Case report: Dihydropyridine receptor (CACNA1S) congenital myopathy, a novel phenotype with early onset periodic paralysis.

Introduction: CACNA1S related congenital myopathy is an emerging recently described entity. In this report we describe 2 sisters with mutations in the CACNA1S gene and the novel phenotype of congenital myopathy and infantile onset episodic weakness. Clinical description: Both sisters had neonatal onset hypotonia, muscle weakness, and delayed walking. Episodic weakness started in infancy and continued thereafter, provoked mostly by cold exposure. Muscle imaging revealed fat replacement of gluteus maximus muscles. Next generation sequencing found the missense p.Cys944Tyr variant and the novel splicing variant c.3526-2A>G in CACNA1S. Minigene assay revealed the splicing variant caused skipping of exon 28 from the transcript, potentially affecting protein folding and/or voltage dependent activation. Conclusion: This novel phenotype supports the notion that there are age related differences in the clinical expression of CACNA1S gene mutations. This expands our understanding of mutations located in regions of the CACNA1S outside the highly conserved S4 segment, where most mutations thus far have been identified.

Transcranial brain parenchyma sonographic findings in patients with myotonic dystrophy type 1 and 2.

Introduction: Myotonic dystrophy type 1 (DM1) and 2 (DM2) are genetically determined progressive muscular disorders with multisystemic affection, including brain involvement. Transcranial sonography (TCS) is a reliable diagnostic tool for the investigation of deep brain structures. We sought to evaluate TCS findings in genetically confirmed DM1 and DM2 patients, and further correlate these results with patients' clinical features. Methods: This cross-sectional study included 163 patients (102 DM1, 61 DM2). Echogenicity of the brainstem raphe (BR) and substantia nigra (SN) as well as the diameter of the third ventricle (DTV) were assessed by TCS. Patients were evaluated using the Hamilton Depression Rating Scale, Fatigue Severity Scale and Daytime Sleepiness Scale. Results: SN hyperechogenicity was observed in 40% of DM1 and 34% of DM2 patients. SN hypoechogenicity was detected in 17% of DM1 and 7% of DM2 patients. BR hypoechogenicity was found in 36% of DM1 and 47% of DM2 subjects. Enlarged DTV was noted in 19% of DM1 and 15% of DM2 patients. Older, weaker, depressive, and fatigued DM1 patients were more likely to have BR hypoechogenicity (p < 0.05). DTV correlated with age and disease duration in DM1 (p < 0.01). In DM2 patients SN hyperechogenicity correlated with fatigue. Excessive daytime sleepiness was associated with hypoechogenic BR (p < 0.05) and enlarged DVT (p < 0.01) in DM2 patients. Conclusions: TCS is an easy applicable and sensitive neuroimaging technique that could offer new information regarding several brainstem structures in DM1 and DM2. This may lead to better understanding of the pathogenesis of the brain involvement in DM with possible clinical implications.

Myotonic dystrophy type 1 in the COVID-19 era.

INTRODUCTION: Myotonic dystrophy type 1 (DM1) is the most prevalent muscular dystrophy in adults. People with DM1 might represent a high-risk population for respiratory infections, including COVID-19. Our aim was to evaluate the characteristics of COVID-19 infection and vaccination rate in DM1 patients. METHODS: This cross-sectional cohort study included 89 patients from the Serbian registry for myotonic dystrophies. Mean age at testing was 48.4 ± 10.4 years with 41 (46.1%) male patients. Mean duration of the disease was 24.0 ± 10.3 years. RESULTS: COVID-19 infection was reported by 36 (40.4%) DM1 patients. Around 14% of patients had a more severe form of COVID-19 requiring hospitalization. The severity of COVID-19 was in accordance with the duration of DM1. A severe form of COVID-19 was reported in 20.8% of patients who were not vaccinated against SARS-CoV-2 and in none of the vaccinated ones. The majority of 89 tested patients (66.3%) were vaccinated against SARS-CoV-2. About half of them (54.2%) received three doses and 35.6% two doses of vaccine. Mild adverse events after vaccination were recorded in 20.3% of patients. CONCLUSIONS: The percentage of DM1 patients who suffered from COVID-19 was like in general population, but with more severe forms in DM1, especially in patients with longer DM1 duration. The study indicated an overall favorable safety profile of COVID-19 vaccines among individuals with DM1 and its ability to protect them from severe COVID-19.

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.

Case report: Sodium and chloride muscle channelopathy coexistence: A complicated phenotype and a challenging diagnosis.

Non-dystrophic myotonias (NDM) encompass chloride and sodium channelopathy. Mutations in CLCN1 lead to either the autosomal dominant form or the recessive form of myotonia congenita (MC). The main symptom is stiffness worsening after rest and improving by physical exercise. Patients with recessive mutations often show muscle hypertrophy, and transient weakness mostly in their lower limbs. Mutations in SCN4A can lead to Hyper-, Hypo- or Normo-kalemic Periodic Paralysis or to different forms of myotonia (Paramyotonia Congenita-PMC and Sodium Channel Myotonia-SCM and severe neonatal episodic laryngospasm-SNEL). SCM often presents facial muscle stiffness, cold sensitivity, and muscle pain, whereas myotonia worsens in PMC patients with the repetition of the muscle activity and cold. Patients affected by chloride or sodium channelopathies may show similar phenotypes and symptoms, making the diagnosis more difficult to reach. Herein we present a woman in whom sodium and chloride channelopathies coexist yielding a complex phenotype with features typical of both MC and PMC. Disease onset was in the second decade with asthenia, weakness, warm up and limb stiffness, and her symptoms had been worsening through the years leading to frequent heavy retrosternal compression, tachycardia, stiffness, and symmetrical pain in her lower limbs. She presented severe lid lag myotonia, a hypertrophic appearance at four limbs and myotonic discharges at EMG. Her symptoms have been triggered by exposure to cold and her daily life was impaired. All together, clinical signs and instrumental data led to the hypothesis of PMC and to the administration of mexiletine, then replaced by acetazolamide because of gastrointestinal side effects. Analysis of SCN4A revealed a new variant, p.Glu1607del. Nonetheless the severity of myotonia in the lower limbs and her general stiffness led to hypothesize that the impairment of sodium channel, Nav1.4, alone could not satisfactorily explain the phenotype and a second genetic "factor" was hypothesized. CLCN1 was targeted, and p.Met485Val was detected in homozygosity. This case highlights that proper identification of signs and symptoms by an expert neurologist is crucial to target a successful genetic diagnosis and appropriate therapy.

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.

Cognitive assessment in patients with myotonic dystrophy type 2.

Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystemic disorder. Previous studies conducted on small cohorts of DM2 patients indicated presence of a cognitive dysfunction. We aimed to assess cognitive functions in a larger cohort of Serbian DM2 patients using an extensive battery of neuropsychological tests. The study included 76 patients with a genetically confirmed DM2, 68 of whom had all tests for different cognitive domains performed. Patients underwent clinical and neuropsychological testing, including cognitive screening and assessment of general intellectual level, attention, executive and visuospatial abilities, memory, and language functions. Only 6% of patients achieved a below-average score on the general intellectual level test. Cognitive screening tests indicated presence of cognitive deficits in 5.5% of patients according to the Mini Mental State Examination test and 25.8% according to the Addenbrooke's Cognitive Examination Revised test. Twenty-four (35.3%) patients had a cognitive impairment (being two standard deviations out of norm in at least two cognitive domains). Around one quarter of DM2 patients had a significant cognitive impairment that interfered with their everyday functioning. Patients with significant cognitive impairment were older at testing and at disease onset, less educated, and had more severe muscle weakness.

Cell environment shapes TDP-43 function with implications in neuronal and muscle disease.

TDP-43 (TAR DNA-binding protein 43) aggregation and redistribution are recognised as a hallmark of amyotrophic lateral sclerosis and frontotemporal dementia. As TDP-43 inclusions have recently been described in the muscle of inclusion body myositis patients, this highlights the need to understand the role of TDP-43 beyond the central nervous system. Using RNA-seq, we directly compare TDP-43-mediated RNA processing in muscle (C2C12) and neuronal (NSC34) mouse cells. TDP-43 displays a cell-type-characteristic behaviour targeting unique transcripts in each cell-type, which is due to characteristic expression of RNA-binding proteins, that influence TDP-43's performance and define cell-type specific splicing. Among splicing events commonly dysregulated in both cell lines, we identify some that are TDP-43-dependent also in human cells. Inclusion levels of these alternative exons are altered in tissues of patients suffering from FTLD and IBM. We therefore propose that TDP-43 dysfunction contributes to disease development either in a common or a tissue-specific manner.

First Family of MATR3-Related Distal Myopathy From Italy: The Role of Muscle Biopsy in the Diagnosis and Characterization of a Still Poorly Understood Disease.

Mutations in the MATR3 gene are associated to distal myopathy with vocal cord and pharyngeal weakness (VCPDM), as well as familiar and sporadic motor neuron disease. To date, 12 VCPDM families from the United States, Germany, Japan, Bulgary, and France have been described in the literature. Here we report an Italian family with a propositus of a 40-year-old woman presenting progressive bilateral foot drop, rhinolalia, and distal muscular atrophy, without clinical signs of motor neuron affection. Her father, deceased some years before, presented a similar distal myopathy phenotype, while her 20-year-old son is asymptomatic. Myopathic changes with vacuolization were observed in muscle biopsy from the propositus. These results, together with the peculiar clinical picture, lead to MATR3 gene sequencing, which revealed a heterozygous p.S85C mutation in the propositus. The same mutation was found in her son. Over a 5-year follow-up, progression is mild in the propositus, while her son remains asymptomatic. Clinical, radiological, and pathological data of our propositus are presented and compared to previously reported cases of VCPDM. VCPDM turns out to be a quite homogenous phenotype of late-onset myopathy associated to p.S85C mutation in MATR3 gene. MATR3-related pathology, encompassing myopathy and motor neuron disease, represents an illustrative example of multisystem proteinopathy (MSP), such as other diseases associated to mutations in VCP, HNRNPA2B1, HNRNPA1, and SQSTM1 genes. The present report contributes to a further characterization of this still poorly understood pathology and points out the diagnostic utility of muscle biopsy in challenging cases.

Co-occurrence of DMPK expansion and CLCN1 mutation in a patient with myotonia.

INTRODUCTION: Myotonic disorders are a group of diseases affecting the muscle, in different ways. Myotonic dystrophy type 1 (DM1) is related to (CTG)n expansion in the 3-untranslated region of the dystrophia myotonica protein kinase (DMPK) gene and is the most frequent and disabling form, causing muscular, visibility, respiratory, and cardiac impairment. Non-dystrophic myotonias (NDMs) affect the skeletal muscle alone. In particular, mutations in the chloride channel (CLCN1) gene cause myotonia congenita (MC), which can have autosomal dominant or recessive inheritance. CASE REPORT: We describe a patient with a family history of asymptomatic or paucisymptomatic myotonia, who presented handgrip myotonia which sharply reduced after mexiletine administration. Molecular analysis showed both a paternally inherited DMPK expansion and a maternally inherited CLCN1 mutation. CONCLUSIONS: Only one other similar case was reported so far; however, the segregation of the two mutations and the characteristics of the muscle were not studied. Since our patient lacked the classical phenotypical and muscle histopathological characteristics of DM1 and showed mild splicing alterations despite a pathogenic DMPK expansion and the nuclear accumulation of toxic RNA, we may speculate that the co-occurrence of a CLCN1 mutation could have attenuated the severity of DM1 phenotype.

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.

Lesion distribution and substrate of white matter damage in myotonic dystrophy type 1: Comparison with multiple sclerosis.

Myotonic Dystrophy type 1 (DM1) is an autosomal dominant condition caused by expansion of the CTG triplet repeats within the myotonic dystrophy protein of the kinase (DMPK) gene. The central nervous system is involved in the disease, with multiple symptoms including cognitive impairment. A typical feature of DM1 is the presence of widespread white matter (WM) lesions, whose total volume is associated with CTG triplet expansion. The aim of this study was to characterize the distribution and pathological substrate of these lesions as well as the normal appearing WM (NAWM) using quantitative magnetization transfer (qMT) MRI, and comparing data from DM1 patients with those from patients with multiple sclerosis (MS). Twenty-eight patients with DM1, 29 patients with relapsing-remitting MS, and 15 healthy controls had an MRI scan, including conventional and qMT imaging. The average pool size ratio (F), a proxy of myelination, was computed within lesions and NAWM for every participant. The lesion masks were warped into MNI space and lesion probability maps were obtained for each patient group. The lesion distribution, total lesion load and the tissue-specific mean F were compared between groups. The supratentorial distribution of lesions was similar in the 2 patient groups, although mean lesion volume was higher in MS than DM1. DM1 presented higher prevalence of anterior temporal lobe lesions, but none in the cerebellum and brainstem. Significantly reduced F values were found within DM1 lesions, suggesting a loss of myelin density. While F was reduced in the NAWM of MS patients, it did not differ between DM1 and controls. Our results provide further evidence for a need to compare histology and imaging using new MRI techniques in DM1 patients, in order to further our understanding of the underlying disease process contributing to WM disease.

Molecular and Clinical Implications of Variant Repeats in Myotonic Dystrophy Type 1.

Myotonic dystrophy type 1 (DM1) is one of the most variable monogenic diseases at phenotypic, genetic, and epigenetic level. The disease is multi-systemic with the age at onset ranging from birth to late age. The underlying mutation is an unstable expansion of CTG repeats in the DMPK gene, varying in size from 50 to >1000 repeats. Generally, large expansions are associated with an earlier age at onset. Additionally, the most severe, congenital DM1 form is typically associated with local DNA methylation. Genetic variability of DM1 mutation is further increased by its structural variations due to presence of other repeats (e.g., CCG, CTC, CAG). These variant repeats or repeat interruptions seem to confer an additional level of epigenetic variability since local DNA methylation is frequently associated with variant CCG repeats independently of the expansion size. The effect of repeat interruptions on DM1 molecular pathogenesis is not investigated enough. Studies on patients indicate their stabilizing effect on DMPK expansions because no congenital cases were described in patients with repeat interruptions, and the age at onset is frequently later than expected. Here, we review the clinical relevance of repeat interruptions in DM1 and genetic and epigenetic characteristics of interrupted DMPK expansions based on patient studies.

Sodium Channel Myotonia Due to Novel Mutations in Domain I of Nav1.4.

Sodium channel myotonia is a form of muscle channelopathy due to mutations that affect the Nav1.4 channel. We describe seven families with a series of symptoms ranging from asymptomatic to clearly myotonic signs that have in common two novel mutations, p.Ile215Thr and p.Gly241Val, in the first domain of the Nav1.4 channel. The families described have been clinically and genetically evaluated. p.Ile215Thr and p.Gly241Val lie, respectively, on extracellular and intracellular loops of the first domain of the Nav1.4 channel. We assessed that the p.Ile215Thr mutation can be related to a founder effect in people from Southern Italy. Electrophysiological evaluation of the channel function showed that the voltage dependence of the activation for both the mutant channels was significantly shifted toward hyperpolarized potentials (Ile215Thr: -28.6 ± 1.5 mV and Gly241Val: -30.2 ± 1.3 mV vs. WT: -18.5 ± 1.3 mV). The slow inactivation was also significantly affected, whereas fast inactivation showed a different behavior in the two mutants. We characterized two novel mutations of the SCN4A gene expanding the knowledge about genetics of mild forms of myotonia, and we present, to our knowledge, the first homozygous patient with sodium channel myotonia.

Ventral tegmental area dysfunction affects decision-making in patients with myotonic dystrophy type-1.

The clinical manifestations of Myotonic Dystrophy type-1 (DM1) are associated with a complex mixture of multisystem features including cognitive dysfunctions that strongly impact on patients' social and occupational functioning. Decision making, a function controlled by dopaminergic circuitry, is critical for succeeding in one's social and professional life. We tested here the hypothesis that altered connectivity of the ventral tegmental area (VTA), one of the major sources of diffuse dopaminergic projections in the brain, might account for some higher-level dysfunctions observed in patients with DM1. In this case-control study, we recruited 31 patients with DM1 and 26 healthy controls who underwent the IOWA Gambling task and resting-state functional MRI (RS-fMRI) at 3T. Functional connectivity of the VTA was assessed using RS-fMRI. VTA connectivity was compared between 25 DM1 patients and all the controls, and the presence of associations between VTA connectivity and IOWA Gambling task performance was also investigated. DM1 patients performed significantly worse than controls at the IOWA Gambling task. A significant increase of functional connectivity was observed between VTA and the left supramarginal and superior temporal gyri in DM1 patients. Patients' IOWA Gambling task net-scores were strictly associated with VTA-driven functional connectivity in the bilateral supplementary motor area and right precentral gyrus. This study demonstrates a prominent deficit of decision-making in patients with DM1. It might be related to increased connectivity between VTA and brain areas critically involved in the reward/punishment system and social cognition. These findings indicate that dopaminergic function is a potential target for pharmacological and non-pharmacological interventions in DM1.

Guidelines on clinical presentation and management of nondystrophic myotonias.

The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1 gene. Clinically, they are characterized by myotonia, defined as delayed muscle relaxation after voluntary contraction, which leads to symptoms of muscle stiffness, pain, fatigue, and weakness. Diagnosis is based on history and examination findings, the presence of electrical myotonia on electromyography, and genetic confirmation. In the absence of genetic confirmation, the diagnosis is supported by detailed electrophysiological testing, exclusion of other related disorders, and analysis of a variant of uncertain significance if present. Symptomatic treatment with a sodium channel blocker, such as mexiletine, is usually the first step in management, as well as educating patients about potential anesthetic complications.

Rare Disease: Cardiac Risk Assessment With MRI in Patients With Myotonic Dystrophy Type 1.

Introduction: To evaluate myocardial strain and extracellular volume in myotonic dystrophy type 1 (DM1) patients as potential imaging biomarkers of subclinical cardiac pathology. Materials and methods: We retrospectively analyzed 9 DM1 patients without apparent cardiac disease who had undergone cardiac magnetic resonance at our center. Patients were age- and sex-matched with healthy controls. The Mann-Whitney U test was used to compare cardiac strain between the two groups. The t-test was used to compare the extracellular volume obtained in DM1 patients with that in healthy subject. Spearman's ρ was used for studying the associations among imaging parameters. Results: Global cardiac strain (median -19.1%; IQR -20.5%, -16.5%) in DM1 patients was lower (p = 0.011) than that in controls (median-21.7%; IQR-22.7%,-21.3%). Global extracellular volume in DM1 patients (median 32.3%; IQR 29.3%,36.8%) was significantly (p = 0.008) higher than that reported in literature in healthy subjects (median 25.6%; IQR 19.9%,31.9%). Global cardiac strain showed a strong, positive correlation with septal strain (ρ = 0.767, p = 0.016) and with both global (ρ = 0.733 p = 0.025) and septal extracellular volume (ρ = 0.767, p = 0.016). Discussion: The increase in cardiac extracellular volume and decrease in strain are signs of early cardiac pathology in DM1. Physicians dealing with DM1 may take into consideration cardiac magnetic resonance as a screening tool to identify early cardiac involvement in this condition.