A Multidisciplinary Evaluation of Patients with DMD in An Italian Tertiary Care Center

With more widespread prolonged survival, Duchenne muscular dystrophy patients progressively experience multisystem complications. We retrospectively reviewed the charts of 132 Duchenne patients (112 alive/20 dead, age 3.5÷32.3 years) with the aims: 1) to provide a comprehensive description of the clinical status considering different aspects of the disease; 2) to propose a new scoring tool able to consider and pool together heterogeneous different functional. Five functions were analyzed: cardiac, respiratory, nutritional, ambulation and scoliosis. For each function, different items were considered and classified according to clinical severity (as indicated by international guidelines) and an incremental scoring was assigned. In addition, a global score incorporating all functions was defined. The scoring system confirmed that despite the significant protective role of steroids, all functions deteriorated with age. The severity of the global score became significantly higher since the age of 13 years. The severity of cardiac, respiratory and nutritional dysfunction was higher since 18 years. Deceased patients were characterized by significantly worse cardiac function, absence of steroid therapy and later use of respiratory assistive devices. The index proposed in this pilot study is a promising tool able to aggregate and correlate heterogeneous functions. It could become either an individual prognostic indicator of decline or a global score to evaluate changes in clinical trials therefore allowing multicenter studies, optimizing the management of both the primary and the secondary complications of the disease and understanding their relative impact.

Severe inflammatory myopathy in a pulmonary carcinoma patient treated with Pembrolizumab: An alert for myologists

Immune-related adverse events (irAE) during the administration of immune-checkpoint inhibitors (ICIs) become more evident due to the increased use of these therapies. To remind the importance of early recognition of this phenomenon, we report a paradigmatic case characterized by severe systemic inflammatory myopathy and severe cardiac involvement that abruptly precipitated in an untoward ending after one single dose of Pembrolizumab.

Synaptotagmin 13 is neuroprotective across motor neuron diseases

In amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), spinal and lower brainstem motor neurons degenerate, but some motor neuron subtypes are spared, including oculomotor neurons (OMNs). The mechanisms responsible for this selective degeneration are largely unknown, but the molecular signatures of resistant and vulnerable motor neurons are distinct and offer clues to neuronal resilience and susceptibility. Here, we demonstrate that healthy OMNs preferentially express Synaptotagmin 13 (SYT13) compared to spinal motor neurons. In end-stage ALS patients, SYT13 is enriched in both OMNs and the remaining relatively resilient spinal motor neurons compared to controls. Overexpression of SYT13 in ALS and SMA patient motor neurons in vitro improves their survival and increases axon lengths. Gene therapy with Syt13 prolongs the lifespan of ALS mice by 14% and SMA mice by 50% by preserving motor neurons and delaying muscle denervation. SYT13 decreases endoplasmic reticulum stress and apoptosis of motor neurons, both in vitro and in vivo. Thus, SYT13 is a resilience factor that can protect motor neurons and a candidate therapeutic target across motor neuron diseases.

Effects of short-to-long term enzyme replacement therapy (ERT) on skeletal muscle tissue in late onset Pompe disease (LOPD)

AIMS

Pompe disease is an autosomal recessive lysosomal storage disorder resulting from deficiency of acid α-glucosidase (GAA) enzyme. Histopathological hallmarks in skeletal muscle tissue are fibre vacuolization and autophagy. Since 2006, enzyme replacement therapy (ERT) is the only approved treatment with human recombinant GAA alglucosidase alfa. We designed a study to examine ERT-related skeletal muscle changes in 18 modestly to moderately affected late onset Pompe disease (LOPD) patients along with the relationship between morphological/biochemical changes and clinical outcomes. Treatment duration was short-to-long term.

METHODS

We examined muscle biopsies from 18 LOPD patients at both histopathological and biochemical level. All patients underwent two muscle biopsies, before and after ERT administration respectively. The study is partially retrospective because the first biopsies were taken before the study was designed, whereas the second biopsy was always performed after at least 6 months of ERT administration.

RESULTS

After ERT, 15 out of 18 patients showed improved 6-min walking test (6MWT; P = 0.0007) and most of them achieved respiratory stabilization. Pretreatment muscle biopsies disclosed marked histopathological variability, ranging from an almost normal pattern to a severe vacuolar myopathy. After treatment, we detected morphological improvement in 15 patients and worsening in three patients. Post-ERT GAA enzymatic activity was mildly increased compared with pretreatment levels in all patients. Protein levels of the mature enzyme increased in 14 of the 18 patients (mean increase = +35%; P < 0.05). Additional studies demonstrated an improved autophagic flux after ERT in some patients.

CONCLUSIONS

ERT positively modified skeletal muscle pathology as well as motor and respiratory outcomes in the majority of LOPD patients.

Language Disturbances in a Group of Participants Suffering from Duchenne Muscular Dystrophy: A Pilot Study

Results from several studies suggest that the process of language acquisition may be altered in patients suffering from Duchenne Muscular Dystrophy. In this study, a group of 8 male participants with Duchenne Muscular Dystrophy ( M age = 16 yr., SD = 4.7) underwent an extensive neuropsychological and language assessment. They also performed a discourse production task. Results showed mild mental retardation associated with a specific deficit in Verbal rather than Performance IQ. At the linguistic assessment, 7 of 8 participants showed moderate to severe difficulties on oral language processing with particularly impaired morphosyntactic competence.

Morpholino-mediated SOD1 reduction ameliorates an amyotrophic lateral sclerosis disease phenotype

Neurotoxicity due to the accumulation of mutant proteins is thought to drive pathogenesis in neurodegenerative diseases. Mutations in superoxide dismutase 1 (SOD1) are linked to familial amyotrophic lateral sclerosis (fALS); these mutations result in progressive motor neuron death through one or more acquired toxicities. Interestingly, SOD1 is not only responsible for fALS but may also play a significant role in sporadic ALS; therefore, SOD1 represents a promising therapeutic target. Here, we report slowed disease progression, improved neuromuscular function, and increased survival in an in vivo ALS model following therapeutic delivery of morpholino oligonucleotides (MOs) designed to reduce the synthesis of human SOD1. Neuropathological analysis demonstrated increased motor neuron and axon numbers and a remarkable reduction in astrogliosis and microgliosis. To test this strategy in a human model, we treated human fALS induced pluripotent stem cell (iPSC)-derived motor neurons with MOs; these cells exhibited increased survival and reduced expression of apoptotic markers. Our data demonstrated the efficacy of MO-mediated therapy in mouse and human ALS models, setting the stage for human clinical trials.

LOPED study: looking for an early diagnosis in a late-onset Pompe disease high-risk population

OBJECTIVE

A multicentre observational study was aimed to assess the prevalence of late-onset Pompe disease (LOPD) in a large high-risk population, using the dried blood spot (DBS) as a main screening tool.

DESIGN/METHODS

17 Italian neuromuscular centres were involved in the late-onset Pompe early diagnosis (LOPED) study. Inclusion criteria were: (1) age ≥5 years, (2) persistent hyperCKaemia and (3) muscle weakness at upper and/or lower limbs (limb-girdle muscle weakness, LGMW). Acid α-glucosidase (GAA) activity was measured separately on DBS by fluorometric as well as tandem mass spectrometry methods. A DBS retest was performed in patients resulted positive at first assay. For the final diagnosis, GAA deficiency was confirmed by a biochemical assay in skeletal muscle, whereas genotype was assessed by GAA molecular analysis.

RESULTS

In a 14-month period, we studied 1051 cases: 30 positive samples (2.9%) were detected by first DBS screening, whereas, after retesting, 21 samples were still positive. Biochemical and molecular genetic studies finally confirmed LOPD diagnosis in 17 cases (1.6%). The median time from the onset of symptoms/signs to diagnosis was 5 years. Among those patients, 35% showed presymptomatic hyperCKaemia and 59% showed hyperCKaemia+LGMW, whereas 6% manifested with LGMW.

CONCLUSIONS

LOPED study suggests that GAA activity should be accurately screened by DBS in all patients referring for isolated hyperCKaemia and/or LGMW. A timely diagnosis was performed in five patients with presymptomatic hyperCKaemia, but two had already manifested with relevant changes on muscle morphology and MRI. Consequently, enzyme replacement therapy was started in 14/17 patients, including the 2 patients still clinically presymptomatic but with a laboratory evidence of disease progression.

Revised Genetic Classification of Limb Girdle Muscular Dystrophies

Limb girdle muscular dystrophies (LGMD) are a heterogeneous group of inherited progressive muscle disorders affecting predominantly the shoulder and pelvic girdle muscles. They present both with autosomal dominant and autosomal recessive patterns of inheritance. Recent development, including results from Next Generation Sequencing technology, expanded the number of recognised forms. Therefore a revised genetic classification that takes into account the novel entities is needed, allowing clinicians and researchers to refer to a common nomenclature for diagnostic and research purposes.

Clinical evaluation and cellular electrophysiology of a recessive CLCN1 patient

Here we present the case of a 32-year-old female patient with myotonia congenita. She carried two mutations in the CLCN1 gene that encodes the chloride channel ClC-1: p.Phe167Leu, which was previously identified in several families, and p.Val536Leu, which has been previously reported but not yet characterized by electrophysiological investigations. The patient's symptoms included generalized stiffness, myotonia, and muscle cramps mostly localized in the lower limbs. These symptoms started during childhood and worsened over the following years. The symptoms were exacerbated by low outside temperature, rest, stress, and fasting and were improved by mild exercise, suggesting a warm-up phenomenon. The mutation p.Phe167Leu has previously been associated with a slight shift in the overall open probability. Here we further analysed this mutation to extrapolate the voltage-dependence of the fast and slow gates. In our experimental conditions, p.Phe167Leu exclusively affected the slow gate, increasing the minimum open probability and displacing the voltage-dependence toward depolarized potentials. p.Val536Leu showed more severe effects, dramatically influencing the slow gate as well as modifying properties of the fast gate. Co-expression of the mutants in a human cell line to reproduce the compound heterozygous condition of the patient produced channels with altered voltage-dependence of the slow gate but a restored fast gate. The alteration of the slow mechanism was reflected by the relative open probability, reducing the contribution of ClC-1 channels in maintaining the resting membrane potential of skeletal muscles and thus explaining the myotonic phenotype of the patient.

Fatigue and exercise intolerance in mitochondrial diseases. Literature revision and experience of the Italian Network of mitochondrial diseases

Fatigue and exercise intolerance are common symptoms of mitochondrial diseases, but difficult to be clinically assessed. New methods to quantify these rather common complaints are strongly needed in the clinical practice. Coenzyme Q10 administration and aerobic exercise may improve exercise intolerance, but more definite studies are still pending. Herein, we have revised "how to measure" and "how to treat" these symptoms of mitochondrial patients. Subsequently, we reviewed the clinical data of the 1164 confirmed mitochondrial patients present in the Italian nation-wide database of mitochondrial disease, with special regard to exercise intolerance. We observed that more of 20% of mitochondrial patients complain of exercise intolerance. This symptom seems to be frequently associated with specific patient groups and/or genotypes. Ragged red fibers and COX-negative fibers are more often present in subjects with exercise intolerance, whereas lactate levels could not predict this symptom. Multicenter efforts are strongly needed for rare disorders such as mitochondrial diseases, and may represent the basis for more rigorous longitudinal studies.

A trans-specific polymorphism in ZC3HAV1 is maintained by long-standing balancing selection and may confer susceptibility to multiple sclerosis

The human ZC3HAV1 gene encodes an antiviral protein. The longest splicing isoform of ZC3HAV1 contains a C-terminal PARP-like domain, which has evolved under positive selection in primates. We analyzed the evolutionary history of this same domain in humans and in Pan troglodytes. We identified two variants that segregate in both humans and chimpanzees; one of them (rs3735007) does not occur at a hypermutable site and accounts for a nonsynonymous substitution (Thr851Ile). The probability that the two trans-specific polymorphisms have occurred independently in the two lineages was estimated to be low (P = 0.0054), suggesting that at least one of them has arisen before speciation and has been maintained by selection. Population genetic analyses in humans indicated that the region surrounding the shared variants displays strong evidences of long-standing balancing selection. Selection signatures were also observed in a chimpanzee population sample. Inspection of 1000 Genomes data confirmed these findings but indicated that search for selection signatures using low-coverage whole-genome data may need masking of repetitive sequences. A case–control study of more than 1,000 individuals from mainland Italy indicated that the Thr851Ile SNP is significantly associated with susceptibility to multiple sclerosis (MS) (odds ratio [OR] = 1.47, 95% confidence intervals [CI]: 1.08–1.99, P = 0.011). This finding was confirmed in a larger sample of 4,416 Sardinians cases/controls (OR = 1.18, 95% CI: 1.037–1.344, P = 0.011), but not in a population from Belgium. We provide one of the first instances of human/chimpanzee trans-specific coding variant located outside the major histocompatibility complex region. The selective pressure is likely to be virus driven; in modern populations, this variant associates with susceptibility to MS, possibly via the interaction with environmental factors.

Low abdominal contribution to breathing as daytime predictor of nocturnal desaturation in adolescents and young adults with Duchenne Muscular Dystrophy

In the respiratory management of DMD patients it is still under debate what parameter should indicate the correct timing for institution of nocturnal non-invasive ventilation (NIV), in addition to forced vital capacity, which is generally considered as a prognostic marker of disease progression. The aim of this study was to determine if volume variations of rib cage and abdominal compartments measured by Opto-Electronic Plethysmography can be helpful to distinguish between those patients who are in the early stages of nocturnal oxygen desaturation development and those who do not yet. Pulmonary function, abdominal contribution to tidal volume and to inspiratory capacity (%Abd IC) and a set of breathing pattern indexes were assessed in 40 DMD patients older than 14 years and not yet under nocturnal NIV. ROC analysis revealed that among all the considered parameters, %Abd IC in supine position was the best discriminator between DeSat (at least 10% of the night time with SpO(2) < 95%) and NonDeSat patients, providing an area under the curve with 95%CI equal to 0.752. In conclusion, in adolescents and adults DMD patients who present either no sign or only mild nocturnal oxygen desaturation, a reduced abdominal contribution to inspiratory capacity is a marker of the onset of diaphragm weakness and should be considered to identify the correct timing for the institution of nocturnal NIV.

Novel optineurin mutations in patients with familial and sporadic amyotrophic lateral sclerosis

BACKGROUND

Optineurin (OPTN), a causative gene of hereditary primary open-angle glaucoma, has been recently associated with amyotrophic lateral sclerosis (ALS) with mainly autosomal recessive, but also dominant, traits. To further define the contribution of OPTN gene in ALS, we performed a mutational screening in a large cohort of Italian patients.

METHODS

A group of 274 ALS patients, including 161 familial (FALS) and 113 sporadic (SALS) cases, were screened for OPTN mutations by direct sequencing of its coding sequence. All patients fulfilled the El Escorial criteria for probable or definite ALS and were negative for mutations in SOD1, ANG, TARDBP and FUS/TLS genes.

RESULTS

The genetic analysis revealed six novel variants in both FALS and SALS patients, all occurring in an heterozygous state. We identified three missense (c.844A→C p.T282P, c.941A→T p.Q314L, c.1670A→C p.K557T), one nonsense (c.67G→T p.G23X) and two intronic mutations (c.552+1delG, c.1401+4A→G). The intronic c.552+1delG variant determined a splicing defect as demonstrated by mRNA analysis. All mutations were absent in 280 Italian controls and over 6800 worldwide glaucoma patients and controls screened so far. The clinical phenotype of OPTN-mutated patients was heterogeneous for both age of onset and disease duration but characterised by lower-limb onset and prevalence of upper motor neuron signs.

CONCLUSION

In this cohort, OPTN mutations were present both in FALS (2/161), accounting for 1.2% cases, and in SALS patients (4/113), thereby extending the spectrum of OPTN mutations associated with ALS. The study further supports the possible pathological role of optineurin protein in motor neuron disease.

Growth factors in ischemic stroke

Data from pre-clinical and clinical studies provide evidence that colony-stimulating factors (CSFs) and other growth factors (GFs) can improve stroke outcome by reducing stroke damage through their anti-apoptotic and anti-inflammatory effects, and by promoting angiogenesis and neurogenesis. This review provides a critical and up-to-date literature review on CSF use in stroke. We searched for experimental and clinical studies on haemopoietic GFs such as granulocyte CSF, erythropoietin, granulocyte-macrophage colony-stimulating factor, stem cell factor (SCF), vascular endothelial GF, stromal cell-derived factor-1α and SCF in ischemic stroke. We also considered studies on insulin-like growth factor-1 and neurotrophins. Despite promising results from animal models, the lack of data in human beings hampers efficacy assessments of GFs on stroke outcome. We provide a comprehensive and critical view of the present knowledge about GFs and stroke, and an overview of ongoing and future prospects.

Genetic background predicts poor prognosis in frontotemporal lobar degeneration

BACKGROUND

Ruling out predictors of survival in frontotemporal lobar degeneration (FTLD) is a clinical challenge for defining disease outcomes and monitoring therapeutic interventions. Little is known about determinants of survival in FTLD.

OBJECTIVE

The aim of the present study was to identify whether genetic determinants are key, not only as risk factors but as predictors of survival in FTLD.

METHODS

Ninety-seven FTLD patients were considered in the present study. A clinical evaluation and a standardized assessment were carried out. Each patient underwent blood sampling for genetic testing, and mutations within the progranulin (PGRN) gene, microtubule-associated protein tau (MAPT) haplotype, apolipoprotein E (APOE) genotype and 4 vascular endothelial growth factor (VEGF) polymorphisms were evaluated. Discrete-time survival models were applied.

RESULTS

Monogenic FTLD due to PGRN mutations [odds ratio (OR) = 3.62, 95% confidence interval (CI) = 1.12-11.7; p = 0.032], and MAPT *H2 haplotype (OR = 3.23, 95% CI = 1.08-9.69; p = 0.036) were associated with an increased hazard risk of poor outcome. Conversely, APOE genotype, and VEGF polymorphisms were not associated with survival risk in the FTLD sample.

CONCLUSIONS

Genetic background is not only crucial in disease pathogenesis, but it also modulates disease course. Genetic factors influencing prognosis should be taken into account to include homogeneous groups in future clinical trials and to monitor efficacy of future interventions.

Human motor neuron generation from embryonic stem cells and induced pluripotent stem cells

Motor neuron diseases (MNDs) are a group of neurological disorders that selectively affect motor neurons. There are currently no cures or efficacious treatments for these diseases. In recent years, significant developments in stem cell research have been applied to MNDs, particularly regarding neuroprotection and cell replacement. However, a consistent source of motor neurons for cell replacement is required. Human embryonic stem cells (hESCs) could provide an inexhaustible supply of differentiated cell types, including motor neurons that could be used for MND therapies. Recently, it has been demonstrated that induced pluripotent stem (iPS) cells may serve as an alternative source of motor neurons, since they share ES characteristics, self-renewal, and the potential to differentiate into any somatic cell type. In this review, we discuss several reproducible methods by which hESCs or iPS cells are efficiently isolated and differentiated into functional motor neurons, and possible clinical applications.

Congenital muscular dystrophies with cognitive impairment. A population study

BACKGROUND

Cognitive impairment has been reported in a significant proportion of patients with congenital muscular dystrophies (CMD), generally associated with brain changes.

OBJECTIVES

The aim of this study was to establish 1) the overall prevalence of CMD and cognitive impairment in the Italian population; 2) the frequency of individual genetically defined forms; and 3) the presence of distinct phenotypes not associated with mutations in the known genes.

METHODS

We included all patients with CMD and cognitive impairment followed in all the Italian tertiary neuromuscular centers. Clinical, brain MRI, and morphologic data were collected. Genetic screening of the known genes was performed according to clinical and muscle biopsy findings.

RESULTS

Ninety-two of the 160 (58%) patients with CMD followed in our centers had cognitive impairment. alpha-Dystroglycan (alpha-DG) reduction on muscle biopsy was found in 73/92 (79%), with 42/73 carrying mutations in the known genes. Another 6/92 (7%) showed a laminin alpha2 deficiency on muscle biopsy and 5 of the 6 carried mutations in LAMA2. The remaining 13/92 (14%) patients had normal alpha-DG and laminin alpha2 expression on muscle.

CONCLUSIONS

This is the first population study establishing the prevalence of CMD and cognitive impairment and providing a classification on the basis of clinical, MRI, and genetic findings. We also showed that cognitive impairment was not always associated with alpha-DG or laminin alpha2 reduction or with structural brain changes.

Neuropathological study of skeletal muscle, heart, liver, and brain in a neonatal form of glycogen storage disease type IV associated with a new mutation in GBE1 gene

Glycogen storage disease type IV (GSD IV, or Andersen disease) is an autosomal recessive disorder due to the deficiency of 1,4-alpha-glucan branching enzyme (or glycogen branching enzyme, GBE1), resulting in an accumulation of amylopectin-like polysaccharide in muscle, liver, heart and central and peripheral nervous system. Typically, the presentation is in childhood with liver involvement up to cirrhosis. The neuromuscular form varies in onset (congenital, perinatal, juvenile and adult) and in severity. Congenital cases are rare, and fewer than 20 cases have been described and genetically determined so far. This form is characterized by polyhydramnios, neonatal hypotonia, and neuronal involvement; hepatopathy is uncommon, and the babies usually die between 4 weeks and 4 months of age. We report the case of an infant who presented severe hypotonia, dilatative cardiomyopathy, mild hepatopathy, and brain lateral ventricle haemorrhage, features consistent with the congenital form of GSD IV. He died at one month of life of cardiorespiratory failure. Muscle biopsy and heart and liver autoptic specimens showed many vacuoles filled with PAS-positive diastase-resistant materials. Electron-microscopic analysis showed mainly polyglucosan accumulations in all the tissues examined. Postmortem examination showed the presence of vacuolated neurons containing this abnormal polysaccharide. GBE1 biochemical activity was virtually absent in muscle and fibroblasts, and totally lacking in liver and heart as well as glycogen synthase activity. GBE1 gene sequence analysis revealed a novel homozygous nonsense mutation, p.E152X, in exon 4, correlating with the lack of enzyme activity and with the severe neonatal involvement. Our findings contribute to increasing the spectrum of mutation associated with congenital GSD IV.

Abdominal volume contribution to tidal volume as an early indicator of respiratory impairment in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is characterised by progressive loss of muscular strength that leads to an increasingly restrictive pulmonary syndrome. However, it is still not clear whether this determines alterations in the breathing pattern. We studied: 66 DMD patients at different stages of the disease (mean+/- sem age 12.6+/-0.6 yrs, range 5-22 yrs of age), subdivided into four groups according to age; and 21 age-matched healthy male controls. Spirometry, lung volumes and nocturnal oxygen saturation were measured in all DMD patients. Ventilatory pattern and chest wall volume variations were assessed by optoelectronic plethysmography during spontaneous breathing both in seated and supine positions. Whilst in a seated position, no significant differences were found between patients and controls or between different age groups. In the supine position, the average contribution of abdominal volume change (DeltaV(AB)) to tidal volume progressively decreased with age (p<0.001). The patients who showed nocturnal hypoxaemia showed significantly lower Delta V(AB). In conclusion, chest wall motion during spontaneous breathing in awake conditions and in supine position is an important indicator of the degree of respiratory muscle impairment in DMD. DeltaV(AB) is not only an important marker of the progression of the disease but is also an early indicator of nocturnal hypoxaemia.

Congenital muscular dystrophies with defective glycosylation of dystroglycan: a population study

BACKGROUND

Congenital muscular dystrophies (CMD) with reduced glycosylation of alpha-dystroglycan (alpha-DG) are a heterogeneous group of conditions associated with mutations in six genes encoding proven or putative glycosyltransferases.

OBJECTIVES

The aim of the study was to establish the prevalence of mutations in the six genes in the Italian population and the spectrum of clinical and brain MRI findings.

METHODS

As part of a multicentric study involving all the tertiary neuromuscular centers in Italy, FKRP, POMT1, POMT2, POMGnT1, fukutin, and LARGE were screened in 81 patients with CMD and alpha-DG reduction on muscle biopsy (n = 76) or with a phenotype suggestive of alpha-dystroglycanopathy but in whom a muscle biopsy was not available for alpha-DG immunostaining (n = 5).

RESULTS

Homozygous and compound heterozygous mutations were detected in a total of 43/81 patients (53%), and included seven novel variants. Mutations in POMT1 were the most prevalent in our cohort (21%), followed by POMT2 (11%), POMGnT1 (10%), and FKRP (9%). One patient carried two heterozygous mutations in fukutin and one case harbored a new homozygous variant in LARGE. No clear-cut genotype-phenotype correlation could be observed with each gene, resulting in a wide spectrum of clinical phenotypes. The more severe phenotypes, however, appeared to be consistently associated with mutations predicted to result in a severe disruption of the respective genes.

CONCLUSIONS

Our data broaden the clinical spectrum associated with mutations in glycosyltransferases and provide data on their prevalence in the Italian population.

Mutated mitofusin 2 presents with intrafamilial variability and brain mitochondrial dysfunction

BACKGROUND

The axonal forms of Charcot-Marie-Tooth (CMT2) disease are a clinically and genetically heterogeneous group of disorders. Mitofusin 2 gene (MFN2) mutations are the most common cause of CMT2. Complex phenotypes have been described in association with MFN2 gene mutations, including CMT2 with pyramidal features (hereditary motor and sensory neuropathy [HSMN V]) and CMT2 with optic atrophy (HMSN VI).

OBJECTIVE

To report on the clinical, neurophysiologic, and neuropathologic features of an Italian family with a novel MFN2 gene mutation and investigate brain functional parameters using magnetic resonance spectroscopy (MRS).

METHODS

Three family members, a father and his two sons, were affected by peripheral neuropathy, cognitive impairment, and poor nocturnal vision (also optic neuropathy in one case). A member of this family also showed spastic paraparesis. The MFN2 gene sequence was analyzed. A sural nerve biopsy as well as brain (1)H-MRS and (31)P-MRS were evaluated in two patients.

RESULTS

Affected family members carried a novel MFN2 missense mutation, namely R104W, located within the critical GTPase domain of the protein which affects a highly conserved amino acid position. Sural nerve biopsies showed a normal mitochondrial network, particularly at the nodes of Ranvier, upon electron microscopy examination. A significant defect of high energy phosphates (HEPs) in the visual cortex was observed at rest by (31)P-MRS in the adult proband, while his son showed a defective recovery of HEPs after stimulation of the visual cortex.

CONCLUSION

Cognitive impairment may be another feature of the MFN2-related phenotype. The widespread peripheral and CNS involvement, as well as the neurosensorial defects, underline the similarities among MFN2-related and primary mitochondrial disorders.

Preliminary evidence that VEGF genetic variability confers susceptibility to frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) recognizes a strong genetic background, with 30-50% of cases with a positive family history. Despite several efforts to identify monogenic causes of the disease, no clear-cut genetic risk factors for sporadic FTLD are yet known. Recently, increasing evidence points to a pivotal role of vascular endothelial growth factor (VEGF) in the neurodegenerative process, suggesting functions not confined to its originally described vascular effects. The aim of this study was to investigate the role of VEGF as a genetic determinant to FTLD susceptibility. We evaluated a cohort of 274 unrelated Italian patients, including 161 subjects with frontotemporal dementia (FTD), 56 with corticobasal degeneration syndrome, and 57 with progressive supranuclear palsy. Genotype and allele frequencies of four well-known polymorphisms located within the VEGF promoter (-2578C/A, -1190G/A, -1154G/A, and -634G/C) were calculated in patients and in 216 age-matched healthy subjects. Genetic analysis revealed the presence of several significant changes in terms of allele, genotype, and haplotype frequency distributions between patients and controls. Marked differences were observed when the FTD patient subgroup was compared with healthy subjects. Overall, these data provide evidence for the first time that VEGF gene variability represents a susceptibility factor for sporadic FTLD, at least in an Italian population. Future confirmatory studies are mandatory.

Colocalization of ribonuclear inclusions with muscle blind like-proteins in a family with myotonic dystrophy type 2 associated with a short CCTG expansion

Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystemic disorder caused by a CCTG repeat expansion in intron 1 of the zinc finger protein 9 (ZNF9) gene. We present a three first-degree relative Italian family (proband, his mother and his sister) with a mild DM2 phenotype associated with a short (CCTG)(100) expansion as far as regards the proband and his mother, while his sister shows larger expansion correlated to a more severe phenotype. FISH analysis with (CAGG)(5) probe demonstrated that nuclear foci of mutant RNA were present in the proband muscle and co-localized with muscleblind-like proteins, determining their sequestration in the nucleus. This is one of the smallest expansion reported and the shortest with the evidence of nuclear foci. These data contribute to the clinical and molecular correlation of ZNF9 gene short expansion.

Autologous transplantation of muscle-derived CD133+ stem cells in Duchenne muscle patients

Duchenne muscular dystrophy (DMD) is a lethal X-linked recessive muscle disease due to defect on the gene encoding dystrophin. The lack of a functional dystrophin in muscles results in the fragility of the muscle fiber membrane with progressive muscle weakness and premature death. There is no cure for DMD and current treatment options focus primarily on respiratory assistance, comfort care, and delaying the loss of ambulation. Recent works support the idea that stem cells can contribute to muscle repair as well as to replenishment of the satellite cell pool. Here we tested the safety of autologous transplantation of muscle-derived CD133+ cells in eight boys with Duchenne muscular dystrophy in a 7-month, double-blind phase I clinical trial. Stem cell safety was tested by measuring muscle strength and evaluating muscle structures with MRI and histological analysis. Timed cardiac and pulmonary function tests were secondary outcome measures. No local or systemic side effects were observed in all treated DMD patients. Treated patients had an increased ratio of capillary per muscle fibers with a switch from slow to fast myosin-positive myofibers.

Clinical features and new molecular findings in Carnitine Palmitoyltransferase II (CPT II) deficiency

Carnitine palmitoyltransferase II (CPT II) deficiency is the most common inherited disorder of lipid metabolism characterized in its adult form by attacks of myalgia and myoglobinuria. We analyzed a cohort of 22 CPT II-deficient patients (representing 20 independent probands) to correlate clinical presentation and molecular data. The common p.Ser113Leu mutation was detected with an allelic frequency of 67.5% (27/40), in association with mild adult-onset phenotype. In addition to the p.Ser113Leu mutation, other 10 disease-causing mutations were identified, 5 of which were novel. They are a micro-insertion within exon 5, three aminoacid substitutions within the coding region, namely p.Arg151Trp, p.Asp576Gly, p.Arg247Trp and a truncating stop codon mutation (p.Arg554Ter). Our data expand the spectrum of CPT II mutations and help to evaluate possible correlations between genotypes and phenotypes.

Clinical, biochemical and genetic features of glycogen debranching enzyme deficiency

Deficiency of debrancher enzyme causes Glycogen Storage Disease (GSD) type III, an autosomal recessive disorder, characterized by tissue accumulation of abnormally structured glycogen. This report reviews current clinical and molecular knowledge about this disorder and describes the variability at phenotype and genotype levels of a large group of Italian GSDIII patients.

Hepatic and neuromuscular forms of glycogenosis type III: nine mutations in AGL

Glycogenosis type III (Cori disease) is an autosomal recessive disorder caused by the deficiency of the glycogen debranching enzyme, encoded by the AGL gene, and existing in six isoforms alternately spliced in a tissue-specific way. Generally, disease onset occurs early on starting from the first year of life, with hepatomegaly, hypoglycemia, hyperlipidemia, increased CK levels, and, in some cases, short stature and slight mental retardation. Frequently, hepatomegaly tends to resolve spontaneously and inexplicably during childhood, when myopathy, often associated with cardiomyopathy, arises. This disease is known to lack almost invariably clear links between the genotype and clinical phenotype. We describe nine new mutations in Italian patients: four nonsense (p.Arg285X, p.Lys422X, p.Arg910X, p.Arg977X), three frameshift (c.442delA, c.753_756delGACA, c.3963delG), and two missense (p.Ala1120Pro, p.Arg524His). Particularly, the nonsense p.Arg285X is linked to an exonic splicing enhancer and it was found to produce two species of transcripts at the same time. Moreover, we discuss a subgroup of subjects carrying c.2681+1G>A, which has proven to be the most frequent mutation among our patients. The previously described c.664+3A>G was also detected in two patients, both homozygous. The present work is yet another confirmation that the individual genetic background plays a pivotal role in influencing the phenotypes, as occurs in other metabolic diseases.

Coexistence of CMT-2D and distal SMA-V phenotypes in an Italian family with a GARS gene mutation

An Italian multigenerational family with four members affected by an axonal Charcot-Marie-Tooth type 2D (CMT-2D) or distal spinal muscular atrophy (dSMA) phenotype with upper limb predominance, variable age at onset, degree of disability, and autosomal dominant inheritance is reported. A novel heterozygous missense GARS gene mutation (D500N) was identified.

Somatic stem cell research for neural repair: current evidence and emerging perspectives

Recent evidence supports the existence of adult mammalian stem cell subpopulations, particularly within the bone marrow, that may be able to "transdifferentiate" across tissue lineage boundaries, thus offering an accessible source for therapeutic applications even for neural tissue repair. However, the difficulties in reproducing some experimental data, the rarity of the transdifferentiation events and observations that cell fusion may be an alternative explanation argue against the idea of stem cell plasticity. Investigations going beyond descriptive experiments and more mechanicistic approaches may provide a more solid foundation to adult stem cell therapeutic potential.

Nuclear reprogramming and adult stem cell potential

Cell-based therapy may represent a new strategy to treat a vast array of clinical disorders including neurodegenerative diseases. Recent observations indicate that adult somatic stem cells have the capacity to contribute to the regeneration of different tissues, suggesting that differentiative restrictions are not completely irreversible and can be reprogrammed. Cell fusion might account for some changed phenotype of adult cells but it seems to be biologically irrelevant for its extreme rarity. Other experimental evidences are compatible with the hypothesis of wide multipotency of well-defined stem cell populations, but also with transdifferentiation and/or dedifferentiation. Further studies on nuclear reprogramming mechanisms are necessary to fulfil the promise for developing autologous cellular therapies.

Neuronal differentiation of murine bone marrow Thy-1- and Sca-1-positive cells

Recent evidence suggests that cells from bone marrow can acquire neuroectodermal phenotypes in cell culture or after transplantation in animal models and in the human brain. However, isolation of the bone marrow cell subpopulation with neuronal differentiation potential remains a challenge. To isolate and expand neural progenitors from whole murine bone marrow, bone marrow was obtained from hind limb bone of C57BL6 mice and plated in culture with neuronal medium with basic fibroblast growth factor and epidermal growth factor. After 5-7 days in culture, cellular spheres similar to brain neurospheres appeared either floating or attached to culture dishes. These spheres were collected, dissociated, and expanded. The bone marrow-derived spheres were positive for nestin as assessed by immunocytochemistry and by reverse transcriptase polymerase chain reaction. Thy-1- and Sca-1-positive bone marrow cells selected by magnetic cell sorting resulted in a higher yield of nestin-positive spheres. After exposure to neuronal differentiative medium retinoic acid with and without Sonic hedgehog, cells positive for neuronal markers tubulin III (TuJ-1) and neurofilament (NF) were detected. The mRNA profile of these cells included the expression of TuJ-1, neuronal-specific enolase (NSE), and NF-light chain. To evaluate the in vivo behavior of these cells, spheres derived from bone marrow-derived cells of transgenic green fluorescent protein (GFP) mice were transplanted into newborn mouse brain. Two months later, the mouse neural cortex contained a minor proportion of GFP(+) cells co-expressing neuronal markers (TuJ-1, NF, MAP-2, NeuN). Although cell fusion phenomena with the host cells could not be ruled out, bone marrow-derived neurosphere transplantation could be a strategy for cellular mediated gene therapy.

A CAV3 microdeletion differentially affects skeletal muscle and myocardium

BACKGROUND

Caveolin-3 is the muscle-specific protein product of the caveolin gene family and an integral membrane component of caveolae. Mutations in the gene encoding caveolin-3 (CAV3) underlie four distinct disorders of skeletal muscle: the autosomal dominant form of limb-girdle muscular dystrophy type 1C (LGMD-1C), rippling muscle disease (RMD), sporadic and familial forms of hyperCKemia, and distal myopathy.

OBJECTIVE

To characterize a multigenerational Italian family affected by an autosomal dominant myopathic disorder and to assess the expression of caveolin-3, dystrophin, dystrophin-associated glycoproteins, and neuronal nitric oxide synthase in the myocardium of an affected patient.

METHODS

Clinical analysis involved 15 family members. Skeletal muscle expression of sarcolemmal proteins was evaluated by immunohistochemistry and western blot analysis in three affected individuals. Caveolar structures were analyzed through electron microscopy in muscle biopsies and in one heart biopsy.

RESULTS

CAV3 genetic analysis showed a heterozygous 3-bp microdeletion (328-330del) in affected individuals, resulting in the loss of a phenylalanine (Phe97del) in the transmembrane domain. In the skeletal muscle, the mutation was associated with severe caveolin-3 deficiency and caveolar disorganization, whereas the expression of the other analyzed muscle proteins was unaltered. Remarkably, caveolin-3 was expressed in myocardium at a level corresponding to about 60% of that of control individuals and was correctly localized at the myocardial cell membranes, with preservation of cardiac myofiber caveolar structures. Clinical analysis revealed the concomitant presence in this family of the following phenotypes: RMD, LGMD, and hyperCKemia.

CONCLUSIONS

Intrafamilial phenotypic heterogeneity is associated with caveolin-3 Phe97 microdeletion. The molecular network interacting with caveolin-3 in skeletal muscle and heart may differ.

Molecular analysis of LGMD-2B and MM patients: identification of novel DYSF mutations and possible founder effect in the Italian population

Dysferlin, the protein product of the dysferlin gene (DYSF), has been shown to have a role in calcium-induced membrane fusion and repair. Dysferlin is absent or drastically reduced in patients with the following autosomal recessive disorders: limb-girdle muscular dystrophy type 2B (LGMD-2B), Miyoshi myopathy (MM) and distal anterior compartment myopathy. To date, less than 45 mutations have been described in DYSF and a wide inter- and intra-familial variation in clinical phenotype has been associated with the same mutation. This observation underlines the relevance of any new report describing genotype/phenotype correlations in dysferlinopathic patient and families. Here we present the results of clinical, biochemical and genetic analysis performed on one MM and three LGMD Italian families. By screening the entire coding region of DYSF, we identified three novel mutations (two missense substitutions and one frame shift microdeletion). The possible existence of a founder effect for the Arg959Trp mutation in the Italian population is discussed.

Remarkable infidelity of polymerase A associated with mutations in POLG1 exonuclease domain

OBJECTIVE

To better understand the still unknown pathologic mechanism involved in the accumulation of multiple mtDNA deletions in stable tissues.

METHODS

A large-scale screening of mtDNA molecules from skeletal muscle was performed in 14 patients with progressive external ophthalmoplegia (PEO) and 2 patients with mitochondrial neurogastrointestinal encephalomyopathy carrying mutations on ANT1, C10ORF2 or POLG1, and TP genes.

RESULTS

Patients with at least one mutation in the exonuclease domain of POLG1 showed the highest frequency of individually rare point mutations only in the mtDNA control region; in addition, high levels, in terms of frequency and heteroplasmy, of recurrent mutations (A189G, T408A, and T414G) and alterations affecting the (HT)D310 region were detectable in many of the patients. Two homozygous POLG1 mutations, within the exonuclease domain, were able to induce an increased mutational burden also in fibroblasts from patients with PEO.

CONCLUSIONS

Specific POLG1 mutations directly affect the integrity of the mtDNA by reducing its proof-reading exonuclease activity, resulting in the accumulation of heteroplasmic levels of both randomly rare and recurrent point mutations in the skeletal muscle tissue and fibroblasts.

Mutational analysis of the AGL gene: five novel mutations in GSD III patients

Total or partial lack of glycogen debranching enzyme (GDE or AGL, amylo-1,6-glucosidase, 4-alpha-glucanotransferase) is responsible for Glycogen Storage Disease type III (GSDIII), a rare autosomal recessive disorder of glycogen metabolism. The clinical and biochemical features of GSDIII subjects are quite heterogeneous, and this mirrors the genotype-phenotype heterogeneity among patients. In this paper, we report the molecular characterisation of five unrelated subjects, four Italian and one Tunisian. The following new mutations are described and confirm the genetic heterogeneity of this disease: p.R864X, p.R428K, c.3911 insA, p.G1087R and c.3512_3549dup+c.3512_3519del. The functional relevance of these mutations is discussed on the basis of the recently acquired knowledge about the boundaries and structures of the two catalytic domains.

Clinical, morphological and immunological evaluation of six patients with dysferlin deficiency

Limb girdle muscular dystrophy (LGMD) type 2B and distal Miyoshi myopathy (MM) are caused by mutations in a recently discovered mammalian gene coding for a skeletal muscle protein called dysferlin. The protein is normally expressed at the skeletal muscle level and absent or reduced in affected patients. We selected a clinically heterogeneous population of Italian myopathic patients with clinical evidence of myopathy and/or hyperCKemia, EMG myopathic pattern, and no alterations of the dystrophin-sarcoglycan complex. Calpain, merosin, emerin and caveolin were also tested and found normal in all patients. Dysferlin immunohistochemical and Western blot analyses allowed us to identify six patients with dysferlin deficiency: one with distal myopathy, four with limb girdle myopathy and one with hyperCKemia. No apoptosis was found in any of the six muscle specimens, although expression of the pro-apoptotic Fas antigen was mildly increased in two cases. Inflammatory reactions were present in two of the six cases, but we found no evidence of immune-mediated processes.

Neuronal generation from somatic stem cells: current knowledge and perspectives on the treatment of acquired and degenerative central nervous system disorders

Stem cell transplantation through cell replacement or as vector for gene delivery is a potential strategy for the treatment of neurodegenerative diseases. Several studies have reported the transdifferentiation of different somatic stem cells into neurons in vitro or after transplantation into animal models. This observation has pointed out the perspective of using an ethical and accessible cell source to "replace" damaged neurons or provide support to brain tissue. However, recent findings such as the cell fusion phenomenon have raised some doubts about the real existence of somatic stem cell plasticity. In this review, we will discuss current evidence and controversial issues about the neuroneogenesis from various sources of somatic cells focusing on the techniques of isolation, expansion in vitro as well as the inductive factors that lead to transdifferentiation in order to identify the factors peculiar to this process. The morphological, immunochemical, and physiological criteria to correctly judge whether the neuronal transdifferentation occurred are critically presented. We will also discuss the transplantation experiments that were done in view of a possible clinical therapeutic application. Animal models of stroke, spinal cord and brain trauma have improved with Mesenchymal Stem Cells or Bone Marrow transplantation. This improvement does not seem to depend on the replacement of the lost neurons but may be due to increased expression levels of neurotrophic factors, thus suggesting a beneficial effect of somatic cells regardless of transdifferentiation. Critical understanding of available data on the mechanisms governing the cell fate reprogramming is a necessary achievement toward an effective cell therapy.

A mitochondrial tRNA(His) gene mutation causing pigmentary retinopathy and neurosensorial deafness

We have identified a heteroplasmic G to A mutation at position 12,183 of the mitochondrial transfer RNA Histidine (tRNA(His)) gene in three related patients. These phenotypes varied according to mutation heteroplasmy: one had severe pigmentary retinopathy, neurosensorial deafness, testicular dysfunction, muscle hypotrophy, and ataxia; the other two had only retinal and inner ear involvement. The mutation is in a highly conserved region of the T(psi)C stem of the tRNA(His) gene and may alter secondary structure formation. This is the first described pathogenic, maternally inherited mutation of the mitochondrial tRNA(His) gene.

Trans-acting factors may cause dystrophin splicing misregulation in BMD skeletal muscles

We analyzed dystrophin alternative splicing events in a large number of Becker muscular dystrophy (BMD) affected individuals presenting major hot-spot deletions. Evidence is shown that altered splicing patterns in these patients do not directly result from the gene defect but probably derive from modifications in trans- rather than cis-acting factors. Several potential CUG-binding protein 2 (CUG-BP2) binding sites were found to be located in the dystrophin gene region encompassing exons 43-60 and CUG-BP2 transcript analysis indicated that not only expression levels are increased in dystrophic muscles but also that different CUG-BP2 isoforms are expressed. The possibility that CUG-BP2 might have a role in dystrophin splicing regulation is discussed.

Two dystrophin proteins and transcripts in a mild dystrophinopathic patient

Two muscle dystrophin transcripts and proteins were detected in a 17-year-old boy with a persistently elevated serum creatine kinase level. A decreased amount of full-length dystrophin and a 360 kDa polypeptide lacking the COOH-terminus were detectable in the patient's muscle biopsy; accordingly, transcript analysis revealed the expression of a wild type messenger RNA together with a shorter frameshifted one. No genomic DNA mutation was found and the presence of a somatic mosaicism was excluded. This dystrophinopathy may be caused by a novel dystrophin gene transcriptional defect, namely aberrant intraexonic splicing.