We performed a clinical, functional, and pharmacologic characterization of the novel p.P1158L Nav1.4 mutation identified in a young girl presenting a severe myotonic phenotype.
Wild-type hNav1.4 ...channel and P1158L mutant were expressed in tsA201 cells for functional and pharmacologic studies using patch-clamp.
The patient shows pronounced myotonia, slowness of movements, and generalized muscle hypertrophy. Because of general discomfort with mexiletine, she was given flecainide with satisfactory response. In vitro, mutant channels show a slower current decay and a rightward shift of the voltage dependence of fast inactivation. The voltage dependence of activation and slow inactivation were not altered. Mutant channels were less sensitive to mexiletine, whereas sensitivity to flecainide was not altered. The reduced inhibition of mutant channels by mexiletine was also observed using clinically relevant drug concentrations in a myotonic-like condition.
Clinical phenotype and functional alterations of P1158L support the diagnosis of myotonia permanens. Impairment of fast inactivation is consistent with the possible role of the channel domain III S4-S5 loop in the inactivation gate docking site. The reduced sensitivity of P1158L to mexiletine may have contributed to the unsatisfactory response of the patient. The success of flecainide therapy underscores the usefulness of in vitro functional studies to help in the choice of the best drug for each individual.
Myotonic dystrophy type 1 (DM1) is a spliceopathy related to the mis-splicing of several genes caused by sequestration of nuclear transcriptional RNA-binding factors from non-coding CUG repeats of ...DMPK pre-mRNAs. Dysregulation of ryanodine receptor 1 (RYR1), sarcoplasmatic/endoplasmatic Ca
-ATPase (SERCA) and α1S subunit of voltage-gated Ca
channels (Ca
1.1) is related to Ca
homeostasis and excitation-contraction coupling impairment. Though no pharmacological treatment for DM1 exists, aberrant splicing correction represents one major therapeutic target for this disease. Resveratrol (RES, 3,5,4'-trihydroxy-trans-stilbene) is a promising pharmacological tools for DM1 treatment for its ability to directly bind the DNA and RNA influencing gene expression and alternative splicing. Herein, we analyzed the therapeutic effects of RES in DM1 myotubes in a pilot study including cultured myotubes from two DM1 patients and two healthy controls. Our results indicated that RES treatment corrected the aberrant splicing of RYR1, and this event appeared associated with restoring of depolarization-induced Ca
release from RYR1 dependent on the electro-mechanical coupling between RYR1 and Ca
1.1. Interestingly, immunoblotting studies showed that RES treatment was associated with a reduction in the levels of CUGBP Elav-like family member 1, while RYR1, Ca
1.1 and SERCA1 protein levels were unchanged. Finally, RES treatment did not induce any major changes either in the amount of ribonuclear foci or sequestration of muscleblind-like splicing regulator 1. Overall, the results of this pilot study would support RES as an attractive compound for future clinical trials in DM1. Ethical approval was obtained from the Ethical Committee of IRCCS Fondazione Policlinico Universitario A. Gemelli, Rome, Italy (rs9879/14) on May 20, 2014.
Central nervous system involvement occurs in most patients with myotonic dystrophy type 1 (DM1): mental retardation characterizes congenital forms, while a mild cognitive impairment has been ...described in adult patients with classic DM1. Neuropathological studies documented neurofibrillary tangles and an aberrant tau-protein expression in brain tissues of patients and animal models of DM1.
To characterize the pattern of cognitive dysfunction occurring in DM1 and to analyze genotype-phenotype correlations in patients with DM1.
We assessed the results of a detailed neuropsychological study, including Mini-Mental State Examination, memory, linguistic level, praxis, attentional and frontal-executive tasks, in a group of 70 patients with DM1, including 10 congenital and 60 classic forms. Statistical analysis of data was performed using analysis of variance for multiple tests.
Our study documented 2 distinct patterns of cognitive impairment in DM1: in particular, we confirmed the presence of a cognitive pattern characteristic of mental retardation in congenital cases, whereas in adult forms we documented an aging-related decline of frontal and temporal cognitive functions. No correlations were found between cognitive impairment and (CTG)(n) in leukocytes or severity of muscle involvement.
Adult patients with DM1 frequently develop, with aging, a focal dementia: such findings agree with recent studies documenting an abnormal tau-protein expression in the brain tissues of patients with DM1. Cognitive decline may represent the only relevant clinical manifestation of DM1 in patients carrying very small (CTG)(n) expansions in leukocytes.
Recent studies documented an increased risk of neoplasm in patients with myotonic dystrophies (DM). Yet, none of these studies evaluated the contribution of common cancer risk factors in such ...observation. In this study, we included a cohort of patients (
n
= 255) with an established molecular diagnosis of DM type 1 (DM1), and who receives their treatment in one of the four centers with recognized expertise in neuromuscular disorders in Rome. We estimated the prevalence of benign and malignant tumors, and assessed if lifestyle factors and/or specific disease features would be associated to their occurrence. Overall, 59 benign tumors in 54 patients and 19 malignant tumors in 17 patients were diagnosed. The most common malignant neoplasms were cancers of the skin (31.6 %), thyroid (21.0 %), ovary (10.5 %), and breast (10.5 %). Uterine fibroid was the most common benign tumor (37.6 %) in women, while pilomatricoma was the most common in men (28.6 %). Age at enrollment (OR = 1.02, 95 % CI 1.00–1.05), and female gender (OR = 5.71, 95 % CI 2.90–11.22) were associated with tumor development in DM1 patients, while thyroid disorders was associated with malignant tumors only in women (OR = 5.12, 95 % CI 1.35–19.37). There was no association between tumor development and evaluated lifestyle factors. In conclusion, the lack of association between common cancer risk factors and tumor development in DM1 support a pathogenic link between tumors and DM1 itself, emphasizing the need for a systematic surveillance. Our observation of an association between thyroid diseases in women and cancer development needs confirmation.
Objective : To characterize the progression of the cognitive involvement in patients affected by myotonic dystrophy type 1 (DM1) by a longitudinal neuropsychological follow-up study. Methods : In a ...previous study we documented an ageing-related decline of frontal and temporal cognitive functions in juvenile/adult forms of DM1, irrespectively of the n(CTG) in leukocytes and the severity of muscle weakness. Here we present the results of a neuropsychological follow-up study performed in 34 out of 70 DM1 patients previously studied. Patients were divided into four groups according to their genotype (E1:50-150; E2:150-500; E3:500-1000; E4: >>1000 CTG). The neuropsychological test battery included MMSE, memory, linguistic, level, praxis, attentional and frontal-executive tasks. Statistical analysis was performed by One way MANOVA with repeated measures analysis and by Wilcoxon match paired test. Results : The whole group of patients showed a significant deterioration in linguistic functions, together with a tendency towards decline in executive abilities, confirming a predominant involvement of cognitive functions subserved by fronto-temporal areas. We found no significant correlation between the progression of cognitive decline and the n(CTG) in leukocytes. Moreover, we observed that patients belonging to E2 group, with the highest mean age, got scores lower than E3 patients, with particular regard both to linguistic and executive tasks. Conclusions : These data support our previous hypothesis that the cognitive damage is confined to frontotemporal functions in adult DM1 patients, with a tendency towards a decline with aging.
Wernicke-Korsakoff encephalopathy (WKE) is a neurologic disease due to a severe thiamine deficiency. This vitamin, an essential cofactor for cellular metabolism, is not produced by the human ...organism, so its total supply comes from diet, being absorbed from the duodenum
Myotonia congenita (MC) is caused by loss-of-function mutations of the muscle ClC-1 chloride channel. Clinical manifestations include the variable association of myotonia and transitory weakness. We ...recently described a cohort of recessive MC patients showing, at a low rate repetitive nerves stimulation protocol, different values of compound muscle action potential (CMAP) transitory depression, which is considered the neurophysiologic counterpart of transitory weakness. From among this cohort, we studied the chloride currents generated by G190S (associated with pronounced transitory depression), F167L (little or no transitory depression), and A531V (variable transitory depression) hClC-1 mutants in transfected HEK293 cells using patch-clamp. While F167L had no effect on chloride currents, G190S dramatically shifts the voltage dependence of channel activation and A531V reduces channel expression. Such variability in molecular mechanisms observed in the hClC-1 mutants may help to explain the different clinical and neurophysiologic manifestations of each ClCN1 mutation. In addition we examined five different mutations found in compound heterozygosis with F167L, including the novel P558S, and we identified additional molecular defects. Finally, the G190S mutation appeared to impair acetazolamide effects on chloride currents in vitro.
•Myotonia congenita is a muscle disorder due to mutations in ClC-1 chloride channel.•Eight ClC-1 channel mutants were studied using patch-clamp technique.•Mutations induce a variety of molecular defects in ClC-1 channel function.•We discuss the relationship between genotype and clinical phenotype.
In Huntington's Disease (HD) cognitive decline can occur before unequivocal motor signs become apparent. As cognitive decline often starts early in the course of the disease and has a progressive ...nature over time, cognition can be regarded as a key target for symptomatic treatment. The specific progressive profile of cognitive decline over time is unknown.
The aim of this study is to quantify the progression of cognitive decline across all HD stages, from pre-motormanifest to advanced HD, and to investigate if CAG length mediates cognitive decline.
In the European REGISTRY study 2669 HD expansion gene carriers underwent annual cognitive assessment. General linear mixed models were used to model the cognitive decline for each cognitive task across all disease stages. Additionally, a model was developed to evaluate the cognitive decline based on CAG length and age rather than disease stage.
There was significant cognitive decline on all administered tasks throughout pre-motormanifest (close to estimated disease onset) participants and the subsequent motormanifest participants from stage 1 to stage 4. Performance on the Stroop Word and Stroop Color tests additionally declined significantly across the two pre-motormanifest groups: far and close to estimated disease onset.
The evaluation of cognition performance in relation to CAG length and age revealed a more rapid cognitive decline in participants with longer CAG length than participants with shorter CAG length over time.
Cognitive performance already shows decline in pre-motormanifest HD gene expansion carriers and gradually worsens to late stage HD. HD gene expansion carriers with certain CAG length have their own cognitive profile, i.e., longer CAG length is associated with more rapid decline.
•Cognitive decline is mediated by CAG length in HD.•Stroop Word and Color test are sensitive in tracking cognitive decline in HD.•Cognitive decline starts early in the course of HD.
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