DOI: 10.20452/pamw.15130, Published online: January 09, 2020, Authors: Martina Lipari, Ewa Wypasek, Marek Karpinski, Lidia Tomkiewicz-Pajak, Luigi Laino, Francesco Binni, Diana Giannarelli, Paweł Rubis, Pawel Petkow-Dimitrow, Anetta Undas, Paola Grammatico, Irene Bottillo

Neuromuscular disorders (NMDs) include a wide range of diseases affecting the peripheral nervous system. The genetic diagnoses are increasingly obtained with using the next generation sequencing (NGS). We applied the custom-design targeted NGS panel including 89 genes, together with genotyping and multiplex ligation-dependent probe amplification (MLPA) to identify a genetic spectrum of NMDs in 52 Polish patients. As a result, the genetic diagnosis was determined by NGS panel in 29 patients so its diagnostic utility is estimated at 55.8%. The most pathogenic variants were found in CLCN1, followed by CAPN3, SCN4A, and SGCA genes. Genotyping of myotonic dystrophy type 1 and 2 (DM1 and DM2) as a secondary approach has been performed. The co-occurrence of CAPN3 and CNBP mutations in one patient as well as DYSF and CNBP mutations in another suggests possibly more complex inheritance as well as expression of a phenotype. In 7 individuals with single nucleotide variant found in NGS testing, the MLPA of the CAPN3 gene was performed detecting the deletion encompassing exons 2—8 in the CAPN3 gene in one patient, confirming recessive limb-girdle muscular dystrophy type 1 (LGMDR1). Thirty patients obtained a genetic diagnosis (57.7%) after using NGS testing, genotyping and MLPA analysis. The study allowed for the identification of 27 known and 4 novel pathogenic/likely pathogenic variants and variants of uncertain significance (VUS) associated with NMDs.In conclusion, the diagnostic approach with diverse molecular techniques enables to broaden the mutational spectrum and maximizes the diagnostic yield. Furthermore, the co-occurrence of DM2 and LGMD has been detected in 2 individuals.

Brugada syndrome (BrS) is an arrhythmogenic disorder increasing the risk of syncopal episodes and sudden cardiac death. BrS usually runs through families with reduced penetrance and variable expression. We analyzed the multigenerational family of a patient who died after sudden cardiac arrest with post-mortem diagnosis of BrS. We analyzed clinical history, comprehensive arrhythmic risk, genetic findings, and additional tests, including electrocardiogram (ECG), detailed 24-hour Holter ECG results, and standard echocardiography findings, and followed up the patients in the ambulatory clinic. We analyzed a pedigree of 33 members of four generations of the family (19 male and 14 female patients). In this family, we identified 7 patients with BrS (median Modified Shanghai Score and Sieira model: 4.5 (4–6) and 1 (0–4) points, respectively), including both parents of the deceased patient, and 8 relatives with negative sodium channel blocker drug challenge test. Genetic testing revealed a novel mutation in sodium voltage-gated channel alpha subunit 5 (SCN5A) c.941A>G, (p.Tyr314Cys) inherited from the father of the proband. Patients with BrS were characterized by longer P-wave duration (120 (102–155) vs. 92.5 (88–110) ms, p = 0.013) and longer PR intervals (211.3 ±26.3 vs. 161.6 ± 18.9 ms, p = 0.001), along with more frequent positive aVR sign, but did not differ in terms of QRS duration or T-wave characteristics in resting ECGs. BrS patients were characterized by lower mean, minimal, and maximal (for all p ≤ 0.01) heart rates obtained from Holter ECG monitoring, while there was no difference in arrhythmias among investigated patients. Moreover, visual diurnal variability of ST segment changes and fragmented QRS complexes were observed in patients with BrS in Holter ECG monitoring. There were no major arrhythmic events during median follow-up of 68.7 months of alive BrS patients. These results suggest ECG features which may be associated with a diagnosis of BrS and indicate a novel SCN5A variant in BrS patients. Twelve-lead Holter ECG monitoring, with modified precordial leads placement, may be useful in BrS diagnostics and risk stratification in personalized medicine.

The clinical manifestations of dementia are often rapidly matched to a specific clinical syndrome, but the underlying neuropathology is not always obvious. A genetic factor often plays an important role in early onset dementia, but there are cases in which the phenotype has a different genetic basis than is assumed. Two patients, at different times, presented to the Memory Clinic because of memory problems and difficulty in performing daily activities and work. Neither caregiver complained of marked behavioural or personality changes, except for apathy. Patients underwent standard dementia evaluation procedures including clinical symptoms, family history, neuroimaging, neuropsychological evaluation, and genetic analysis of selected genes. Based on specific clinical phenotypes and genetic analysis of selected genes, both patients were diagnosed with frontal variant of Alzheimer’s disease. The presence of a rare polymorphism in PSEN2 in both patients allowed the discovery that they belong to the same family. This fact reinforced the belief that there is a strong genetic factor responsible for causing dementia in the family. Next-generation sequencing based on a panel of 118 genes was performed to identify other potential genetic factors that may determine the background of the disease. A mutation in the GRN gene was identified, and the previous diagnosis was changed to frontotemporal dementia. The described cases show how important it is to combine all diagnostic tests available in the diagnostic centre, including new generation genetic tests, in order to establish/confirm the pathological background of clinical symptoms of dementia. If there is any doubt about the final diagnosis, persistent efforts should be made to verify the cause.

We would like to thank Dr. Imamura for their interest in our study and their valuable comments on diagnostics and risk stratification in Brugada syndrome (BrS)