High frequency of gastrointestinal manifestations in myotonic dystrophy type 1 and type 2

Disturbance of the human gut microbiota in patients with Myotonic Dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a rare autosomal dominant genetic disorder. Although DM1 is primarily characterized by progressive muscular weakness, it exhibits many multisystemic manifestations, such as cognitive deficits, cardiac conduction abnormalities, and cataracts, as well as endocrine and reproductive issues. Additionally, the gastrointestinal (GI) tract is frequently affected, encompassing the entire digestive tract. However, the underlying causes of these GI symptoms remain uncertain, whether it is biomechanical problems of the intestine, involvement of bacterial communities, or both. The primary objective of this study is to investigate the structural changes in the gut microbiome of DM1 patients. To achieve this purpose, 35 patients with DM1 were recruited from the DM-Scope registry of the neuromuscular clinic in the Saguenay-Lac-St-Jean region of the province of Québec, Canada. Stool samples from these 35 patients, including 15 paired samples with family members living with them as controls, were collected. Subsequently, these samples were sequenced by 16S MiSeq and were analyzed with DADA2 to generate taxonomic signatures. Our analysis revealed that the DM1 status correlated with changes in gut bacterial community. Notably, there were differences in the relative abundance of Bacteroidota, Euryarchaeota, Fusobacteriota, and Cyanobacteria Phyla compared to healthy controls. However, no significant shift in gut microbiome community structure was observed between DM1 phenotypes. These findings provide valuable insights into how the gut bacterial community, in conjunction with biomechanical factors, could potentially influence the gastrointestinal tract of DM1 patients.

Gastrointestinal and genitourinary symptoms in facioscapulohumeral muscular dystrophy: Prevalence and impact

INTRODUCTION/AIMS

Anecdotally, patients with facioscapulohumeral muscular dystrophy (FSHD) describe gastrointestinal (GI) and genitourinary (GU) symptoms. We explored the prevalence of GI and GU symptoms and their impact on quality of life (QOL) in people with FSHD compared to healthy household controls.

METHODS

In this descriptive, cross-sectional study, we emailed a survey exploring GI and GU symptoms to all FSHD Society patient contacts (n = 3507). We invited those with FSHD and unaffected household controls to respond. Non-parametric statistics were used to compare symptom frequency and impact of symptoms between respondents with FSHD and household controls. Within the FSHD group, symptom frequency was assessed relative to measures of disease progression (need for ambulatory or respiratory support).

RESULTS

Surveys from 701 respondents (652 with FSHD) ≥18 years old were included in analysis. Those with FSHD had symptoms affecting both GI and GU systems more frequently than controls using ordinal rating of symptom frequency. Within the FSHD group, more advanced disease was associated with increased symptom frequency. QOL was negatively impacted by the GI and GU symptoms. There was no difference between groups in use of medications to treat these symptoms.

DISCUSSION

Recognition and treatment of GI and GU symptoms in people with FSHD, particularly those with more advanced disease, could improve QOL. Additional investigation is required to confirm these findings and understand the physiology.

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.

Myotonic dystrophy type 1: 13 years of experience at a tertiary hospital. Clinical and epidemiological study and genotype-phenotype correlation

INTRODUCTION

The incidence of myotonic dystrophy type 1 (DM1), a disease with great phenotypic variety, in our region is unknown. This study aims to estimate the incidence of DM1 at our hospital (a reference centre in Aragon, Spain) and to identify the characteristics of our population (genotype-phenotype correlation).

METHODS

Retrospective, descriptive study of 459 patients classified according to the number of CTG repeats, as follows: normal (5-35), premutation (36-50), protomutation (51-80), small expansions (81-150), intermediate expansions (151-1000), and large expansions (> 1000). Furthermore, according to clinical phenotype, patients were categorised as unaffected (5-50 CTG repeats), mild form or asymptomatic (51-150), classical form (151-1000), and severe form (> 1000).

RESULTS

The incidence of DM1 was 20.61 cases per million person-years (95% CI, 19.59-21.63). An inverse correlation was observed between the number of CTG repeats and the age at genetic diagnosis (ρ = -0.547; 95% CI, -0.610 to -0.375; P < .001). CTG5 was the most frequent polymorphic allele in healthy individuals. Of all patients with DM1, 28.3% presented the mild or asymptomatic form, 59.1% the classical form, and 12.6% the severe form. Inheritance was maternal in 35.1% of cases, paternal in 59.4%, and uncertain in 5.5%. In mild forms, frontal balding in men was the most prevalent phenotypic trait, as well as myotonia and cataracts, while in the classical form, ptosis, facial weakness, voice and pronunciation alterations, myotonia, and fatigue/sleepiness were most frequent.

CONCLUSIONS

The incidence of DM1 in Aragon is significant. Multidisciplinary study of the phenotype of patients with DM1 is key to early diagnosis and personalised management.

European Neuromuscular Centre consensus statement on anaesthesia in patients with neuromuscular disorders

BACKGROUND AND PURPOSE

Patients with neuromuscular conditions are at increased risk of suffering perioperative complications related to anaesthesia. There is currently little specific anaesthetic guidance concerning these patients. Here, we present the European Neuromuscular Centre (ENMC) consensus statement on anaesthesia in patients with neuromuscular disorders as formulated during the 259th ENMC Workshop on Anaesthesia in Neuromuscular Disorders.

METHODS

International experts in the field of (paediatric) anaesthesia, neurology, and genetics were invited to participate in the ENMC workshop. A literature search was conducted in PubMed and Embase, the main findings of which were disseminated to the participants and presented during the workshop. Depending on specific expertise, participants presented the existing evidence and their expert opinion concerning anaesthetic management in six specific groups of myopathies and neuromuscular junction disorders. The consensus statement was prepared according to the AGREE II (Appraisal of Guidelines for Research &amp; Evaluation) reporting checklist. The level of evidence has been adapted according to the SIGN (Scottish Intercollegiate Guidelines Network) grading system. The final consensus statement was subjected to a modified Delphi process.

RESULTS

A set of general recommendations valid for the anaesthetic management of patients with neuromuscular disorders in general have been formulated. Specific recommendations were formulated for (i) neuromuscular junction disorders, (ii) muscle channelopathies (nondystrophic myotonia and periodic paralysis), (iii) myotonic dystrophy (types 1 and 2), (iv) muscular dystrophies, (v) congenital myopathies and congenital dystrophies, and (vi) mitochondrial and metabolic myopathies.

CONCLUSIONS

This ENMC consensus statement summarizes the most important considerations for planning and performing anaesthesia in patients with neuromuscular disorders.

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.

Clinical and Molecular Insights into Gastrointestinal Dysfunction in Myotonic Dystrophy Types 1 & 2

Myotonic dystrophy (DM) is a highly variable, multisystemic disorder that clinically affects one in 8000 individuals. While research has predominantly focused on the symptoms and pathological mechanisms affecting striated muscle and brain, DM patient surveys have identified a high prevalence for gastrointestinal (GI) symptoms amongst affected individuals. Clinical studies have identified chronic and progressive dysfunction of the esophagus, stomach, liver and gallbladder, small and large intestine, and rectum and anal sphincters. Despite the high incidence of GI dysmotility in DM, little is known regarding the pathological mechanisms leading to GI dysfunction. In this review, we summarize results from clinical and molecular analyses of GI dysfunction in both genetic forms of DM, DM type 1 (DM1) and DM type 2 (DM2). Based on current knowledge of DM primary pathological mechanisms in other affected tissues and GI tissue studies, we suggest that misregulation of alternative splicing in smooth muscle resulting from the dysregulation of RNA binding proteins muscleblind-like and CUGBP-elav-like is likely to contribute to GI dysfunction in DM. We propose that a combinatorial approach using clinical and molecular analysis of DM GI tissues and model organisms that recapitulate DM GI manifestations will provide important insight into defects impacting DM GI motility.

Myotonic dystrophy type 1 presenting with dyspnea: A case report

BACKGROUND

Myotonic dystrophy type 1 (DM1) is a genetic neuromuscular disease involving multiple systems, especially the cardiopulmonary system. The clinical phenotype of DM1 patients is highly variable, which limits early diagnosis and treatment. In the present study, we reported a 35-year-old female DM1 patient with dyspnea as the primary onset clinical manifestation, analyzed her family's medical history, and reviewed related literature.

CASE SUMMARY

A 35-year-old woman was admitted to the hospital with dyspnea of 1 mo duration, and sleep apnea for 3 d. Her respiratory pattern and effort were normal, but limb muscle tension was low. Investigation into the patient's medical history revealed that she might have hereditary neuromuscular disease. Electromyography showed that her myotonia potentials were visible in the resting state of the examined muscles, with decreased motor unit potential time limit and amplitude. Genetic testing for DM1 revealed that the cytosine-thymine-guanine (CTG) repeat number of the DMPK gene exceeded 50, while cytosine-CTG expansion in intron 1 of ZNF9 gene was < 30 repeats. The patient was diagnosed with DM1.

CONCLUSION

DM1 is a genetic neuromuscular disease involving multiple systems, and the clinical phenotype in DM1 is extremely variable. Some patients with DM1 may be presented at the respiratory department because of dyspnea, which should be cautioned by the pulmonologists. There may be no obvious or specific symptoms in the early stage of disease, and clinicians should improve their understanding of DM1 and make an early diagnosis, which will improve patients’ quality of life.

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.

Cardiac Pathology in Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy affecting adults and children, is a multi-systemic disorder affecting skeletal, cardiac, and smooth muscles as well as neurologic, endocrine and other systems. This review is on the cardiac pathology associated with DM1. The heart is one of the primary organs affected in DM1. Cardiac conduction defects are seen in up to 75% of adult DM1 cases and sudden death due to cardiac arrhythmias is one of the most common causes of death in DM1. Unfortunately, the pathogenesis of cardiac manifestations in DM1 is ill defined. In this review, we provide an overview of the history of cardiac studies in DM1, clinical manifestations, and pathology of the heart in DM1. This is followed by a discussion of emerging data about the utility of cardiac magnetic resonance imaging (CMR) as a biomarker for cardiac disease in DM1, and ends with a discussion on models of cardiac RNA toxicity in DM1 and recent clinical guidelines for cardiologic management of individuals with DM1.

Deciphering the mechanisms underlying brain alterations and cognitive impairment in congenital myotonic dystrophy

Myotonic dystrophy type 1 (DM1) is a multisystemic and heterogeneous disorder caused by the expansion of CTG repeats in the 3' UTR of the myotonic dystrophy protein kinase (DMPK) gene. There is a congenital form (CDM1) of the disease characterized by severe hypotonia, respiratory insufficiency as well as developmental delays and intellectual disabilities. CDM1 infants manifest important brain structure abnormalities present from birth while, in contrast, older patients with adult-onset DM1 often present neurodegenerative features and milder progressive cognitive deficits. Promising therapies targeting central molecular mechanisms contributing to the symptoms of adult-onset DM1 are currently in development, but their relevance for treating cognitive impairment in CDM1, which seems to be a partially distinct neurodevelopmental disorder, remain to be elucidated. Here, we provide an update on the clinical presentation of CDM1 and review recent in vitro and in vivo models that have provided meaningful insights on its consequences in development, with a particular focus on the brain. We discuss how enhanced toxic gain-of-function of the mutated DMPK transcripts with larger CUG repeats and the resulting dysregulation of RNA-binding proteins may affect the developing cortex in utero. Because the methylation of CpG islets flanking the trinucleotide repeats has emerged as a strong biomarker of CDM1, we highlight the need to investigate the tissue-specific impacts of these chromatin modifications in the brain. Finally, we outline promising potential therapeutic treatments for CDM1 and propose future in vitro and in vivo models with great potential to shed light on this disease.

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.

Zebrafish mbnl mutants model physical and molecular phenotypes of myotonic dystrophy

The muscleblind RNA-binding proteins (MBNL1, MBNL2 and MBNL3) are highly conserved across vertebrates and are important regulators of RNA alternative splicing. Loss of MBNL protein function through sequestration by CUG or CCUG RNA repeats is largely responsible for the phenotypes of the human genetic disorder myotonic dystrophy (DM). We generated the first stable zebrafish (Danio rerio) models of DM-associated MBNL loss of function through mutation of the three zebrafish mbnl genes. In contrast to mouse models, zebrafish double and triple homozygous mbnl mutants were viable to adulthood. Zebrafish mbnl mutants displayed disease-relevant physical phenotypes including decreased body size and impaired movement. They also exhibited widespread alternative splicing changes, including the misregulation of many DM-relevant exons. Physical and molecular phenotypes were more severe in compound mbnl mutants than in single mbnl mutants, suggesting partially redundant functions of Mbnl proteins. The high fecundity and larval optical transparency of this complete series of zebrafish mbnl mutants will make them useful for studying DM-related phenotypes and how individual Mbnl proteins contribute to them, and for testing potential therapeutics. This article has an associated First Person interview with the first author of the paper.

New developments in myotonic dystrophies from a multisystemic perspective

PURPOSE OF REVIEW

The multisystemic involvement of myotonic dystrophies (DMs) intricates disease monitoring, patients' care and trial design. This update of the multifaceted comorbidities observed in DMs aims to assist neurologists in the complex management of patients and to encourage further studies for still under-investigated aspects of the disease.

RECENT FINDINGS

We reviewed the most recent studies covering pathogenesis and clinical aspects of extra-muscular involvement in DM1 and DM2. The largest body of evidence regards the cardiac and respiratory features, for which experts' recommendations have been produced. Gastrointestinal symptoms emerge as one of the most prevalent complaints in DMs. The alteration of insulin signaling pathways, involved in gastrointestinal manifestations, carcinogenesis, muscle function, cognitive and endocrinological aspects, gain further relevance in the light of recent evidence of metformin efficacy in DM1. Still, too few studies are performed on large DM2 cohorts, so that current recommendations mainly rely on data gathered in DM1 that cannot be fully translated to DM2.

SUMMARY

Extra-muscular manifestations greatly contribute to the overall disease burden. A multidisciplinary approach is the key for the management of patients. Consensus-based recommendations for DM1 and DM2 allow high standards of care but further evidence are needed to implement these recommendations.

Myotonic dystrophy type1: 13years of experience at a tertiary hospital. Clinical and epidemiological study and genotype-phenotype correlation

INTRODUCTION

The incidence of myotonic dystrophy type1 (DM1), a disease with great phenotypic variety, in our region is unknown. This study aims to estimate the incidence of DM1 at our hospital (a reference centre in Aragon, Spain) and to identify the characteristics of our population (genotype-phenotype correlation).

METHODS

Retrospective, descriptive study of 459 patients classified according to the number of CTG repeats, as follows: normal (5-35), premutation (36-50), protomutation (51-80), small expansions (81-150), intermediate expansions (151-1000), and large expansions (>1000). Furthermore, according to clinical phenotype, patients were categorised as unaffected (5-50 CTG repeats), mild form or asymptomatic (51-150), classical form (151-1000), and severe form (>1000).

RESULTS

The incidence of DM1 was 20.61 cases per million person-years (95%CI: 19.59-21.63). An inverse correlation was observed between the number of CTG repeats and the age at genetic diagnosis (ρ=-0.547; 95%CI: -0.610 to -0.375; P<.001). CTG5 was the most frequent polymorphic allele in healthy individuals. Of all patients with DM1, 28.3% presented the mild or asymptomatic form, 59.1% the classical form, and 12.6% the severe form. Inheritance was maternal in 35.1% of cases, paternal in 59.4%, and uncertain in 5.5%. In mild forms, frontal balding in men was the most prevalent phenotypic trait, as well as myotonia and cataracts, while in the classical form, ptosis, facial weakness, voice and pronunciation alterations, myotonia, and fatigue/sleepiness were most frequent.

CONCLUSIONS

The incidence of DM1 in Aragon is significant. Multidisciplinary study of the phenotype of patients with DM1 is key to early diagnosis and personalised management.

Gastrointestinal motility disorders in neurologic disease

The extrinsic and autonomic nervous system intricately controls the major functions of the gastrointestinal tract through the enteric nervous system; these include motor, secretory, sensory, storage, and excretory functions. Disorders of the nervous system affecting gastrointestinal tract function manifest primarily as abnormalities in motor (rather than secretory) functions. Common gastrointestinal symptoms in neurologic disorders include sialorrhea, dysphagia, gastroparesis, intestinal pseudo-obstruction, constipation, diarrhea, and fecal incontinence. Diseases of the entire neural axis ranging from the cerebral hemispheres to the peripheral autonomic nerves can result in gastrointestinal motility disorders. The most common neurologic diseases affecting gastrointestinal function are stroke, parkinsonism, multiple sclerosis, and diabetic neuropathy. Diagnosis involves identification of the neurologic disease and its distribution, and documentation of segmental gut dysfunction, typically using noninvasive imaging, transit measurements, or intraluminal measurements of pressure activity and coordination of motility. Apart from treatment of the underlying neurologic disease, management focuses on restoration of normal hydration and nutrition and pharmacologic treatment of the gut neuromuscular disorder.

Myotonic dystrophy type 2: the 2020 update

The myotonic dystrophies are the commonest cause of adult-onset muscular dystrophy. Phenotypes of DM1 and DM2 are similar, but there are some important differences, including the presence or absence of congenital form, muscles primarily affected (distal vs proximal), involved muscle fiber types (type 1 vs type 2 fibers), and some associated multisystemic phenotypes. There is currently no cure for the myotonic dystrophies but effective management significantly reduces the morbidity and mortality of patients. For the enormous understanding of the molecular pathogenesis of myotonic dystrophy type 1 and myotonic dystrophy type 2, these diseases are now called "spliceopathies" and are mediated by a primary disorder of RNA rather than proteins. Despite clinical and genetic similarities, myotonic dystrophy type 1 and type 2 are distinct disorders requiring different diagnostic and management strategies. Gene therapy for myotonic dystrophy type 1 and myotonic dystrophy type 2 appears to be very close and the near future is an exciting time for clinicians and patients.

High Prevalence and Gender-Related Differences of Gastrointestinal Manifestations in a Cohort of DM1 Patients: A Perspective, Cross-Sectional Study

Myotonic dystrophy type 1 (DM1, MIM #160900), the most common muscular dystrophy among adults, is a multisystem disorder, which affects, besides the skeletal muscle, several other tissues and/or organs, including the gastrointestinal apparatus, with manifestations that frequently affect the quality of life of DM1 patients. So far, only few, mainly retrospective studies evaluated this specific topic in DM1, so we performed a perspective study, enrolling 61 DM1 patients who underwent an extensive diagnostic protocol, including administration of the Gastrointestinal Symptom Rating Scale (GSRS), a validated patient-reported questionnaire about GI symptoms, laboratory tests, liver US scan, and an intestinal permeability assay, in order to characterize frequency and assess correlations regarding specific gastrointestinal manifestations with demographic or other DM1-related features. Our results in our DM1 cohort confirm the high frequency of various gastrointestinal manifestations, with the most frequent being constipation (45.9%). γGT levels were pathologically increased in 65% of DM1 patients and GPT in 29.82%; liver ultrasound studies showed steatosis in 34.4% of patients. Significantly, 91.22% of DM1 patients showed signs of altered intestinal permeability at the specific assay. We documented a gender-related prevalence and severity of gastrointestinal manifestations in DM1 females compared to DM1 males, while males showed higher serum GPT and γGT levels than females. Correlation studies documented a direct correlation between severity of muscle weakness estimated by MIRS score and γGT and alkaline phosphatase levels, suggesting their potential use as biomarkers of muscle disease severity in DM1.

Combined achalasia and cricopharyngeal achalasia in a patient with type 1 myotonic dystrophy: a case report

Type 1 myotonic dystrophy (MD) is a rare inherited disease which presents with skeletal muscle weakness and myotonia. Involvement of smooth muscles is also common and mainly manifests in the gastrointestinal tract. We report a case of type 1 MD who presented with dysphagia and was found to have unique esophageal manometry findings. A 57-year-old male patient presented with dysphagia for the last few months. Past medical history was significant for type 1 myotonic muscular dystrophy, gastroesophageal reflux disease, diaphragmatic paralysis, and obstructive sleep apnea. Both his father and brother died in their 50s because of unclear respiratory problems. He was a former smoker and did not drink alcohol. Review of systems was unremarkable. His neurological examination was significant for bilateral facial muscle weakness and mild ptosis. He had atrophy and weakness of the distal upper and lower extremities. Deep tendon reflexes were absent. Upper endoscopy and 24-hour esophageal pH testing were non-diagnostic. Finally, esophageal manometry revealed elevated lower esophageal sphincter (LES) pressure, elevated upper esophageal sphincter (UES) pressure, and very week peristalsis of the esophageal body. Esophageal involvement is common in type 1 MD manifesting with dysfunction of UES, esophageal body, and LES. Manometry usually describes a reduced resting tone of the UES and LES. The patient had elevated LES pressure and week peristalsis of the esophageal body consistent with achalasia. He also had an elevated UES pressure consistent with cricopharyngeal achalasia. This is the opposite of what is expected in type 1 MD.

Clinical and genetic characteristics of childhood-onset myotonic dystrophy

INTRODUCTION

Myotonic dystrophy type 1 (DM1) is caused by a CTG (cytosine-thymine-guanine) trinucleotide repeat expansion. Congenital DM (CDM) presents in the first month of life, whereas individuals with infantile and juvenile DM1 have later onset of symptoms.

METHODS

We performed a retrospective chart review of patients with childhood-onset DM1 seen at one of three locations in Dallas, Texas between 1990 and 2018. Symptoms, disease course, cognitive features, and family history were reviewed.

RESULTS

Seventy-four patients were included; CDM was diagnosed in 52 patients. There was maternal inheritance in 74% of patients. CTG repeat number ranged from 143 to 2300. Neuropsychiatric and cognitive deficits were common. Over half of the patients had GI disturbances, and orthopedic complications were common.

DISCUSSION

Myotonic dystrophy type 1 in children requires a multidisciplinary approach to management. Presenting symptoms vary, and repeat expansion size does not necessarily directly relate to severity of symptoms. A consensus for outcome measures is required.

The prevalence of faecal incontinence in myotonic dystrophy type 1

Faecal incontinence is recognised as a feature of myotonic dystrophy along with other symptoms of bowel dysfunction, but its prevalence is poorly defined. We have surveyed 152 unselected myotonic dystrophy patients. We identified issues with bowel control in 104 (68% of the study population). Forty-eight (32%) reported faecal incontinence in the 4 weeks prior to completion of the questionnaire. Fifty-six patients (37%) reported having to change their lifestyle because of incontinence issues at some point in the prior 4 weeks. This study shows a high frequency of life-changing symptoms in a large unselected, cohort of patients with myotonic dystrophy type 1, and highlights lower gastrointestinal symptoms as an important issue for further research.

Oropharyngeal dysphagia in early stages of myotonic dystrophy type 1

INTRODUCTION

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder characterized mainly by skeletal muscle alterations. Although oropharyngeal dysphagia is a prominent clinical feature of DM1, it remains poorly studied in its early disease stages.

METHODS

Dysphagia was investigated in 11 presymptomatic DM1 carriers, 14 patients with DM1 and 12 age-matched healthy controls, by using fiberoptic endoscopic evaluation of swallowing (FEES) and clinical scores.

RESULTS

Scores for the FEES variables, delayed pharyngeal reflex, posterior pooling, and postswallow residue were significantly greater in patients with DM1 and in presymptomatic DM1 carriers than in healthy controls (P < 0.05); oropharyngeal dysfunction was more severe in patients than in presymptomatic carriers. Penetration/aspiration was found altered exclusively in patients with DM1 (P < 0.05).

DISCUSSION

Swallowing dysfunction occurs in presymptomatic DM1 carriers. Timely diagnosis of dysphagia in preclinical stages of the disease will aid in the timely management of presymptomatic carriers, potentially preventing medical complications. Muscle Nerve, 2019.

Consensus-based care recommendations for adults with myotonic dystrophy type 2

Purpose of review

Myotonic dystrophy type 2 (DM2) is a rare, progressive multisystem disease particularly affecting the skeletal muscle. A causal therapy is not yet available; however, prompt, appropriate symptomatic treatments are essential to limit disease-related complications. Evidence-based guidelines to assist medical practitioners in the care of DM2 patients do not exist.

Recent findings

The Myotonic Dystrophy Foundation (MDF) previously worked with an international group of 66 clinicians to develop consensus-based care recommendations for myotonic dystrophy type 1. Following a similar approach, the MDF recruited 15 international clinicians with long-standing experience in the care of DM2 patients to develop consensus-based care recommendations. The single text procedure was adopted. This process generated a 4-page Quick Reference Guide and a comprehensive 55-page document that provides care recommendations for DM2 patients.

Summary

The resulting recommendations will help standardize and improve care for DM2 patients and facilitate appropriate management in centers without neuromuscular specialists.

Gender difference in clinical conditions among hospitalized adults with myotonic dystrophy

INTRODUCTION

In this study we examined gender differences in adult hospitalizations with myotonic dystrophy (DM).

METHODS

From the Nationwide Inpatient Sample (NIS) 2010-2014, we identified 1,891 adult hospitalizations with a DM diagnosis and constructed a comparison group of hospitalizations without DM using propensity score matching. We calculated relative risk by gender for 44 clinical diagnoses that each accounted for at least 5% of DM hospitalizations.

RESULTS

Hospitalizations with DM were longer (4.8 vs. 4.1 days, P < 0.0001) and more costly ($13,241 vs. $11,458, P < 0.0001) than those without DM. More than half (25 of 44) of the conditions co-occurring with DM hospitalizations did not differ in their relative risks by gender. For those that differed by gender, only 5 were specific to DM, compared with hospitalizations without DM.

DISCUSSION

Our findings highlight the importance of comprehensive and coordinated care for DM rather than gender-oriented care in the inpatient setting. Muscle Nerve 59:348-353, 2019.

Meet and eat, an interdisciplinary group intervention for patients with myotonic dystrophy about healthy nutrition, meal preparation, and consumption: a feasibility study

Purpose: To develop and evaluate an interdisciplinary group intervention for patients with myotonic dystrophy regarding healthy nutrition, meal preparation, and consumption, called Meet and Eat.Materials and methods: A design-based approach was used, exploring experiences and needs of patients with myotonic dystrophy and their next of kin. This resulted in a 4-week interdisciplinary outpatient group intervention to increase awareness and change behavior. In a mixed-method feasibility study this intervention was evaluated with participants and facilitators.Results: Participants reported on social impact of difficulties with eating and drinking (speaking, swallowing, and social embarrassment) and a variety of complaints affecting meal preparation and consumption. Patients and family members expressed the wish to learn from others. After delivery of the intervention, self-reported outcome measures demonstrated improvement on eating and drinking issues in daily life. The qualitative evaluation showed increased awareness and appreciation of the following design principles: peer support, multidisciplinary approach, active involvement of patient with myotonic dystrophy and their next of kin by using personal goals and motivational interviewing.Conclusion: Participation in Meet and Eat seemed to increase insight in patients' condition and ways of management. However, a longer self-management life style program is recommended to change behavior.Implications for rehabilitationPatients with myotonic dystrophy experience physical, cognitive and psychosocial problems to manage healthy nutrition, meal preparation, and consumption;This multidisciplinary group intervention Meet and Eat in patients with myotonic dystrophy appears to be feasible and seems to result in increased insight and management strategies;Peer support, multidisciplinary approach, personal goals, and involvement of family were key factors;To change eating and drinking behavior, a 4-week intervention is too short.

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.

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.