Hematopoietic Prostaglandin D Synthase Is Increased in Mast Cells and Pericytes in Autopsy Myocardial Specimens from Patients with Duchenne Muscular Dystrophy.

The leading cause of death for patients with Duchenne muscular dystrophy (DMD), a progressive muscle disease, is heart failure. Prostaglandin (PG) D2, a physiologically active fatty acid, is synthesized from the precursor PGH2 by hematopoietic prostaglandin D synthase (HPGDS). Using a DMD animal model (mdx mice), we previously found that HPGDS expression is increased not only in injured muscle but also in the heart. Moreover, HPGDS inhibitors can slow the progression of muscle injury and cardiomyopathy. However, the location of HPGDS in the heart is still unknown. Thus, this study investigated HPGDS expression in autopsy myocardial samples from DMD patients. We confirmed the presence of fibrosis, a characteristic phenotype of DMD, in the autopsy myocardial sections. Additionally, HPGDS was expressed in mast cells, pericytes, and myeloid cells of the myocardial specimens but not in the myocardium. Compared with the non-DMD group, the DMD group showed increased HPGDS expression in mast cells and pericytes. Our findings confirm the possibility of using HPGDS inhibitor therapy to suppress PGD2 production to treat skeletal muscle disorders and cardiomyopathy. It thus provides significant insights for developing therapeutic drugs for DMD.

RNA-seq analysis, targeted long-read sequencing and in silico prediction to unravel pathogenic intronic events and complicated splicing abnormalities in dystrophinopathy.

Dystrophinopathy is caused by alterations in DMD. Approximately 1% of patients remain genetically undiagnosed, because intronic variations are not detected by standard methods. Here, we combined laboratory and in silico analyses to identify disease-causing genomic variants in genetically undiagnosed patients and determine the regulatory mechanisms underlying abnormal DMD transcript generation. DMD transcripts from 20 genetically undiagnosed dystrophinopathy patients in whom no exon variants were identified, despite dystrophin deficiency on muscle biopsy, were analyzed by transcriptome sequencing. Genome sequencing captured intronic variants and their effects were interpreted using in silico tools. Targeted long-read sequencing was applied in cases with suspected structural genomic abnormalities. Abnormal DMD transcripts were detected in 19 of 20 cases; Exonization of intronic sequences in 15 cases, exon skipping in one case, aberrantly spliced and polyadenylated transcripts in two cases and transcription termination in one case. Intronic single nucleotide variants, chromosomal rearrangements and nucleotide repeat expansion were identified in DMD gene as pathogenic causes of transcript alteration. Our combined analysis approach successfully identified pathogenic events. Detection of diseasing-causing mechanisms in DMD transcripts could inform the therapeutic options for patients with dystrophinopathy.

The current status of medical care for myotonic dystrophy type 1 in the national registry of Japan.

INTRODUCTION/AIMS: Myotonic dystrophy (DM) is a systemic disease with multiple organ complications, making the standardization of medical care a challenge. We analyzed data from Japan's national registry to clarify the current treatment patterns and demographic features of Japanese DM patients. METHODS: Using the Japanese National Registry of Muscular Dystrophy (Remudy), we analyzed medical care practice for the multisystemic issues associated with adult DM type 1 patients, excluding congenital DM. RESULTS: We included 809 patients with a median age of 44.2 years. Among these patients, 15.8% used ventilators; 31.7% met the index considered at risk for sudden death due to cardiac conduction defects (PR interval over 240 milliseconds or QRS duration over 120 milliseconds) and 2.8% had implanted cardiac devices. Medication for heart failure was prescribed to 9.6% of patients. Overall, 21.2% of patients had abnormal glucose metabolism, of whom 42.9% were treated with oral medications. Among the oral medications, dipeptidyl peptidase-4 inhibitors were the most common. Cancers were observed in 3.7% of the patients, and endometrial and breast cancers were dominant. Mexiletine was prescribed for myotonia in 1.9% of the patients, and only 1% of the patients received medication for daytime sleepiness. DISCUSSION: This study shows difference in treatment patterns for DM1 in Japan compared with other countries, such as lower rates of use of implantable cardiac devices and higher rates of ventilator use. These data may be useful in discussions aimed at standardizing medical care for patients with DM.

Safety and immunogenicity of mRNA COVID-19 vaccine in inpatients with muscular dystrophy.

INTRODUCTION/AIMS: Due to muscular weakness and cardiopulmonary dysfunction, patients with muscular dystrophy (MD) have an increased risk of serious complications from coronavirus disease-2019 (COVID-19). Although vaccination is recommended, COVID-19 vaccination safety and immunogenicity in these patients are unknown. We investigated reaction frequency, post-vaccine antibody titers after two mRNA COVID-19 vaccine doses, and clinical predictors of antibody response among patients with MD. METHODS: We recruited 171 inpatients with MD receiving two BNT162b2 mRNA COVID-19 vaccine doses from seven hospitals. Blood samples were obtained from 53 inpatients before the first dose and 28 to 30 days after the second dose, and antibody titers were measured. RESULTS: Overall, 104 (60.8%) and 115 (67.6%) patients had side effects after the first and second doses, respectively. These were generally mild and self-limited. Multiple logistic regression analysis showed that a bedridden state was associated with reduced side effects (odds ratio [OR] = 0.29; 95% confidence interval [CI], 0.12 to 0.71). The antibody titers of all participants changed from negative to positive after two vaccine doses. The geometric mean titer (GMT) of the inpatients was 239 (95% CI, 159.3 to 358.7). Older age (relative risk [RR] = 0.97; 95% CI, 0.95 to 0.99) and bedridden state (RR = 0.27; 95% CI, 0.14 to 0.51) were associated with a lower antibody titer. Patients with myotonic dystrophy type 1 (DM1) had a lower GMT than patients with other MDs (RR = 0.42; 95% CI, 0.21 to 0.85). DISCUSSION: COVID-19 vaccination is safe and immunogenic in inpatients with MD. Patients with DM1 appear to have a poorer COVID-19 antibody response than those with other MDs.

Impact of the TRPV2 Inhibitor on Advanced Heart Failure in Patients with Muscular Dystrophy: Exploratory Study of Biomarkers Related to the Efficacy of Tranilast.

Cardiomyopathy is the leading cause of death in patients with muscular dystrophy (MD). Tranilast, a widely used anti-allergic drug, has displayed inhibitory activity against the transient receptor potential cation channel subfamily V member 2 and improved cardiac function in MD patients. To identify urinary biomarkers that assess improved cardiac function after tranilast administration, we performed a urinary metabolomic study focused on oxidative fatty acids. Accompanying the clinical trial of tranilast, urine specimens were collected over 24 weeks from MD patients with advanced heart failure. Urinary levels of tetranor-PGDM (tetranor-prostaglandin D metabolite), a metabolite of prostaglandin D2, significantly decreased 12 weeks after tranilast administration and were correlated with BNP. These results suggest that prostaglandin-mediated inflammation, which increases with the pathological progression of heart failure in MD patients, was attenuated. Urinary prostaglandin E3 (PGE3) levels significantly increased 4 weeks after tranilast administration. There were positive correlations between the urinary levels of PGE3 and 8-hydroxy-2'-deoxyguanosine, an oxidative stress marker. High PGE3 levels may have a protective effect against cardiomyopathy in MD patients with high oxidative stress. Although further validation studies are necessary, urinary tetranor-PGDM and PGE3 levels may help the current understanding of the extent of advanced heart failure in patients with MD after tranilast administration.

Simultaneous measurement of the size and methylation of chromosome 4qA-D4Z4 repeats in facioscapulohumeral muscular dystrophy by long-read sequencing.

BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant muscular disorder characterized by asymmetric muscle wasting and weakness. FSHD can be subdivided into two types: FSHD1, caused by contraction of the D4Z4 repeat on chromosome 4q35, and FSHD2, caused by mild contraction of the D4Z4 repeat plus aberrant hypomethylation mediated by genetic variants in SMCHD1, DNMT3B, or LRIF1. Genetic diagnosis of FSHD is challenging because of the complex procedures required. METHODS: We applied Nanopore CRISPR/Cas9-targeted resequencing for the diagnosis of FSHD by simultaneous detection of D4Z4 repeat length and methylation status at nucleotide level in genetically-confirmed and suspected patients. RESULTS: We found significant hypomethylation of contracted 4q-D4Z4 repeats in FSHD1, and both 4q- and 10q-D4Z4 repeats in FSHD2. We also found that the hypomethylation in the contracted D4Z4 in FSHD1 is moderately correlated with patient phenotypes. CONCLUSIONS: Our method contributes to the development for the diagnosis of FSHD using Nanopore long-read sequencing. This finding might give insight into the mechanisms by which repeat contraction causes disease pathogenesis.

Quality of life and subjective symptom impact in Japanese patients with myotonic dystrophy type 1.

BACKGROUND: Although functional impairment in patients with myotonic dystrophy is an important determinant of the quality of life (QoL), patients' subjective evaluation of their symptoms may also affect their QoL. The aim of this study was to investigate the association between subjective symptom impact and the QoL of patients with myotonic dystrophy, after controlling for functional impairment. METHODS: Eligible patients with myotonic dystrophy type 1 (DM1) were recruited from four hospitals in Japan. The subjective symptom impact of four symptoms (muscle weakness, fatigue, pain, and myotonia) and overall QoL were evaluated using the Individualized Neuromuscular Quality of Life (INQoL) questionnaire. Functional impairment was assessed using the modified Rankin Scale. RESULTS: Seventy-seven patients with DM1 were included in this study. Overall QoL was significantly associated with subjective symptom impact of muscular weakness, fatigue, pain, myotonia, swallowing difficulty, and droopy eyelids. In the regression models, disease duration (beta = 0.11) and moderate to severe functional impairment (beta = 0.33) explained a significant part of the overall QoL. Furthermore, muscular weakness, fatigue, and myotonia significantly explained additional variance of the overall QoL (beta = 0.17-0.43). CONCLUSIONS: Subjective symptom impact and functional impairment are independent features influencing the QoL of Japanese patients with DM1.

The myotonic dystrophy health index: Japanese adaption and validity testing.

INTRODUCTION: The Myotonic Dystrophy Health Index (MDHI) is a disease-specific, patient-reported outcome measure. The objective of this study was to translate, evaluate, and validate a Japanese version of the MDHI (MDHI-J). METHODS: We utilized forward and backward translations and qualitative interviews with 11 myotonic dystrophy type 1 (DM1) participants. We subsequently tested the internal consistency, test-retest reliability, concurrent validity against muscle strength, and 3 quality-of-life measures, and the known-groups validity of the MDHI-J with 60 adult patients. RESULTS: The MDHI-J was found to be culturally appropriate, comprehensive, and clinically relevant. The MDHI-J and its subscales had high internal consistency (mean Cronbach's α = 0.91), test-retest reliability (intraclass coefficient 0.678-0.915), and concurrent validity (Spearman's ρ - 0.869 to 0.904). MDHI-J scores were strongly associated with employment, duration of symptoms, and modified Rankin Scale. DISCUSSION: The MDHI-J is suitable and valid to measure patient-reported disease burden in adult Japanese patients with DM1. Muscle Nerve 59:577-577, 2019.

Blockade of TRPV2 is a Novel Therapy for Cardiomyopathy in Muscular Dystrophy.

Muscular dystrophy and dilated cardiomyopathy are intractable diseases and their treatment options are very limited. Transient receptor potential cation channel subfamily V, member 2 (TRPV2), is a stretch-sensitive Ca2+-permeable channel that causes sustained intracellular Ca2+ increase in muscular cells, which is a pathophysiological feature of degenerative muscular disease. Recent reports have clarified that TRPV2 is concentrated and activated in the sarcolemma of cardiomyocytes/myocytes during cardiomyopathy/heart failure and muscular dystrophy. Furthermore, these reports showed that inactivation of TRPV2 ameliorates muscle dysgenesis to improve cardiac function and survival prognosis. Although TRPV2 is a potential therapeutic target for cardiomyopathy, there were no TRPV2 inhibitors available until recently. In this review, we introduce our recent findings and discuss the current progress in the development of TRPV2 inhibitors and their therapeutic applications for cardiomyopathy associated with muscular dystrophy.

Validation of The Individualized Neuromuscular Quality of Life in Japanese patients with myotonic dystrophy.

INTRODUCTION: The Individualized Neuromuscular Quality of Life (INQoL) is used to measure the quality of life (QoL) of patients with neuromuscular disease. We conducted this study to translate and validate the Japanese version of the INQoL in patients with myotonic dystrophy. METHODS: Forward and backward translation, patient testing, and psychometric validation were performed. We used the 36-Item Short Form Health Survey (SF-36) and the modified Rankin scale for concurrent validation. RESULTS: The Japanese INQoL was administered to 90 adult patients. The coefficients for internal consistency and test-retest reliability were adequately high in most domains (Cronbach α 0.88-0.96 and intraclass coefficient 0.64-0.99). INQoL domains were moderately to strongly associated with relevant SF-36 subscales (Spearman's ρ -0.23 to -0.74). Symptom severity, disease duration, employment status, and use of a ventilator influenced overall QoL. DISCUSSION: The INQoL is a reliable and validated measure of QoL for Japanese patients with myotonic dystrophy. Muscle Nerve, 2018.

Cognitive impairment and quality of life in patients with myotonic dystrophy type 1.

INTRODUCTION: This study sought to clarify whether specific cognitive abilities are impaired in patients with myotonic dystrophy type 1 (DM1) as well as to investigate the relationships among quality of life (QoL), cognitive function, and psychological factors. METHODS: Sixty patients with DM1 were evaluated on cognitive functioning (abstract reasoning, attention/working memory, executive function, processing speed, and visuoconstructive ability), apathy, depression, excessive daytime sleepiness, fatigue, and QoL. QoL was assessed by 2 domains of the Muscular Dystrophy Quality of Life Scale (Psychosocial Relationships and Physical Functioning and Health). RESULTS: More than half of the patients exhibited cognitive impairment in attention/working memory, executive function, processing speed, and visuoconstructive ability. The Psychosocial Relationships factor was associated with processing speed, attention/working memory, and apathy, whereas depression and fatigue were associated with 2 QoL domains. DISCUSSION: Our study identified specific cognitive impairments in DM1. Specific cognitive functions and psychological factors may be potential contributors to QoL. Muscle Nerve 57: 742-748, 2018.

Autism spectrum disorders are prevalent among patients with dystrophinopathies.

Recent studies have reported a higher prevalence of autism spectrum disorders among patients with dystrophinopathies. The aim of this study was to investigate the prevalence of autism spectrum disorder (ASD) among those with dystrophinopathies. The possible role of dystrophin isoforms in patients was also explored. Fifty-six patients recruited from Toneyama National Hospital were included in this study (mean age = 12.9 years, SD = 5.2 years). Autistic symptoms were evaluated using the Pervasive Developmental Disorders/Autism Spectrum Disorders Rating Scale (PARS), a clinician rating scale. Eleven patients (19.6%; 95% confidence interval 10.2-32.4) met the criteria for ASD based on their PARS scores. Patients were separated into two groups based on the cumulative loss of dystrophin isoforms predicted from the mutation location. The prevalence of ASD was examined between these groups. Infantile and current autistic symptoms did not differ between the groups, except on one subscale of the PARS. This study revealed that there was a high prevalence of ASD in patients with dystrophinopathies.

Necklace cytoplasmic bodies in hereditary myopathy with early respiratory failure.

BACKGROUND: In hereditary myopathy with early respiratory failure (HMERF), cytoplasmic bodies (CBs) are often localised in subsarcolemmal regions, with necklace-like alignment (necklace CBs), in muscle fibres although their sensitivity and specificity are unknown. OBJECTIVE: To elucidate the diagnostic value of the necklace CBs in the pathological diagnosis of HMERF among myofibrillar myopathies (MFMs). METHODS: We sequenced the exon 343 of TTN gene (based on ENST00000589042), which encodes the fibronectin-3 (FN3) 119 domain of the A-band and is a mutational hot spot for HMERF, in genomic DNA from 187 patients from 175 unrelated families who were pathologically diagnosed as MFM. We assessed the sensitivity and specificity of the necklace CBs for HMERF by re-evaluating the muscle pathology of our patients with MFM. RESULTS: TTN mutations were identified in 17 patients from 14 families, whose phenotypes were consistent with HMERF. Among them, 14 patients had necklace CBs. In contrast, none of other patients with MFM had necklace CBs except for one patient with reducing body myopathy. The sensitivity and specificity were 82% and 99%, respectively. Positive predictive value was 93% in the MFM cohort. CONCLUSIONS: The necklace CB is a useful diagnostic marker for HMERF. When muscle pathology shows necklace CBs, sequencing the FN3 119 domain of A-band in TTN should be considered.

An autopsy case of neuronal intermediate filament inclusion disease with regard to immunophenotypic and topographical analysis of the neuronal inclusions.

We report an autopsy case of neuronal intermediate filament inclusion disease (NIFID), in which pyramidal motor dysfunction preceded cognitive disturbance for 3 years from the onset. A 41-year-old Japanese man presented progressive spastic tetraparesis followed by cognitive impairment. His neurological symptoms gradually deteriorated and he died of pneumonia 16 years from the onset. His brain showed severe generalized atrophy with enlargement of ventricles. The microscopic examination revealed severe neuronal loss with gliosis and sponginess predominantly in the fronto-temporal cortices, caudate and putamen. Many hyaline conglomerate inclusions (HC) without immunoreactivity for 'fused in sarcoma' protein (FUS) and some granular and small round FUS-immunoreactive (FUS-ir) neuronal cytoplasmic inclusions (NCI) were observed in the remaining neurons. Some neurons with HC had small basophilic inclusions which showed positive FUS-ir, attached to HC in the cytoplasm. Otherwise, FUS-ir large compact inclusions (so-called Pick-like) were also observed but were scarce. In the cerebral cortex and the neostriatum, frequency of the inclusions was well correlated with neuronal loss. In the brainstem, neuronal loss was mild and FUS-ir inclusions dominated. In the subthalamic nucleus and red nucleus, there was no HC but there were many FUS-ir inclusions without neuronal loss. The above findings suggest that cytoplasmic mislocalization and aggregation of FUS appear at the early stage of the disease, and the FUS aggregate process may not be a direct precedent structure of HC.

Caregiver Burden with Duchenne and Becker Muscular Dystrophy in Japan: A Clinical Observation Study.

Objective Skeletal muscle weakness and cardiomyopathy can be seen in carriers of dystrophinopathy. Therefore, the health management of caregivers of Duchenne/Becker muscular dystrophy (DMD/BMD) patients who are themselves carriers is an important issue. However, few studies have focused on caregivers who have dystrophin mutations. Methods In this cross-sectional study conducted at five hospitals, the daily living, situation medical treatment status, genetic testing, physical assessment, care burden, and quality of life of caregivers of DMD/BMD patients were surveyed. Results The subjects were 36 main caregivers (mean age 55.7±8.4 years old), of whom 52.8% were diagnosed as carriers, 8.3% were noncarriers, and 38.9% were not confirmed. In addition, half of the caregivers were not examined regularly at medical institutions. Of all caregivers, 54.3% had muscle or cardiac symptoms, and 75% had elevated serum creatine kinase levels. The mean Zarit Caregiver Burden Interview (ZBI) total score of current caregivers was 20.9±13.1. The frequency of a ZBI total score ≥25 was significantly higher in caregivers diagnosed as carriers than in caregivers unexamined as carriers (p=0.04). The health-related quality of life score (Short Form 36; SF-36) in caregivers was slightly lower than the Japanese standard scores in the sections of physical functioning, role limitations-physical, bodily pain, and social functioning. Conclusion Some caregivers of DMD/BMD patients can themselves have muscular or cardiac symptoms and a heavy care burden. It is therefore necessary for carrier caregivers, especially women, to undergo regular health checkups and receive appropriate health management.

The Association Between Physical Activity/Heart Rate Variability Data Obtained Using a Wearable Device and Timed Motor Functional Tests in Patients with Duchenne Muscular Dystrophy: A Pilot Study.

Background: Duchenne muscular dystrophy (DMD) is a devastating X-linked muscle disease. Clinical evaluation of DMD uses patient-intensive motor function tests, and the recent development of wearable devices allows the collection of a variety of biometric information, including physical activity. Objective: In this study, we examined differences in physical activity and heart rate variability (HRV) between patients with DMD and healthy subjects using a wearable device, and investigated any association between these parameters and motor function in patients with DMD. Methods: Participants were 7 patients with DMD and 8 healthy males, whose physical activity and HRV were provided by a wearable device. These data were used to investigate the relationship between both physical activity and HRV parameters and timed motor functional tests [Time to stand from supine, 10-meter walking time (10MWT), North Star Ambulatory Assessment (NSAA), and 6-minute walking test (6MWT)] in patients with DMD. Results: Results of 24-hours physical activity, fat burning, total number of steps and active distance, average step rate, average exercise intensity during walking, exercise, degree of forward lean during walking, maximum heart rate, normalized low frequency power (LF norm), and maximum exercise intensity in patients with DMD were lower than those in control subjects. Physical activity and HRV parameters did not correlate with the time to stand from supine. The 10MWT positively correlated with average heart rate, while NSAA negatively correlated with average heart rate, total frequency power (TF), and very low frequency power (VLF) during arousal. The 6MWT negatively correlated with ratio LF/high frequency power (HF). CONCLUSIONS: Physical activity and HRV indices that differ from those of normal children and that correlate with motor function assessment may serve as digital biomarkers.

Analysis of splicing abnormalities in the white matter of myotonic dystrophy type 1 brain using RNA sequencing.

Myotonic dystrophy type 1 (DM1) is a neuromuscular disorder caused by the genomic expansion of CTG repeats, in which RNA-binding proteins, such as muscleblind-like protein, are sequestered in the nucleus, and abnormal splicing is observed in various genes. Although abnormal splicing occurs in the brains of patients with DM1, its relation to central nervous system symptoms is unknown. Several imaging studies have indicated substantial white matter defects in patients with DM1. Here, we performed RNA sequencing and analysis of CTG repeat lengths in the frontal lobe of patients with DM1, separating the gray matter and white matter, to investigate splicing abnormalities in the DM1 brain, especially in the white matter. Several genes showed similar levels of splicing abnormalities in both gray and white matter, with an observable trend toward an increased number of repeats in the gray matter. These findings suggest that white matter defects in DM1 stem from aberrant RNA splicing in both gray and white matter. Notably, several of the genes displaying abnormal splicing are recognized as being dominantly expressed in astrocytes and oligodendrocytes, leading us to hypothesize that splicing defects in the white matter may be attributed to abnormal RNA splicing in glial cells.

Facioscapulohumeral muscular dystrophy Health Index: Japanese translation and validation study.

PURPOSE: The Facioscapulohumeral Muscular Dystrophy Health Index (FSHD-HI) is a patient-reported outcome measure developed for patients with FSHD. This study aimed to translate the FSHD-HI into Japanese (FSHD-HI-J), evaluate cultural adaptation, and examine its psychometric properties. MATERIALS AND METHODS: We created two forward translations, integrated them into a single Japanese version, and evaluated the back-translated version of the FSHD-HI. After finalizing the translation and cultural adaptation, we conducted a survey of 66 patients with FSHD to examine the reliability and validity of the FSHD-HI-J. For psychometric evaluations, we used Cronbach's alpha to assess internal consistency, the intraclass correlation coefficient (ICC) for test-retest reliability, and assessed validity based on the associations between FSHD-HI-J, clinical variables, and quality of life measures. RESULTS: The FSHD-HI-J was found to be clinically relevant, indicating high internal consistency and test-retest reliability (ICC = 0.92 [95% confidence interval: 0.86-0.95] for the total score), as well as significant associations with clinical variables (D4Z4 repeats and functional impairment) and other quality of life measures (|rho| = 0.25-0.73). CONCLUSIONS: The FSHD-HI-J is a valid and reliable patient-reported outcome measure for Japanese patients with FSHD. This validated, disease-specific patient-reported outcome is essential for future clinical practice and clinical trials.

Facioscapulohumeral muscular dystrophy (FSHD) affects not only a patient's physical abilities but also their social activities, participation, and overall quality of life.The FSHD-Health Index (FSHD-HI) is an instrument developed as a disease-specific patient-reported outcome measure to evaluate the burden experienced by patients.The Japanese version of the FSHD-HI has been established as a reliable and validated measure for Japanese-speaking patients with FSHD.The Japanese version of the FSHD-HI can serve as a useful instrument for evaluating the effectiveness of interventions in future trials.

Investigation of Glucose Metabolism by Continuous Glucose Monitoring and Validation of Dipeptidyl Peptidase 4 Inhibitor Use in Patients with Myotonic Dystrophy Type 1.

Objectives: We characterized blood glucose fluctuations in patients with myotonic dystrophy type 1 (DM1). After confirming the incretin secretion capacity of patients with DM1, we intended to clarify whether dipeptidyl peptidase 4 (DPP-4) inhibitor administration was appropriate in cases of DM1 with diabetes mellitus. Methods: A 48 h continuous glucose monitoring (CGM) was performed in 29 Japanese patients with DM1. An oral glucose tolerance test (OGTT) was performed in patients with DM1 and five disease controls, and levels of blood glucose, insulin, and incretin (glucagon-like peptide-1 and gastric inhibitory polypeptide) were measured. DPP-4 inhibitors were administered to patients with diabetes mellitus complicated by DM1, and the CGM results were compared. Results: The CGM showed distinct patterns of blood glucose variability among patients classified by an OGTT pattern with significant differences in glucose parameters such as time above 140 mg/dL and mean amplitude of glycemic excursions between the groups. High sensor glucose values were observed in a certain number of patients who were classified as having normal or impaired glucose tolerance by the OGTT. The CGM confirmed the presence of low glucose levels in several patients. Incretin secretion, the target of DPP-4 inhibitors, was preserved in patients with DM1. DPP-4 inhibitor treatment resulted in lower glucose levels and improved insulin secretion in some patients. Conclusions: This is the first CGM study for DM1 patients. The CGM identified potential early abnormalities in glucose metabolism in DM1. In the future, it will be crucial to explore effective methods for harnessing CGM and assessing it quantitatively in DM1.

CTG repeat length underlying cardiac events and sudden death in myotonic dystrophy type 1.

Aims: Myotonic dystrophy Type 1 (DM1) is caused by the expansion of CTG repeats (CTGn) in the DM1 protein kinase (DMPK) gene, while it remains unclear whether CTGn may be associated with the incidence of cardiac events or sudden death in Japan as well as Europe. The aim of this study was to investigate the association between CTGn and cardiac involvements. Methods and results: This cohort study included patients with DM1 who were retrospectively recruited from nine Japanese hospitals specializing in neuromuscular diseases. A total of 496 patients with DM1 who underwent a genetic test in the DMPK gene were analysed. Patients with congenital form or under 15 years old were excluded and patients were assigned into the quartiles. When we compared the incidence of cardiac events including advanced/complete atrioventricular block, pacemaker implantation, and ventricular tachycardias or mortality among four groups, patients with 1300 or longer CTGn experienced composite cardiac events [hazard ratio (HR): 3.19, 95% confidence interval (CI): 1.02-9.99, P = 0.014] more frequently and had significantly higher mortality rate (HR: 6.79, 95% CI: 2.05-22.49, P < 0.001) than those under 400 CTGn while the rate of sudden death was not significantly different. Conclusion: Regarding the cardiac events and mortality in patients with DM1, patients with 1300 or longer CTGn are at especially high risk.