change with the disease progress in Duchenne muscular dystrophy (DMD). Serum creatine kinase (CK) activity was used as an index of the stage of DMD, because this activity is exponentially decreases with the progress of the disease. The glucose concentration in DMD patients with CK activity of less than 1,000 U/l (low CK) was significantly lower than that in controls, although there was no significant difference between that in DMD patients with CK activity of more than 1,00 U/l (high CK) and that in controls. The FFA concentration in both high CK and low CK patients was significantly higher than that in controls. The FFA concentration in low CK patients tended to be higher than that in high CK patients. The ketone body concentration in low CK patients was significantly higher than that in controls and that in high CK patients. The [glucagon]:[insulin] ratio in low CK patients was significantly higher than that in controls and that in high CK patients. It was also observed in a correlational study that the glucose concentration decreased with the age and the decrease in CK activity, i.e., with the progress of DMD. The FFA and ketone body concentrations increased with the decrease in the glucose concentration. The decrease in the glucose concentration may be due to a caloric shortage and/or degenerated muscle, which cannot supply enough gluconeogenic substrates, such as alanine. The kinetics of insulin and glucagon in DMD may help to maintain the glucose metabolism. Increased concentrations of FFA and ketone bodies may be helpful in the advanced stage of DMD, as energy sources and as substrates, sparing muscle protein.

Adolescent↗

A descriptive epidemiological study of Duchenne muscular dystrophy in childhood in Estonia.

Duchenne muscular dystrophy (DMD) is the most frequent muscle disorder in childhood. There are no data on the epidemiology of muscular dystrophy in Estonia and the other Baltic States. The present study assessed the incidence and prevalence of DMD in Estonia. A descriptive epidemiological study of DMD was carried out in children born and diagnosed between 1977 and 1999 in Estonia. Patients were identified using four different approaches. DMD was considered present in children with features that corresponded to the criteria established by the European Neuromuscular Centre. 20 incidence cases and 25 prevalence cases of definite DMD were identified. We found a DMD incidence rate of 11.91 x 10(-5) (95% CI; 7.28-18.4) live born males from 1977 to 1990. The point prevalence rate of DMD was 12.76 x 10(-5) (95% CI; 8.26-18.84) of the under-20 male population as of January 1, 1998. The incidence and prevalence estimates in this report were in the range of similar studies from other countries. A muscle biopsy database and a neuromuscular disorders database were launched with this study. Considering the course of the disease, the prevalence should be estimated on the basis of the total male population <20 years of age.

Adolescent↗

Duchenne muscular dystrophy gene product is not identical in muscle and brain.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder resulting in progressive degeneration of the muscle. It affects about 1 in 3,500 male children. Becker's muscular dystrophy is a less severe disease allelic to DMD. Some 30% of DMD patients suffer from various degrees of mental retardation. The giant DMD gene spans about 2,000 kilobases and codes for a 14-kilobase messenger RNA and a protein of molecular weight 427,000. DMD mRNA is most abundant in skeletal and cardiac muscle and less so in smooth muscle. We reported that the expression of the gene is developmentally regulated during the differentiation of primary muscle cultures and in myogenic cell lines in a way similar to the expression of muscle-specific genes such as myosin light chain 2 and skeletal muscle actin. Similar results have been obtained with human primary myogenic cells. Significant levels of DMD mRNA are found in brain tissue. Here we show that the transcript of the DMD gene and the amino terminal of the encoded protein differ in brain and muscle. The 5' ends of these mRNA species are derived from different exons. The results suggest that the two mRNA types are transcribed from different promoters.

Animals↗