Development and validation of the Myasthenia Gravis TeleScore (MGTS).

OBJECTIVE: The aim of our study was to validate the Myasthenia Gravis TeleScore (MGTS), a scale for the evaluation of MG patients in telemedicine. INTRODUCTION: COVID-19 pandemic has boosted telemedicine in clinical practice. It could be crucial in the care of neurological patients with chronic disease. However, there is a lack of validated disease-specific tools to evaluate MG patients in telemedicine. METHODS: The MGTS included ten items divided in four districts: ocular, generalized muscular strength, bulbar, and respiratory. Patients were assessed with two different scales: the MGTS and the INCB-MG chosen as a reference from which MGTS was partially derived. Visit in presence with INCB-MG and televisit with MGTS were performed consecutively. Televisit was conducted by another neurologist between two rooms. A blind method was adopted. The strength of correlation was determined by the correlation coefficient (r); analysis of covariance (ANOVA-Kruskal-Wallis test) was used to compare subgroups. Significance was set to p < 0.05. RESULTS: One hundred thirty-one patients were included in the study, 71 females and 60 males. The Spearman correlation coefficient between the INCB-MG scale and the MGTS was 0.825 (p < 0.001), indicating a very strong correlation between them. Different items showed different correlations from low to high (0.32 to 0.80). As expected, correlation was lower between items with different evaluation modality (anamnestic vs clinical). DISCUSSION: The MGTS demonstrated a good correlation with INCB-MG, reliability and construct validity.

Severe multiple sclerosis reactivation during prolonged lymphopenia after dimethyl fumarate discontinuation.

BACKGROUND: Delayed-release dimethyl fumarate (DMF) treatment can be associated with reduced lymphocyte and leucocyte counts, which might persist after DMF discontinuation. CASE PRESENTATION: We report the case of a patient with severe disease reactivation despite prolonged lymphopenia after DMF discontinuation. We describe the frequency and impact of prolonged lymphopenia after DMF discontinuation at two tertiary MS centres. A 36-year-old female patient with multiple sclerosis was switched to DMF after 14 years of treatment with interferon beta-1a. DMF was suspended after 4 months because of persistent lymphopenia for 3 months. Six months later, the patient had a severe relapse with multiple enhancing brain lesions at MRI although lymphopenia was still persistent. Haematological assessment excluded other causes of lymphopenia, which was evaluated as a probable iatrogenic complication of DMF. The patient was treated with i.v. methylprednisolone 1 gr daily for 3 days with clinical recovery. CONCLUSIONS: Prolonged lymphopenia after DMT discontinuation does not protect against disease reactivation. Starting a new immune therapy should be balanced against the option of a "wait and see." A different immunotherapeutic strategy such as an anti-B therapeutic approach could be considered.

ClC-1 mutations in myotonia congenita patients: insights into molecular gating mechanisms and genotype-phenotype correlation.

KEY POINTS: Loss-of-function mutations of the skeletal muscle ClC-1 channel cause myotonia congenita with variable phenotypes. Using patch clamp we show that F484L, located in the conducting pore, probably induces mild dominant myotonia by right-shifting the slow gating of ClC-1 channel, without exerting a dominant-negative effect on the wild-type (WT) subunit. Molecular dynamics simulations suggest that F484L affects the slow gate by increasing the frequency and the stability of H-bond formation between E232 in helix F and Y578 in helix R. Three other myotonic ClC-1 mutations are shown to produce distinct effects on channel function: L198P shifts the slow gate to positive potentials, V640G reduces channel activity, while L628P displays a WT-like behaviour (electrophysiology data only). Our results provide novel insight into the molecular mechanisms underlying normal and altered ClC-1 function. ABSTRACT: Myotonia congenita is an inherited disease caused by loss-of-function mutations of the skeletal muscle ClC-1 chloride channel, characterized by impaired muscle relaxation after contraction and stiffness. In the present study, we provided an in-depth characterization of F484L, a mutation previously identified in dominant myotonia, in order to define the genotype-phenotype correlation, and to elucidate the contribution of this pore residue to the mechanisms of ClC-1 gating. Patch-clamp recordings showed that F484L reduced chloride currents at every tested potential and dramatically right-shifted the voltage dependence of slow gating, thus contributing to the mild clinical phenotype of affected heterozygote carriers. Unlike dominant mutations located at the dimer interface, no dominant-negative effect was observed when F484L mutant subunits were co-expressed with wild type. Molecular dynamics simulations further revealed that F484L affected the slow gate by increasing the frequency and stability of the H-bond formation between the pore residue E232 and the R helix residue Y578. In addition, using patch-clamp electrophysiology, we characterized three other myotonic ClC-1 mutations. We proved that the dominant L198P mutation in the channel pore also right-shifted the voltage dependence of slow gating, recapitulating mild myotonia. The recessive V640G mutant drastically reduced channel function, which probably accounts for myotonia. In contrast, the recessive L628P mutant produced currents very similar to wild type, suggesting that the occurrence of the compound truncating mutation (Q812X) or other muscle-specific mechanisms accounted for the severe symptoms observed in this family. Our results provide novel insight into the molecular mechanisms underlying normal and altered ClC-1 function.

Development and validation of the multiple sclerosis questionnaire for the evaluation of job difficulties (MSQ-Job).

OBJECTIVE: Multiple sclerosis (MS) affects young adults of working age. Difficulties in work-related activities are usually ascribed to MS symptoms, while the impact of workplace features is underestimated. This article presents the Multiple Sclerosis Questionnaire for Job Difficulties (MSQ-Job), designed to assess working difficulties due to MS symptoms and workplace features. METHODS: A sample of employed MS patients completed the MSQ-Job, the WHO-Disability Assessment Schedule (WHODAS 2.0) and the 54-items MS Quality of Life Questionnaires (MSQOL-54); the expanded disability status scale (EDSS) was used to define MS severity. Factor structure was evaluated using principal component extraction and Oblimin rotation; internal consistency was assessed with Cronbach's alpha; construct and discriminant validity using t-test (EDSS 0-2 vs >2; patients self-reporting need for support vs patients reporting no needs; full-time vs part-time employees); and Pearson's correlation with WHODAS 2.0 and MSQOL-54. RESULTS: The MSQ-Job is a 42-item questionnaire with six scales and an overall factor. Scores range on a 0-100 scale (higher scores indicate more and more severe difficulties); patients with EDSS>2 and self-reporting support needs had worse scores than those with EDSS 0-2 and without needs. Correlations with WHODAS 2.0 and MSQOL-54 were generally significant (P < 0.0007) and below 0.70. CONCLUSIONS: The MSQ-Job jointly measures the impact of respondents' symptoms and workplace features on work activities and enables to assess the effects of clinical and occupational interventions and better describe the impact of MS indirect costs.

A comprehensive analysis of the epidemiology and clinical characteristics of anti-LRP4 in myasthenia gravis.

Double-seronegative myasthenia gravis (dSN-MG, without detectable AChR and MuSK antibodies) presents a serious gap in MG diagnosis and understanding. Recently, autoantibodies against the low-density lipoprotein receptor-related protein 4 (LRP4) have been identified in several dSN-MG sera, but with dramatic frequency variation (∼2-50%). We have developed a cell based assay (CBA) based on human LRP4 expressing HEK293 cells, for the reliable and efficient detection of LRP4 antibodies. We have screened about 800 MG patient sera from 10 countries for LRP4 antibodies. The overall frequency of LRP4-MG in the dSN-MG group (635 patients) was 18.7% but with variations among different populations (range 7-32.7%). Interestingly, we also identified double positive sera: 8/107 anti-AChR positive and 10/67 anti-MuSK positive sera also had detectable LRP4 antibodies, predominantly originating from only two of the participating groups. No LRP4 antibodies were identified in sera from 56 healthy controls tested, while 4/110 from patients with other neuroimmune diseases were positive. The clinical data, when available, for the LRP4-MG patients were then studied. At disease onset symptoms were mild (81% had MGFA grade I or II), with some identified thymic changes (32% hyperplasia, none with thymoma). On the other hand, double positive patients (AChR/LRP4-MG and MuSK/LRP4-MG) had more severe symptoms at onset compared with any single positive MG subgroup. Contrary to MuSK-MG, 27% of ocular dSN-MG patients were LRP4 antibody positive. Similarly, contrary to MuSK antibodies, which are predominantly of the IgG4 subtype, LRP4 antibodies were predominantly of the IgG1 and IgG2 subtypes. The prevalence was higher in women than in men (female/male ratio 2.5/1), with an average disease onset at ages 33.4 for females and 41.9 for males. Overall, the response of LRP4-MG patients to treatment was similar to published responses of AChR-MG rather than to MuSK-MG patients.

Italian recommendations for Lambert-Eaton myasthenic syndrome (LEMS) management.

Lambert-Eaton myasthenic syndrome (LEMS) is a pre-synaptic disorder of the neuromuscular and autonomic transmission mediated by antibodies to voltage-gated calcium channels at the motor nerve terminal. LEMS is a quite rare and probably under-diagnosed disease: the onset may be slow and clinical signs are typically fluctuating, thus adding to the delay in diagnosis. LEMS weakness typically involves lower and upper limbs and the proximal muscles are predominantly affected. A significant proportion of patients also have dysfunction of the autonomic nervous system that may include dry mouth, constipation, blurred vision, impaired sweating, and orthostatic hypotension. LEMS recognition is based on clinical, electrophysiological and immunological criteria. Nearly 50-60% of patients with LEMS have an underlying tumour that, in almost all cases, is a small-cell lung cancer; the onset of neurological symptoms generally precedes tumour detection. A careful screening for the early detection of the possible associated cancer is a crucial step for optimal disease management. The Italian Working Group on Myasthenic Syndromes developed diagnostic and therapeutic algorithms that could serve in routine clinical practice as tools for a patient-tailored approach.

Fibroblasts from the muscles of Duchenne muscular dystrophy patients are resistant to cell detachment apoptosis.

Extracellular matrix (ECM) proteins, including collagen and growth factors, are greatly increased in tissue fibrosis and mainly secreted by fibroblasts. We previously demonstrated that muscle-derived fibroblasts from Duchenne muscular dystrophy (DMD) patients have a profibrotic phenotype, that includes significantly reduced expression of tissue inhibitor of metalloprotease 3 (TIMP-3) compared to control. Since TIMP-3 induces apoptosis in various cell types, we hypothesized increased resistance of DMD fibroblasts to apoptosis. To address this, we evaluated apoptotic nuclei, caspase 3, caspase 3 substrate expression, and migration and adhesion properties of muscle-derived fibroblasts, after applying different apoptosis-inducing treatments. We found that DMD fibroblasts were less susceptible to cell death, more adhesive, and had greater tendency to migrate than control fibroblasts - findings further supported by alterations in FAK and ERK/MAPK expression. Resistance to apoptosis and greater adhesion are likely to contribute to muscle fibrosis so a pharmacological treatment that targets dysregulated pathways involved in cell detachment apoptosis (anoikis) may limit the progressive fibrotic remodeling characteristic of DMD.

Clinical management of patients with thymic epithelial tumors: the recommendations endorsed by the Italian Association of Medical Oncology (AIOM).

The Italian Association of Medical Oncology recommendations on thymic epithelial tumors, which have been drawn up for the first time in 2020 through an evidence-based approach, report indications on all the main aspects of clinical management of this group of rare diseases, from diagnosis and staging, to new available systemic treatments, such as targeted therapies and immunotherapies. A summary of key recommendations is presented here and complete recommendations are reported as Supplementary Materials, available at https://doi.org/10.1016/j.esmoop.2021.100188.

Adjuvant role of a new emollient cream in patients with palmar and/or plantar psoriasis: a pilot randomized open-label study.

Emollients are considered important adjunctive tools for the therapeutic management of psoriasis patients. In spite of the widespread use, the actual impact of emollients on psoriasis is far to be completely elucidated. The objective of this study was to evaluate the effect of a new emollient cream containing milk proteins and Glycyrrhiza glabra extracts in patients with palmar and/or plantar psoriasis treated with topical corticotherapy. This pilot open parallel-group trial was carried out in 40 patients with palmar and/or plantar psoriasis. Patients were randomized to receive monotherapy with mometasone furoate ointment, applied once daily to the palmoplantar lesions until remission and for a maximum of 4 weeks (N=20), or the same topical corticotherapy in combination with the emollient cream (N=20). The emollient was applied twice a day for 4 weeks. Clinical assessments were performed at baseline and 2 and 4 weeks after the start of treatment. All patients completed the study and showed a progressive improvement of their palmo-plantar psoriasis over the treatment period, achieving at week 4 a statistical significant reduction in the severity of all clinical signs (erythema, desquamation and infiltration) and in the surface area affected. The comparison between the two groups showed no differences in the mean average duration of corticosteroid therapy, whereas a significantly greater improvement of desquamation, surface area affected, and subjective symptoms was observed at week 4 in the group treated with the corticotherapy combined with the emollient as compared to patients who received the corticotherapy alone. This pilot experience suggests the importance of the adjuvant role of particular emollients in the management of psoriasis.

Risk of arrhythmia in type I myotonic dystrophy: the role of clinical and genetic variables.

OBJECTIVE: To examine the association between the presence of arrhythmia in type 1 myotonic dystrophy (DM1) and clinical-genetic variables, evaluating their role as predictors of the risk of arrhythmia. METHODS: 245 patients with genetically proven DM1 underwent clinical and non-invasive cardiological evaluation. Severity of muscular involvement was assessed according to the 5 point Muscular Disability Rating Score (MDRS). Data were analysed by univariate and multivariate models. RESULTS: 245 patients were examined and cardiac arrhythmias were found in 63 subjects, 40 of whom required a device implant. Statistical analyses revealed that men had more than double the risk of developing arrhythmias compared with women (p = 0.018). Addition of each year of age caused an increased risk of arrhythmia equal to 3% (p = 0.030). Subjects with MDRS 5 had a risk of arrhythmia 12 times higher than patients with MDRS 1-2 (p<0.001). Although all of these variables were significantly associated with cardiac rhythm dysfunction, they had a low sensitivity for the prediction of arrhythmic risk CONCLUSION: Male sex, age and muscular disability were strongly associated with the development of arrhythmia in DM1. However, all of these variables were weak predictors of arrhythmic risk. These results suggest that other factors may be involved in the development of cardiac conduction abnormalities in DM1.

Atypical Post-Injection Reactions with Delayed Onset Following Glatiramer Acetate 40 mg: Need for Titration?

BACKGROUND: Glatiramer acetate (GA) 20 mg/day (GA20) is associated with immediate post-injection reactions (PIRs). For convenience of use, approved GA 40 mg three times weekly (GA40) delivers a similar weekly dose. The dose and concentration of a single GA40 injection are, however, twice as high as for GA20, and post-injection adverse events may differ. Cases of atypical PIRs to GA40 prompted us to systematically monitor such events. OBJECTIVE: The aim was to characterize atypical PIRs in multiple sclerosis (MS) patients treated with GA40. METHODS: Clinical practice data were prospectively collected in consecutive relapsing-remitting MS patients. Descriptive statistics for categorical and continuous variables, Mann-Whitney and Chi-squared tests for baseline comparisons, and Cox regression models for association of variables to first atypical PIRs were applied. RESULTS: Forty-six out of 173 patients (26.6%) given GA40 experienced any PIRs. Of those, 38 (22.0%) had atypical, 14 (8.1%) had combined typical and atypical, and 26 (15.0%) had recurrent atypical PIRs, most frequently shivering (13.3%) and nausea/vomiting (8.1%). Compared to typical PIRs, onset of atypical PIRs was significantly delayed (median 30 vs 1 min, p < 0.0001), and their median duration longer (median 120 vs 6 min, p = 0.00013). Previous exposure to GA20 was associated with a lower risk of atypical PIRs [hazard ratio (HR) = 0.35, 95% confidence interval (CI) 0.17-0.72, p = 0.0039]. Patients experiencing PIRs with GA20 were at elevated risk for atypical PIRs with GA40 (HR = 5.75, 95% CI 1.66-19.94, p = 0.0059). CONCLUSIONS: Atypical PIRs with GA40, especially gastrointestinal symptoms and/or fever/shivering, had a delayed onset and occurred in a significant proportion of our patients. Their real prevalence should be assessed in appropriately designed studies accounting for  nocebo responses. Initial dose titration might reduce PIR frequency.

Analysis of T cell receptor repertoire of muscle-infiltrating T lymphocytes in polymyositis. Restricted V alpha/beta rearrangements may indicate antigen-driven selection.

Polymyositis is an inflammatory myopathy characterized by mononuclear cell infiltration of muscle tissue. Myocytotoxic T lymphocytes have been recognized in the infiltrates, but the muscle antigen, target of the immune attack, has not been identified. Molecular characterization of the variable regions of T cell receptors (TCRs) on the infiltrating lymphocytes can be expected to provide insights into the pathogenic process. The V alpha/beta TCR repertoire was investigated by RNA-PCR in muscle biopsies from 15 polymyositis patients and 16 controls (6 Duchenne muscular dystrophy and 10 with no inflammatory or dystrophic myopathy). A variety of rearranged variable TCR genes was found in polymyositis, V alpha 1, V alpha 5, V beta 1, and V beta 15 being the most common (present in 60-100% of patients). In Duchenne muscular dystrophy patients TCR V alpha or beta rearrangements were found although no restriction was observed; no rearrangements were found in muscles from the other controls. Sequence analysis revealed the presence of the J beta 2.1 region in 90% of the V beta 15 clones studied, no random N additions in the diversity region, and a common motif within the CDR3 region. These results suggest that selection of muscle-infiltrating T lymphocytes is antigen driven in polymyositis.

Expression of transforming growth factor-beta 1 in dystrophic patient muscles correlates with fibrosis. Pathogenetic role of a fibrogenic cytokine.

Duchenne muscular dystrophy is a fatal disorder characterized by progressive muscular weakness, wasting, and severe muscle contractures in later disease stages. Muscle biopsy reveals conspicuous myofiber degeneration and fibrosis substituting muscle tissue. We quantitatively determined mRNA of the potent fibrogenic cytokine transforming growth factor-beta 1 by quantitative PCR in 15 Duchenne muscular dystrophy, 13 Becker muscular dystrophy, 11 spinal muscular atrophy patients, and 16 controls. Higher transforming growth factor-beta 1 expression was greater in Duchenne muscular dystrophy patients than controls (P = 0.012) and Becker patients (P = 0.03). Fibrosis was significantly more prominent in Duchenne muscular dystrophy than Becker muscular dystrophy, spinal muscular atrophy, and controls. The proportion of connective tissue in muscle biopsies increased progressively with age in Duchenne muscular dystrophy patients, while transforming growth factor-beta 1 levels peaked at 2 and 6 yr of age. Transforming growth factor-beta 1 protein was also detected by immunocytochemistry and immunoblotting. Our findings suggest that transforming growth factor-beta 1 stimulates fibrosis in Duchenne muscular dystrophy. Expression of transforming growth factor-beta 1 in the early stages of Duchenne muscular dystrophy may be critical in initiating muscle fibrosis and antifibrosis treatment could slow progression of the disease, increasing the utility of gene therapy.

Oral administration of an immunodominant T-cell epitope downregulates Th1/Th2 cytokines and prevents experimental myasthenia gravis.

The mucosal administration of the native antigen or peptide fragments corresponding to immunodominant regions is effective in preventing or treating several T cell-dependent models of autoimmune disease. No data are yet available on oral tolerance with immunodominant T-cell peptides in experimental autoimmune myasthenia gravis (EAMG), an animal model of B cell-dependent disease. We report that oral administration of the T-cell epitope alpha146-162 of the Torpedo californica acetylcholine receptor (TAChR) alpha-subunit suppressed T-cell responses to AChR and ameliorated the disease in C57Bl/6 (B6) mice. Protection from EAMG was associated with reduced serum Ab's to mouse AChR and reduced AChR loss in muscle. The effect of Talpha146-162 feeding was specific; treatment with a control peptide did not affect EAMG manifestations. The protective effect induced by peptide Talpha146-162 was mediated by reduced production of IFN-gamma, IL-2, and IL-10 by TAChR-reactive cells, suggesting T-cell anergy. TGF-beta-secreting Th3 cells did not seem to be involved in tolerance induction. We therefore demonstrate that feeding a single immunodominant epitope can prevent an Ab-mediated experimental model of autoimmune disease.

Pathogenesis, diagnosis and treatment of Rasmussen encephalitis: a European consensus statement.

Rasmussen encephalitis (RE) is a rare but severe immune-mediated brain disorder leading to unilateral hemispheric atrophy, associated progressive neurological dysfunction and intractable seizures. Recent data on the pathogenesis of the disease, its clinical and paraclinical presentation, and therapeutic approaches are summarized. Based on these data, we propose formal diagnostic criteria and a therapeutic pathway for the management of RE patients.

Early effect of dalfampridine in patients with MS: A multi-instrumental approach to better investigate responsiveness.

BACKGROUND: 4-aminopyridine (4-AP) is a potassium-channel blocker able to enhance walking speed in MS improving the action potentials of demyelinated axons on which internodal potassium channels are exposed. OBJECTIVE: to study early 4-AP effect with clinical, subjective, neurophysiological and neuroradiological tools. METHODS: Clinical (Timed 25-Foot Walk - T25FW, Timed Up-And-Go - TUG), subjective (MS Walking Scale-12 - MSWS-12), neurophysiological (Motor Evoked Potentials - MEPs) and imaging (Diffusion Tensor Imaging - DTI) evaluations were performed before (T0) and after (T1) 14days of 4-AP treatment. MEPs were recorded from Abductor Hallucis of both legs. A Tract-Based-Spatial-Statistics (TBSS) was performed on DTI. RESULTS: We found a significant difference between T0 and T1 for T25FW, TUG, MSWS-12 (p≤0.001) in the whole patients' sample (23 subjects, median EDSS 6.0) and decrease of Central Motor Conduction Time and increase of mean Amplitude (Amp) at T1 (p=0.008 and p=0.006). We also recorded a significant difference of T25FW, TUG, MSWS-12 and Amp in clinical responder (CR) patients (CR: amelioration >20% at T25FW). TBSS showed a significant Mean and Radial Diffusivity reduction in the corticospinal tracts (p<0.05) of the whole group of patients; this reduction was also found in the CR subgroup. CONCLUSION: Neurophysiological and neuroradiological parameters were modified in MS patients treated with 4-AP, and most of them reported a subjective improvement of their motor performances after treatment. The use of clinical, subjective, neurophysiological and neuroradiological tools could help to better explore MS patients responsiveness to 4-AP.

Titin antibodies in "seronegative" myasthenia gravis--A new role for an old antigen.

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction of skeletal muscles. Triple-seronegative MG (tSN-MG, without detectable AChR, MuSK and LRP4 antibodies), which accounts for ~10% of MG patients, presents a serious gap in MG diagnosis and complicates differential diagnosis of similar disorders. Several AChR antibody positive patients (AChR-MG) also have antibodies against titin, usually detected by ELISA. We have developed a very sensitive radioimmunoprecipitation assay (RIPA) for titin antibodies, by which many previously negative samples were found positive, including several from tSN-MG patients. The validity of the RIPA results was confirmed by western blots. Using this RIPA we screened 667 MG sera from 13 countries; as expected, AChR-MG patients had the highest frequency of titin antibodies (40.9%), while MuSK-MG and LRP4-MG patients were positive in 14.6% and 16.4% respectively. Most importantly, 13.4% (50/372) of the tSN-MG patients were also titin antibody positive. None of the 121 healthy controls or the 90 myopathy patients, and only 3.6% (7/193) of other neurological disease patients were positive. We thus propose that the present titin antibody RIPA is a useful tool for serological MG diagnosis of tSN patients.

MuSK autoantibodies in myasthenia gravis detected by cell based assay--A multinational study.

Seronegative myasthenia gravis (MG) presents a serious gap in MG diagnosis and understanding. We applied a cell based assay (CBA) for the detection of muscle specific kinase (MuSK) antibodies undetectable by radioimmunoassay. We tested 633 triple-seronegative MG patients' sera from 13 countries, detecting 13% as positive. MuSK antibodies were found, at significantly lower frequencies, in 1.9% of healthy controls and 5.1% of other neuroimmune disease patients, including multiple sclerosis and neuromyelitis optica. The clinical data of the newly diagnosed MuSK-MG patients are presented. 27% of ocular seronegative patients were MuSK antibody positive. Moreover, 23% had thymic hyperplasia suggesting that thymic abnormalities are more common than believed.

Identification of three novel mutations in the major human skeletal muscle chloride channel gene (CLCN1), causing myotonia congenita.

Myotonia congenita (MC) is a genetic disease characterized by mutations in the CLCN1 gene (OMIM*118425) encoding the skeletal muscle voltage-gated chloride channel (ClC-1). Autosomal dominant and recessive forms are observed, characterized by impaired muscle relaxation after forceful contraction (myotonia), which is more pronounced after inactivity and improves with exercise. We report three novel and one known mutations of the CLCN1 gene in four unrelated MC families. In two families the mutations were missense: 803C>T (T268M) and 1272C>G (I424M) in exons 7 and 12, respectively. The third was a splice mutation in intron 5 (696+2T>A), which induced a frame shift with a stop codon in exon 6 (fs213X). In the fourth family the previously-reported missense mutation 689G>A (G230E) was found. We also report two known polymorphisms: 261C>T (T87T) and 2154T>C (D718D) in exons 2 and 17 of two MC families; also found in 14 (33%) and 28 (67%) of 42 healthy controls, respectively. These findings expand our knowledge of mutations responsible for myotonia congenita, reducing the proportion of MC patients in whom genetic alterations have not been found.

Transforming growth factor-beta 1 in polymyositis and dermatomyositis correlates with fibrosis but not with mononuclear cell infiltrate.

The idiopathic inflammatory myopathies are diseases of unknown etiology characterized by T cell-mediated myocytotoxicity in polymyositis and complement-mediated angiopathy of muscle fibers in dermatomyositis. A variable degree of fibrosis is present in muscles in these conditions both perimysially and endomysially. We evaluated the expression of TGF-beta 1, a pleiotropic cytokine with fibrogenic and immunomodulating activity, by means of quantitative-polymerase chain reaction and immunocytochemistry in DM and PM muscle biopsies. TGF-beta 1 mRNA was significantly higher in DM compared with controls, whereas in PM the values were not significantly different when compared with controls and DM. TGF-beta 1 was localized in connective tissue but did not correspond with mononuclear cell infiltrates. These findings suggest a correlation between TGF-beta 1 and connective tissue proliferation in inflammatory myopathy, while its immunomodulatory role remains to be elucidated.