Diagnostic odyssey of patients with myotonic dystrophy

Diagnoses of muscular dystrophy in a veterans health system

INTRODUCTION/AIMS

Early diagnosis of a chronic neuromuscular disease such as muscular dystrophy (MD) generally excludes an individual from active-duty military service. However, it is not known whether veterans are sometimes diagnosed with milder forms of MD at a later timepoint. We aimed to determine the prevalence of MD in a veterans health system.

METHODS

We abstracted clinical and genetic test data on patients who received care for a diagnosis of MD at the North Florida/South Georgia Veterans Health System between 2008 and 2021. We then determined which of these individuals would meet criteria for a definite diagnosis of MD, based on electrodiagnostic testing, muscle biopsy, and genetic testing of the individual or an affected first degree relative.

RESULTS

We identified 12 patients with definite MD and 36 with possible or probable MD. The definite cases included myotonic dystrophy type 1 (4), myotonic dystrophy type 2 (3), oculopharyngeal MD (2), Becker MD (1), distal MD (1), and facioscapulohumeral MD (1). At least five of the cases classified as definite developed symptoms after discharge from active duty.

DISCUSSION

Clinicians who care for veterans should be knowledgeable about, and have access to, diagnostic testing and treatment options for MD. When conducting MD surveillance, it is important to include veterans health systems as a data source. Mild cases of MD and those of later onset appear to be compatible in some cases with successful completion of military service.

Diagnosis and Management of Myotonic Dystrophy Type 1

This JAMA Insights discusses the signs and symptoms, diagnosis, and treatment of myotonic dystrophy type 1.

Prevalence and Diagnostic Journey of Friedreich's Ataxia in the State of São Paulo, Brazil

Friedreich's Ataxia (FRDA) is the leading cause of ataxia worldwide, but data on epidemiology and diagnostic journey are scarce, particularly in Latin America. Herein we estimated the prevalence of FRDA in the most populous Brazilian state and characterized the diagnostic odyssey of the disease. We received anonymized data of patients with FRDA from advocacy groups and physicians. Prevalence was estimated dividing the number of patients by the population of the state as reported in the last census. Patients were invited to answer an online survey to describe clinical data and diagnostic journey of the disease. FRDA estimated prevalence was 0.367:100,000, with a slight predominance of women (58.2% vs 41.7%). One hundred and four patients answered the survey (mean age of 37.3 ± 13.8 years; 75.9% classical and 24.0% late onset). On average, 6.2 ± 4.1 physicians were visited before reaching the diagnosis. Mean diagnostic delay was 7.8 ± 6.7 years; no difference between classical and LOFA groups was found. Most of the patients reported unsteadiness and gait abnormalities as the first symptom. Neurologists and orthopedical surgeons were the main specialties first sought by patients. We found a prevalence of 0.36:100,000 for FRDA in the state of São Paulo, Brazil. The disease is characterized by remarkable diagnostic delay, with no relevant differences between classical and LOFA patients.

Patient engagement in clinical trial design for rare neuromuscular disorders: impact on the DELIVER and ACHIEVE clinical trials

BACKGROUND

Engaging individuals living with disease in drug development and regulatory processes leads to more thoughtful and sensitive trial designs, drives more informative and meaningful outcomes from clinical studies, and builds trust between the public, government, and industry stakeholders. This engagement is especially important in the case of rare diseases, where affected individuals and their families face many difficulties getting information, treatment, and support. Dyne Therapeutics is developing therapeutics for people with genetically-driven muscle diseases. During the development of potential treatments for Duchenne muscular dystrophy (DMD) and myotonic dystrophy type 1 (DM1), Dyne sought the opinions of individuals living with these diseases to inform its clinical trial design and to decrease the difficulties that participants and families might experience participating in them.

METHODS

Dyne engaged individuals and families living with DMD and DM1 as expert partners in its clinical development programs. Dyne convened panels of affected individuals and care partners/parents of individuals living with DMD (n = 8) or DM1 (n = 18). Workshops focused on how affected individuals and their families evaluate and select clinical trials for participation, the importance, quality, and burden associated with individual trial design elements, participation considerations such as site location and the study visit design, patient privacy, the suitability and scope of travel and participant support programs, and the accessibility of content in the informed consent (or assent) forms. Dyne also engaged the DMD Community Advisory Board (CAB) to collect feedback and advice on designing optimal and meaningful clinical trials and measuring relevant outcomes.

RESULTS

The issues most important to individuals living with DM1 and DMD regarding clinical trials were the ability to participate/access to the trial, perceptions of benefit and risk of trials and potential treatments, the flexibility of participation, clear communication from the sponsor, availability of information from trusted sources, and patient enrollment. In response to the patient advisory workshops and CAB feedback, Dyne refined clinical trial inclusion/exclusion criteria and clinic visit design, developed a travel service program to address the burden of clinical trial travel and enable long-distance and cross-border participation, planned for home visits when feasible, and allowed for adequate rest before clinic visit initiation and between assessments. Additionally, Dyne developed and implemented a transparent and consistent communications plan (including age-appropriate content) for trial participants and community members, and assessed and adjusted procedures to provide maximum participant comfort and lower anxiety, particularly with younger participants.

CONCLUSIONS

Ongoing communication with the Duchenne CAB and with DMD and DM1 patient advisory committee members allows Dyne to stay current with disease community perspectives and feedback on the needs and preferences of those affected and has provided valuable insights into the participant experience thereby helping Dyne initiate clinical trials that better meet the needs of affected individuals and their families.

Sporadic Myotonic Dystrophy Type 2 in a Japanese Patient

We herein report a Japanese patient with myotonic dystrophy type 2 (DM2), which is rare in Japan. A 64-year-oldman had proximal muscle weakness and grip myotonia. Electromyography showed myotonic discharges, but dystrophia-myotonica protein kinase (DMPK) was negative for CTG repeats. A muscle biopsy revealed increased central nuclei, pyknotic nuclear clumps and muscle fiber atrophy, mainly in type 2 fibers, raising the possibility of DM2. The diagnosis was genetically confirmed by the abnormal CCTG repeat size in cellular nucleic acid-binding protein (CNBP) on repeat-primed polymerase chain reaction, which was estimated to be around 4,500 repeats by Southern blotting.

A diagnostic support system based on pain drawings: binary and k-disease classification of EDS, GBS, FSHD, PROMM, and a control group with Pain2D

BACKGROUND AND OBJECTIVE

The diagnosis of rare diseases (RDs) is often challenging due to their rarity, variability and the high number of individual RDs, resulting in a delay in diagnosis with adverse effects for patients and healthcare systems. The development of computer assisted diagnostic decision support systems could help to improve these problems by supporting differential diagnosis and by prompting physicians to initiate the right diagnostic tests. Towards this end, we developed, trained and tested a machine learning model implemented as part of the software called Pain2D to classify four rare diseases (EDS, GBS, FSHD and PROMM), as well as a control group of unspecific chronic pain, from pen-and-paper pain drawings filled in by patients.

METHODS

Pain drawings (PDs) were collected from patients suffering from one of the four RDs, or from unspecific chronic pain. The latter PDs were used as an outgroup in order to test how Pain2D handles more common pain causes. A total of 262 (59 EDS, 29 GBS, 35 FSHD, 89 PROMM, 50 unspecific chronic pain) PDs were collected and used to generate disease specific pain profiles. PDs were then classified by Pain2D in a leave-one-out-cross-validation approach.

RESULTS

Pain2D was able to classify the four rare diseases with an accuracy of 61-77% with its binary classifier. EDS, GBS and FSHD were classified correctly by the Pain2D k-disease classifier with sensitivities between 63 and 86% and specificities between 81 and 89%. For PROMM, the k-disease classifier achieved a sensitivity of 51% and specificity of 90%.

CONCLUSIONS

Pain2D is a scalable, open-source tool that could potentially be trained for all diseases presenting with pain.

Clinical score for early diagnosis of myotonic dystrophy type 2

INTRODUCTION

Myotonic dystrophy type 2 (DM2) is a rare, multisystemic, autosomal dominant disease with highly variable clinical presentation. DM2 is considered to be highly underdiagnosed.

OBJECTIVE

The aim of this study was to determine which symptoms, signs, and diagnostic findings in patients referred to neurological outpatient units are the most indicative to arouse suspicion of DM2. We tried to make a useful and easy-to-administer clinical scoring system for early diagnosis of DM2-DM2 early diagnosis score (DM2-EDS).

PATIENTS AND METHODS

Two hundred ninety-one patients with a clinical suspicion of DM2 were included: 69 were genetically confirmed to have DM2, and 222 patients were DM2 negative. Relevant history, neurological, and paraclinical data were obtained from the electronic medical records.

RESULTS

The following parameters appeared as significant predictors of DM2 diagnosis: cataracts (beta = 0.410, p < 0.001), myotonia on needle EMG (beta = 0.298, p < 0.001), hand tremor (beta = 0.211, p = 0.001), positive family history (beta = 0.171, p = 0.012), and calf hypertrophy (beta = 0.120, p = 0.043). In the final DM2-EDS, based on the beta values, symptoms were associated with the following values: cataracts (present 3.4, absent 0), myotonia (present 2.5, absent 0), tremor (present 1.7, absent 0), family history (positive 1.4, negative 0), and calf hypertrophy (present 1.0, absent 0). A cut-off value on DM2-EDS of 3.25 of maximum 10 points had a sensitivity of 84% and specificity of 81% to diagnose DM2.

CONCLUSION

Significant predictors of DM2 diagnosis in the neurology outpatient unit were identified. We made an easy-to-administer DM2-EDS score for early diagnosis of DM2.

Myotonic Dystrophy

PURPOSE OF REVIEW

Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) are genetic disorders affecting skeletal and smooth muscle, heart, brain, eyes, and other organs. The multisystem involvement and disease variability of myotonic dystrophy have presented challenges for clinical care and research. This article focuses on the diagnosis and management of the disease. In addition, recent advances in characterizing the diverse clinical manifestations and variability of the disease are discussed.

RECENT FINDINGS

Studies of the multisystem involvement of myotonic dystrophy, including the most lethal cardiac and respiratory manifestations and their molecular underpinnings, expand our understanding of the myotonic dystrophy phenotype. Advances have been made in understanding the molecular mechanisms of both types of myotonic dystrophy, providing opportunities for developing targeted therapeutics, some of which have entered clinical trials in DM1.

SUMMARY

Continued efforts focus on advancing our molecular and clinical understanding of DM1 and DM2. Accurately measuring and monitoring the diverse and variable clinical manifestations of myotonic dystrophy in clinic and in research is important to provide adequate care, prevent complications, and find treatments that improve symptoms and life quality.

Continuing the sequence? Towards an economic evaluation of whole genome sequencing for the diagnosis of rare diseases in Scotland

Novel developments in genomic medicine may reduce the length of the diagnostic odyssey for patients with rare diseases. Health providers must thus decide whether to offer genome sequencing for the diagnosis of rare conditions in a routine clinical setting. We estimated the costs of singleton standard genetic testing and trio-based whole genome sequencing (WGS), in the context of the Scottish Genomes Partnership (SGP) study. We also explored what users value about genomic sequencing. Insights from the costing and value assessments will inform a subsequent economic evaluation of genomic medicine in Scotland. An average cost of £1,841 per singleton was estimated for the standard genetic testing pathway, with significant variability between phenotypes. WGS cost £6625 per family trio, but this estimate reflects the use of WGS during the SGP project and large cost savings may be realised if sequencing was scaled up. Patients and families valued (i) the chance of receiving a diagnosis (and the peace of mind and closure that brings); (ii) the information provided by WGS (including implications for family planning and secondary findings); and (iii) contributions to future research. Our costings will be updated to address limitations of the current study for incorporation in budget impact modelling and cost-effectiveness analysis (cost per diagnostic yield). Our insights into the benefits of WGS will guide the development of a discrete choice experiment valuation study. This will inform a user-perspective cost-benefit analysis of genome-wide sequencing, accounting for the broader non-health outcomes. Taken together, our research will inform the long-term strategic development of NHS Scotland clinical genetics testing services, and will be of benefit to others seeking to undertake similar evaluations in different contexts.

Autoimmune Diseases in Patients With Myotonic Dystrophy Type 2

Introduction

Myotonic dystrophy type 2 (DM2) is a rare autosomal dominant multisystemic disease with highly variable clinical presentation. Several case reports and one cohort study suggested a significant association between DM2 and autoimmune diseases (AIDs).

Aim

The aim of this study is to analyze the frequency and type of AIDs in patients with DM2 from the Serbian DM registry.

Patients and Methods

A total of 131 patients with DM2 from 108 families were included, [62.6% women, mean age at DM2 onset 40.4 (with standard deviation 13) years, age at entering the registry 52 (12.8) years, and age at analysis 58.4 (12.8) years]. Data were obtained from Akhenaten, the Serbian registry for DM, and through the hospital electronic data system.

Results

Upon entering the registry, 35 (26.7%) of the 131 patients with DM2 had AIDs including Hashimoto thyroiditis (18.1%), rheumatoid arthritis, diabetes mellitus type 1, systemic lupus, Sjogren's disease, localized scleroderma, psoriasis, celiac disease, Graves's disease, neuromyelitis optica, myasthenia gravis, and Guillain-Barre syndrome. At the time of data analysis, one additional patient developed new AIDs, so eventually, 36 (28.8%) of 125 DM2 survivors had AIDs. Antinuclear antibodies (ANAs) were found in 14 (10.7%) of 63 tested patients, including 12 without defined corresponding AID (all in low titers, 1:40 to 1:160). Antineutrophil cytoplasmic antibodies (ANCAs) were negative in all 50 tested cases. The percentage of women was significantly higher among patients with AIDs (82.9% vs. 55.2%, p <0.01).

Conclusion

AIDs were present in as high as 30% of the patients with DM2. Thus, screening for AIDs in DM2 seems reasonable. Presence of AIDs and/or ANAs may lead to under-diagnosis of DM2.

Milestones of progression in myotonic dystrophy type 1 and type 2

INTRODUCTION/AIMS

Disease progression in myotonic dystrophy (DM) is marked by milestone events, when functional thresholds are crossed. DM type 2 (DM2) is considered less severe than DM type 1 (DM1), but whether this applies uniformly to all features is unknown. We compared the age-dependent risk for milestone events in DM1 and DM2, and tested for associations with age of onset and sex.

METHODS

We studied a large cohort of adult participants in a national registry of DM1 and DM2. Using annual surveys from participants, we ascertained milestone events for motor involvement (use of cane, walker, ankle brace, wheelchair, or ventilatory device), systemic involvement (diabetes, pacemaker, cancer), loss of employment due to DM, and death.

RESULTS

Mean follow-up of registry participants (DM1 = 929, DM2=222) was 7 years. Disability and motor milestones occurred at earlier ages in DM1 than in DM2. In contrast, the risk of diabetes was higher and tended to occur earlier in DM2 (HR=0.56, p=<0.001). In DM1, the milestone events tended to occur earlier, and life expectancy was reduced, when symptoms began at younger ages. In DM1, men were at greater risk for disability (HR=1.34, p=<0.01), use of ankle braces (HR=1.41, p=0.02), and diabetes (HR=2.2, p=<0.0001), whereas women were at greater risk for using walkers (HR=0.68, p=0.001) or malignancy (0.66, p=<0.01).

DISCUSSION

Milestone events recorded through registries can be used to assess long-term impact of DM in large cohorts. Except for diabetes, the age-related risk of milestone events is greater in DM1 than in DM2.

Cellular Senescence and Aging in Myotonic Dystrophy

Myotonic dystrophy (DM) is a dominantly inherited multisystemic disorder affecting various organs, such as skeletal muscle, heart, the nervous system, and the eye. Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are caused by expanded CTG and CCTG repeats, respectively. In both forms, the mutant transcripts containing expanded repeats aggregate as nuclear foci and sequester several RNA-binding proteins, resulting in alternative splicing dysregulation. Although certain alternative splicing events are linked to the clinical DM phenotypes, the molecular mechanisms underlying multiple DM symptoms remain unclear. Interestingly, multi-systemic DM manifestations, including muscle weakness, cognitive impairment, cataract, and frontal baldness, resemble premature aging. Furthermore, cellular senescence, a critical contributor to aging, is suggested to play a key role in DM cellular pathophysiology. In particular, several senescence inducers including telomere shortening, mitochondrial dysfunction, and oxidative stress and senescence biomarkers such as cell cycle inhibitors, senescence-associated secretory phenotype, chromatin reorganization, and microRNA have been implicated in DM pathogenesis. In this review, we focus on the clinical similarities between DM and aging, and summarize the involvement of cellular senescence in DM and the potential application of anti-aging DM therapies.

An integrated approach to the evaluation of patients with asymptomatic or minimally symptomatic hyperCKemia

Introduction/Aims

Currently, there are no straightforward guidelines for the clinical and diagnostic management of hyperCKemia, a frequent and nonspecific presentation in muscle diseases. Therefore, we aimed to describe our diagnostic workflow for evaluating patients with this condition.

Methods

We selected 83 asymptomatic or minimally symptomatic patients with persistent hyperCKemia for participation in this Italian multicenter study. Patients with facial involvement and distal or congenital myopathies were excluded, as were patients with suspected inflammatory myopathies or predominant respiratory or cardiac involvement. All patients underwent a neurological examination and nerve conduction and electromyography studies. The first step of the investigation included a screening for Pompe disease. We then evaluated the patients for myotonic dystrophy type II–related CCTG expansion and excluded patients with copy number variations in the DMD gene. Subsequently, the undiagnosed patients were investigated using a target gene panel that included 20 genes associated with isolated hyperCKemia.

Results

Using this approach, we established a definitive diagnosis in one third of the patients. The detection rate was higher in patients with severe hyperCKemia and abnormal electromyographic findings.

Discussion

We have described our diagnostic workflow for isolated hyperCKemia, which is based on electrodiagnostic data, biochemical screening, and first‐line genetic investigations, followed by successive targeted sequencing panels. Both clinical signs and electromyographic abnormalities are associated with increased diagnostic yields.

Current Treatment Options for Patients with Myotonic Dystrophy Type 2

Purpose of the review

Myotonic dystrophy types 1 and 2 are frequent forms of muscular dystrophies in adulthood. Their clinical differences need to be taken into account for the most appropriate treatment of patients. The aim of this article is to provide an overview on the current and upcoming therapeutic options for patients with myotonic dystrophy type 2 (DM2).

Recent findings

At the moment, no disease-modifying therapies are available for DM2; next-generation therapies may however be available in the near future. In the meanwhile, the symptomatic management of patients has greatly improved, thank to the production of consensus-based standards of care and the growing evidence of efficacy of anti-myotonic drugs, promising employment of cannabinoids for symptom’s relief, regular monitoring, and early detection of treatable extra-muscular manifestations.

Summary

The treatment of DM2 is currently symptomatic and relies on the coordinated intervention of a multidisciplinary team. It remains to be determined whether upcoming causal therapies for myotonic dystrophy type 1 will be applicable also in DM2.

Ancestral Origin of the First Indian Families with Myotonic Dystrophy Type 2

BACKGROUND

Myotonic dystrophy type 2 (DM2) is caused by a CCTG repeat expansion in intron 1 of the CCHC-Type Zinc Finger Nucleic Acid Binding Protein (CNBP) gene. Previous studies indicated that this repeat expansion originates from separate founders.

OBJECTIVE

This study was set out to determine whether or not patients with DM2 originating from European and non-European countries carry the previously described European founder haplotypes.

METHODS

Haplotype analysis was performed in 59 DM2 patients from 29 unrelated families. Twenty-three families were from European descent and 6 families originated from non-European countries (India, Suriname and Morocco). Seven short tandem repeats (CL3N122, CL3N99, CL3N59, CL3N117, CL3N119, CL3N19 and CL3N23) and 4 single nucleotide polymorphisms (SNP) (rs1871922, rs1384313, rs4303883 and CGAP_886192) in and around the CNBP gene were used to construct patients' haplotypes. These haplotypes were compared to the known DM2 haplotypes to determine the ancestral origin of the CNBP repeat expansion.

RESULTS

Of 41 patients, the haplotype could be assigned to the previously described Caucasian haplotypes. Three patients from Morocco and Portugal had a haplotype identical to the earlier reported Moroccan haplotype. Twelve patients from India and Suriname, however, carried a haplotype that seems distinct from the previously reported haplotypes. Three individuals could not be assigned to a specific haplotype.

CONCLUSION

The ancestral origin of DM2 in India might be distinct from the Caucasian families and the solely described Japanese patient. However, we were unable to establish this firmly due to the limited genetic variation in the region surrounding the CNBP gene.

A 14-Year Italian Experience in DM2 Genetic Testing: Frequency and Distribution of Normal and Premutated CNBP Alleles

Myotonic dystrophy type 2 (DM2) is a multisystemic disorder caused by a (CCTG)_n in intron 1 of the CNBP gene. The CCTG repeat tract is part of a complex (TG)_v(TCTG)_w(CCTG)_x(NCTG)_y(CCTG)_z motif generally interrupted in CNBP healthy range alleles. Here we report our 14-year experience of DM2 postnatal genetic testing in a total of 570 individuals. The DM2 locus has been analyzed by a combination of SR-PCR, TP-PCR, LR-PCR, and Sanger sequencing of CNBP alleles. DM2 molecular diagnosis has been confirmed in 187/570 samples analyzed (32.8%) and is mainly associated with the presence of myotonia in patients. This set of CNBP alleles showed unimodal distribution with 25 different alleles ranging from 108 to 168 bp, in accordance with previous studies on European populations. The most frequent CNBP alleles consisted of 138, 134, 140, and 136 bps with an overall locus heterozygosity of 90%. Sequencing of 103 unexpanded CNBP alleles in DM2-positive patients revealed that (CCTG)₅(NCTG)₃(CCTG)₇ and (CCTG)₆(NCTG)₃(CCTG)₇ are the most common interruption motifs. We also characterized five CNBP premutated alleles with (CCTG)_n repetitions from n = 36 to n = 53. However, the molecular and clinical consequences in our cohort of samples are not unequivocal. Data that emerged from this study are representative of the Italian population and are useful tools for National and European centers offering DM2 genetic testing and counseling.

Cerebral involvement and related aspects in myotonic dystrophy type 2

Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystemic disorder caused by CCTG repeats expansion in the first intron of the CNBP gene. In this review we focus on the brain involvement in DM2, including its pathogenic mechanisms, microstructural, macrostructural and functional brain changes, as well as the effects of all these impairments on patients' everyday life. We also try to understand how brain abnormalities in DM2 should be adequately measured and potentially treated. The most important pathogenetic mechanisms in DM2 are RNA gain-of-function and repeat-associated non-ATG (RAN) translation. One of the main neuroimaging findings in DM2 is the presence of diffuse periventricular white matter hyperintensity lesions (WMHLs). Brain atrophy has been described in DM2 patients, but it is not clear if it is mostly caused by a decrease of the white or gray matter volume. The most commonly reported specific cognitive symptoms in DM2 are dysexecutive syndrome, visuospatial and memory impairments. Fatigue, sleep-related disorders and pain are also frequent in DM2. The majority of key symptoms and signs in DM2 has a great influence on patients' daily lives, their psychological status, economic situation and quality of life.

Facilitations and Hurdles of Genetic Testing in Neuromuscular Disorders

Neuromuscular disorders (NMDs) comprise a heterogeneous group of disorders that affect about one in every thousand individuals worldwide. The vast majority of NMDs has a genetic cause, with about 600 genes already identified. Application of genetic testing in NMDs can be useful for several reasons: correct diagnostic definition of a proband, extensive familial counselling to identify subjects at risk, and prenatal diagnosis to prevent the recurrence of the disease; furthermore, identification of specific genetic mutations still remains mandatory in some cases for clinical trial enrollment where new gene therapies are now approaching. Even though genetic analysis is catching on in the neuromuscular field, pitfalls and hurdles still remain and they should be taken into account by clinicians, as for example the use of next generation sequencing (NGS) where many single nucleotide variants of “unknown significance” can emerge, complicating the correct interpretation of genotype-phenotype relationship. Finally, when all efforts in terms of molecular analysis have been carried on, a portion of patients affected by NMDs still remain “not genetically defined”. In the present review we analyze the evolution of genetic techniques, from Sanger sequencing to NGS, and we discuss “facilitations and hurdles” of genetic testing which must always be balanced by clinicians, in order to ensure a correct diagnostic definition, but taking always into account the benefit that the patient could obtain especially in terms of “therapeutic offer”.

Facilitations and Hurdles of Genetic Testing in Neuromuscular Disorders

Neuromuscular disorders (NMDs) comprise a heterogeneous group of disorders that affect about one in every thousand individuals worldwide. The vast majority of NMDs has a genetic cause, with about 600 genes already identified. Application of genetic testing in NMDs can be useful for several reasons: correct diagnostic definition of a proband, extensive familial counselling to identify subjects at risk, and prenatal diagnosis to prevent the recurrence of the disease; furthermore, identification of specific genetic mutations still remains mandatory in some cases for clinical trial enrollment where new gene therapies are now approaching. Even though genetic analysis is catching on in the neuromuscular field, pitfalls and hurdles still remain and they should be taken into account by clinicians, as for example the use of next generation sequencing (NGS) where many single nucleotide variants of "unknown significance" can emerge, complicating the correct interpretation of genotype-phenotype relationship. Finally, when all efforts in terms of molecular analysis have been carried on, a portion of patients affected by NMDs still remain "not genetically defined". In the present review we analyze the evolution of genetic techniques, from Sanger sequencing to NGS, and we discuss "facilitations and hurdles" of genetic testing which must always be balanced by clinicians, in order to ensure a correct diagnostic definition, but taking always into account the benefit that the patient could obtain especially in terms of "therapeutic offer".

Neurocognitive Features of Motor Premanifest Individuals With Myotonic Dystrophy Type 1

Objective

The goal of the study was to identify brain and functional features associated with premanifest phases of adult-onset myotonic dystrophy type 1 (i.e., PreDM1).

Methods

This cross-sectional study included 68 healthy adults (mean age = 43.4 years, SD = 12.9), 13 individuals with PreDM1 (mean age: 47.4 years, SD = 16.3), and 37 individuals with manifest DM1 (mean age = 45.2 years, SD = 9.3). The primary outcome measures included fractional anisotropy (FA), motor measures (Muscle Impairment Rating Scale, Grooved Pegboard, Finger-Tapping Test, and grip force), general cognitive abilities (Wechsler Adult Intelligence Scales), sleep quality (Scales for Outcomes in Parkinson's Disease–Sleep), and apathy (Apathy Evaluation Scale).

Results

Individuals with PreDM1 exhibited an intermediate level of white matter FA abnormality, where whole-brain FA was lower relative to healthy controls (difference of the estimated marginal mean [EMM_difference] = 0.02, 95% confidence interval (CI) 0.01–0.03, p < 0.001), but the PreDM1 group had significantly higher FA than did individuals with manifest DM1 (EMM_difference = 0.02, 95% CI 0.009–0.03, p < 0.001). Individuals with PreDM1 exhibited reduced performance on the finger-tapping task relative to control peers (EMM_difference = 5.70, 95% CI 0.51–11.00, p = 0.03), but performance of the PreDM1 group was better than that of the manifest DM1 group (EMM_difference = 5.60, 95% CI 0.11–11.00, p = 0.05). Hypersomnolence in PreDM1 was intermediate between controls (EMM_difference = −1.70, 95% CI −3.10–0.35, p = 0.01) and manifest DM1 (EMM_difference = −2.10, 95% CI −3.50–0.60, p = 0.006).

Conclusions

Our findings highlight key CNS and functional deficits associated with PreDM1, offering insight in early disease course.

Myotonic Muscular Dystrophy Type 2 in CT, USA: A Single-Center Experience With 50 Patients

ABSTRACT

Myotonic dystrophy type 2 (DM2) is an autosomal dominant disorder due to a (CCTG)n repeat expansion in intron 1 of the CNBP gene. In this article, we report the clinicopathologic findings in 50 patients seen at a single site over a 27 year period. DM2 was the fifth most common type of muscular dystrophy seen at our center with a 5-fold lower frequency as compared to DM1. Age of symptom onset ranged from 15 to 72 years, and the mean duration between symptom onset and diagnosis was 7.4 years. Weakness referable to the proximal lower extremities was the presenting symptom in 62% of patients. The degree of generalized weakness varied from severe in 30% to no weakness in 20% of patients. Clinical myotonia was noted in 18% and myotonic discharges on electromyography in 97% of patients. Pain symptoms were uncommon in our cohort. A significant correlation was noted between limb weakness and degree of muscle pathologic changes. There was no correlation between CCTG repeat size and other clinicopathologic findings. Six patients (12%) had cardiac abnormalities including one who developed progressive nonischemic dilated cardiomyopathy ultimately leading to cardiac transplantation. In 21 patients followed for 2 or more years, we noted a mean rate of decline in total Medical Research Council score of about 1% per year.

High throughput screening for expanded CTG repeats in myotonic dystrophy type 1 using melt curve analysis

Background

Myotonic dystrophy type 1 (DM1) is caused by CTG repeat expansions in the DMPK gene and is the most common form of muscular dystrophy. Patients can have long delays from onset to diagnosis, since clinical signs and symptoms are often nonspecific and overlapping with other disorders. Clinical genetic testing by Southern blot or triplet‐primed PCR (TP‐PCR) is technically challenging and cost prohibitive for population surveys.

Methods

Here, we present a high throughput, low‐cost screening tool for CTG repeat expansions using TP‐PCR followed by high resolution melt curve analysis with saturating concentrations of SYBR GreenER dye.

Results

We determined that multimodal melt profiles from the TP‐PCR assay are a proxy for amplicon length stoichiometry. In a screen of 10,097 newborn blood spots, melt profile analysis accurately reflected the tri‐modal distribution of common alleles from 5 to 35 CTG repeats, and identified the premutation and full expansion alleles.

Conclusion

We demonstrate that robust detection of expanded CTG repeats in a single tube can be achieved from samples derived from specimens with minimal template DNA such as dried blood spots (DBS). This technique is readily adaptable to large‐scale testing programs such as population studies and newborn screening programs.

Population-Based Prevalence of Myotonic Dystrophy Type 1 Using Genetic Analysis of Statewide Blood Screening Program

OBJECTIVE

To determine whether the genetic prevalence of the CTG expansion in the DMPK gene associated with myotonic dystrophy type 1 (DM1) in an unbiased cohort is higher than previously reported population estimates, ranging from 5 to 20 per 100,000 individuals.

METHODS

This study used a cross-sectional cohort of deidentified dried blood spots from the newborn screening program in the state of New York, taken from consecutive births from 2013 to 2014. Blood spots were screened for the CTG repeat expansion in the DMPK gene using triplet-repeat primed PCR and melt curve analysis. Melt curve morphology was assessed by 4 blinded reviewers to identify samples with possible CTG expansion. Expansion of the CTG repeat was validated by PCR fragment sizing using capillary electrophoresis for samples classified as positive or premutation to confirm the result. Prevalence was calculated as the number of samples with CTG repeat size ≥50 repeats compared to the overall cohort.

RESULTS

Of 50,382 consecutive births, there were 24 with a CTG repeat expansion ≥50, consistent with a diagnosis of DM1. This represents a significantly higher DM1 prevalence of 4.76 per 10,000 births (95% confidence interval 2.86-6.67) or 1 in every 2,100 births. There were an additional 96 samples (19.1 per 10,000 or 1 in 525 births) with a CTG expansion in the DMPK gene in the premutation range (CTG)_35-49.

CONCLUSION

The prevalence of individuals with CTG repeat expansions in DMPK is up to 5 times higher than previous reported estimates. This suggests that DM1, with multisystemic manifestations, is likely underdiagnosed in practice.

Utility and Results from a Patient-Reported Online Survey in Myotonic Dystrophies Types 1 and 2

INTRODUCTION

Myotonic dystrophies (DMs) are the most frequent autosomal dominant neuromuscular disorders in adults. Our objective was to evaluate the utility of an online survey in a rare disease as well as to assess and compare the onset and the progression of clinical symptoms in patients with myotonic dystrophy types 1 (DM1) and 2 (DM2).

METHODS

We conducted a patient's reported online survey assessing demographics, disease-related symptoms (age of onset, first symptom, time of diagnosis, current symptoms, inheritance, and family history) combined with capturing current symptoms by validated questionnaires. The questionnaire consisted of open, closed, single- and multiple-choice questions. Multiple answers were possible in some cases. Patients with genetically confirmed DM1 or DM2 who were registered in the German DM registry or the Deutsche Gesellschaft für Muskelkranke e.V. - Diagnostic Group for DMs were invited to participate in this online survey. We calculated descriptive and exploratory analysis, where applicable.

RESULTS

Out of 677 data sets from respondents, 394 were suitable for final analysis, containing completed questionnaires from 207 DM1 (56% female) and 187 DM2 patients (71% female). The median age of onset was 28 years for DM1 and 35 years for DM2. Muscular symptoms were most frequently reported as the first symptom. The onset of myotonia was earlier than the onset of muscle weakness in both DM1 and DM2. Forty-four percent of patients with DM1 and one-third of patients with DM2 indicated muscle weakness as the first symptom. Patients with DM1 were significantly younger when experiencing muscle weakness as first symptom. Fatigue was only mentioned by a small fraction of patients as a first symptom but increased significantly in the course of the disease. There was no statistically significant difference in the incidence of cataracts, cardiac symptoms, and gastrointestinal symptoms between DM1 and DM2. Falls were reported almost equally in both groups, and most of the patients reported 2-3 falls within the past year.

DISCUSSION

Overall, as our results are consistent with the results of clinical studies and online registries, it can be assumed that this type of systematic gathering of data from patients with rare diseases is useful and provides realistic and appropriate results. Due to the nature of online surveys and the absence of an assessor, some uncertainty remains. Furthermore, survey frauds cannot be completely excluded. An additional clinical assessment could confirm the given information and will improve the utility and validity of reported symptoms participants provide in online surveys. Therefore, we recommend a combination of data collecting by online surveys and clinical assessments.

Efficacy and safety of ropivacaine HCl in peribulbar anaesthesia for cataract surgery in patients with myotonic dystrophy type 1

Myotonic dystrophy (DM1) is the most common muscle disease in adults, affecting approximately 1:8000 individuals, characterized by myotonia and muscular wasting and a multisystemic involvement that includes heart, brain, respiratory and endocrine system, and eye. Conduction system is selectively involved, often causing cardiac sudden death. Early onset posterior subcapsular cataract is a characteristic feature of myotonic dystrophy, requiring surgical treatment. However, DM1 is associated with many anesthetic hazards; sensitivity to anesthetic drugs, especially muscle relaxants and opioids, may complicate postoperative care. Local anesthesia also requires attention. We investigated the heart response to local anesthesia Ropivacaine Hcl administration in 16 DM1 patients (12M:4F) consecutively undergoing cataract surgery, by analyzing heart rate, ventricular and supraventricular ectopic beats, runs of tachycardia and pauses ≥ 2.5 sec., through a 24h-Holter monitoring, registered before and within 24 hours after surgery. The average age of patients was 47.4 years (range 30.2-55.9). At baseline, one patient had a pacemaker and 3 a defibrillator. Two patients presented a first-degree atrio-ventricular-block; three showed ectopic ventricular beats, on anti-arrhythmic drug treatment. No significant differences in heart rate values (73 ± 15b/m versus 76 ± 13b/m) were observed after cataract surgery, nor in the onset of ectopic beats. Only patients who presented ventricular ectopic beats at baseline, showed an increase in their number after surgery, likely related to an arbitrary interruption of the specific treatment. These data confirm the safety and efficacy of ropivacaine HCl used as a local anesthetic in patients with myotonic dystrophy.

Characterization of individuals with selected muscular dystrophies from the expanded pilot of the Muscular Dystrophy Surveillance, Tracking and Research Network (MD STARnet) in the United States

INTRODUCTION

Data on muscular dystrophies (MDs), a heterogeneous group of heritable diseases hallmarked by progressive muscle deterioration, are scarce.

OBJECTIVE

We describe cross-sectional sociodemographic and clinical characteristics of individuals with congenital, distal, Emery-Dreifuss, facioscapulohumeral, limb-girdle, myotonic, or oculopharyngeal MD.

METHODS

The study was conducted in four sites (Arizona, Colorado, Iowa, and 12 western New York counties) as a pilot expansion of the Muscular Dystrophy Surveillance, Tracking and Research Network, funded by the Centers for Disease Control and Prevention. MDs were detected in healthcare facilities and administrative data sources using International Classification of Disease codes. Our sample contains 1,723 individuals with a MD diagnosis and a healthcare encounter between January 1, 2007 and December 31, 2011.

RESULTS AND CONCLUSIONS

Individuals were mostly non-Hispanic and white. Median ages ranged from 9.2 to 66.0 years. Most (98%) had health insurance. The proportion of individuals who were disabled or unable to work increased with age (range: 8.6-46.4%). People with limb-girdle MD aged ≥18 years were more likely to be nonambulatory (range: 24.5-44.7%). The percentages of individuals with documented clinical interventions during the surveillance period were low. The most common cause of death was respiratory causes (46.3-57.1%); an ICD-10 code for MD (G71.1 or G71.0) was reported for nearly one-half. Our findings show wide variability in sociodemographic and clinical characteristics across MDs.

Diagnosis of Myotonic Dystrophy Based on Resting State fMRI Using Convolutional Neural Networks

Myotonic dystrophies (DM) are neuromuscular conditions that cause widespread effects throughout the body. There are brain white matter changes on MRI in patients with DM that correlate with neuropsychological functional changes. How these brain alterations causally relate to the presence and severity of cognitive symptoms remains largely unknown. Deep neural networks have significantly improved the performance of image classification of huge datasets. However, its application in brain imaging is limited and not well described, due to the scarcity of labeled training data. In this work, we propose an approach for the diagnosis of DM based on a spatio-temporal deep learning paradigm. The obtained accuracy (73.71%) and sensitivities and specificities showed that the implemented approach based on 4-D convolutional neural networks leads to a compact, discriminative, and fast computing DM-based clinical medical decision support system.Clinical relevance- Many adults with DM experience cognitive and neurological effects impacting their quality of life, and ability to maintain employment. A robust and reliable DM-based clinical decision support system may help reduce the long diagnostic delay common to DM. Furthermore, it can help neurologists better understand the pathophysiology of the disease and analyze effects of new drugs that aim to address the neurological symptoms of DM.

Myotonic Muscular Dystrophies

PURPOSE OF REVIEW

This article describes the clinical features, pathogenesis, prevalence, diagnosis, and management of myotonic dystrophy type 1 and myotonic dystrophy type 2.

RECENT FINDINGS

The prevalence of myotonic dystrophy type 1 is better understood than the prevalence of myotonic dystrophy type 2, and new evidence indicates that the risk of cancer is increased in patients with the myotonic dystrophies. In addition, descriptions of the clinical symptoms and relative risks of comorbidities such as cardiac arrhythmias associated with myotonic dystrophy type 1 have been improved.

SUMMARY

Myotonic dystrophy type 1 and myotonic dystrophy type 2 are both characterized by progressive muscle weakness, early-onset cataracts, and myotonia. However, both disorders have multisystem manifestations that require a comprehensive management plan. While no disease-modifying therapies have yet been identified, advances in therapeutic development have a promising future.

Association of Sjögren's syndrome with myotonic dystrophy type 1

A 47-year-old woman presented with sicca symptoms, polyarthralgias, polymyalgias and dysphagia. She was found to have positive antinuclear, anti-SSA-Ro and anti-SSB-La antibodies. Slit lamp exam confirmed the presence of keratoconjunctivitis sicca, and the patient was diagnosed with Sjögren's syndrome. Three years later, she was referred for evaluation of gait instability associated with recent falls. On physical examination, the patient was found to have bilateral ptosis, percussion myotonia, distal upper and lower extremity weakness, and a steppage gait. Electromyography demonstrated electrical myotonia. Genetic testing revealed expanded CTG repeats (733 and 533) in the myotonic dystrophy type 1 (DM1) protein kinase gene, confirming the diagnosis of DM1. Dysphagia, pain and eye discomfort may occur in both Sjögren's syndrome and DM1, and in this case, may have delayed the diagnosis of muscular dystrophy.

Misdiagnosis and diagnostic delay in non-paraneoplastic sensory neuronopathies

METHODS

Sensory neuronopathies (SN) are a group of peripheral nerve disorders characterized by multifocal non-length-dependent sensory deficits and sensory ataxia. Its recognition is essential not only for proper management but also to guide the etiological investigation. The uncommon SN clinical picture and its rarity set the conditions for the misdiagnosis and the diagnostic delay, especially in non-paraneoplastic SN. Therefore, our objectives were to characterize the diagnostic odyssey for non-paraneoplastic SN patients, as well as to identify possible associated factors. We consecutively enrolled 48 non-paraneoplastic SN patients followed in a tertiary neuromuscular clinic at the University of Campinas (Brazil). All patients were instructed to retrieve their previous medical records, and we collected the data regarding demographics, disease onset, previous incorrect diagnoses made and the recommended treatments.

RESULTS

There were 34 women, with a mean age at the diagnosis of 45.9 ± 12.2 years, and 28/48 (58%) of the patients were idiopathic. Negative sensory symptoms were the heralding symptoms in 25/48 (52%); these were asymmetric in 36/48 (75%) and followed a chronic course in 35/48 (73%). On average, it took 5.4 ± 5.3 years for SN to be diagnosed; patients had an average of 3.4 ± 1.5 incorrect diagnoses. A disease onset before the age of 40 was associated to shorter diagnosis delay (3.7 ± 3.4 vs. 7.8 ± 6.7 years, p = 0.01).

CONCLUSIONS

These results suggest that diagnostic delay and misdiagnosis are frequent in non-paraneoplastic SN patients. As in other rare conditions, increased awareness in all the healthcare system levels is paramount to ensure accurate diagnosis and to improve care of these patients.

PhenoPro: a novel toolkit for assisting in the diagnosis of Mendelian disease

Motivation

Whole-exome sequencing (WES) is now being used in clinical practice for the diagnosis of the causal genes of Mendelian diseases. In order to make the diagnosis, however, the clinical phenotypes [e.g. Human Phenotype Ontology (HPO) terms] of a patient are needed for prioritizing the variants called from the WES data of the patient. Computational tools are therefore needed to standardize and accelerate this process.

Results

Here, we introduce a tool named PhenoPro for prioritizing the causal gene of Mendelian disease given both the HPO terms assigned to and the variants called from the WES data of a patient. PhenoPro has been benchmarked using both simulated patients and 287 real diagnosed patients of Chinese ancestry, and shows significant improvements over five previous tools. Moreover, the addition of an internal variant data of Chinese ancestry and the variant data from the patients’ parents can further improve PhenoPro’s performance. To make PhenoPro a fully automated tool, we also include a natural language processing component for automated HPO term assignment from clinical reports, and demonstrate that the natural language processing is as effective as manual HPO assignment using real clinical reports. In conclusion, PhenoPro can be used as a pre-screening tool to assist in the diagnosis of Mendelian disease genes.

Availability and implementation

The web server of PhenoPro is freely available at http://app.tianlab.cn.

Supplementary information

Supplementary data are available at Bioinformatics online.

The myotonic dystrophy experience: a North American cross-sectional study

Introduction: Myotonic dystrophy (DM) is a chronic, multisystemic, neurological condition. Patients and caregivers are uniquely suited to identify what symptoms are most important and highlight the unmet needs that are most relevant to DM. Methods: We conducted a North American, cross‐sectional study of people with DM type‐1, congenital DM, and DM type‐2 and their family members. We sent patients and caregivers separate surveys to identify and quantitate the issues of greatest importance, examine the differences between groups, and identify the most important challenges experienced by this population. Results: 1,180 people with DM and 402 family members/caregivers responded to the surveys. They reported considerable physical and cognitive symptoms, extensive diagnostic delays, and varying clinical phenotypes on the basis of DM type. Discussion: Marked disease burden and numerous unmet needs exist in DM. These needs vary based on DM type and highlight the complex clinical phenotypes of these neurological disorders. Muscle Nerve 59:457–464, 2019

Myotonic Dystrophies: Targeting Therapies for Multisystem Disease

Myotonic dystrophy is an autosomal dominant muscular dystrophy not only associated with muscle weakness, atrophy, and myotonia but also prominent multisystem involvement. There are 2 similar, but distinct, forms of myotonic dystrophy; type 1 is caused by a CTG repeat expansion in the DMPK gene, and type 2 is caused by a CCTG repeat expansion in the CNBP gene. Type 1 is associated with distal limb, neck flexor, and bulbar weakness and results in different phenotypic subtypes with variable onset from congenital to very late-onset as well as variable signs and symptoms. The classically described adult-onset form is the most common. In contrast, myotonic dystrophy type 2 is adult-onset or late-onset, has proximal predominant muscle weakness, and generally has less severe multisystem involvement. In both forms of myotonic dystrophy, the best characterized disease mechanism is a RNA toxic gain-of-function during which RNA repeats form nuclear foci resulting in sequestration of RNA-binding proteins and, therefore, dysregulated splicing of premessenger RNA. There are currently no disease-modifying therapies, but clinical surveillance, preventative measures, and supportive treatments are used to reduce the impact of muscular impairment and other systemic involvement including cataracts, cardiac conduction abnormalities, fatigue, central nervous system dysfunction, respiratory weakness, dysphagia, and endocrine dysfunction. Exciting preclinical progress has been made in identifying a number of potential strategies including genome editing, small molecule therapeutics, and antisense oligonucleotide-based therapies to target the pathogenesis of type 1 and type 2 myotonic dystrophies at the DNA, RNA, or downstream target level.

Survival patterns and cancer determinants in families with myotonic dystrophy type 1

BACKGROUND AND PURPOSE

Research indicates that patients with myotonic dystrophy type 1 (DM1) are at increased risk of cancer and early death. Family data may provide insights given DM1 phenotypic heterogeneity, the broad range of non-muscular manifestations and the usual delays in the diagnosis of DM1.

METHOD

Family history data were collected from 397 genetically and/or clinically confirmed DM1 patients (respondents) enrolled in the US or UK myotonic dystrophy registries. Standardized mortality ratios were calculated for DM1 first-degree relatives (parents, siblings and offspring) by their reported DM1 status (affected, unaffected or unknown). For cancer-related analyses, mixed effects logistic regression models were used to evaluate factors associated with cancer development in DM1 families, including familial clustering.

RESULTS

A total of 467 deaths and 337 cancers were reported amongst 1737 first-degree DM1 relatives. Mortality risk amongst relatives reported as DM1-unaffected was comparable to that of the general population [standardized mortality ratio (SMR) 0.82, P = 0.06], whilst significantly higher mortality risks were noted in DM1-affected relatives (SMR = 2.47, P < 0.0001) and in those whose DM1 status was unknown (SMR = 1.60, P < 0.0001). In cancer risk analyses, risk was higher amongst families in which the DM1 respondent had cancer (odds ratio 1.95, P = 0.0001). Unknown DM1 status in the siblings (odds ratio 2.59, P = 0.004) was associated with higher cancer risk.

CONCLUSION

There is an increased risk of death, and probably cancer, in relatives with DM1 and in those whose DM1 status is unknown. This suggests a need to perform a careful history and physical examination, supplemented by genetic testing, to identify family members at risk for DM1 and who might benefit from disease-specific clinical care and surveillance.

Dysautonomia as Onset Symptom of Myotonic Dystrophy Type 2

Myotonic dystrophy type 2 (DM2) is an autosomal dominant muscular dystrophy caused by the expansion of an intronic tetranucleotide CCTG repeat in <i>CNBP</i> on chromosome 3. As DM1, DM2 is a multisystem disorder affecting, beside the skeletal muscle, various other tissues, including peripheral nerves. Indeed, a subclinical involvement of peripheral nervous system has been described in several cohorts of DM2 patients, whereas DM2 patients manifesting clinical signs and/or symptoms of neuropathy have been only rarely reported. Here, we describe 2 related DM2 patients both of whom displayed an atypical disease onset characterized by dysautonomic symptoms, possibly secondary to peripheral neuropathy.

Pain in SCN4A Mutated P.A1156T muscle sodium channelopathy-a postal survey

INTRODUCTION

The p.A1156T mutation alters the function of the voltage-gated sodium channel Nav1.4 on the muscle sarcolemma, causing a channelopathy without overt myotonia or periodic paralysis but with myalgic pain.

METHODS

A postal survey was conducted to assess the prevalence and characteristics of pain and related symptoms in individuals with the p.A1156T mutation. A specific questionnaire, intensity and interference subscales of the Brief Pain Inventory, pain drawing, Widespread Pain Index, quality of life (RAND-36), and the Beck Depression Inventory were completed.

RESULTS

Twenty of 24 patients replied. Current pain was reported by 16 respondents; the other 4 had experienced pain previously. Most commonly, pain was widespread and exercise-induced. The severity and the impact of pain on daily life were considerable, although varied.

DISCUSSION

This sodium channelopathy is another entity in the growing number of diseases causing widespread myalgic pain that resembles the pain seen in fibromyalgia syndrome. Muscle Nerve 57: 1014-1017, 2018.

Early onset posterior subscapular cataract in a series of myotonic dystrophy type 2 patients

PurposeEarly onset posterior subscapular cataract (<50 years of age) is a characteristic feature of myotonic dystrophy type 2 (DM2). Nevertheless, despite being operated at a young age, many patients remain undiagnosed for years. The purpose of this study was to assess the prevalence of early onset posterior subscapular cataract as a presenting symptom of the disease in a cohort of patients with DM2.Patients and methodsWe retrospectively reviewed medical records of DM2 patients followed in our institution for the presence of early onset posterior subscapular cataract, of any secondary causes of cataract, of the age of onset of muscle weakness and of final disease diagnosis.ResultsTwenty-eight patients were studied. Nine patients (32.1%) had presented early onset posterior subscapular cataract at a median age of 43 years (IQR=36-46) and seven (25%) reported it was the presenting sign. No patient was referred for neuromuscular evaluation due to the occurrence of early onset cataract. Median delay between cataract onset and referral for neuromuscular evaluation was 10 years (IQR=6.0-19.5) and final DM2 diagnosis was achieved after a median of 16 years (IQR=6.5-19.5).ConclusionThis study shows that early onset posterior subscapular cataract was the first symptom of the disease in 25% of our DM2 patients. Nevertheless, none was suspected of having cataract in the context of DM2, and referral for neuromuscular evaluation was made after a long delay and usually following the appearance of other symptoms. Ophthalmologists can be the first physicians encountering these patients and should have a low threshold for referring them for neuromuscular evaluation.

Chronic pain has a strong impact on quality of life in facioscapulohumeral muscular dystrophy

Introduction

Earlier small case series and clinical observations reported on chronic pain playing an important role in facioscapulohumeral dystrophy (FSHD). The aim of this study was to determine the characteristics and impact of pain on quality of life (QoL) in patients with FSHD.

Methods

We analyzed patient reported outcome measures collected through the U.K. FSHD Patient Registry.

Results

Of 398 patients, 88.6% reported pain at the time of study. The most frequent locations were shoulders and lower back. A total of 203 participants reported chronic pain, 30.4% of them as severe. The overall disease impact on QoL was significantly higher in patients with early onset and long disease duration. Chronic pain had a negative impact on all Individualised Neuromuscular Quality of Life Questionnaire domains and overall disease score.

Discussion

Our study shows that pain in FSHD type 1 (FSHD1) is frequent and strongly impacts on QoL, similar to other chronic, painful disorders. Management of pain should be considered when treating FSHD1 patients. Muscle Nerve57: 380–387, 2018

Assessing the influence of age and gender on the phenotype of myotonic dystrophy type 2

This study aims to provide a detailed clinical characterization of a large cohort of myotonic dystrophy type 2 (DM2) patients investigating the influence of age and gender as modifying factors of DM2 phenotype. A retrospective study was conducted on 307 patients with genetically confirmed DM2. The following data were analyzed: (1) demographics, (2) clinical features (first symptom, muscular complaints, and multisystemic involvement), (3) diagnostics (serological tests, electromyography, and muscle biopsy). In this cohort (186 females, 121 males), a proximal weakness was the leading symptom at onset (55.4%), followed by myalgia (35.5%) and myotonia (25.4%). Proximal weakness was more common in women than men (64.9 vs. 43.8%, p = 0.0006), whereas being male was associated with higher odds for developing myalgia [OR 2.94 (95% CI 1.53-5.67)]. Patients with muscle weakness at onset were older than those with myalgia and myotonia (p < 0.0001), while each additional disease year was associated with 10% decrease in the odds of developing myotonia [OR 0.9 (95% CI 0.87-0.93)] and 6% decrease of myalgia [OR 0.94 (95% CI 0.91-0.97)]. Cataract and thyroid diseases occurred more frequently in women (p = 0.002 and p = 0.002, respectively). Early onset of DM2 is an independent risk factor for the occurrence of multisystemic involvement [OR 0.94 (95% CI 0.90-0.98)]. In this updated clinical description of DM2 emerges a profound gender and age influence on the phenotype, emphasizing that female gender and ageing may be associated with a higher disease burden. These age- and gender-specific differences should be considered in diagnostics, management, and future clinical studies of DM2.

Magnetic resonance imaging of leg muscles in patients with myotonic dystrophies

Magnetic resonance imaging (MRI) of muscles has recently become a significant diagnostic procedure in neuromuscular disorders. There is a lack of muscle MRI studies in patients with myotonic dystrophy type 1 (DM1), especially type 2 (DM2). To analyze fatty infiltration of leg muscles, using 3.0 T MRI in patients with genetically confirmed DM1 and DM2 with different disease durations. The study comprised 21 DM1 and 10 DM2 adult patients. Muscle MRI was performed in axial plane of the lower limbs using T1-weighted (T1w) sequence. Six-point scale by Mercuri et al. was used. Fatty infiltration registered in at least one muscle of lower extremities was found in 71% of DM1 and 40% of DM2 patients. In DM1 patients, early involvement of the medial head of gastrocnemius and tibialis anterior muscles was observed with later involvement of other lower leg muscles and of anterior and posterior thigh compartments with relative sparing of the rectus femoris. In DM2, majority of patients had normal MRI findings. Early involvement of lower legs and posterior thighs was found in some patients. Less severe involvement of the medial head of the gastrocnemius compared to other lower leg muscles was also observed, while involvement of proximal muscles was rather diffuse than selective. It seems that both in DM1 and DM2 some muscles may be affected before weakness is clinically noted and vice versa. We described characteristic pattern and way of progression of muscle involvement in DM1 and DM2.

Biomolecular diagnosis of myotonic dystrophy type 2: a challenging approach

Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are the most common adult form of muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia, and multiorgan involvement. The onset and symptoms of the myotonic dystrophies are diverse, complicating their diagnoses and limiting a comprehensive approach to their clinical care. Diagnostic delay in DM2 is due not only to the heterogeneous phenotype and the aspecific onset but also to the unfamiliarity with the disorder by most clinicians. Moreover, the DM2 diagnostic odyssey is complicated by the difficulties to develop an accurate, robust, and cost-effective method for a routine molecular assay. The aim of this review is to underline by challenging approach the diagnostic limits and pitfalls that could results in failure to recognize the presence of DM2 disease. Understanding and preventing delays in DM2 diagnosis may facilitate family planning, improve symptom management in the short term, and facilitate more specific treatment in the long term.

Genetic Testing among Children in a Complex Care Program

Little is known about the pattern of genetic testing and frequency of genetic diagnoses among children enrolled in structured complex care programs (CCPs). Such information may inform the suitability of emerging genome diagnostics for this population. The objectives were to describe the proportion of children with undiagnosed genetic conditions despite genetic testing and measure the testing period, types and costs of genetic tests used. A retrospective analysis of 420 children enrolled in Toronto’s Hospital for Sick Children’s CCP from January 2010 until June 2014 was conducted. Among those who underwent genetic testing (n = 319; 76%), a random sample of 20% (n = 63) was further analyzed. A genetic diagnosis was confirmed in 48% of those who underwent testing. Those with no genetic diagnosis underwent significantly more genetic tests than those with a confirmed genetic diagnosis [median interquartile range (IQR): six tests (4–9) vs. three tests (2–4), p = 0.002], more sequence-level tests and a longer, more expensive testing period than those with a genetic diagnosis [median (IQR): length of testing period: 4.12 years (1.73–8.42) vs. 0.35 years (0.12–3.04), p < 0.001; genetic testing costs C$8496 ($4399–$12,480) vs. C$2614 ($1605–$4080), p < 0.001]. A genetic diagnosis was not established for 52% of children. Integrating genome-wide sequencing into clinical care may improve diagnostic efficiency and yield in this population.

The UK Myotonic Dystrophy Patient Registry: facilitating and accelerating clinical research

Myotonic dystrophy type 1 (DM1) is the most frequent muscular dystrophy worldwide with complex, multi-systemic, and progressively worsening symptoms. There is currently no treatment for this inherited disorder and research can be challenging due to the rarity and variability of the disease. The UK Myotonic Dystrophy Patient Registry is a patient self-enrolling online database collecting clinical and genetic information. For this cross-sectional “snapshot” analysis, 556 patients with a confirmed diagnosis of DM1 registered between May 2012 and July 2016 were included. An almost even distribution was seen between genders and a broad range of ages was present from 8 months to 78 years, with the largest proportion between 30 and 59 years. The two most frequent symptoms were fatigue and myotonia, reported by 79 and 78% of patients, respectively. The severity of myotonia correlated with the severity of fatigue as well as mobility impairment, and dysphagia occurred mostly in patients also reporting myotonia. Men reported significantly more frequent severe myotonia, whereas severe fatigue was more frequently reported by women. Cardiac abnormalities were diagnosed in 48% of patients and more than one-third of them needed a cardiac implant. Fifteen percent of patients used a non-invasive ventilation and cataracts were removed in 26% of patients, 65% of which before the age of 50 years. The registry’s primary aim was to facilitate and accelerate clinical research. However, these data also allow us to formulate questions for hypothesis-driven research that may lead to improvements in care and treatment.

Analysis of CTG repeat length variation in the DMPK gene in the general population and the molecular diagnosis of myotonic dystrophy type 1 in Malaysia

OBJECTIVE

The lack of epidemiological data and molecular diagnostic services in Malaysia has hampered the setting-up of a comprehensive management plan for patients with myotonic dystrophy type 1 (DM1), leading to delayed diagnosis, treatment and support for patients and families. The aim of this study was to estimate the prevalence of DM1 in the 3 major ethnic groups in Malaysia and evaluate the feasibility of a single tube triplet-primed PCR (TP-PCR) method for diagnosis of DM1 in Malaysia.

DESIGN, SETTING AND PARTICIPANTS

We used PCR to determine the size of CTG repeats in 377 individuals not known to be affected by DM and 11 DM1 suspected patients, recruited from a tertiary hospital in Kuala Lumpur. TP-PCR was performed on selected samples, followed by Southern blot hybridisation of PCR amplified fragments to confirm and estimate the size of CTG expansion.

OUTCOME MEASURES

The number of individuals not known to be affected by DM with (CTG)_>18 was determined according to ethnic group and as a whole population. The χ² test was performed to compare the distribution of (CTG)_>18 with 12 other populations. Additionally, the accuracy of TP-PCR in detecting CTG expansion in 11 patients with DM1 was determined by comparing the results with that from Southern blot hybridisation.

RESULTS

Of the 754 chromosomes studied, (CTG)_>18 frequency of 3.60%, 1.57% and 4.00% in the Malay, Chinese and Indian subpopulations, respectively, was detected, showing similarities to data from Thai, Taiwanese and Kuwaiti populations. We also successfully detected CTG expansions in 9 patients using the TP-PCR method followed by the estimation of CTG expansion size via Southern blot hybridisation.

CONCLUSIONS

The results show a low DM1 prevalence in Malaysia with the possibility of underdiagnosis and demonstrates the feasibility of using a clinical and TP-PCR-based approach for rapid and cost-effective DM1 diagnosis in developing countries.