Molecular characterisation of congenital myasthenic syndromes in Southern Brazil

Objective To perform genetic testing of patients with congenital myasthenic syndromes (CMS) from the Southern Brazilian state of Parana. Patients and methods Twenty-five CMS patients from 18 independent families were included in the study. Known CMS genes were sequenced and restriction digest for the mutation RAPSN p.N88K was performed in all patients. Results We identified recessive mutations of CHRNE in ten families, mutations in DOK7 in three families and mutations in COLQ, CHRNA1 and CHRNB1 in one family each. The mutation CHRNE c. 70insG was found in six families. We have repeatedly identified this mutation in patients from Spain and Portugal and haplotype studies indicate that CHRNE c. 70insG derives from a common ancestor. Conclusions Recessive mutations in CHRNE are the major cause of CMS in Southern Brazil with a common mutation introduced by Hispanic settlers. The second most common cause is mutations in DOK7. The minimum prevalence of CMS in Parana is 0.18/100 000

Molecular characterisation of congenital myasthenic syndromes in Southern Brazil

Objective To perform genetic testing of patients with congenital myasthenic syndromes (CMS) from the Southern Brazilian state of Parana. Patients and methods Twenty-five CMS patients from 18 independent families were included in the study. Known CMS genes were sequenced and restriction digest for the mutation RAPSN p.N88K was performed in all patients. Results We identified recessive mutations of CHRNE in ten families, mutations in DOK7 in three families and mutations in COLQ, CHRNA1 and CHRNB1 in one family each. The mutation CHRNE c. 70insG was found in six families. We have repeatedly identified this mutation in patients from Spain and Portugal and haplotype studies indicate that CHRNE c. 70insG derives from a common ancestor. Conclusions Recessive mutations in CHRNE are the major cause of CMS in Southern Brazil with a common mutation introduced by Hispanic settlers. The second most common cause is mutations in DOK7. The minimum prevalence of CMS in Parana is 0.18/100 000

Congental myasthenic syndromes - diagnostics and treatment

Kongenitalni mijastenički sindromi (KMS) predstavljaju poremećaje granice sigurnosti neuralne transmisije na presinaptičkoj, sinaptičkoj i postinaptičkoj razini. Dijagnoza kongenitalnog mijasteničkog sindroma postavlja se na temelju kliničke slike koja uključuje mišićnu slabost uzrokovanu zamorom što se pojavljuje od ranog djetinjstva, oftalmoparezu, respiratornu insuficijenciju, poremećaj funkcije mišića inerviranih kranijalnim živcima te pad amplitude mišićnog potencijala pri repetitivnoj stimulaciji (dekrementalni odgovor) i odsutnost protutijela na acetilkolinske receptore (AchR) i mišićno specifičnu tirozinsku kinazu (MuSK). Neki kongenitalni mijastenički sindromi manifestiraju se kasnije, a mišićna slabost i dekrementalni odgovor pojavljuju se intermintentno sa selektivnom raspodjelom u određenim mišićnim skupinama. Molekularno genetska analiza je vrlo značajna u dijagnostici kongenitalnog mijasteničkog sindroma. Presinaptički kongenitalni mijastenički sindrom vezan je za recesivne mutacije gena CHAT (kolinacetiltransferaza). Sinaptički oblik uzrokovan je mutacijom podjedinice kolagenskog repa acetilkolinesteraze (AchE). Većina kongenitalnih mijasteničkih sindroma su postsinaptički, uzrokovani mutacijama gena AchR podjedinica. Najčešće su mutacije gena CHRNE za ε-podjedinicu. Općenito, besmislene ili mutacije s pomakom okvira čitanja uzrokuju kongenitalni mijastenički sindrom zbog smanjene ili odsutne ekpresije proteina i nasljeđuju se autosomno recesivno. Mutacije gena rapsina (RAPSN) uzrokuju primarni nedostatak AchR-a na završnoj ploči. U terapiji kongenitalnog mijasteničkog sindroma ponajprije se primjenjuju inhibitori AchE. Prikazujemo djecu s kongenitalnim presinaptičkim i postinaptičkim poremećajima koji su udruženi sa značajnom varijabilnošću kliničke ekspresije u okviru kongenitalnog mijasteničkog sindroma.Congenital myasthenic syndromes (CMS) are genetically determined disorders affecting safety margins of neural transmission at presynaptic, postsynaptic and synaptic level. Diagnosis of CMS is made based on clinical symptoms including fatigable muscle weakness since infancy or childhood, decremental EMG response and negative antibodies to acetylcholine receptors (AchR) and muscle specific tyrosine kinase (MuSK). In some CMS the onset is delayed, weakness and EMG abnormalities appear intermittently in restricted distribution. Molecular genetic analysis has an important role in diagnosis of CMS. Presynaptic CMS are associated with recessive CHAT (cholinacyltransferase) gene mutations. The synaptic disorder is caused by mutation of the collagenic tail subunit of the AchE gene. However most CMS are postsynaptic, mostly caused by CHRNE gene mutations of AchR ε-subunit. In general, nonsense or frame shifting mutations cause CMS by decreased or absent protein expression and are inherited in autosomal recessive traits. Rapsyn gene (RAPSN) mutations cause primary endplate AchR deficiency. AchE inhibitors are the drugs of first choice in the treatment of CMS. We present children with presynaptic and with postsynaptic defects manifesting remarkable clinical heterogeneity

ANO10 mutations cause ataxia and coenzyme Q(10) deficiency

Inherited ataxias are heterogeneous disorders affecting both children and adults, with over 40 different causative genes, making molecular genetic diagnosis challenging. Although recent advances in next-generation sequencing have significantly improved mutation detection, few treatments exist for patients with inherited ataxia. In two patients with adult-onset cerebellar ataxia and coenzyme Q10 (CoQ10) deficiency in muscle, whole exome sequencing revealed mutations in ANO10, which encodes anoctamin 10, a member of a family of putative calcium-activated chloride channels, and the causative gene for autosomal recessive spinocerebellar ataxia-10 (SCAR10). Both patients presented with slowly progressive ataxia and dysarthria leading to severe disability in the sixth decade. Epilepsy and learning difficulties were also present in one patient, while retinal degeneration and cataract were present in the other. The detection of mutations in ANO10 in our patients indicate that ANO10 defects cause secondary low CoQ10 and SCAR10 patients may benefit from CoQ10 supplementation

“Be an ambassador for change that you would like to see”: a call to action to all stakeholders for co-creation in healthcare and medical research to improve quality of life of people with a neuromuscular disease

BACKGROUND: Patient and public involvement for co-creation is increasingly recognized as a valuable strategy to develop healthcare research targeting patients’ real needs. However, its practical implementation is not as advanced and unanimously accepted as it could be, due to cultural differences and complexities of managing healthcare programs and clinical studies, especially in the rare disease field. MAIN BODY: The European Neuromuscular Centre, a European foundation of patient organizations, involved its key stakeholders in a special workshop to investigate the position of the neuromuscular patient community with respect to healthcare and medical research to identify and address gaps and bottlenecks. The workshop took place in Milan (Italy) on January 19–20, 2018, involving 45 participants who were mainly representatives of the patient community, but also included experts from clinical centers, industry and regulatory bodies. In order to provide practical examples and constructive suggestions, specific topics were identified upfront. The first set of issues concerned the quality of life at specific phases of a patient’s life, such as at the time of diagnosis or during pediatric to adult transition, and patient involvement in medical research on activities in daily living including patient reported outcome measures. The second set of issues concerned the involvement of patients in the management of clinical research tools, such as registries and biobanks, and their participation in study design or marketing authorization processes. Introductory presentations were followed by parallel working group sessions, to gain constructive contributions from all participants. The concept of shared decision making was used to ensure, in discussions, a partnership-based identification of the wishes and needs of all stakeholders involved, and the “ladder of participation” tool served as a model to evaluate the actual and the desired level of patients’ involvement in all topics addressed. A general consensus on the outcome of the meeting was collected during the final plenary session. This paper reports the outcome of the workshop and the specific suggestions derived from the analysis of the first set of topics, related to quality of life. The outcomes of the second set of topics are reported elsewhere and are only briefly summarized herein for the sake of completeness. CONCLUSIONS: The neuromuscular community proved to be very active and engaged at different levels in the healthcare initiatives of interest. The workshop participants critically discussed several topics, providing practical examples where different stakeholders could play a role in making a change and bridging gaps. Overall, they indicated the need for education of all stakeholders for better communication, where everyone should become an ambassador to promote real change. Support should also come from institutions and healthcare bodies both at structural and economic level

Exon skipping and gene transfer restore dystrophin expression in human induced pluripotent stem cells-cardiomyocytes harboring DMD mutations

With an incidence of 1:3,500 to 5,000 in male children, Duchenne muscular dystrophy (DMD) is an X-linked disorder in which progressive muscle degeneration occurs and affected boys usually die in their twenties or thirties. Cardiac involvement occurs in 90% of patients and heart failure accounts for up to 40% of deaths. To enable new therapeutics such as gene therapy and exon skipping to be tested in human cardiomyocytes, we produced human induced pluripotent stem cells (hiPSC) from seven patients harboring mutations across the DMD gene. Mutations were retained during differentiation and analysis indicated the cardiomyocytes showed a dystrophic gene expression profile. Antisense oligonucleotide-mediated skipping of exon 51 restored dystrophin expression to 30% of normal levels in hiPSC-cardiomyocytes carrying exon 47–50 or 48–50 deletions. Alternatively, delivery of a dystrophin minigene to cardiomyocytes with a deletion in exon 35 or a point mutation in exon 70 allowed expression levels similar to those seen in healthy cells. This demonstrates that DMD hiPSC-cardiomyocytes provide a novel tool to evaluate whether new therapeutics can restore dystrophin expression in the heart