Maria Laura Ester Bianchi

Alternative splicing alterations of Ca2+ handling genes are associated with Ca2+ signal dysregulation in myotonic dystrophy type 1 (DM1) and type 2 (DM2) myotubes.

The pathogenesis of myotonic dystrophy type 1 (DM1) and type 2 (DM2) has been related to the aberrant splicing of several genes, including those encoding for ryanodine receptor 1 (RYR1), sarcoplasmatic/endoplasmatic Ca2+‐ATPase (SERCA) and α1S subunit of voltage‐gated Ca2+ channels (Cav1.1). The aim of this study is to determine whether alterations of these genes are associated with changes in the regulation of intracellular Ca2+ homeostasis and signalling.

Alternative splicing alterations of Ca(2+) handling genes are associated with Ca(2+) signal dysregulation in DM1 and DM2 myotubes

The pathogenesis of myotonic dystrophy type 1 (DM1) and type 2 (DM2) has been related to the aberrant splicing of several genes, including those encoding for ryanodine receptor 1 (RYR1), sarcoplasmatic/endoplasmatic Ca2+‐ATPase (SERCA) and α1S subunit of voltage‐gated Ca2+ channels (Cav1.1). The aim of this study is to determine whether alterations of these genes are associated with changes in the regulation of intracellular Ca2+ homeostasis and signalling.

Abnormal Functional Brain Connectivity and Personality Traits in Myotonic Dystrophy Type 1

IMPORTANCE Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy observed in adults, is a genetic multisystem disorder affecting several other organs besides skeletal muscle, including the brain. Cognitive and personality abnormalities have been reported; however, no studies have investigated brain functional networks and their relationship with personality traits/disorders in patients with DM1. OBJECTIVE To use resting-state functional magnetic resonance imaging to assess the potential relationship between personality traits/disorders and changes to functional connectivity within the default mode network (DMN) in patients with DM1. DESIGN, SETTING, AND PARTICIPANTS We enrolled 27 patients with genetically confirmed DM1 and 16 matched healthy control individuals. Patients underwent personality assessment using clinical interview and Minnesota Multiphasic Personality Inventory-2 administration; all participants underwent resting-state functional magnetic resonance imaging. Investigations were conducted at the Istituto di Ricovero e Cura a Carattere Scientifico Santa Lucia Foundation, Catholic University of Sacred Heart, and Azienda Ospedaliera San Camillo Forlanini. INTERVENTION Resting-state functional magnetic resonance imaging. MAIN OUTCOMES AND MEASURES Measures of personality traits in patients and changes in functional connectivity within the DMN in patients and controls. Changes in functional connectivity and atypical personality traits in patients were correlated. RESULTS We combined results obtained from the Minnesota Multiphasic Personality Inventory-2 and clinical interview to identify a continuum of atypical personality profiles ranging from schizotypal personality traits to paranoid personality disorder within our DM1 patients. We also demonstrated an increase in functional connectivity in the bilateral posterior cingulate and left parietal DMN nodes in DM1 patients compared with controls. Moreover, patients with DM1 showed strong associations between DMN functional connectivity and schizotypal-paranoid traits. CONCLUSIONS AND RELEVANCE Our findings provide novel biological evidence that DM1 is a clinical condition that also involves an alteration of functional connectivity of the brain. We speculate that these functional brain abnormalities, similarly to frank psychiatric disorders, may account for the atypical personality traits observed in patients with DM1.

Alternative splicing of human insulin receptor gene (INSR) in type I and type II skeletal muscle fibers of patients with myotonic dystrophy type 1 and type 2

INSR, one of those genes aberrantly expressed in myotonic dystrophy type 1 (DM1) and type 2 (DM2) due to a toxic RNA effect, encodes for the insulin receptor (IR). Its expression is regulated by alternative splicing generating two isoforms: IR-A, which predominates in embryonic tissue, and IR-B, which is highly expressed in adult, insulin-responsive tissues (skeletal muscle, liver, and adipose tissue). The aberrant INSR expression detected in DM1 and DM2 muscles tissues, characterized by a relative increase of IR-A versus IR-B, was pathogenically related to the insulin resistance occurring in DM patients. To assess if differences in the aberrant splicing of INSR could underlie the distinct fiber type involvement observed in DM1 and DM2 muscle tissues, we have used laser capture microdissection (LCM) and RT-PCR, comparing the alternative splicing of INSR in type I and type II muscle fibers isolated from muscle biopsies of DM1, DM2 patients and controls. In the controls, the relative amounts of IR-A and IR-B showed no obvious differences between type I and type II fibers, as in the whole muscle tissue. In DM1 and DM2 patients, both fiber types showed a similar, relative increase of IR-A versus IR-B, as also evident in the whole muscle tissue. Our data suggest that the distinct fiber type involvement in DM1 and DM2 muscle tissues would not be related to qualitative differences in the expression of INSR. LCM can represent a powerful tool to give a better understanding of the pathogenesis of myotonic dystrophies, as well as other myopathies.

Human cord blood endothelial progenitors promote post-ischemic angiogenesis in immunocompetent mouse model

BACKGROUND Human cord blood (CB) endothelial colony forming cells (ECFCs) are endowed with high vascular regenerative ability in immunodeficient mice, but their immunogenicity and susceptibility to rejection in immunocompetent models has yet to be explored. METHODS We injected CB ECFCs in non-immuno-suppressed C57BL/6J mice after having induced the hindlimb ischemia and we investigated their contribution to the recovery from the ischemic injury. Human ECFCs (hECFCs) were administered by intramuscular injection and hindlimb blood perfusion was measured by laser Doppler analysis at 7-day intervals for 28days after treatment. Mice were sacrificed after 7 and 28days and immunohistochemistry for specific human (CD31) and mouse (von Willebrand factor) endothelial antigens was carried out. Before euthanasia, blood samples to assess cytokines and angiogenic growth factor levels were collected. RESULTS Mice injected with hECFCs showed a prompter and greater recovery of blood flow than controls. Several endothelial cells of human origin were detected at day7 after injection and their number declined progressively. Likewise, a progressive increase of mouse-derived vascular structures were observed, paralleled by the amplified endogenous production of various soluble mediators of angiogenesis, including Vascular Endothelial Growth Factor and Fibroblast Growth Factor. CONCLUSIONS Overall, our findings are consistent with the hypothesis that human ECFCs might expand the endogenous vascular repair potential of recipients and support their possible HLA-independent unconventional use.

Dysplastic nevi, cutaneous melanoma, and other skin neoplasms in patients with myotonic dystrophy type 1: A cross-sectional study

BACKGROUND Myotonic dystrophy type 1 (MD1) is reported to be associated with internal malignancies. The association of myotonic dystrophy with cutaneous tumors is not fully understood. OBJECTIVE We sought to explore the total nevi count and the presence of atypical nevi, cutaneous melanoma, and other skin neoplasms in a representative cohort of patients with MD1 and to compare the findings with age- and sex-matched control subjects. METHODS In all, 90 patients with MD1 and 103 age- and sex-matched control subjects were assessed for cutaneous neoplasms by clinical skin and epiluminescence examination (dermoscopy). Where indicated, subsequent excisions were performed. In patients with MD1, leukocyte n(CTG) expansion was measured. RESULTS Patients with MD1 showed significantly higher numbers of nevi, dysplastic nevi, and melanomas despite a significantly greater proportion of the control subjects reporting sunburns. In addition, we found a significantly greater number of pilomatrixoma in patients with MD1. LIMITATIONS Our study is limited by the fact that there is no agreed-upon standardized technique to assess for prior sun exposure. Further research in the association of cutaneous neoplasms and MD1 including vitamin D and molecular biological techniques are also recommended. CONCLUSION MD1 itself may predispose to development of skin tumors.

An Age-Standardized Prevalence Estimate and a Sex and Age Distribution of Myotonic Dystrophy Types 1 and 2 in the Rome Province, Italy

Background: Prevalence estimates for the 2 forms of myotonic dystrophy types 1 and 2 (DM1 and DM2) are not exhaustive or non-available. Our aim was to estimate the minimum prevalence of DM1 and DM2 in Italy in the Rome province, applying standards of descriptive epidemiology. Methods: All patients with a molecular diagnosis of DM1/DM2 and residents in the Rome province in 2013 have been enrolled, and the age-standardized prevalence has been calculated, assuming a Poisson distribution and adjusting for age. Results: We identified 395 DM1 patients: the age-standardized prevalence for total, females and males was 9.65, 8.35 and 11.07/100,000, respectively. The mean age of subjects differed considerably according to CTG repeat length (p = 0.001). Forty DM2 patients were identified. The age-standardized prevalence for total, females and males was 0.99, 1.07 and 0.90/100,000, respectively. The mean age was 57.05. Conclusions: We estimated for the first time the age-standardized prevalence and the sex and age distribution of DM1 and DM2 in a general population. A higher prevalence of males in DM1 and females in DM2 and a higher mean age of DM2 patients (+8 years) were ascertained. Prevalence of DM2 was 10% that of DM1. These prevalence values are probably lower than mutational rates due to the incomplete penetrance of DM1 mutations and to the clinical elusiveness of DM2. Our findings will be useful in designing cohort studies and for developing a disease registry.

Restless legs syndrome and daytime sleepiness are prominent in myotonic dystrophy type 2Author Response

Lam et al.1 studied the frequency of restless legs syndrome, excessive daytime sleepiness (EDS), and fatigue in 30 patients with myotonic dystrophy type 2 (DM2). They did not find obstructive sleep apnea (OSA) or REM sleep behavior disorder. The authors concluded that EDS may also be related to an intrinsic CNS disturbance in DM2. We found that OSA is the most frequent sleep-disordered breathing (SDB) in this disorder. By home-based cardiorespiratory monitoring, we found SDB in 6 …

Myotonic dystrophy type 1 and de novo FSHD mutation double trouble: A clinical and muscle MRI study

Here we describe the first case of myotonic dystrophy type 1 (DM1) associated with facio-scapulo-humeral dystrophy (FSHD). From a clinical point of view, the patient displayed a pattern of muscle involvement reminiscent of both disorders, including hand-grip myotonia, facial, axial and distal limbs muscle weakness as well as a bilateral winged scapula associated with atrophy of the pectoralis major muscle and lumbar lordosis; pelvic muscles were mostly spared. An extensive muscle MRI assessment including neck, shoulder, abdominal, pelvic and lower limb muscles documented radiological features typical of DM1 and FSDH. Molecular genetic studies confirmed that the proband carried both a pathologically expanded DMPK allele, inherited from his father, and a de novo shortened D4Z4 repeat fragment at 4q35 locus.

fNIRS evaluation during a phonemic verbal task reveals prefrontal hypometabolism in patients affected by myotonic dystrophy type 1

OBJECTIVE Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, is characterized by a multisystem involvement. Cognitive involvement predominantly affecting frono-temporal functions is an established clinical feature in this disorder. Brain imaging and metabolic studies showed a predominant involvement of fronto-temporal regions in DM1 patients, yet correlation studies among these findings and neuropsychological data gave contrasting results. In order to contribute to clarify the relationship between the metabolic changes documented in the frontal cortex of DM1 patients and a related cognitive task, we applied the functional near-infrared spectroscopy (fNIRS) during the execution of a phonemic verbal fluency task (pVFT). METHODS We enrolled 29 consecutive right-handed DM1 patients and 30 controls. A 2-channel fNIRS imaging system was used to investigate changes in oxygenated [O2Hb] and deoxygenated [HHb] hemoglobin concentrations in the prefrontal cortex (PFC) during a pVFT. [O2Hb] and [HHb] baseline-corrected activation values were calculated (respectively [O2Hb]c and [HHb]c). RESULTS In the control group [O2Hb] significantly increased and [HHb] significantly decreased during the pVFT, in the DM1 group no significant variation was found for both parameters revealing no activation of both PFCs during the task. On the other hand, in the DM1 sample, statistical analysis revealed a direct correlation between [O2Hb]c of the left PFC and the pVFT score, while no correlation was observed in the control group. CONCLUSIONS Our study reveals that DM1 patients show prefrontal hypometabolism during a specific frontal cognitive task compared to controls. Moreover the rapid temporal discrimination of fNIRS allows revealing the correlation between the PFC hypometabolism and the cognitive performance in DM1 patients. SIGNIFICANCE fNIRS can be helpful to understand the functional correlates of the frontal cognitive impairment in DM1.