Matteo Garibaldi

The increase of pericyte population in human neuromuscular disorders supports their role in muscle regeneration in vivo

Pericytes are periendothelial cells that have been involved in many different functions including a possible role as mesodermal stem/progenitor cells. In the present study we demonstrate that alkaline phosphatase (AP) expression is specific for human muscular pericytes and can be used as a marker to identify them in skeletal muscle biopsies. We studied the pericyte population in skeletal muscle biopsies from controls, myopathic and neuropathic patients. We observed a significant increase in the number of pericytes only in myopathies that correlated with the number of NCAM+ fibres, suggesting that an active muscular degenerative/regenerative process is related to an increase in the pericyte population. AP+ pericytes sorted from skeletal muscle samples were able to activate the myogenic programme and fuse with both mononucleate satellite cells and mature multinucleated myotubes in vitro, demonstrating that they could participate in muscle regeneration. In accordance, pericytes expressing the myogenic transcription factor MyoD were found in biopsies of myopathic biopsies. All these data support the hypothesis that, apart from satellite cells, pericytes may play an important role in muscle regeneration in adult human muscles in vivo. Copyright

RecessiveMYPNmutations cause cap myopathy with occasional nemaline rods: MYPNMutations

Congenital myopathies are phenotypically and genetically heterogeneous. We describe homozygous truncating mutations in MYPN in 2 unrelated families with a slowly progressive congenital cap myopathy. MYPN encodes the Z‐line protein myopalladin implicated in sarcomere integrity. Functional experiments demonstrate that the mutations lead to mRNA defects and to a strong reduction in full‐length protein expression. Myopalladin signals accumulate in the caps together with alpha‐actinin. Dominant MYPN mutations were previously reported in cardiomyopathies. Our data uncover that mutations in MYPN cause either a cardiac or a congenital skeletal muscle disorder through different modes of inheritance. Ann Neurol 2017;81:467–473

Estrogens enhance myoblast differentiation in facioscapulohumeral muscular dystrophy by antagonizing DUX4 activity

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant neuromuscular disorder that is characterized by extreme variability in symptoms, with females being less severely affected than males and presenting a higher proportion of asymptomatic carriers. The sex-related factors involved in the disease are not known. Here, we have utilized myoblasts isolated from FSHD patients (FSHD myoblasts) to investigate the effect of estrogens on muscle properties. Our results demonstrated that estrogens counteract the differentiation impairment of FSHD myoblasts without affecting cell proliferation or survival. Estrogen effects are mediated by estrogen receptor &bgr; (ER&bgr;), which reduces chromatin occupancy and transcriptional activity of double homeobox 4 (DUX4), a protein whose aberrant expression has been implicated in FSHD pathogenesis. During myoblast differentiation, we observed that the levels and activity of DUX4 increased progressively and were associated with its enhanced recruitment in the nucleus. ER&bgr; interfered with this recruitment by relocalizing DUX4 in the cytoplasm. This work identifies estrogens as a potential disease modifier that underlie sex-related differences in FSHD by protecting against myoblast differentiation impairments in this disease.

A novel gain-of-function mutation in ORAI1 causes late-onset Tubular Aggregate Myopathy and congenital miosis

We present three members of an Italian family affected by tubular aggregate myopathy (TAM) and congenital miosis harboring a novel missense mutation in ORAI1. All patients had a mild, late onset TAM revealed by asymptomatic creatine kinase (CK) elevation and congenital miosis consistent with a Stormorken‐like Syndrome, in the absence of thrombocytopathy. Muscle biopsies showed classical histological findings but ultrastructural analysis revealed atypical tubular aggregates (TAs). The whole body muscle magnetic resonance imaging (MRI) showed a similar pattern of muscle involvement that correlated with clinical severity. The lower limbs were more severely affected than the scapular girdle, and thighs were more affected than legs. Molecular analysis revealed a novel c.290C>G (p.S97C) mutation in ORAI1 in all affected patients. Functional assays in both human embryonic kidney (HEK) cells and myotubes showed an increased rate of Ca2+ entry due to a constitutive activation of the CRAC channel, consistent with a ‘gain‐of‐function’ mutation. In conclusion, we describe an Italian family harboring a novel heterozygous c.290C>G (p.S97C) mutation in ORAI1 causing a mild‐ and late‐onset TAM and congenital miosis via constitutive activation of the CRAC channel. Our findings extend the clinical and genetic spectrum of the ORAI1‐related TAM.

Long term follow-up of cerebrovascular abnormalities in late onset Pompe disease (LOPD)

Pompe disease or glycogen storage disease type II (GSDII; OMIM #232300) is a rare recessive metabolic disorder caused by a deficiency in the lysosomal acid a-glucosidase activity resulting in lysosomal glycogen accumulation in different tissues. Glycogen accumulation has been detected in skeletal and heart muscles, in smooth muscle of blood vessels, gastrointestinal tract and urinary bladder, leading a multisystemic clinical or subclinical involvement [1]. Enzyme replacement therapy (ERT) changed the natural history of classic form of Pompe disease (infantile onset) and showed to improve or stabilize motor and respiratory performance in 2/3 of LOPD patients [2]. Intracranial artery abnormalities (IAA) in late onset Pompe disease (LOPD) have been described so far in several reports and few systematic studies [3–7]. Previous evidences suggest a potential link between blood vessels anomalies and glycogen storage in smooth muscle cells of the media [1]. The most frequent alterations described are vertebrobasilar dolichoectasia (VTD), internal carotid ectasia (ICE) and aneurysms of middle cerebral artery (AMCA) [6, 7]. Even if the overall prevalence of IAA among Pompe population is estimated around 50% with variable outcome [8–11], the natural course of intracranial vascular anomalies has not been systematically investigated. Between 2006 and 2016, we have systematically monitored the IAA in five out of six previously reported LOPD patients on ERT by magnetic resonance angiography (MRA) performed with the same protocol over the time [6]. One patient required CT scan imaging because of cardiac pacing requirement during the follow-up [12]. Stable radiological follow-up after the first year had been observed [6]. Here, we present the radiological data of the longextended term follow-up of this cohort. The median disease duration was 28.6 years (range 17–39 years) and the median radiological follow-up was 8 years and half (range 7–10 years). At the beginning, three out of five patients (P1, P2, P5) had cerebral arterial anomalies (VBD, ICE, or both) detected by MRA and two (P1, P2) of them had related symptoms (eyelid ptosis due to a neurovascular conflict, transient ischemic attack). The two patients (P3, P4) with normal MRA had the shortest disease duration and milder clinical phenotype. Four patients (P1, P2, P3 and P5) continued ERT therapy without adverse effect all along follow-up duration and one patient (P4) required permanent discontinuation few months later the start of ERT because of major adverse effect. Globally, the MRA findings did not show significant changes between the first and last study in all the patients (Table 1) and none of the patient showed major vascular events (ischemic or hemorrhagic strokes and subarachnoid hemorrhages) during the follow-up. Noteworthy, in our cohort none of the patients had or developed vascular aneurysms. VBD and ICE remained stable (diameter variation\1 mm) in all patients. Novel intracranial arterial abnormalities were not detected in any patients. None of & Matteo Garibaldi matteo.garibaldi@uniroma1.it

Muscle MRI in neutral lipid storage disease (NLSD)

Neutral lipid storage disease (NLSD) is a rare inherited disorder of lipid metabolism resulting in lipid droplets accumulation in different tissues. Skeletal muscle could be affected in both two different form of disease: NLSD with myopathy (NLSD-M) and NLSD with ichthyosis (NLSD-I). We present the muscle imaging data of 12 patients from the Italian Network for NLSD: ten patients presenting NLSD-M and two patients with NLSD-I. In NLSD-M gluteus minimus, semimembranosus, soleus and gastrocnemius medialis in the lower limbs and infraspinatus in the upper limbs were the most affected muscles. Gracilis, sartorius, subscapularis, pectoralis, triceps brachii and sternocleidomastoid were spared. Muscle involvement was not homogenous and characteristic “patchy” replacement was observed in at least one muscle in all the patients. Half of the patients showed one or more STIR positive muscles. In both NLSD-I cases muscle involvement was not observed by T1-TSE sequences, but one of them showed positive STIR images in more than one muscle in the leg. Our data provides evidence that muscle imaging can identify characteristic alterations in NLSD-M, characterized by a specific pattern of muscle involvement with “patchy” areas of fatty replacement. Larger cohorts are needed to assess if a distinct pattern of muscle involvement exists also for NLSD-I.

Teaching Video NeuroImages: The Beevor sign in late-onset Pompe disease.

The Beevor sign, an upward deflection of the umbilicus on flexion of the neck, is a characteristic finding in facioscapulohumeral muscular dystrophy.1 Many other neuromuscular disorders involving axial muscles can present a Beevor sign.2 We report a 45-year-old man with late-onset Pompe disease showing a major Beevor sign (figure 1 and video on the Neurology® Web site at Neurology.org). He had progressive limb-girdle weakness that started in his 20s and severe axial weakness. Whole-body muscle MRI showed a complete fatty replacement and atrophy of the lower part of rectus abdominis (figure 2, arrowheads) and a milder involvement of the upper part (figure 2, arrows).

Novel Dominant Mutation in BIN1 Gene Causing Mild Centronuclear Myopathy Revealed by Myalgias and CK Elevation

We present the clinical, morphological and molecular data of an Italian family with centronuclear myopathy, carrying a novel pathogenic mutation of BIN1 gene in heterozygous state, consistent with autosomal dominant inheritance. The proband, a 56-years-old man suffered of lower limbs myalgia and slight CK elevation. Clinical examination revealed no muscle weakness, short stature, mild symmetric eyelid ptosis, scapular winging, ankle retraction and well-developed muscles. Muscle biopsy showed nuclear centralization and clustering, deep sarcolemmal invaginations and type 1 fibers hypotrophy. Muscle MRI revealed fatty infiltration of posterior legs compartments, lumbar paraspinal and serratus muscles. By sequencing BIN1, we identified a heterozygous pathogenic mutation [c.107C>A (p.A36E)], and we demonstrate that the mutation strongly impairs the membrane tubulation property of the protein. One affected sister with similar phenotype carried the same mutation. Our findings expand the clinical, morphological and genetic spectrum of the autosomal dominant CNM associated with BIN1 mutations.

Dropped-head in recessive oculopharyngeal muscular dystrophy

A 69-year-old woman presented a dropped head, caused by severe neck extensor weakness that had started two years before. She had also developed a mild degree of dysphagia, rhinolalia, eyelid ptosis and proximal limb weakness during the last months. EMG revealed myopathic changes. Muscle MRI detected fatty infiltration in the posterior neck muscles and tongue. Muscle biopsy revealed fiber size variations, sporadic rimmed vacuoles, small scattered angulated fibers and a patchy myofibrillar network. Genetic analysis revealed homozygous (GCN)11 expansions in the PABPN1 gene that were consistent with recessive oculopharyngeal muscular dystrophy (OPMD). There are a few reports of the recessive form, which has a later disease onset with milder symptoms and higher clinical variability than the typical dominantly inherited form. This patient, who is the first Italian and the eighth worldwide reported case of recessive OPMD, is also the first case of OPMD with dropped-head syndrome, which thus expands the clinical phenotype of recessive OPMD.

Erectile dysfunction in myotonic dystrophy type 1 (DM1)

JO N 2912 and personal life of these patients. Hypothesizing that impotence may be an intrinsic characteristic in DM1, we performed a study to assess its frequency and characteristics. The complete series of male patients (aged 18-60 years) with genetically-confirmed DM1, under clinical surveillance in our Neuromuscular Unit in January 2005, was clinically evaluated for any disease or medication and tested with both the Mini-Mental State Examination and Hamilton Depression Rating Scale. Subjects with physical or mental diseases known to interfere with sexual activity [4] and those with congenital DM1, or cognitive dysfunction or HAM-D “severe” or “very severe” scores, were excluded. Patients are shown in Fig. 1. A total of 31 patients and 31 age-matched healthy controls filled out the questionnaire of the Internationally Validated Index of ErecGiovanni Antonini Alessandro Clemenzi Elisabetta Bucci Stefania Morino Matteo Garibaldi Micaela Sepe-Monti Franco Giubilei Giuseppe Novelli