Clinical utility of 12-lead electrocardiogram in evaluating heart disease in patients with muscular dystrophy: Assessment of left ventricular hypertrophy, conduction disease, and cardiomyopathy.

INTRODUCTION: Heart disease remains a leading cause of mortality in patients with muscular dystrophy (MD), and cardiac assessment by standard imaging modalities is challenging due to the prominence of physical limitations. METHODS: In this prospective cohort study of 169 MD patients and 34 negative control patients, we demonstrate the clinical utility of a 12-lead electrocardiogram (ECG) as an effective modality for the assessment of cardiac status in patients with MD. We assessed the utility of conventional criteria for electrocardiogram-indicated left ventricular hypertrophy (ECG-LVH) as well as ECG morphologies. RESULTS: Cornell voltage, Cornell voltage-duration, Sokolow-Lyon voltage, and Romhilt-Estes point score criteria demonstrated low sensitivity and minimal positive predictive value for ECG-LVH when compared with cardiac imaging. Patients with LBBB had a high probability of a cardiomyopathy (relative risk [RR], 2.75; 95% confidence interval [CI], 2.14-3.53; p < .001), and patients with QRS fragmentation (fQRS) had a high probability of a cardiomyopathy (RR, 1.76; 95% CI, 1.20-2.59; p = .004), requiring cardiac medication and device intervention. We found that an R/S ratio >1 in V1 and V2 is highly specific (specificity, 0.89; negative predictive value [NPV], 0.89 and specificity, 0.82; NPV, 0.89, respectively) for patients with dystrophinopathies compared with other types of MD. CONCLUSION: The identification of LBBB and fQRS was linked to cardiomyopathy in patients with MD, while ECG-LVH was of limited utility. Importantly, these findings can be applied to effectively screen a broad cohort of MD patients for structural heart disease and prompt further evaluation and therapeutic intervention.

Chart validation of an algorithm for identifying hereditary progressive muscular dystrophy in healthcare claims.

BACKGROUND: Muscular dystrophies (MDs) are a group of inherited conditions characterized by progressive muscle degeneration and weakness. The rarity and heterogeneity of the population with MD have hindered therapeutic developments as well as epidemiological and health outcomes research. The objective of the study was to develop and validate a case-finding algorithm utilizing administrative claims data to identify and characterize patients with MD. METHODS: This retrospective cohort study used medical chart validation to evaluate an ICD-9/10 coding algorithm in a large commercial claims database. Patients were identified who had ≥2 office visits with a diagnosis of hereditary progressive MDs from January 1, 2013 through December 31, 2016, were male, and younger than 18 years at the time of first MD diagnosis. Cases who met the algorithm were then validated against medical charts. Diagnoses of MD and specific type (Duchenne, Becker, or other MD) were confirmed by medical chart review by trained reviewers. Positive predictive value (PPV) and 95% confidence intervals (CI) were calculated using a 2 × 2 contingence table. Patient demographic, clinical, and health utilization characteristics were summarized using basic descriptive statistics. RESULTS: Charts were obtained and reviewed for 109 patients who met the algorithm. The PPV of the case-identifying algorithm for MD was 95% (95% CI 88-98%). Of the 103 confirmed MD cases, 87 patients (85%, 95% CI 76-91%) had Duchenne or Becker MD; 76 patients (74%, 95% CI 64-82%) had Duchenne MD, and 11 patients (11%, 95% CI 5-18%) had Becker MD. A total of 74 (67.9%) patients had ≥1 pediatric complex chronic condition (other than neurologic/neuromuscular disease); 54 (49.5%) had cardiovascular conditions; 14 (12.8%) had respiratory conditions; 50 (45.9%) had bone-related issues; 11 (10.1%) had impaired growth; and 6 (5.5%) had puberty delay. CONCLUSIONS: The results of this study demonstrate that the case-finding algorithm accurately identified patients with MD, primarily Duchenne MD, within a large administrative database. The algorithm, which was constructed using a few items easily accessible from claims, can be used to facilitate epidemiological and health outcomes research in the Duchenne patient population.

Targeted massively parallel sequencing and histological assessment of skeletal muscles for the molecular diagnosis of inherited muscle disorders.

BACKGROUND: Inherited skeletal muscle diseases are genetically heterogeneous diseases caused by mutations in more than 150 genes. This has made it challenging to establish a high-throughput screening method for identifying causative gene mutations in clinical practice. AIM: In the present study, we developed a useful method for screening gene mutations associated with the pathogenesis of skeletal muscle diseases. METHODS: We established four target gene panels, each covering all exonic and flanking regions of genes involved in the pathogenesis of the following muscle diseases: (1) muscular dystrophy (MD), (2) congenital myopathy/congenital myasthenic syndrome, (3) metabolic myopathy and (4) myopathy with protein aggregations/rimmed vacuoles. We assigned one panel to each patient based on the results of clinical and histological analyses of biopsied muscle samples and performed high-throughput sequencing by using Ion PGM next-generation sequencer. We also performed protein analysis to confirm defective proteins in patients with major muscular dystrophies. Further, we performed muscle-derived cDNA analysis to identify splice-site mutations. RESULTS: We identified possible causative gene mutations in 33% of patients (62/188) included in this study. Our results showed that the MD panel was the most useful, with a diagnostic rate of 46.2%. CONCLUSIONS: Thus, we developed a high-throughput sequencing technique for diagnosing inherited muscle diseases. The use of this technique along with histological and protein analyses may be useful and cost-effective for screening mutations in patients with inherited skeletal muscle diseases.

Bounded influence function based inference in joint modelling of ordinal partial linear model and accelerated failure time model.

A common objective in longitudinal studies is to characterize the relationship between a longitudinal response process and a time-to-event data. Ordinal nature of the response and possible missing information on covariates add complications to the joint model. In such circumstances, some influential observations often present in the data may upset the analysis. In this paper, a joint model based on ordinal partial mixed model and an accelerated failure time model is used, to account for the repeated ordered response and time-to-event data, respectively. Here, we propose an influence function-based robust estimation method. Monte Carlo expectation maximization method-based algorithm is used for parameter estimation. A detailed simulation study has been done to evaluate the performance of the proposed method. As an application, a data on muscular dystrophy among children is used. Robust estimates are then compared with classical maximum likelihood estimates.

Assessment of disease activity in muscular dystrophies by noninvasive imaging.

Muscular dystrophies are a class of disorders that cause progressive muscle wasting. A major hurdle for discovering treatments for the muscular dystrophies is a lack of reliable assays to monitor disease progression in animal models. We have developed a novel mouse model to assess disease activity noninvasively in mice with muscular dystrophies. These mice express an inducible luciferase reporter gene in muscle stem cells. In dystrophic mice, muscle stem cells activate and proliferate in response to muscle degeneration, resulting in an increase in the level of luciferase expression, which can be monitored by noninvasive, bioluminescence imaging. We applied this noninvasive imaging to assess disease activity in a mouse model of the human disease limb girdle muscular dystrophy 2B (LGMD2B), caused by a mutation in the dysferlin gene. We monitored the natural history and disease progression in these dysferlin-deficient mice up to 18 months of age and were able to detect disease activity prior to the appearance of any overt disease manifestation by histopathological analyses. Disease activity was reflected by changes in luciferase activity over time, and disease burden was reflected by cumulative luciferase activity, which paralleled disease progression as determined by histopathological analysis. The ability to monitor disease activity noninvasively in mouse models of muscular dystrophy will be invaluable for the assessment of disease progression and the effectiveness of therapeutic interventions.

Assessment of target enrichment platforms using massively parallel sequencing for the mutation detection for congenital muscular dystrophy.

Sequencing individual genes by Sanger sequencing is a time-consuming and costly approach to resolve clinically heterogeneous genetic disorders. Panel testing offers the ability to efficiently and cost-effectively screen all of the genes for a particular genetic disorder. We assessed the analytical sensitivity and specificity of two different enrichment technologies, solution-based hybridization and microdroplet-based PCR target enrichment, in conjunction with next-generation sequencing (NGS), to identify mutations in 321 exons representing 12 different genes involved with congenital muscular dystrophies. Congenital muscular dystrophies present diagnostic challenges due to phenotypic variability, lack of standard access to and inherent difficulties with muscle immunohistochemical stains, and a general lack of clinician awareness. NGS results were analyzed across several parameters, including sequencing metrics and genotype concordance with Sanger sequencing. Genotyping data showed that both enrichment technologies produced suitable calls for use in clinical laboratories. However, microdroplet-based PCR target enrichment is more appropriate for a clinical laboratory, due to excellent sequence specificity and uniformity, reproducibility, high coverage of the target exons, and the ability to distinguish the active gene versus known pseudogenes. Regardless of the method, exons with highly repetitive and high GC regions are not well enriched and require Sanger sequencing for completeness. Our study demonstrates the successful application of targeted sequencing in conjunction with NGS to screen for mutations in hundreds of exons in a genetically heterogeneous human disorder.

Factors relating to carer burden for families of persons with muscular dystrophy.

OBJECTIVE: To assess the burden on family carers of persons with muscular dystrophy living in their homes and to determine factors contributing to carer burden. METHODS: The study included 56 dyads of people with muscular dystrophy and their family carers. The variables for carer burden were compared by logistic regression in 2 carer groups (burden + /burden-). RESULTS: The mean age of the patients with muscular dystrophy was 32.7 years (median 26.7, range 15-65 years) and that of the carers 51 years (median 48, range 30-80 years). The carers reported the care burden using the Zarit Burden Inventory (median score 23, range 0-57/88). Multivariate analysis produced 3 adjusted explicative factors: carer characteristics related to risk of perceived burden are self-report of poor social functioning on the SF-36 (OR = 26.6 (2.6-278); p=0.006), self report of anxiety on the Hospital Anxiety Scale (OR = 7.1 (1.4-36); p=0.02) and being a carer under 48 years of age (OR = 7.8 (1.7-34.5); p=0.007). However, it was difficult to dissociate the different health variables of the carers from each other. CONCLUSION: This approach should lead to better decision-making by medical teams, patients and their carers.

Random urine calcium/osmolality in the assessment of calciuria in children with decreased muscle mass.

BACKGROUND: Random urine Ca/creatinine (UCa/Cr) is used to estimate 24-hour Ca excretion. However, due to decreased urine creatinine excretion in children with decreased muscle mass (DMM), UCa/Cr overestimates their Ca excretion. OBJECTIVE: To evaluate whether in children with DMM random urine Ca/osmolality (UCa/Osm) can accurately predict hypercalciuria (24-hour urine Ca > 4.0 mg/kg) and at which "cutoff" value. METHODS: 19 children with DMM and 29 with normal muscle mass (NMM), ages 6 - 17 years, were studied. DMM was diagnosed based on clinical findings and decreased serum creatinine, and confirmed by low urine creatinine excretion. Over 24 hours, subjects collected each void separately. After each sample was analyzed, samples of each participant were combined to form a 24-hour specimen from which an aliquot (AL) was obtained; 24-hour urine Ca was first correlated with the corresponding AL Ca/Cr and Ca/Osm. As an internal control, a similar assessment ofproteinuria was conducted. In the next step, AL data were compared with individual urine samples to identify the time of day when a random sample best correlates with AL. RESULTS: The correlation coefficient between 24-hour Ca and AL Ca/Cr in all children was 0.61, in NMM 0.96, and in DMM 0.69 (in all p < 0.001). The correlation coefficient between 24-hour urine Ca and AL Ca/Osm in all children was 0.90, in NMM 0.90, and in DMM 0.91 (in all p < 0.001). In children with DMM, the correlation coefficient of 24-hour protein with AL protein/Cr was 0.75, and with protein/Osm 0.98 (both p < 0.001). Receiver operating characteristic curves showed UCa/Cr as a better predictor of 24-hour Ca > 4.0 mg/kg in NMM, whereas UCa/Osm was a better predictor of hypercalciuria in DMM patients. In NMM, UCa/Cr ratio > 0.20 had sensitivity of 88% and specificity of 96% in detecting 24-hour Ca > 4.0 mg/kg, whereas in those with DMM UCa/Osm (x 10) ratio of > 0.25 had sensitivity of 100% and specificity of 93% in detecting hypercalciuria. It was further found that random urine specimens collected between 9:00 a.m. and 2:00 p.m. best represented 24-hour urine data. CONCLUSION: In children with DMM, UCa/Osm can successfully replace UCa/Cr as a screening tool for hypercalciuria.

Assessment of left ventricular systolic and diastolic functions in children with merosin-positive congenital muscular dystrophy.

Cardiopathy is an expected finding in X-linked Duchenne and Becker muscular dystrophies. This holds true for some other forms such as autosomal recessive limb-girdle dystrophies. However, data on early-onset and usually severe congenital muscular dystrophies are limited. The purpose of this study was to investigate the presence of cardiac involvement in children with merosin-positive congenital muscular dystrophy. A total of 42 patients and 22 healthy subjects were evaluated by M-mode, 2D, and Doppler echocardiography. Cardiac anatomy, left ventricular dimensions, wall thickness and systolic and diastolic functions were investigated in patients and compared with those of healthy control subjects. Mean left ventricular ejection fraction and shortening fraction were significantly lower in the patient group (P<0.05 and P<0.001, respectively) and in three patients ejection fraction was below 55%. Although some impairments in left ventricular inflow indexes which were suggestive of left ventricular diastolic dysfunction were detected in patients with merosin-positive congenital muscular dystrophy they were not statistically significant. Our results suggest that left ventricular systolic abnormalities may occur in children with merosin-positive congenital muscular dystrophy.

Distrofia Muscular

Traz como tema a distrofia muscular que é uma doença neuromuscular de origem genética, cuja característica principal é o enfraquecimento progressivo da musculatura esquelética, prejudicando os movimentos e levando na maioria das vezes o portador a uma cadeira de rodas. Ela possui uma especificidade que a distingue sobremaneira das demais deficiências motoras: qualquer esforço muscular que cause um mínimo de fadiga contribui para a deterioração do tecido muscular. Isso porque o defeito genético ocorre pela ausência ou formação inadequada de proteínas essenciais para o funcionamento da fisiologia da célula muscular(Au)

Role of exercise in the assessment and management of neuromuscular disease in children.

In the child with a neuromuscular disease (NMD), one can use exercise for the assessment of physiological function and as a therapeutic modality. Functions most relevant for assessment are muscle strength, muscle endurance, peak mechanical power, and O2 cost of movement. Maximal aerobic power is less important because it seldom is the limiting factor in the child's ability to perform daily physical activities. There are very few well-designed controlled training interventions in children with NMD. There is, however, some evidence to suggest that maximal aerobic power, muscle strength, and O2 cost of locomotion are trainable in children with NMD.

Transfer of DNA tests from research to routine laboratories: some lessons from the French experience in the case of Duchenne muscular dystrophy.

In the last few years, the activity of research laboratories has led to the emergence of new DNA diagnostic tests in France. They permit the origin of genetic diseases to be identified and provide an answer concerning the detection of carriers and prevention. Nevertheless, given this, new actors have emerged on the health care scene: the research workers who developed the tests and who work in public research laboratories. The economic question of the transfer of the test practice from research to hospital laboratories is the main topic of this paper, taking Duchenne Muscular Dystrophy (DMD) DNA diagnostic tests as the example. After a presentation of the complexity of DNA tests for DMD, the fact that financial and human constraints do not allow the actors to continue to produce the DNA tests is discussed. The financial role of the non-profit-making associations is then explained and leads to the conclusion that a more global policy on DNA tests, such as carried out in the UK and the Netherlands, should be adopted in France by the Social Security if it wants DNA testing activity to be pursued.

[Relations between delayed diagnosis and forms of onset in Duchenne muscular dystrophy]. / Relación entre el retraso del diagnóstico y las formas de inicio de la distrofia muscular de Duchenne.

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.

[Cognitive and affective aspects of psychomotor assessment of myodystrophic children with the aim of specific treatment]. / Gli aspetti cognitivi ed affettivi del bilancio psicomotorio del bambino miodistrofico ai fini di un trattamento mirato.

The aim of this study was to evaluate the incidence of cognitive and affective problems in the treatment of children suffering from myodystrophy. It was hypothesised that psychomotory assessment taking appropriate account of data regarding the evaluation of cognitive and affective development might allow an adequate and realistic therapeutic protocol to be defined. For this purpose the authors examined 55 myodystrophic patients aged between 6 and 10 years old during the period January 1980 and June 1993 using traditional psychomotory tests (Stanford-Binet and/or WISC in relation to the various age groups), projective tests (CAT, TAT) and graphic tests. The latter were also evaluated according to Koppitz's criterion which enabled emotional indicators (EI) to be assessed. All 55 cases were evaluated in collaboration with the 1st Pediatric Clinic of the Neuro-Psychomotory Unit of "G. Gaslini" Institute. Psychomotory treatment, which by definition is addressed to the entire person, specifically took cognitive and affective data into consideration. In fact, as observed by Johnson and Alexander, in myodystrophy functional skills are more often limited by cognitive and motivational factors than by actual menomation. The results showed that the concentration on psychological aspects in the rehabilitation of myodystrophic children allows the neuropsychological component of movement (practognosia) to be preserved for as long as possible despite the progress of instrumental deficit (anatomic degeneration). In the authors' experience and in comparison to that of other Authors, it was possible to state that a "personalized" approach allows the subjects to improve their own "presence in the world".

The resource implications and service outcomes of genetic services in the context of DNA technology.

The use of DNA technology has transformed genetic counselling services for single gene disorders. For conditions such as Duchenne muscular dystrophy and cystic fibrosis, both of which cause severe morbidity and premature death, DNA tests mean that individuals can be told with greater certainty whether they are carriers of a genetic trait and of the likelihood of their having a child affected by the disorder. This paper presents the findings of an evaluation of the resource implications and service outcomes of genetic services in the context of DNA technology (DNA services). Results are based on data collected over a 4-year period from three large genetics centres throughout the United Kingdom. Our conclusions are that for the conditions for which they are commonly used, and as a regionally based service, DNA services are effective and relatively inexpensive. For severe conditions, and for neurological disorders, although tests will not alter family size plans the demand for tests during pregnancy will be high and the results will have a significant impact on individuals' decisions regarding the continuation of their pregnancies. For conditions of variable severity, those that start late in life or are amenable to treatment, the demand for tests is likely to be low. In comparison with the general population we found a greater existence of psychological side effects amongst counsellees. These effects were linked to individuals having a close relative, usually a child, already affected by a disorder rather than being a consequence of the genetic counselling process.

A DNA diagnostic service.

We describe the use of techniques of DNA analysis for the diagnosis of certain inherited diseases during life and in the prenatal period, and for the diagnosis of some infectious diseases. Most local and some national needs for predictive genetic testing have been met. The costs of establishing our service are presented and are compared with those of similar services recently established in the United Kingdom. In the 12 month period described, running costs were approximately $57,000 and salaries for the two scientific officers and the medical technologist required to run the service were $97,000. The prerequisites for the successful running of such a service are discussed.