Search

Objectives: Mandatory newborn screening (NBS) for spinal muscular atrophy (SMA) was implemented for the first time in Italy at the end of 2021, allowing the identification and treatment of patients at an asymptomatic stage. Methods: DNA samples extracted from dried blood spot (DBS) from newborns in Apulia region were analysed for SMA screening by using a real‐time PCR‐based assay. Infants harbouring homozygous deletion of SMN1 exon 7 confirmed by diagnostic molecular tests underwent clinical and neurophysiological assessment and received a timely treatment. Results: Over the first 20 months since regional NBS introduction, four out of 42,492 (0.009%) screened children were found to carry a homozygous deletion in the exon 7 of SMN1 gene, with an annual incidence of 1:10,623. No false negatives were present. Median age at diagnosis was 7 days and median age at treatment was 20.5 days. Three of them had two copies of SMN2 and received gene therapy, while the one with three SMN2 copies was treated with nusinersen. All but one were asymptomatic at birth, showed no clinical signs of disease after a maximum follow‐up of 16 months and reached motor milestones appropriate with their age. The minimum interval between diagnosis and the treatment initiation was 9 days. Interpretation: The timely administration of disease‐modifying therapies prevented presymptomatic subjects to develop disease symptoms. Mandatory NBS for SMA should be implemented on a national scale. [ABSTRACT FROM AUTHOR]

Charcot–Marie‐Tooth type 2A (CMT2A) is an inherited sensorimotor neuropathy associated with mutations within the Mitofusin 2 (MFN2) gene. These mutations impair normal mitochondrial functioning via different mechanisms, disturbing the equilibrium between mitochondrial fusion and fission, of mitophagy and mitochondrial axonal transport. Although CMT2A disease causes a significant disability, no resolutive treatment for CMT2A patients to date. In this context, reliable experimental models are essential to precisely dissect the molecular mechanisms of disease and to devise effective therapeutic strategies. The most commonly used models are either in vitro or in vivo, and among the latter murine models are by far the most versatile and popular. Here, we critically revised the most relevant literature focused on the experimental models, providing an update on the mammalian models of CMT2A developed to date. We highlighted the different phenotypic, histopathological and molecular characteristics, and their use in translational studies for bringing potential therapies from the bench to the bedside. In addition, we discussed limitations of these models and perspectives for future improvement. [ABSTRACT FROM AUTHOR]

Background and Objective: Early‐onset Parkinson's disease (EOPD) commonly recognizes a genetic basis; thus, patients with EOPD are often addressed to diagnostic testing based on next‐generation sequencing (NGS) of PD‐associated multigene panels. However, NGS interpretation can be challenging in a diagnostic setting, and few studies have addressed this issue so far. Methods: We retrospectively collected data from 648 patients with PD with age at onset younger than 55 years who underwent NGS of a minimal shared panel of 15 PD‐related genes, as well as PD‐multiplex ligation‐dependent probe amplification in eight Italian diagnostic laboratories. Data included a minimal clinical dataset, the complete list of variants included in the diagnostic report, and final interpretation (positive/negative/inconclusive). Patients were further stratified based on age at onset ≤40 years (very EOPD, n = 157). All variants were reclassified according to the latest American College of Medical Genetics and Genomics criteria. For classification purposes, PD‐associated GBA1 variants were considered diagnostic. Results: In 186 of 648 (29%) patients, the diagnostic report listed at least one variant, and the outcome was considered diagnostic (positive) in 105 (16%). After reanalysis, diagnosis changed in 18 of 186 (10%) patients, with 5 shifting from inconclusive to positive and 13 former positive being reclassified as inconclusive. A definite diagnosis was eventually reached in 97 (15%) patients, of whom the majority carried GBA1 variants or, less frequently, biallelic PRKN variants. In 89 (14%) cases, the genetic report was inconclusive. Conclusions: This study attempts to harmonize reporting of PD genetic testing across several diagnostic labs and highlights current difficulties in interpreting genetic variants emerging from NGS‐multigene panels, with relevant implications for counseling. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

HTT full‐penetrance pathogenic repeat expansions, the genetic cause of Huntington's disease (HD), have been recently reported in a minority of frontotemporal dementia/amyotrophic lateral sclerosis (ALS) patients (0.13%). We analyzed HTT CAG repeats in an Italian cohort of ALS patients (n = 467) by repeat‐primed polymerase chain reaction. One patient harbored two expanded alleles in the HTT gene (42 and 37 CAG repeats). The absence of HD typical symptoms and the clinical picture consistent with ALS, corroborated by the diagnostic assessment, apparently excluded a misdiagnosis of HD. [ABSTRACT FROM AUTHOR]

Background: Parkinsonian features have been described in patients harboring variants in nuclear genes encoding for proteins involved in mitochondrial DNA maintenance, such as TWNK.Objectives: The aim was to screen for TWNK variants in an Italian cohort of Parkinson's disease (PD) patients and to assess the occurrence of parkinsonism in patients presenting with TWNK-related autosomal dominant progressive external ophthalmoplegia (TWNK-adPEO).Methods: Genomic DNA of 263 consecutively collected PD patients who underwent diagnostic genetic testing was analyzed with a targeted custom gene panel including TWNK, as well as genes causative of monogenic PD. Genetic and clinical data of 18 TWNK-adPEO patients with parkinsonism were retrospectively analyzed.Results: Six of 263 PD patients (2%), presenting either with isolated PD (n = 4) or in combination with bilateral ptosis (n = 2), carried TWNK likely pathogenic variants. Among 18 TWNK-adPEO patients, 5 (28%) had parkinsonism.Conclusions: We show candidate TWNK variants occurring in PD without PEO. This finding will require further confirmatory studies. © 2022 Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Becker muscular dystrophy (BMD) is an X‐linked neuromuscular disorder due to mutation in the DMD gene, encoding dystrophin. Despite a wide clinical variability, BMD is characterized by progressive muscle degeneration and proximal muscle weakness. Interestingly, a dysregulated expression of muscle‐specific microRNAs (miRNAs), called myomirs, has been found in patients affected with muscular dystrophies, although few studies have been conducted in BMD. We analysed the serum expression levels of a subset of myomirs in a cohort of 29 ambulant individuals affected by BMD and further classified according to the degree of alterations at muscle biopsy and in 11 age‐matched healthy controls. We found a significant upregulation of serum miR‐1, miR‐133a, miR‐133b and miR‐206 in our cohort of BMD patients, supporting the role of these miRNAs in the pathophysiology of the disease, and we identified serum cut‐off levels discriminating patients from healthy controls, confiming the potential of circulating miRNAs as promising noninvasive biomarkers. Moreover, serum levels of miR‐133b were found to be associated with fibrosis at muscle biopsy and with patients' motor performances, suggesting that miR‐133b might be a useful prognostic marker for BMD patients. Taken together, our data showed that these serum myomirs may represent an effective tool that may support stratification of BMD patients, providing the opportunity of both monitoring disease progression and assessing the treatment efficacy in the context of clinical trials. [ABSTRACT FROM AUTHOR]

Introduction:/Aims Patients with neuromuscular disorders (NMDs), including many elderly, immunosuppressed, and disabled individuals, may have been particularly affected during the coronavirus disease 2019 (COVID‐19) pandemic in Lombardy, a COVID‐19 high‐incidence area between February and May 2020. We aimed to evaluate the effects of the COVID‐19 pandemic on the quality of life (QoL) and perceived disease burden of this group of patients. Methods: We conducted a cross‐sectional phone‐based survey study between June 1 and June 14, 2020, on a sample of 240 NMD patients followed at our clinic in Milan, Italy. We asked about perceived NMD burden and QoL before and during the COVID‐19 pandemic. We collected responses on access to outpatient care and ancillary services. We investigated the presence of symptoms suggestive of COVID‐19 infection and confirmed cases. Results: We collected 205 responses: 53 patients (25.9%) reported a subjective worsening of the underlying NMD. QoL measures showed a significant worsening between pre and pandemic time frames (odds ratio, 2.14 95%; confidence interval, 1.82–2.51). Outpatient visits were postponed in more than half of cases (57.1%), with 104 patients (50.7%) experiencing a cancellation of scheduled diagnostic tests. 79 patients (38.5%) reported at least one symptom attributable to COVID‐19 infection. Among the 10 patients tested with nasopharyngeal swabs, 6 tested positive and 3 died from respiratory failure, including 2 patients on corticosteroid/ immunosuppressive therapy. Discussion: The COVID‐19 pandemic affected QoL and limited access to outpatient care and ancillary services of NMD patients in Lombardy between February and May 2020. [ABSTRACT FROM AUTHOR]

Objective: This work aims to expand knowledge regarding the genetic spectrum of HSPB1‐related diseases. HSPB1 is a gene encoding heat shock protein 27, and mutations in HSPB1 have been identified as the cause of axonal Charcot–Marie–Tooth (CMT) disease type 2F and distal hereditary motor neuropathy (dHMN). Methods: Two patients with axonal sensorimotor neuropathy underwent detailed clinical examinations, neurophysiological studies, and next‐generation sequencing with subsequent bioinformatic prioritization of genetic variants and in silico analysis of the likely causal mutation. Results: The HSPB1 p.S135F and p.R136L mutations were identified in homozygosis in the two affected individuals. Both mutations affect the highly conserved alpha‐crystallin domain and have been previously described as the cause of severe CMT2F/dHMN, showing a strictly dominant inheritance pattern. Interpretation: Thus, we report for the first time two cases of biallelic HSPB1 p.S135F and p.R136L mutations in two families. [ABSTRACT FROM AUTHOR]

The antisense oligonucleotide Nusinersen has been recently licensed to treat spinal muscular atrophy (SMA). Since SMA type 3 is characterized by variable phenotype and milder progression, biomarkers of early treatment response are urgently needed. We investigated the cerebrospinal fluid (CSF) concentration of neurofilaments in SMA type 3 patients treated with Nusinersen as a potential biomarker of treatment efficacy. The concentration of phosphorylated neurofilaments heavy chain (pNfH) and light chain (NfL) in the CSF of SMA type 3 patients was evaluated before and after six months since the first Nusinersen administration, performed with commercially available enzyme‐linked immunosorbent assay (ELISA) kits. Clinical evaluation of SMA patients was performed with standardized motor function scales. Baseline neurofilament levels in patients were comparable to controls, but significantly decreased after six months of treatment, while motor functions were only marginally ameliorated. No significant correlation was observed between the change in motor functions and that of neurofilaments over time. The reduction of neurofilament levels suggests a possible early biochemical effect of treatment on axonal degeneration, which may precede changes in motor performance. Our study mandates further investigations to assess neurofilaments as a marker of treatment response. [ABSTRACT FROM AUTHOR]

The maintenance of mitochondrial DNA (mtDNA) relies on proteins encoded by nuclear genes. Mutations in their coding sequences result in heterogenous clinical presentations featuring mtDNA instability in affected tissues. DNA2 is a multi‐catalytic protein involved in the removal of single strand DNA during mtDNA replication or Long Patch Base Excision Repair pathway. We have previously described DNA2 mutations in adult patients affected with familial and sporadic forms of mitochondrial myopathy. Here we describe four novel probands presenting with limb weakness associated with novel DNA2 molecular defects. Biochemical assays were established to investigate the functional effects of these variants. [ABSTRACT FROM AUTHOR]

Expanding the genotypic and phenotypic spectrum of Beta-propeller potein-associated neurodegeneration Beta-propeller protein-associated neurodegeneration (BPAN) is a very rare early-onset neurodevelopmental-neurodegenerative disorder due to X-linked dominant mutations of the I WDR45 i gene [1,2]. The pathognomonic MRI finding is the T1-weighted mesencephalic hyperintense signal surrounding the substantia nigra. [Extracted from the article]

Mutations in the SPG7 gene encoding a mitochondrial protein termed paraplegin, are responsible for a recessive form of hereditary spastic paraparesis. Only few studies have so far been performed in large groups of hereditary spastic paraplegia (HSP) patients to determine the frequency of SPG7 mutations. Here, we report the result of a mutation screening conducted in a large cohort of 135 Italian HSP patients with the identification of six novel point mutations and one large intragenic deletion. Sequence analysis of the deletion breakpoint, together with secondary structure predictions of the deleted region, indicate that a complex rearrangement, likely caused by extensive secondary structure formation mediated by the short interspersed nuclear element (SINE) retrotransposons, is responsible for the deletion event. Biochemical studies performed on fibroblasts from three mutant patients revealed mild and heterogeneous mitochondrial dysfunctions that would exclude a specific association of a complex I defect with the pathology at the fibroblast level. Overall, our data confirm that SPG7 point mutations are rare causes of HSP, in both sporadic and familial forms, while underlying the puzzling and intriguing aspects of histological and biochemical consequences of paraplegin loss. Hum Mutat 29(4), 522-531, 2008. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Objective Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease characterized by selective motoneuron death. Understanding of the molecular mechanisms that trigger and regulate motoneuron degeneration could be relevant to ALS and other motoneuron disorders. This study investigates the role of Fas-linked motoneuron death in the pathogenesis of ALS. Methods We performed in vitro and in vivo small interfering RNA-mediated interference, by silencing the Fas receptor on motoneurons that carry the superoxide dismutase-1 (SOD1)-G93A mutation. Results We observed a significant reduction in Fas expression at messenger RNA ( p < 0.001) and protein levels. Treated motoneurons demonstrated an increase in survival and a reduction in cytochrome c release from mitochondria. In vivo, continuous intrathecal administration of Fas small interfering RNA by an osmotic minipump improved motor function and survival in SOD1-G93A mice (mean increase, 18 days; p < 0.0001). Treated mice showed a significant reduction in Fas and Fas mediators p38 mitogen-activated protein kinase, neuronal nitric oxide synthase, and caspase-8. Interpretation Fas silencing interferes with motoneuron-specific downstream death pathways and results in increased motoneuron survival and amelioration of the SOD1-G93A phenotype, suggesting new possible strategies for molecular therapy of ALS. Ann Neurol 2007 [ABSTRACT FROM AUTHOR]

Presents a study which examined skeletal muscle gene expression profiling in mitochondrial disorders. Analysis of the role for the nuclear genome in the variability of phenotypic presentation; Information on the genes expressed in mitochondrial DNA; Conclusion and findings of the study.