Valley sign in Becker muscular dystrophy and outliers of Duchenne and Becker muscular dystrophy

Valley sign has been described in patients with Duchenne muscular dystrophy (DMD). As there are genetic and clinical similarities between DMD and Becker muscular dystrophy (BMD), this clinical sign is evaluated in this study in BMD and DMD/BMD outliers. To evaluate the sign, 28 patients with Becker muscular dystrophy (BMD), 8 DMD/BMD outliers and 44 age-matched male controls with other neuromuscular diseases were studied. The sign was examined after asking patients to abduct their arms to about 90 cent with hands directed upwards; the muscle bulk over the back of the shoulders was observed. The sign was considered positive if the infraspinatus and deltoid muscles were enlarged and between these two muscles, the muscles forming the posterior axillary fold were wasted as if there were a valley between the two mounts. Twenty-five BMD patients and 7 DMD/BMD outliers had positive valley sign. However, it was less remarkable in comparison to DMD. It was absent in all the 44 controls. It was concluded that the presence of valley sign may help in differentiating BMD from other progressive neuromuscular disorders of that age group.     

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.     

Neurodevelopmental,behavioral, and emotional symptoms in Becker muscular dystrophy

Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative disorder with complex biology and significant clinical heterogeneity. Many preclinical and early phase ALS clinical trials have yielded promising results that could not be replicated in larger phase 3 confirmatory trials. One reason for the lack of reproducibility may be ALS biological and clinical heterogeneity. Therefore, in this review, we explore sources of ALS heterogeneity that may reduce statistical power to evaluate efficacy in ALS trials. We also review efforts to manage clinical heterogeneity, including use of validated disease outcome measures, predictive biomarkers of disease progression, and individual clinical risk stratification. We propose that personalized prognostic models with use of predictive biomarkers may identify patients with ALS for whom a specific therapeutic strategy may be expected to be more successful. Finally, the rapid application of emerging clinical and biomarker strategies may reduce heterogeneity, increase trial efficiency, and, in turn, accelerate ALS drug development.     

Cardiomyopathy in Becker muscular dystrophy

In 6 patients with dystrophin-verified Becker muscular dystrophy (BMD), 3 patients had dilated cardiomyopathy (DCM group). The other 3 patients (non-DCM group) also had ECG abnormalities including incomplete right bundle branch block, left ventricular enlargement and intraventricular conduction defect. Between DCM and non-DCM group, there was no prominent difference in ages at onset, mean duration and severity of muscular weakness. Serum CK levels, and molecular weight and amount of dystrophin also showed no significant difference between two groups. On reviewing 14 BMD patients, including 3 present patients with cardiomyopathy, the cardiac symptoms appeared from 4 to 41 years, averaging 17.1 years of age. The mean duration of muscle symptoms was 9 years, ranging from 0 to 33 years. There was no correlation between severity of muscle weakness and cardiomyopathy. Six patients died of heart failure and 3 received cardiac transplantation. Thus there was no characteristic clinical feature in BMD patients with cardiomyopathy except for very poor prognosis. Since the myocardial involvement is not related with clinical severity and duration of the disease, careful observation for cardiac function should be carried out in all BMD patients even in the early stage of muscle weakness.     

迪谢内/贝克肌营养不良患者视网膜眼电图改变特征

目的 研究迪谢内／贝克肌营养不良（ＤＭＤ／ＢＭＤ）患者视网膜眼电图（ＥＲＧ）的改变特征,探讨ＥＲＧ对ＤＭＤ／ＢＭＤ的诊断价值及ｄｙｓｔｒｏｐｈｉｎ在视网膜信号传导上的作用。方法 对２２例临床确诊的ＤＭＤ／ＢＭＤ患者进行详细的眼科检查和ＥＲＧ检测,采用ＥＲＧ国际测量标准记录结果。结果 全部患者眼科检查无明显异常。２２例患者中１６例（７２．７％）出现异常ＥＲＧ改变;其中１５例为暗适应蓝光ｂ波波幅下降或（和）消失（Ｐ〈０．００１）。１３例暗适应白光ｂ波波幅下降或（和）替伏期延长（Ｐ〈０．００１）。１２例ｂ／ａ波波幅比≤（Ｐ〈０．００１）。１６例振荡电位ＯＰｓ１～４波波幅下降。结论 ＥＲＧ可作为ＤＭＤ／ＢＭＤ诊断和症状的一项有价值的检查。ｄｙｓｔｒｏｐｈｉｎ及同源蛋白在视网膜电信号的传导上起着重要作用。     

COVID-19 in advanced Duchenne/Becker muscular dystrophy patients

Duchenne muscular dystrophy (DMD) is the most common childhood muscular dystrophy. As a result of progressive muscle weakness, pulmonary function decreases during the second decade of life and lung disease contributes significantly to morbidity and mortality in these patients. Corticosteroids are the current standard of care for patients with DMD, despite known adverse effects such as obesity and immunosuppression. Over the past year (2020), the novel coronavirus (COVID-19/SARS-CoV2) outbreak has caused a global pandemic. Restrictive lung disease due to low lung volumes, chronic immunosuppressive treatment with corticosteroids, and obesity are potential risk factors that may contribute to a more severe course of the disease. Out of 116 Duchenne/Becker muscular dystrophy patients treated in our tertiary neuromuscular center, six patients with DMD and one with advanced Becker muscular dystrophy were found to be positive for COVID-19 infection. Two of the DMD patients were admitted for hospitalization, of whom one was dependent on daily nocturnal non-invasive ventilation. All patients recovered without complications despite obesity, steroid treatment and severe restrictive lung disease.     

Molecular deletion patterns in Turkish Duchenne and Becker muscular dystrophy patients

The dystrophin gene deletion patterns of Duchenne / Becker muscular dystrophy were investigated in 57 DMD, 7 BMD and 1 DMD-BMD intermediate muscular dystrophy patients. Deletions, analyzed by multiplex amplification of selected exons, were observed in 58% (38 cases) of the patients. It was found that exon 48 was the most frequently affected, while exon 44 was the least frequently affected. The number of deleted exons was variable, but single exon deletions were more frequent (41%) than larger deletions in our population and the great majority of deletions began distal to exon 44. The application of PCR to deletion analysis in D /BMD was found to be very useful in delineating the extent of the deletion in most of the cases (82%). It was seen that the frequency of deletion breakpoints in distal part of the dystrophin gene (exons 42–52) was detected in 64% of our cases. In our group, the frequency of deletion breakpoints in the same area of the dystrophin gene was between that of the French and the Finnish patients. The distribution of deletion breakpoints within the dystrophin gene of the Turkish population seems to have some differences from other populations. Deletion breakpoints were found to be clustered mainly in three separate regions covering introns 44, 45 and 50 within the central region of the dystrophin gene. Intron 44 was mostly 5′ breakpoints but it was found not to be involved as 3′ breakpoints. The correlation between phenotype and type of deletion agreed with the reading frame theory except for one DMD case.     

Muscle histology in Becker muscular dystrophy.

Twenty patients with Becker muscular dystrophy (BMD), confirmed by dystrophin tests, were studied histologically. There were several morphological differences between younger (less than or equal to 15-year-old) and older (greater than 15-year-old) patients. In the younger patients, active muscle fiber necrosis followed by a regenerating process was conspicuous. In the older patients, the active degenerative changes appeared less prominent and, instead, more chronic myopathic changes such as moth-eaten fibers, fiber splitting, and hypertrophic fibers were evident. These age-dependent differences in the pathology of BMD were irrespective of the duration of clinical symptoms, i.e., BMD patients of a similar age showed a similar morphological feature regardless of age at onset. Although the presence of mild fiber type grouping and some small angulated atrophic fibers suggested a certain degree of neurogenic involvement, none of biopsies showed significant grouped atrophy as seen in neuropathic disorders. There was no correlation between the histological changes and the specific dystrophin abnormality.     

Cardiac transplantation in Becker muscular dystrophy.

Becker muscular dystrophy is associated with abnormal cardiac features in about 75% of cases; up to one-third will develop ventricular dilatation leading to congestive cardiac failure. As this form of muscular dystrophy is relatively benign, failure to respond to medical treatment warrants assessment for cardiac transplantation.     

Neuropsychological profile in myotonic dystrophy

Summary Twenty patients with myotonic dystrophy underwent neuropsychological evaluation. Performances were analysed with respect to general cognitive profile, family patterns of cognitive impairment, relation with sex, age, extent of muscular involvement, and sex of affected parent. Results showed severe intellectual deficit in 50% of patients and selective impairment of visuospatial and constructional functions. Female patients showed significantly worse global intellectual status than males. No difference in intellectual level was observed in patients with respect to age, extent of muscular involvement and sex of affected parent. No family pattern of cognitive impairment could be identified. Our results show that an extensive neuropsychological battery can reveal the existence of selective mental impairment. It may provide further data on cognitive impairment onset, progression and relation to muscular involvement.     

Enormous dystrophin in a patient with Becker muscular dystrophy

We describe a patient with a duplication of more than 400,000 bp of the dystrophin gene. The duplication is completely contained within the gene, and the duplicated exons are predicted to be "in frame" with the rest of the gene. Dystrophin protein is detected in the patient's muscle as a single species of approximately 600 kDa (normal, approximately 400 kDa), indicating that the resulting mutated gene codes for a translatable mRNA of over 100 exons (normal, approximately 70 exons). The patient's mother carries the duplicated gene as determined by both DNA and protein analysis. The described duplication of the dystrophin gene is by far the largest characterized to date. This observation is of significant biologic interest in that, despite the gross alteration of the gene and the encoded protein, the patient has a relatively mild clinical progression compatible with a diagnosis of Becker muscular dystrophy.     

Neuropsychological impairment in Duchenne muscular dystrophy

Fourteen younger (ages 6 to 10 years) and 11 older (ages 11 to 16 years) Duchenne Muscular Dystrophy (DMD) patients were tested with the WISC-R and neuropsychological language, visual-motor, and motor tasks. Older boys had an average IQ; younger boys were in the low average IQ range. Younger DMD boys were inferior to the older DMD group on tasks requiring some language and attentional-organizational skills, but not on visual-motor tasks. Older DMD boys were inferior on motor tasks. Results suggest that the reported low cognitive skills in DMD patients are not fixed or global, but reflect selective deficits in the younger boys. Possible bases for age differences in performance are discussed.     

Neuropsychological impairment in duchenne muscular dystrophy

Abstract

Fourteen younger (ages 6 to 10 years) and 11 older (ages 11 to 16 years) Duchenne Muscular Dystrophy (DMD) patients were tested with the WISC-R and neuropsy-chological language, visual-motor, and motor tasks. Older boys had an average IQ; younger boys were in the low average IQ range. Younger DMD boys were inferior to the older DMD group on tasks requiring some language and attentional-organizational skills, but not on visual-motor tasks. Older DMD boys were inferior on motor tasks. Results suggest that the reported low cognitive skills in DMD patients are not fixed or global, but reflect selective deficits in the younger boys. Possible bases for age differences in performance are discussed.     

Recent advances in Duchenne and Becker muscular dystrophy

The recent identification of the gene and gene product altered in Duchenne and Becker dystrophy has opened up new and exciting avenues to an understanding of these diseases. This article presents the clinical features, pathology, genetics, and management of Duchenne and Becker muscular dystrophy. These issues are discussed in light of the rapidly accumulating knowledge concerning the molecular basis for the two disorders.     

DNA微阵列技术检测Duchenne型/Becker型肌营养不良患者的临床应用研究

目的 研究检测Duchenne型肌营养不良(：DMD)／Becker型肌营养不良(BMD)患者基因缺失的可行技术。方法 应用分子克隆的方法扩增DMD基因18个常见易缺失外显子片段，以此作为探针制备出简易DNA微阵列，对30例DMD／BMD患者和5例健康对照的基因进行检测分析。部分结果与PCR的方法作了比较。结果 应用简易：DNA微阵列检测出21例DMD／BMD患者具有不同程度的外显子缺失，10例经PCR检测得到了完全验证。结论 DNA微阵列技术检测：DMD／BMD患者简便、准确、灵敏，可在临床诊断中应用。     

Heterogeneity of dystrophin expression in patients with Duchenne and Becker muscular dystrophy

Summary This report documents the results of an integrated biochemical and immunocytochemical investigation into the expression of dystrophin (the protein product of the Duchenne muscular dystrophy gene) in muscle biopsies from 226 patients. It is the first study in which dystrophin has been analysed on blots and on tissue sections in such a large number of patients using the same (monoclonal) antibody. The 140 patients with Xp21 muscular dystrophy who were included in this study represent a continuous spectrum of disease severity and this range was reflected in the heterogeneity of dystrophin expression which was observed with respect to abundance, size and the pattern of tissue localisation. Approximately 40% of biopsies obtained from patients diagnosed as having Duchenne muscular, dystrophy (DMD) contained isolated clearly positive fibres and a further 20% had very weak labelling on a large number of fibres. Biopsies from patients with Becker muscular dystrophy (BMD) showed labelling patterns which varied from weak labelling on the majority of fibres to clear labelling on all fibres. Typically, however, there was inter-and intra-fibre variation in labelling intensity. Approximately 85% of the 52 BMD and 54 DMD patients who had unequivocal labelling on blots demonstrated a protein of abnormal size. The remaining 15% had a protein of normal size but reduced abundance. Overall, the estimated abundance of dystrophin correlated well with clinical assessments of the disease severity expressed in patients: We conclude that dystrophin analysis is an essential and dependable technique for the differential diagnosis of patients with Xp21 muscular dystrophy.Supported by the University of Newcastle-upon-Tyne Research Committee, the Muscular Dystropy Group of Great Britain and the Medical Research Council     

Molecular pathology of Duchenne and Becker muscular dystrophy

The gene for Duchenne (DMD) and Becker (BMD) types of muscular dystrophy has been isolated by Kunkel's and Worton's groups and shown to be the largest one over known in human, spanning more than 65 exons distributed over 2,500 kb in P21 region of X-chromosome. Fourteen kb cDNA encodes 427 kD cytoskeletal protein "dystrophin", supposed to form an anti-parallel homodimer like alpha-actinin and spectrin. The polyclonal antibodies against the synthetic peptides or fusion proteins predicted from dystrophin cDNA disclosed the complete absence of dystrophin at the surface membrane of both skeletal and cardiac muscles of DMD in marked contrast with the continuous and uniform staining in normal muscles. In manifested carriers, the mosaic expression of dystrophin was observed at the surface membrane of the skeletal muscle. BMD, which is thought to be allelic to DMD, revealed a faint or patchy immunostaining along with the abnormal and/or lower amount of dystrophin. In BMD, there is an intimate connection between the amount of dystrophin and the severity of the clinical course. It should be noted that 5 out of 39 patients with clinical diagnosis of limb-girdle (L-G) muscular dystrophy showed a patchy staining pattern, suggesting BMD not L-G. On the basis of dystrophin discovery, a possible therapeutic trial of DMD is discussed.     

Coinheritance of Noonan syndrome and Becker muscular dystrophy

We describe for the first time a case of a 9-year old boy with co-existence of dystrophinopathy and Noonan syndrome (NS). Although the patient has a severe muscular clinical phenotype, consistent with Duchenne muscular dystrophy (DMD), the diagnosis of Becker muscular dystrophy (BMD) was proposed based on family history (brother with BMD) and confirmed by muscle immunohistochemistry, and molecular study shown an in-frame DMD gene mutation. The patient also fulfilled the clinical criteria of NS and he harbors a hotspot mutation on PTPN11 gene. This genetic combination may be an explanation for the variability of clinical expression in the family.