Effects of Nogo-A and its receptor on the repair of sciatic nerve injury in rats

Regeneration of injured peripheral nerves is an extremely complex process. Nogo-A (neurite outgrowth inhibitor-A) inhibits axonal regeneration by interacting with Nogo receptor in the myelin sheath of the central nervous system (CNS). The aim of this study was to investigate the effects of Nogo-A and its receptor on the repair of sciatic nerve injury in rats. Sprague-Dawley rats (n=96) were randomly divided into 4 groups: control group (control), sciatic nerve transection group (model), immediate repair group (immediate repair), and delayed repair group (delayed repair). The rats were euthanized 1 week and 6 weeks after operation. The injured end tissues of the spinal cord and sciatic nerve were obtained. The protein expressions of Nogo-A and Nogo-66 receptor (NgR) were detected by immunohistochemistry. The protein expressions of Nogo-A, NgR, and Ras homolog family member A (RhoA) were detected by western blot. At 1 week after operation, the pathological changes in the immediate repaired group were less, and the protein expressions of Nogo-A, NgR, and RhoA in the spinal cord and sciatic nerve tissues were decreased (P<0.05) compared with the model group. After 6 weeks, the pathological changes in the immediate repair group and the delayed repair group were alleviated and the protein expressions decreased (P<0.05). The situation of the immediate repair group was better than that of the delayed repair group. Our data suggest that the expression of Nogo-A and its receptor increased after sciatic nerve injury, indicating that Nogo-A and its receptor play an inhibitory role in the repair process of sciatic nerve injury in rats.

Altered Translational Control of Fragile X Mental Retardation Protein on Myelin Proteins in Neuropsychiatric Disorders

Myelin is a specialized structure of the nervous system that both enhances electrical conductance and insulates neurons from external risk factors. In the central nervous system, polarized oligodendrocytes form myelin by wrapping processes in a spiral pattern around neuronal axons through myelin-related gene regulation. Since these events occur at a distance from the cell body, post-transcriptional control of gene expression has strategic advantage to fine-tune the overall regulation of protein contents in situ. Therefore, many research interests have been focused to identify RNA binding proteins and their regulatory mechanism in myelinating compartments. Fragile X mental retardation protein (FMRP) is one such RNA binding protein, regulating its target expression by translational control. Although the majority of works on FMRP have been performed in neurons, it is also found in the developing or mature glial cells including oligodendrocytes, where its function is not well understood. Here, we will review evidences suggesting abnormal translational regulation of myelin proteins with accompanying white matter problem and neurological deficits in fragile X syndrome, which can have wider mechanistic and pathological implication in many other neurological and psychiatric disorders.

Analysis of heterozygous duplication of PMP22 gene in a pedigree affected with Charcot Marie Tooth disease / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze mutation of the PMP22 gene in a pedigree affected with Charcot-Marie-Tooth disease.</p><p><b>METHODS</b>Genomic DNA was extracted from peripheral blood samples of the proband and members from his family, and fetal DNA was extracted from amniotic fluid sample. Multiplex ligation-dependent probe amplification (MLPA) and array-based comparative genomic hybridization (array-CGH) analyses were carried out to determine the copy number of the PMP22 gene. Sanger sequencing was carried out to detect point mutations of the PMP22 gene.</p><p><b>RESULTS</b>A heterozygous duplication of the PMP22 gene was detected in the proband and his father, while no point mutation, insertion or deletion was found in them. No duplication or deletion of the PMP22 gene was found in other family members.</p><p><b>CONCLUSION</b>Based on clinical symptoms and genetic findings, the heterozygous duplication of the PMP22 gene is probably the cause of the disease in the proband. The fact that the father has carried the same duplication but with no detectable symptom may be due to irregular transmission pattern of the mutation. Genetic counseling for the family should therefore be with caution.</p>

Analysis of the clinical, electrophysiological and genetic features of a family affected with hereditary neuropathy with liability to pressure palsies / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To delineate the clinical, electrophysiological and genetics features of a family where 4 members were affected with hereditary neuropathy with liability to pressure palsies (HNPP).</p><p><b>METHODS</b>Clinical features of the 4 patients were summarized. Electrophysiological examination and genetic analysis were carried out.</p><p><b>RESULTS</b>All of the patients showed recurrent motor and sensory disturbances after minor traction or constriction. Electrophysiology study revealed that the prolonged latency and reduced conduction velocity of peripheral nerve were general and with multiple sites of affection. The nerve locations liable to entrapment showed conduction block. A deletion mutation of peripheral myelin protein 22 (PMP22) gene was identified by genetic analysis.</p><p><b>CONCLUSION</b>HNPP usually affects areas where nerves are liable to entrapment, and presents with motor and sensory disturbances of the innervated areas. Electrophysiological study reveals general nervous demyelination. Genetic analysis can clarify the diagnosis of HNPP.</p>

Effects of Jisuikang on Nogo-NgR gene expression in spinal cord rats with injury / 中国骨伤

<p><b>OBJECTIVE</b>To study the effects of Jisuikang (Chinese characters) on Nogo-NgR gene expression, and to explore the protective effects and mechanism of Jisuikang (Chinese characters) on spinal cord injury in rats.</p><p><b>METHODS</b>One hundred eighty female rats were randomly assigned to 6 groups(30 rats per group). Sham group: T10 lamina was resected only and spinal cord was untreated. Model group: spine cord injury (SCI) was created with a modified impinger of Allen's by impacting on the T10 spinal cord. Prednisolone group: Prednisolone (0.06 g/kg) was given by intragastric administration at a time interval of 24 hours after operation. The Jisuikang (Chinese characters) high, moderate and low dose groups: Jisuikang (Chinese characters) was supplied with different dose (50 g/kg, 25 g/kg, 12.5 g/kg) by intragastric administration in rats after operation,for the first time at 30 min after surgery. Animals were killed 3, 7, 14 days after surgery. The expression levels of Nogo-A and NgR were observed by Western Blot and Real-time PCR.</p><p><b>RESULTS</b>The expression of Nogo-A and NgR was at the basic level at all time points in sham group. Compared with model group, the protein expression levels of Nogo-A and NgR in sham, prednisolone, Jisuikang (Chinese characters) moderate dose groups were statistically significant at all time points (P < 0.05). No difference was found in Jisuikang (Chinese characters) high and low dose groups (P > 0.05). Three days after surgery, the mRNA levels of Nogo-A and NgR in treatment group were significantly lower than that in model group (P < 0.01); 7 days after surgery,Nogo-A and NgR mRNA expression were dramatically upregulated and peaked; 14 days after operation, the expression was decreased, but still significantly higher than that in other treatment groups (P < 0.01). Prednisolone and Jisuikang (Chinese characters) moderate dose groups showed the most significant effects among all groups,but there was no statistically significant difference between two groups (P > 0.05).</p><p><b>CONCLUSION</b>The decoction Jisuikang (Chinese characters) can promote the nerve cell regeneration by regulating Nogo-A and NgR gene expression, activating Nogo- NgR signaling pathways after acute spinal cord injury.</p>

Exploring Myelin Dysfunction in Multiple System Atrophy

Multiple system atrophy (MSA) is a rare, yet fatal neurodegenerative disease that presents clinically with autonomic failure in combination with parkinsonism or cerebellar ataxia. MSA impacts on the autonomic nervous system affecting blood pressure, heart rate and bladder function, and the motor system affecting balance and muscle movement. The cause of MSA is unknown, no definitive risk factors have been identified, and there is no cure or effective treatment. The definitive pathology of MSA is the presence of alpha-synuclein aggregates in the brain and therefore MSA is classified as an alpha-synucleinopathy, together with Parkinson's disease and dementia with Lewy bodies. Although the molecular mechanisms of misfolding, fibrillation and aggregation of alpha-synuclein partly overlap with other alpha-synucleinopathies, the pathological pathway of MSA is unique in that the principal site for alpha-synuclein deposition is in the oligodendrocytes rather than the neurons. The sequence of pathological events of MSA is now recognized as abnormal protein redistributions in oligodendrocytes first, followed by myelin dysfunction and then neurodegeneration. Oligodendrocytes are responsible for the production and maintenance of myelin, the specialized lipid membrane that encases the axons of all neurons in the brain. Myelin is composed of lipids and two prominent proteins, myelin basic protein and proteolipid protein. In vitro studies suggest that aberration in protein distribution and lipid transport may lead to myelin dysfunction in MSA. The purpose of this perspective is to bring together available evidence to explore the potential role of alpha-synuclein, myelin protein dysfunction, lipid dyshomeostasis and ABCA8 in MSA pathogenesis.

Silenced NgR gene expression by RNA interference to promote rats facial nerve regeneration in vitro / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To suppress NgR gene expression in neural stem cells and observe differentiation of neural stem cells in vitro after interfered which provide nutritional support for the facial nerve repair in vivo.@*METHOD@#PCR amplification, restriction endonuclease digestion, T4DNA ligase connections were used to connected NgR with rector pGCsi, and constructed recombinant vector (NgR shRNA). Lipofectamine 2000 were used to transfect the NSC. The expression of NgR was examined by Western Blot. The proportion of neural stem cells transformed into neurons after transfection was tested by Immunocytochemistry. Neural stem cells were planted in PLGA tubes after transfected, and were scanned by electron microscopy.@*RESULT@#NgR shRNA plasmid was constructed and infected neural stem cells successfully. Western Blot showed that the expression of NgR decreased in neural stem cells after interference. Immunocytochemistry showed that the rate of the neural stem cells transformed into neurons after interfered was significantly higher (P < 0.01).@*CONCLUSION@#Neural stem cells were transformed into neurons after NgR shRNA plasmid infected neural stem cells, which promoted axonal regeneration more effectively and provided a efficient and stable gene platform for facial nerve repair.

Effect of electric acupuncture on the expression of NgR in the cerebral cortex, the medulla oblongata, and the spinal cord of hypertensive rats after cerebral infarction / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the effect of electric acupuncture (EA) on the Nogo receptors (NgR) protein expression in the cerebral cortex, the medulla oblongata, and the spinal cord of cerebral ischemia-reperfusion (I/R) stroke-prone renovascular hypertensive rats (RHRSP) with middle cerebral artery occlusion (MCAO) at different time points, and to investigate its possible mechanisms for remote-organ injury of acute cerebral infarction (ACI).</p><p><b>METHODS</b>The RHRSP model was duplicated in male SPF grade SD rats. Then the MCAO model was prepared by a thread stringing method. Rats were divided into the hypertension group,the sham-operation group, the MCAO group, the EA group, and the sham-acupoint group by random number table method, 60 in each group. Rats in the MCAO group only received MCAO reperfusion treatment. Those in the sham-operation group only received surgical trauma. Baihui (DU20) and Dazhui (DU14) were needled in the EA group, once daily for a total of 28 days.The needles were acupunctured at the skin one cun distant from Baihui (DU20) and Dazhui (DU14) and then the same EA treatment was performed in the sham-acupoint group. At day 1, 7, 14, 28 after treatment, six rats were executed from each group, and their right cortex and medulla oblongata, and the left spinal cord were isolated. The infarct volume was detected by Nissl's staining method. The NgR expression was detect by Western blot.</p><p><b>RESULTS</b>(1) In the cortex area: compared with the hypertension group,the NgR expression increased in the MCAO group at day 1,7,14,and 28 after MCAO (P < 0.05). Compared with the MCAO group, the NgR expression of the EA group and the sham-acupoint group were equivalent at 1 day af ter MCAO (P > 0.05). At day 7, 14,and 28 after MCAO, the NgR expression decreased in the EA group (P < 0.05), it was quite similar to that in the sham-acupoint group (P > 0.05). (2) In the medulla oblongata area: compared with the hypertension group, the NgR expression was equivalent in the sham-operation group. the MCAO group,the EA group, and the sham-acupoint group at 1 day after MCAO (P > 0.05). At day 7.14, and 28 after MCAO, the NgR expression increased in the MCAO group (P < 0.05). Compared with the MCAO group,the NgR expression decreased in the EA group at day 7, 14, and 28 after MCAO (P < 0.05), whereas it was similar in the sham-acupoint group (P > 0.05). (3) In the spinal cord area: compared with the hypertension group, the NgR expression was equivalent in the sham-operation group, the MCAO group,the EA group, and the sham-acupoint group at day 1 and 7 after MCAO (P > 0.05). At day 14 and 28 after MCAO, the NgR expression increased in the MCAO group (P < 0.05). Compared with the MCAO group, the NgR expression decreased in the EA group at day 14 and 28 after MCAO (P < 0.05), whereas it was equivalent in the sham-acupoint group (P > 0.05).</p><p><b>CONCLUSIONS</b>Increased NgR expression in the cerebral cortex, the medulla oblongata, and the spinal cord of cerebral infarct rats was an important reason for involving remote-organ injury of ACI. The protective effect of EA on hypertensive I/R cerebral injury rats might be closely related to down-regulating central nervous system myelin growth inhibition mediated factors Nogo-A receptor NgR protein expression.</p>

Biological function of Nogo-B / 生理学报

Nogo-B is a major family member of the reticulon protein family 4. It is widely expressed in the central nervous system and peripheral tissues, and is mainly located in endoplasmic reticulum and cell membrane. Previous studies have revealed that Nogo-B plays a key role in vascular injury, tissue repair and inflammation process. It also may be critical for apoptosis of tumor cells and central diseases. Further investigation of the molecular characteristics and biological function of Nogo-B might be of great help to understand its role in diverse diseases.

Hypertelorism in Charcot-Marie-Tooth disease 1A from the common PMP22 duplication: a case report

The 1.4Mb tandem-duplication in the PMP22 gene at 17p11.2 usually manifests as hereditary sensorimotor polyneuropathy with foot deformity, sensorineural hearing-loss, moderate developmental delay, and gait disturbance. Hypertelorism and marked phenotypic variability within a single family has not been reported. In a single family, the PMP22 tandem-duplication manifested as short stature, sensorimotor polyneuropathy, tremor, ataxia, sensorineural hearing-loss, and hypothyroidism in the 27 years-old index case, as mild facial dysmorphism, muscle cramps, tinnitus, intention tremor, bradydiadochokinesia, and sensorimotor polyneuropathy in the 31 year-old half-brother of the index-patient, and as sensorimotor polyneuropathy and footdeformity in the father of the two. The half-brother additionally presented with hypertelorism, not previously reported in PMP22 tandem-duplication carriers. The presented cases show that the tandem-duplication 17p11.2 may present with marked intrafamilial phenotype variability and that mild facial dysmorphism with stuck-out ears and hypertelorism may be a rare phenotypic feature of this mutation. The causal relation between facial dysmorphism and the PMP22 tandem-duplication, however, remains speculative

Inhibition of Nogo expression to promote repair after spinal cord injury / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>One of the reasons for poor neuroregeneration after central nervous system injury is the presence of inhibitory factors such as Nogo. Here, we tested the inhibition of Nogo by RNA interference both in vitro and in vivo, using recombinant adenovirus-mediated transfection of short hairpin RNAs, to explore a new method of treatment for spinal cord injury.</p><p><b>METHODS</b>We designed and cloned two Nogo-specific short hairpin RNAs and an unrelated short hairpin RNA, packaged the clones into adenovirus, and amplified the recombinant virus in 293 cells. We then tested the inhibition of Nogo expression both in vitro in adenovirus-transfected oligodendrocytes and in vivo in spinal cord tissue from adenovirus-transfected spinal cord injury model rats. We tested Nogo expression at the mRNA level by reverse-transcription PCR and at the protein level by Western blotting and immunohistochemistry.</p><p><b>RESULTS</b>In vitro, the two specific Nogo short hairpin RNAs decreased Nogo mRNA expression by 51% and 49%, respectively, compared with Nogo expression in cells transfected with the unrelated control small hairpin RNA (P < 0.005). Similarly, Nogo protein expression decreased by 50% and 48%, respectively (P < 0.005). In vivo, in spinal cord injury model rats, the two specific Nogo short hairpin RNAs decreased Nogo mRNA expression by 45% and 40%, respectively, compared with Nogo expression in spinal cord injury model rats transfected with the unrelated control short hairpin RNA (P < 0.005). The Nogo protein level was similarly decreased.</p><p><b>CONCLUSIONS</b>We were successful in specifically downregulating Nogo at the mRNA and protein levels by adenovirus-mediated delivery of short hairpin RNAs, both in vitro and in vivo. This confirms the effectiveness of RNA interference for the inhibition of Nogo gene expression and the efficiency of using adenovirus for delivery. Thus gene therapy may be an effective treatment for spinal cord injury.</p>

Effects of electroacupuncture on the ultrastructure and the Nogo-A expressions in the cerebral cortex in rats with cerebral ischemia-reperfusion / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the effects of electroacupuncture (EA) on the expressions of Nogo-A and the ultrastructure in the cerebral cortex at different time points after the cerebral ischemia-reperfusion in rats.</p><p><b>METHODS</b>One hundred and thirty male Sprague Dawley (SD) rats were randomly divided into the EA group (n = 30), the sham-EA group (n = 30), the model group (n = 30), the sham-operation group (n = 30), and the blank group (n = 10). The modified ZeaLonga method was used to prepare the left middle cerebral artery occlusion (MCAO) model in the first three groups. After the operation Baihui (DU20) and Dazhui (DU14) were daily needled in the EA group. One inch beside Baihui (DU20) and Dazhui (DU14) were daily needled in the sham-EA group. Rats in the model group were only treated with MCAO ischemia/reperfusion. Rats in the sham-operation group only received surgical wound. No treatment was given to rats in the blank group. The ultrastructures of ischemic cells and the intervention of the Nogo-A expressions were observed using the immunohistochemical staining and the transmission electron microscope 1, 7, and 28 days after EA.</p><p><b>RESULTS</b>(1) In the EA group, the damage of ultrastructures of neurons, gliocytes, and blood brain barrier in the ischemic region was alleviated when compared with that of the sham-EA group and the model group. (2) On the 1st, 7th and 28th day after the cerebral ischemia-reperfusion, the expressions of Nogo-A in the ischemic cortex in the EA group was lower when compared with those in the sham-EA group and the model group at the corresponding time points, showing significant difference (P < 0.05). But there was no statistical difference between the sham-EA group and the model group at the same time point (P > 0.05).</p><p><b>CONCLUSION</b>The mechanism of EA for protecting cerebral ischemia/reperfusion might be closely associated with alleviating the damage on the ultrastructures of brain cells, and down-regulating the expressions of Nogo-A.</p>

Effects on serum myelin proteins of n-hexane exposure / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>Exploring the effects of n-hexane on expression of serum myelin proteins in occupational exposure workers, and finding the early biomarker of n-hexane exposure.</p><p><b>METHODS</b>In the study, 373 subjects were recruited, 269 exposure workers (work experience of more than1 year) and 104 non-exposure workers were selected. Firstly examined the level of urinary 2,5-hexanedione in the two groups, based on urinary 2,5-hexanedione biological limit value (4 mg/L), the exposed group was divided into high-exposed group and low-exposed group. And then collected blood samples and extracted serum. Human peripheral myelin protein zero (P0) antibody (IgG, IgM) and human peripheral myelin protein two (P2) antibody (IgG, IgM) analysis was performed according to ELISA kit.</p><p><b>RESULTS</b>The concentration of urinary 2,5-hexanedione in the exposed group was (3.10 ± 1.35) mg/L. The level of P0 antibody (IgG, IgM) and P2 antibody (IgG, IgM) in the high-exposed group and low-exposed group were both higher than that in the controls (P < 0.01).</p><p><b>CONCLUSION</b>P0 antibody and P2 antibody could be used as the early biomarkers of n-hexane exposure, which not only evaluate the occupational hazards in the early, but also provide the policy maker with scientific evidence.</p>

PMP22 mutation of an infant-onset Charcot-Marie-Tooth disease family / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the mutation of PMP22 gene of an early-onset family with Charcot-Marie-Tooth disease (CMT) and the genetic features of the disease.</p><p><b>METHODS</b>Two patients with CMT, fifteen unaffected members in the family and 20 healthy controls were enrolled. STR-PCR and gene scanning were used to detect PMP22 duplication mutation.</p><p><b>RESULTS</b>The mutations of PMP22 were found in the two patients and other five unaffected members in the family. The mutations were located in the STR locus D17S921 in 5 cases and in the STR locus D17S4A in 2 cases. The other members in the family and 20 healthy controls did not show the mutations of PMP22.</p><p><b>CONCLUSIONS</b>The gene causing CMT in the family is found in the 17p11.2-p12 region containing PMP22 gene duplication mutation, resulting in the subtype CMT1A.</p>

[Development and application of real-time quantitative polymerase chain reaction technique using SYBR green I in the diagnosis of Down syndrome]

Rapid diagnosis of Trisomy 21 Syndrome [Down Syndrome] patients using Real-Time quantitative Polymerase Chain Reaction [Real-Time qPCR] in order to establish a novel method for prenatal diagnosis in the future. A total of 5 ml of peripheral blood was obtained from each patient and normal controls [NR]. Then, genomic DNA from lymphocytes was extracted using the salting out procedure. Gene dosage levels of DSCAM and [PMP22, DSCAM] in Down Syndrome and NR were analyzed using real-time quantitative PCR. The DSCAM/ PMP22 ratio was calculated according to the 2-delta delta Ct formula for all samples. Real-time PCR showed a DSCAM/PMP22 ratio of 1.48 +/- 0.18 and 1.01 +/- 0.10 [p<0.001] in Down Syndrome and normal samples, respectively, demonstrating three copies of the target [DSCAM] gene in Trisomy 21 Syndrome. DSCAM/PMP22 ratio is increased significantly in Down Syndrome patients than NR [1.5 times]. Therefore, the real-time quantitative PCR technique can be used as a sensitive, accurate and reliable technique for rapid and prenatal diagnosis of Trisomy 21 Syndrome

Research on the mechanism of Zuogui Pill and Yougui Pill in promoting axonal regeneration in model rats of autoimmune encephalomyelitis / 中国结合医学杂志

<p><b>OBJECTIVE</b>To study the molecular mechanism of Zuogui Pill (ZGP) and Yougui Pill (YGP) on axonal regeneration in rats with experimental autoimmune encephalomyelitis (EAE).</p><p><b>METHODS</b>EAE rat model was established by bilateral rear pedes subcutaneous injection of antigen made by mixing myelin basic protein (MBP) and complete Freud's adjuvant (CFA) in the volume ratio of 1:1. The pathological changes of axonal injury and regeneration in the brain and the spinal cord were observed on the 14th (the acute stage) and the 28th day (the remission stage) after modeling, with hematoxylin-eosin (HE) staining, silver stain, and immunohistochemical staining. The rats treated with prednisone acetate were taken as controls.</p><p><b>RESULTS</b>Observation under the light microscope with HE staining showed a sleeve-like change in rats' cerebrospinal parenchyma with inflammatory cell infiltration around the small vessels and neuronic denaturation, while silver staining showed excessive tumefaction and abscission of axon, and immunohistochemical analysis showed decreasing of nerve growth factor (NGF) expression at the acute stage of EAE, which was even more remarkable at the remission stage, showing significant difference as compared with the normal control (P<0.05). And the expressions of Nogo A, an axon growth inhibitor, and its receptor (Nogo-66 receptor, Ng R) were significantly higher than those in the normal control at the acute stage (P<0.01). However, after the intervention of ZGP and YGP, the pathological changes and axon damage in rats' brain and spinal cord were much more alleviated, and the NGF expression was significantly higher than that in the model group at the acute stage (P<0.05). The expression of NGF was even stronger during the remission stage, and a better effect was shown by YGP. As for Nogo A and Ng R expressions, they were significantly lower than those in the model group at the acute stage (P<0.05), but a better effect was shown by ZGP.</p><p><b>CONCLUSIONS</b>ZGP and YGP can prevent axonal injury and promote the axonal regeneration in rats of EAE, and the possible mechanism is to increase the expression of NGF and reduce the expression of Nogo A and its receptor. However, some differences are observed between the two Chinese preparations in their acting times and points, which provides a certain basis for revealing the modern connotation of the Chinese medicine theory on tonifying Shen ()-yin and Shen-yang.</p>

A new mutation in the GJB1 gene of a Chinese family with Charcot-Marie-Tooth disease associated with vocal cord paresis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To report an X-linked dominant Charcot-Marie-Tooth disease (CMTX) Chinese family with vocal cord paresis and to identify the mutation of gap junction protein beta 1 gene (GJB1).</p><p><b>METHODS</b>Part of the family members with dysphagia, dysphonia and lethal respiratory failure were studied through flexible laryngoscope, clinical, brain MRI and electrophysiological examinations. After excluding large fragment tandem duplication containing peripheral myelin protein 22 gene (PMP22), direct sequencing was performed to analyze the mutation of the GJB1 gene in 5 patients including the proband, 5 unaffected family members and 50 unrelated healthy individuals.</p><p><b>RESULTS</b>Eight members spanning 3 generations in this family were affected with CMTX characterized by progressive atrophy and weakness of the anterior tibial and peroneal muscles, especially in the proband. Vocal cord paresis was observed through flexible laryngoscope in total of 4 affected members with dysarthria and dysphagia, 2 of them died of severe respiratory failure due to complete bilateral vocal cord involvement. Normal brain MRI was observed in the proband. The electrophysiological data showed predominant demyelization involving the motor and sensory nerves in the proband. DNA sequencing revealed a de novo c.186 C>G missense mutation in exon 2 of the GJB1 gene, the mutation cosegregated with phenotype.</p><p><b>CONCLUSION</b>Respiratory failure associated with vocal cord involvement may be a rare and severe symptom in CMTX. The present report provides further evidence for clinical and genetic heterogeneity in the X-linked Charcot-Marie-Tooth disease.</p>