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The cell adhesion molecule TAG-1 is expressed by neurons and glial cells and plays a role in axon outgrowth, migration and fasciculation during development. TAG-1 is also required for the clustering of Kv1.1/1.2 potassium channels and Caspr2 at the juxtaparanodes of myelinated fibers. Behavioral examination of TAG-1 deficient mice (Tag-1amp;8722;/amp;8722;) showed cognitive impairments in the Morris water maze and novel object recognition tests, reduced spontaneous motor activity, abnormal gait coordination and increased response latency to noxious stimulation. Investigation at the molecular level revealed impaired juxtaparanodal clustering of Caspr2 and Kv1.1/1.2 in the hippocampus, entorhinal cortex, cerebellum and olfactory bulb, with diffusion into the internode. Caspr2 and Kv1.1 levels were reduced in the cerebellum and olfactory bulb. Moreover, Tag-1amp;8722;/amp;8722; mice had shorter internodes in the cerebral and cere bellar white mat ter. The detected molecular alterations may account for the behavioural deficits and hyperexcitability in these animals.

Autoantibodies to Shaker -type (Kv1) K+ channels are now known to be associated with three syndromes. Peripheral nerve hyperexcitability is the chief manifestation of acquired neuromyotonia; the combination of neuromyotonia with autonomic and CNS involvement is called Morvan's syndrome (MoS); and CNS manifestations without peripheral involvement is called limbic encephalitis (LE). To determine the cellular basis of these clinical manifestations, we immunostained mouse neural tissues with sera from patients with neuromyotonia ( n = 10), MoS ( n = 2) or LE ( n = 5), comparing with specific antibodies to relevant K+ channel subunits. Fourteen of 17 patients' sera were positive for Kv1.1, Kv1.2 or Kv1.6 antibodies by immunoprecipitation of 125I-α-dendrotoxin-labelled rabbit brain K+ channels. Most sera (11 out of 17) labelled juxtaparanodes of peripheral myelinated axons, co-localizing with Kv1.1 and Kv1.2. In the CNS, all sera tested ( n = 12) co-localized with one or more areas of high Kv1.1, Kv1.2 or Kv1.6 channel expression: 10 out of 12 sera co-localized with Kv1.1 and Kv1.2 at spinal cord juxtaparanodes or cerebellar layers, while 3 out of 12 sera co-localized additionally ( n = 2) or exclusively ( n = 1) with Kv1.6 subunits in Purkinje cells, motor and hippocampal neurons. However, only sera from LE patients labelled the hippocampal areas that are enriched in excitatory, Kv1.1-positive axon terminals. All sera (17 out of 17) labelled one or more of these Kv1 subunits when expressed at the cell membrane of transfected HeLa cells, but not when they were retained in the endoplasmic reticulum. Again, LE sera labelled Kv1.1 subunits more prominently than did MoS or neuromyotonia sera, suggesting an association between higher Kv1.1 specificity and limbic manifestations. In contrast, neuromyotonia sera bound more strongly to Kv1.2 subunits than to Kv1.1 or Kv1.6. These studies support the hypothesis that antibodies to mature surface membrane-expressed Shaker -type K+ channels cause acquired neuromyotonia, MoS and LE, and suggest that future assays based on immunofluorescence of cells expressing individual Kv1 subunits will prove more sensitive than the immunoprecipitation assay. Although more than one type of antibody is often detectable in individual sera, higher affinity for certain subunits or subunit combinations may determine the range of clinical manifestations.

Although there is good experimental data that utrophin, the autosomal analog of dystrophin, can ameliorate the phenotype in dystrophinopathies, there is scant evidence from human data to support this hypothesis. We investigated in diagnostic muscle biopsies from 16 patients with Duchenne muscular dystrophy (DMD) the level of utrophin expression using quantitative immunoblot analysis. In 13 of 16 patients, in whom there was adequate follow-up data, utrophin expression was correlated to two clinical endpoints: age at reaching Hammersmith score of 30/40 and age at becoming wheelchair-bound. We found that utrophin expression increases with age in DMD and that there is a significant positive correlation between the quantity of utrophin at initial biopsy and time to becoming wheelchair-bound.

Peripheral neuropathies occur in 5% of patients with Non-Hodgkin Lymphoma and represent the effects of therapy, direct compression or nerve infiltration by tumor, or paraneoplastic effects. Multifocal motor neuropathy with conduction block (MMNCB) is a rare demyelinating disorder of unknown etiology characterized by progressive, distal, asymmetric weakness mostly of the upper limbs with minimal or no sensory loss. We report a patient, who developed MMNCB at the time of isolated CNS relapse from a diffuse large B-cell lymphoma. Marked neurological improvement was achieved using intravenous immunoglobulin treatment. To our knowledge, MMNCB has thus far not been described as part of the spectrum of lymphoma-related peripheral neuropathies.

Oligodendrocytes of adult rodents express three different connexins: connexin29 (Cx29), Cx32, and Cx47. In this study, we show that Cx29 is localized to the inner membrane of small myelin sheaths, whereas Cx32 is localized on the outer membrane of large myelin sheaths; Cx29 does not colocalize with Cx32 in gap junction plaques. All oligodendrocytes appear to express Cx47, which is largely restricted to their perikarya. Cx32 and Cx47 are colocalized in many gap junction plaques on oligodendrocyte somata, particularly in gray matter. Cx45 is detected in the cerebral vasculature, but not in oligodendrocytes or myelin sheaths. This diversity of connexins in oligodendrocytes (in different populations of cells and in different subcellular compartments) likely reflects functional differences between these connexins and perhaps the oligodendrocytes themselves.

Four patients, aged 25 to 42 years presented with acute onset of a movement disorder characterized by a tonic, sustained, lateral and outward protrusion of one half of the lower lip. The movement disorder was present at rest, while in some patients, it was also present during speech. In all cases, the abnormal lip posture could be suppressed voluntarily. Neurological examination was otherwise normal. Extensive laboratory investigation failed to reveal any causative factors for secondary focal dystonia. Treatment with oral medications and botulinum toxin was mostly ineffective. Spontaneous remissions were frequent.

Mutations in the gene encoding the K+channel KCNQ2 cause neonatal epilepsy and myokymia, indicating that KCNQ2 regulates the excitability of CNS neurons and motor axons, respectively. We show here that KCNQ2 channels are functional components of axon initial segments and nodes of Ranvier, colocalizing with ankyrin-G and voltage-dependent Na+channels throughout the CNS and PNS. Retigabine, which opens KCNQ channels, diminishes axonal excitability. Linopirdine, which blocks KCNQ channels, prolongs the repolarization of the action potential in neonatal nerves. The clustering of KCNQ2 at nodes and initial segments lags that of ankyrin-G during development, and both ankyrin-G and KCNQ2 can be coimmunoprecipitated in the brain. KCNQ3 is also a component of some initial segments and nodes in the brain. The diminished activity of mutant KCNQ2 channels accounts for neonatal epilepsy and myokymia; the cellular locus of these effects may be axonal initial segments and nodes.

We describe a Cypriot family in which some family members presented with episodes of pressure palsies, while other family members had a slowly progressive chronic polyneuropathy typical of the Charcot-Marie-Tooth type 1 phenotype. All family members were evaluated clinically, with nerve conduction studies, and with genetic testing. In all affected individuals there was clinical and electrophysiological evidence of diffuse demyelinating sensorimotor polyneuropathy and a novel point mutation in the PMP22 gene (Ser22Phe) was identified.

Publisher Summary Neuropathy is a frequent component of numerous inherited syndromes. It is called Charcot-Marie-Tooth disease (CMT), when in isolation. The biology of axons and myelinating Schwann cells makes them vulnerable to the effects of mutations in a large number of genes. This chapter emphasizes on the varieties of inherited demyelinating neuropathies, their clinical phenotypes, the mutations that cause these phenotypes, and update their pathogenesis gene-by-gene. The genetic classification of the nonsyndromic inherited neuropathies is also provided. Inherited neuropathies are usually caused by mutations in genes that are expressed by myelinating Schwann cells or neurons, which is the biological basis for the long-standing distinction between primary “demyelinating” and “axonal” neuropathies. Neuropathies can be isolated, the primary manifestation of a more complex syndrome, or overshadowed by other aspects of the inherited disease. Increasing knowledge of the molecular genetics causes of inherited neuropathies facilitates a faster and more accurate diagnosis, setting the stage for the development of specific therapeutic interventions.

Four patients presented with slowly progressive, bilateral, asymmetric weakness and muscle atrophy in the lower extremities, accompanied by cramps and fasciculations. Sensory symptoms were insignificant. There was no bladder or bowel disturbance. Upper extremities and cranial nerves were normal. Weakness was found in lumbosacral myotomes, ranging from L2 to S1. The tendon reflexes varied, and extensor plantar responses were found in one case with proximal leg involvement. Nerve conduction studies were normal, but segmental chronic and often active denervation confined to the weak myotomes in the lower extremities was found in the electromyogram. Magnetic resonance imaging showed evidence of spondylotic lumbosacral myelopathy associated with disc herniation or osteophytic arthropathy at the T11/T12 spinal level in all patients, with increased signal within the adjacent cord. This unusual purely motor presentation may result from ischemic myelopathy secondary to compression of the anterior spinal artery.

Background: Charcot-Marie-Tooth (CMT) neuropathy is a heterogeneous group of inherited disorders of the peripheral nervous system. The authors recently mapped an autosomal dominant demyelinating form of CMT type 1 (CMT1C) to chromosome 16p13.1-p12.3. Objective: To find the gene mutations underlying CMT1C. Methods: The authors used a combination of standard positional cloning and candidate gene approaches to identify the causal gene for CMT1C. Western blot analysis was used to determine relative protein levels in patient and control lymphocyte extracts. Northern blotting was used to characterize gene expression in 1) multiple tissues; 2) developing sciatic nerve; and 3) nerve-crush and nerve-transection experiments. Results: The authors identified missense mutations (G112S, T115N, W116G) in the LITAFgene (lipopolysaccharide-induced tumor necrosis factor-α factor) in three CMT1C pedigrees. LITAF, which is also referred to as SIMPLE, is a widely expressed gene encoding a 161-amino acid protein that may play a role in protein degradation pathways. The mutations associated with CMT1C were found to cluster, defining a domain of the LITAF protein having a critical role in peripheral nerve function. Western blot analysis suggested that the T115N and W116G mutations do not alter the level of LITAF protein in peripheral blood lymphocytes. The LITAF transcript is expressed in sciatic nerve, but its level of expression is not altered during development or in response to nerve injury. This finding is in stark contrast to that seen for other known genes that cause CMT1. Conclusions: Mutations in LITAF may account for a significant proportion of CMT1 patients with previously unknown molecular diagnosis and may define a new mechanism of peripheral nerve perturbation leading to demyelinating neuropathy.

✓ This 7-year-old boy with Dejerine—Sottas syndrome caused by a mutation in the myelin protein zero gene began to suffer rapid deterioration with increasing leg weakness, loss of the ability to ambulate, and bowel and bladder incontinence. Magnetic resonance imaging of the spine revealed nerve root hypertrophy resulting in compression of the conus medullaris and cauda equina. Decompressive surgery was successful in reversing some of his deficits.

Ion channels are complex proteins that span the lipid bilayer of the cell membrane, where they orchestrate the electrical signals necessary for normal function of the central nervous system, peripheral nerve, and both skeletal and cardiac muscle. The role of ion channel defects in the pathogenesis of numerous disorders, many of them neuromuscular, has become increasingly apparent over the last decade. Progress in molecular biology has allowed cloning and expression of genes that encode channel proteins, while comparable advances in biophysics, including patch-clamp electrophysiology and related techniques, have made the study of expressed proteins at the level of single channel molecules possible. Understanding the molecular basis of ion channel function and dysfunction will facilitate both the accurate classification of these disorders and the rational development of specific therapeutic interventions. This review encompasses clinical, genetic, and pathophysiological aspects of ion channels disorders, focusing mainly on those with neuromuscular manifestations.

Although both Schwann cells and oligodendrocytes express connexin32 (Cx32), the loss of this connexin causes demyelination only in the PNS. To determine whether oligodendrocytes might express another connexin that can function in place of Cx32, we searched for novel CNS-specific connexins using reverse transcriptase-PCR and degenerate primers. We identified Cx29, whose transcript was restricted to brain, spinal cord, and sciatic nerve. Developmental expression of Cx29 mRNA in the CNS paralleled that of other myelin-related mRNAs, including Cx32. In the CNS, Cx29 antibodies labeled the internodal and juxtaparanodal regions of small myelin sheaths, whereas Cx32 staining was restricted to large myelinated fibers. In the PNS, Cx29 expression preceded that of Cx32 and declined to lower levels than Cx32 in adulthood. In adult sciatic nerve, Cx29 was primarily localized to the innermost aspects of the myelin sheath, the paranode, the juxtaparanode, and the inner mesaxon. Cx29 displayed a striking coincidence with Kv1.2 K(+) channels, which are localized in the axonal membrane. Both Cx29 and Cx32 were found in the incisures. Cx29 expressed in N2A cells did not induce intercellular conductances but did participate in the formation of active channels when coexpressed with Cx32. Together, these data show that Cx29 and Cx32 are expressed by myelinating glial cells with distinct distributions.

Both oligodendrocytes and myelinating Schwann cells express the gap junction protein connexin32 (Cx32). Mutations in the gene encoding Cx32 (GJB1) cause the X-linked form of Charcot-Marie-Tooth disease (CMTX). Although most CMTX patients do not have clinical central nervous system (CNS) manifestations, subclinical evidence of CNS dysfunction is common. We investigated the cellular effects of a subgroup of GJB1/Cx32 mutations that have been reported to cause clinical CNS dysfunction. We hypothesized that these mutants have dominant-negative effects on other connexins expressed by oligodendrocytes, specifically Cx45. We expressed these and other Cx32 mutants in communication-incompetent as well as Cx45-expressing HeLa cells, and analyzed the transfected cells by immunocytochemistry and immunoblotting. In communication-incompetent cells, the mutants associated with CNS phenotypes failed to reach the cell membrane and were instead retained in the endoplasmic reticulum (A39V, T55I) or Golgi apparatus (M93V, R164Q, R183H), although rare gap junction plaques were found in cells expressing M93V or R183H. In HeLa cells stably expressing Cx45, these Cx32 mutants showed a similar expression pattern, and did not alter the pattern of Cx45 expression. These results indicate that Cx32 mutants that are associated with a CNS phenotype do not interact with Cx45, but may instead have other toxic effects in oligodendrocytes. © 2002 Wiley-Liss, Inc.

Editor—Recently, Reid et al 1 reported reduction of the chromosome 12q locus for autosomal dominant hereditary spastic paraplegia. We now report reduction of the chromosome 14q locus for autosomal dominant hereditary spastic paraplegia (SPG3, OMIM 182600). Hereditary spastic paraplegia (HSP) (also known as Strumpell-Lorrain syndrome2) is a heterogeneous group of disorders characterised by progressive lower extremity weakness and spasticity. Gait disturbance may begin at any age and progresses insidiously. Postmortem studies show axonal degeneration that is maximal in the distal ends of the corticospinal tracts and fasciculus gracilis fibres3 4 (websitehttp://www.geneclinics.org). Loci for autosomal dominant HSP have been identified on chromosomes 2p22 (SPG4), 2q24-34 (SPG13), 8q23-q24 (SPG8), 12q13 (SPG10), 10q23.3-q24.2 (SPG9), 14q11-q21 (SPG3), 15q11.1 (SPG6), and 19q13 (SPG12).5-16 Forty-five percent of kindreds with autosomal dominant, uncomplicated HSP are linked to the SPG4 locus on chromosome 2p22. Mutations in a novel gene (designated …

Gap junctions (GJs) are vital for oligodendrocyte survival and myelination. In order to examine how different stages of inflammatory demyelination affect oligodendrocyte GJs, we studied the expression of oligodendrocytic connexin32 (Cx32) and Cx47 and astrocytic Cx43 in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis (MS) induced by recombinant myelin oligodendrocyte glycoprotein. EAE was characterized by remissions and relapses with demyelination and axonal loss. Formation of GJ plaques was quantified in relation to the lesions and in normal appearing white matter (NAWM). During acute EAE at 14 days postimmunization (dpi) both Cx47 and Cx32 GJs were severely reduced within and around lesions but also in the NAWM. Cx47 was localized intracellularly in oligodendrocytes while protein levels remained unchanged, and this redistribution coincided with the loss of Cx43 GJs in astrocytes. Cx47 and Cx32 expression increased during remyelination at 28 dpi but decreased again at 50 dpi in the relapsing phase. Oligodendrocyte GJs remained reduced even in NAWM, despite increased formation of Cx43 GJs toward lesions indicating astrogliosis. EAE induced in Cx32 knockout mice resulted in an exacerbated clinical course with more demyelination and axonal loss compared with wild-type EAE mice of the same backcross, despite similar degree of inflammation, and an overall milder loss of Cx47 and Cx43 GJs. Thus, EAE causes persistent impairment of both intra- and intercellular oligodendrocyte GJs even in the NAWM, which may be an important mechanism of MS progression. Furthermore, GJ deficient myelinated fibers appear more vulnerable to CNS inflammatory demyelination. © 2012 Wiley Periodicals, Inc.

Gap junctions (GJs) provide channels for direct cell-to-cell connectivity serving the homeostasis in several organs of vertebrates including the central (CNS) and peripheral (PNS) nervous systems. GJs are composed of connexins (Cx), which show a highly distinct cellular and subcellular expression pattern. Oligodendrocytes, the myelinating cells of the CNS, are characterized by extensive GJ connectivity with each other as well as with astrocytes. The main oligodendrocyte connexins forming these GJ channels are Cx47 and Cx32. The importance of these channels has been highlighted by the discovery of human diseases caused by mutations in oligodendrocyte connexins, manifesting with leukodystrophy or transient encephalopathy. Experimental models have provided further evidence that oligodendrocyte GJs are essential for CNS myelination and homeostasis, while a strong inflammatory component has been recognized in the absence of oligodendrocyte connexins. Further studies revealed that connexins are also disrupted in multiple sclerosis (MS) brain, and in experimental models of induced inflammatory demyelination. Moreover, induced demyelination was more severe and associated with higher degree of CNS inflammation in models with oligodendrocyte GJ deficiency, suggesting that disrupted connexin expression in oligodendrocytes is not only a consequence but can also drive a pro-inflammatory environment in acquired demyelinating disorders such as MS. In this review, we summarize the current insights from human disorders as well as from genetic and acquired models of demyelination related to oligodendrocyte connexins, with the remaining challenges and perspectives.

Human hGDH2 arose via duplication in the apes and driven by positive selection acquired enhanced catalytic ability under conditions inhibitory to its precursor hGDH1 (common to all mammals). To explore the biological advantage provided by the novel enzyme, we studied, by immunohistochemistry (IHC) and immunofluorescence (IF), hGDH1 and hGDH2 expression in the human brain. Studies on human cortical tissue using anti-hGDH1-specific antibody revealed that hGDH1 was expressed in glial cells (astrocytes, oligodendrocytes, and oligodendrocyte precursors) with neurons being devoid of hGDH1 staining. In contrast, an hGDH2-specific antiserum labeled both astrocytes and neurons. Specifically, hGDH2 immunoreactivity was found in the cytoplasm of large neuronal cells within coarse structures resembling mitochondria. These were distributed either in the perikaryon or in the cell periphery. Double immunofluorescence (IF) suggested that the latter represented hGDH2-labeled mitochondria of presynaptic nerve terminals. Hence, hGDH2 evolution bestowed large human neurons with enhanced glutamate metabolizing capacity, thus strengthening cortical excitatory transmission.

The X-linked form of Charcot-Marie-Tooth disease (CMT1X) is the second most common form of hereditary motor and sensory neuropathy. The clinical phenotype is characterized by progressive muscle atrophy and weakness, areflexia, and variable sensory abnormalities; central nervous system manifestations occur, too. Affected males have moderate to severe symptoms, whereas heterozygous females are usually less affected. Neurophysiology shows intermediate slowing of conduction and distal axonal loss. Nerve biopsies show more prominent axonal degeneration than de/remyelination. More than 400 different mutations in GJB1, the gene that encodes the gap junction (GJ) protein connexin32 (Cx32), cause CMT1X. Many Cx32 mutants fail to form functional GJs, or form GJs with abnormal biophysical properties. Schwann cells and oligodendrocytes express Cx32, and the GJs formed by Cx32 play an important role in the homeostasis of myelinated axons. Animal models of CMT1X demonstrate that loss of Cx32 in myelinating Schwann cells causes a demyelinating neuropathy. An effective therapy remains to be developed.

Greig cephalopolysyndactyly syndrome (GCPS) is typically characterized by preaxial or mixed preaxial and postaxial polydactyly with or without syndactyly and craniofacial features including hypertelorism and macrocephaly. Although GLI3 shows considerable pleiotropy, it is the only gene known to cause this particular phenotype. We report on a patient with GCPS caused by a novel GLI3 mutation. In addition, the patient had asymmetry of the calf muscles, most likely secondary to chronic hypertrophic radiculopathy. The GLI3 mutation identified by targeted Sanger sequencing analysis in our patient is predicted to lead to premature termination of translation. This is the first report of a Cypriot patient with a GCPS because of a novel GLI3 mutation. The report provides additional evidence in support of the rich variability in phenotypic expression, the mutational heterogeneity and ethnic diversity associated with this rare condition.

The segregation of myelinated fibers into distinct domains around the node of Ranvier--the perinodal areas--is crucial for nervous system homeostasis and efficient nerve conduction. Perinodal areas are formed by axo-glial interactions, namely the interaction of molecules between the axon and the myelinating glia. In a variety of demyelinating pathologies including multiple sclerosis, the molecular architecture of the myelinated fiber is disrupted, leading to axonal degeneration. In this study we have analyzed the alterations of TAG-1, Caspr2, and voltage-gated potassium channels (VGKCs), forming the juxtaparanodal tripartite complex, in relation to adjacent paranodal and nodal molecules, in two different models of CNS demyelination, the experimental autoimmune encephalomyelitis (EAE) and the cuprizone model of toxic demyelination. We found extensive alterations of the juxtaparanodal molecular architecture under de- and remyelinating conditions. Inflammation alone was sufficient to disrupt the borders between the domains leading to the diffusion of juxtaparanodal components to the adjacent paranodal area. EAE induction and cuprizone-induced demyelination resulted initially in paranodal domain elongation with subsequent diffusion of the juxtaparanodal components and the reduction of their expression levels. At later stages, with decreasing inflammation and spontaneous remyelination there was a partial restoration of the paranodal domain but not sufficient re-organization of the juxtaparanodes. The latter were re-formed only when complete remyelination was allowed in the cuprizone model, indicating that juxtaparanodal domain reorganization is a later event that may remain incomplete in a hostile inflammatory milieu.

X-linked Charcot-Marie-Tooth disease (CMT1X) is a common form of inherited neuropathy resulting from different mutations affecting the gap junction (GJ) protein connexin32 (Cx32). A subset of CMT1X patients may additionally present with acute fulminant CNS dysfunction, typically triggered by conditions of systemic inflammation and metabolic stress. To clarify the underlying mechanisms of CNS phenotypes in CMT1X we studied a mouse model of systemic inflammation induced by lipopolysaccharide (LPS) injection to compare wild type (WT), connexin32 (Cx32) knockout (KO), and KO T55I mice expressing the T55I Cx32 mutation associated with CNS phenotypes. Following a single intraperitoneal LPS or saline (controls) injection at the age of 40–60 days systemic inflammatory response was documented by elevated TNF-α and IL-6 levels in peripheral blood and mice were evaluated 1 week after injection. Behavioral analysis showed graded impairment of motor performance in LPS treated mice, worse in KO T55I than in Cx32 KO and in Cx32 KO worse than WT. Iba1 immunostaining revealed widespread inflammation in LPS treated mice with diffusely activated microglia throughout the CNS. Immunostaining for the remaining major oligodendrocyte connexin Cx47 and for its astrocytic partner Cx43 revealed widely reduced expression of Cx43 and loss of Cx47 GJs in oligodendrocytes. Real-time PCR and immunoblot analysis indicated primarily a down regulation of Cx43 expression with secondary loss of Cx47 membrane localization. Inflammatory changes and connexin alterations were most severe in the KO T55I group. To examine why the presence of the T55I mutant exacerbates pathology even more than in Cx32 KO mice, we analyzed the expression of ER-stress markers BiP, Fas and CHOP by immunostaining, immunoblot and Real-time PCR. All markers were increased in LPS treated KO T55I mice more than in other genotypes. In conclusion, LPS induced neuroinflammation causes disruption of the main astrocyte-oligodendrocyte GJs, which may contribute to the increased sensitivity of Cx32 KO mice to LPS and of patients with CMT1X to various stressors. Moreover the presence of an intracellularly retained, misfolded CMT1X mutant such as T55I induces ER stress under inflammatory conditions, further exacerbating oligodendrocyte dysfunction and pathological changes in the CNS. Electronic supplementary material The online version of this article (doi:10.1186/s40478-016-0369-5) contains supplementary material, which is available to authorized users.

Introduction: Parkinson's disease (PD) is a neurodegenerative disorder affecting a substantial proportion of the elderly Cypriot population. The objective of this study was to evaluate PD risk variants that have been identified previously in Genome Wide Association Studies (GWAS) and to find environmental factors that are predictors for PD onset in the Cypriot population. Methods: A case-control study was conducted with a total of 235 PD patients and 464 healthy controls of Greek-Cypriot ethnicity. Demographic and lifestyle characteristics, exposure to PD risk factors and clinical data were collected. Moreover, 13 previously GWAS-identified PD risk variants were genotyped. Univariate and multivariate regression analyses examined the association between a number of environmental and genetic factors and PD. Results: Multivariable regression analysis revealed that exposure to both pesticides and other toxic substances (P = 0.03), severe head injury accompanied with fainting (P = 0.001), nuts consumption (P = 0.004), red meat consumption (P = 0.02), and soft drinks consumption (P = 0.008) were increasing the risk for PD, whereas cumulative smoking (P = 0.02), and fish consumption (P = 0.02) were decreasing the risk for PD. Five out of the 13 tested SNPs (rs12185268, rs6599389, rs356220, rs13312, and rs17649553) were confirmed to be nominally significantly associated (P < 0.05) with PD risk in the Cypriot population. Conclusions: Collectively, this case-control study has shed some light on the nature of PD epidemiology in Cyprus, by demonstrating a number of genetic and environmental determinants of PD in the Cypriot population.

Introduction Amyotrophic lateral sclerosis (ALS) is a rare, progressive neurodegenerative disease. There is heterogeneity of clinical phenotypes while a clinical characterization of ALS in Cyprus is still lacking. The aim of this 30-year retrospective study of ALS in Cyprus is to determine the demographic characteristics of patients, the clinical features of the disease, the uptake of supportive therapies and factors influencing survival. Methods All ALS patients seen at the Cyprus Institute of Neurology and Genetics from January 1985 until July 2015 were included. Medical records of eligible patients were used for data extraction and compilation of an ALS database. Clinical features were compared between gender categories using univariate tests, while survival was assessed using Kaplan-Meier curves. Cox proportional hazards models were used to identify prognostic factors for survival. Results One hundred and seventy-nine ALS patients were included in the study, of whom 7 had a positive family history. Most clinical characteristics of ALS did not differ from what is observed in other European countries. However, some clinical characteristics were unique to our population, such as an increased acceptability and utilisation of supportive treatments such as gastrostomy. Conclusions Overall, clinical characteristics of patients with ALS in the Republic of Cyprus do not differ from other European counties. Our study demonstrates a high acceptance and utilisation of supportive interventions enhancing survival, in the context of a multidisciplinary approach offered in the single tertiary centre that services the whole Cypriot ALS population. The findings of this paper are of value to the health professionals treating ALS in Cyprus.

Pelizaeus-Merzbacher-like disease or hypomyelinating leukodystrophy-2 is an autosomal recessively inherited leukodystrophy with childhood onset resulting from mutations in the gene encoding the gap junction protein connexin 47 (Cx47, encoded by GJC2). Cx47 is expressed specifically in oligodendrocytes and is crucial for gap junctional communication throughout the central nervous system. Previous studies confirmed that a cell autonomous loss-of-function mechanism underlies hypomyelinating leukodystrophy-2 and that transgenic oligodendrocyte-specific expression of another connexin, Cx32 (GJB1), can restore gap junctions in oligodendrocytes to achieve correction of the pathology in a disease model. To develop an oligodendrocyte-targeted gene therapy, we cloned the GJC2/Cx47 gene under the myelin basic protein promoter and used an adeno-associated viral vector (AAV.MBP.Cx47myc) to deliver the gene to postnatal Day 10 mice via a single intracerebral injection in the internal capsule area. Lasting Cx47 expression specifically in oligodendrocytes was detected in Cx47 single knockout and Cx32/Cx47 double knockout mice up to 12 weeks post-injection, including the corpus callosum and the internal capsule but also in more distant areas of the cerebrum and in the spinal cord. Application of this oligodendrocyte-targeted somatic gene therapy at postnatal Day 10 in groups of double knockout mice, a well characterized model of hypomyelinating leukodystrophy-2, resulted in significant improvement in motor performance and coordination at 1 month of age in treated compared to mock-treated mice, as well as prolonged survival. Furthermore, immunofluorescence and morphological analysis revealed improvement in demyelination, oligodendrocyte apoptosis, inflammation, and astrogliosis, all typical features of this leukodystrophy model in both brain and spinal cord. Functional dye transfer analysis confirmed the re-establishment of oligodendrocyte gap junctional connectivity in treated as opposed to untreated mice. These results provide a significant advance in the development of oligodendrocyte-cell specific gene therapy. Adeno-associated viral vectors can be used to target therapeutic expression of a myelin gene to oligodendrocytes. We show evidence for the first somatic gene therapy approach to treat hypomyelinating leukodystrophy-2 preclinically, providing a potential treatment for this and similar forms of leukodystrophies.