Comparison of neuromuscular junction of two kinds of mouse models of Duchenne muscular dystrophy / 中国组织工程研究

BACKGROUND:Neuromuscular junction structure has defects in patients with Duchenne muscular dystrophy, mainly presenting acetylcholine receptor structure fragmentation and the reduction of spine-like processes on thepostsynaptic membrane. It is generaly recognized that the structural defects are induced by structural damage of muscle cels and muscle fiber necrosis. OBJECTIVE:To explore the reasons of damage on neuromuscular junction in mouse models of Duchenne muscular dystrophy. METHODS: We introduced Duchenne muscular dystrophy models of male mdx mice and male Dko mice. After gene identification, they were used for tests. Male C57BL/6 mice were selected as normla controls. Hematoxylin-eosin staining was utilized to detect pathological changes in muscles. Neuromuscular junction structure was revealed using immunofluorescence staining. The differences in dystrophin expression, pathological features and neuromuscular junction structure were compared in mouse models of two kinds of Duchenne muscular dystrophy. RESULTS AND CONCLUSION:The introduced mouse models were accorded with the requirement of our experiment in aspects of genotype and protein expression levels. The number of acetylcholine receptor was apparently reduced in the neuromuscular junction of two kinds of mouse models. Although dko mouse muscles presented more obvious inflammatory infiltration and muscle fiber damage compared with mdx mice, but there was no significant difference in the damage to neuromuscular junction between them, and acetylcholine receptor fragmentation was identical. The evidence suggested that structural damage of neuromuscular junction and inflammatory pathological response are independent events. There is no direct relationship between them. Dystrophin gene deficiency is the main cause of the fragmentation of the acetylcholine receptor.

Analysis of phenotype and genotype in a family with late infantile metachromatic leukodystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study genotype-phenotype correlation of a family with late infantile metachromatic leukodystrophy(MLD).</p><p><b>METHODS</b>Clinical data were collected and ARSA gene was tested by PCR and sequencing in a pedigree.</p><p><b>RESULTS</b>The male proband onset with walking dysfunction at 19 months, arylsulfatase A activity of leucocyte from his peripheral blood was 20.2 nmol/mg.17h, and his cranial MRI showed wildly symmetrical demyelination. Homozygosis for novel c.622delC (p.His208Metfs46X) in exon 3 of ARSA gene was identified in proband, and heterozygous for the same mutation in parents and grandma of the proband.</p><p><b>CONCLUSION</b>Late infantile metachromatic leukodystrophy is characterized by rapid and progressive regression of neuropsychiatric and motor development. There is a significant correlation between the mutation of c.622delC(p.His208Metfs*46) in the ARSA gene and the phenotype presenting as O/O patients.</p>

Effects of the dystrophin hydrophobic regions in the pathogenesis of Duchenne muscular dystrophy A three-dimensional reconstruction verification / 中国组织工程研究

BACKGROUND:Duchenne muscular dystrophy is recognized as a fatal X-linked recessive inheritance. It is caused by the dystrophin gene mutation, resulting in the deficiency of dystrophin and consequent degeneration and necrosis of muscle fibers gradual y. Becker muscular dystrophy is also caused by the mutation of the same gene, but presented with less severe clinical symptoms compared with Duchenne muscular dystrophy. Frameshift mutation destroys the reading frames, and thus the translation cannot proceed smoothly to transcript functional proteins. In-frame mutation cannot destroy the reading frames and hence the translation can proceed smoothly. But in-frame mutation involves the whole hydrophobic regions. The three-dimensional structure of these regions and their functionality are not interpreted clearly. The effects of these regions on disease development need to be clarified in detail from the point of structure and function. OBJECTIVE:By analyzing Kate and Dolittle scale mean hydrophobicity profile, to investigate the dystrophin hydrophobic regions using Swiss-model so as to provide the supplement explanation on the reading frame rule. METHODS:Form 2002 to 2013, 1 038 cases diagnosed as Duchenne muscular dystrophy or Becker muscular dystrophy were col ected in the First Hospital of Sun Yat-sen University in China and Leiden DMD information database was searched with deletion of codon mutation information available. The correlation between clinical types and genotypes was analyzed upon resources col ected above. The mean hydrophobicity profile of dystrophin was analyzed by Bioedit as wel as the reconstruction of hydrophobic domains using Swiss-model. Thus, the important functional domain of dystrophin was confirmed by analysis and the correlation between clinical types and genotypes. RESULTS AND CONCLUSION:Four hydrophobic regions were confirmed:Calponin homology domain CH2 on actin-binding domain, repeat 16 domain, Hinge Ⅲ domain and EF Hand domain. Duchenne muscular dystrophy was developed as a result of the destruction of the 1st, 2nd and 4th hydrophobic regions which were the conjunction of dystrophin and associated protein in dystrophin-glycoprotein complex. When the 3rd hydrophobic was deleted, the repeat domain located on central rob domain remained its continuity so that the clinical symptoms were less severe. These findings indicate that the dystrophin hydrophobic regions act as an important role on the pathogenesis of Duchenne muscular dystrophy.

Long-term follow up of four patients with dopa-responsive dystonia / 中华神经科杂志

Objective To investigate the clinical characteristics,treatment effect,long-term follow up results,guanosine triphosphate (GTP) cyrclohydrolase Ⅰ (GCH Ⅰ)gene and tyrosine hydroxylase(TH) gene mutations in patients with dopa-responsive dystonia (DRD).Methods The clinical features of 3 families with 4 affected members were analyzed and all of 4 patients were screened for mutations of the GCH Ⅰ gene and TH gene with DNA sequences.Results Four patients were females,average age at onset was (15.3 ± 5.6) years (range:from 9 to 20 years).The initial symptoms were a gait disorder,stiffness or tremor of the lower limbs in all patients presented with diurnal fluctuation.As the increase of disease duration,bilateral hand tremor was found in three patients,systemic torsion was found in one patient and torticollis was found in one patient.All patients' symptoms were in complete remission after administration of low dose of levodopa.Four patients were followed up for 0.5 to 10.0 years,and all were still responsive to the levodopa treatment and effective dosage was decreased as the increase of the disease duration.No longterm side effects of levodopa had occurred after long-term treatment.One patient was found to have c.607G ＞A(p,Gly203Arg) heterogenetic mutation in GCH I gene.Molecular analysis revealed a compound heterozygous mutation in the TH gene (p.Y447Ter and p.V468M) in one patient.No point mutations in both genes were found in other patients.Conclusions DRD patients have dramatic and sustained response to levodopa and no long-term side effects of levodopa after long-term treatment.The detection of GCH Ⅰ and TH gene mutations is helpful in early diagnosis but the negative results could not exclude the diagnosis of DRD.

Clinical characteristics of adult-onset type Ⅱ citrullinemia: one case report / 中华神经科杂志

Objective To enhance clinicians' intention to the importance of early diagnosis,early therapy and follow-up of type Ⅱ citrullinemia.Methods The clinical data of one adult-onset type Ⅱ citrullinemia pedigree were collected. The gene mutation type of SLC25A13 of proband and her daughter were determined by PCR and direct gene sequencing.Results The patient was a 27 years-old female,who complained of repeated dizziness, vomiting for more than 2 years and recurrent attacks of altered consciousness for about one and a half year.An abdominal ultrasonogram,liver magnetic resonance imaging and liver histology obtained by needle biopsy all determined the liver pathological changes of liver cirrhosis.Electroencephalogram showed sharp waves. The plasma amino acid showed a marked elevation of blood citrulline.Laboratory findings revealed a highly increased concentration of plasma ammonia during every episode. Mutation analysis of the SLC25A13 gene identified a homozygote of 851del4 in the patient,and heterozygote of 851del4 in her daughter. Conclusions For adults,unexplained dizziness,vomiting,but liver function still in the compensation,especially accompanied by neuropsychologic symptoms are highly suggestive of adult-onset type Ⅱ citrullinemia.SLC25A13 gene analysis contributes to the diagnosis of this disease,avoids invasive investigations and early confirmation of this disease means long-term dietary advice,genetic counseling,medical surveillance and early preparation for liver transplantation if is necessary.

Clinical, familial and hereditary analysis of myotonic dystrophy / 中南大学学报(医学版)

OBJECTIVE@#To analyze the clinical, familial and hereditary features of myotonic dystrophy to improve the knowledge and provide molecule evidence for gene diagnosis and prenatal diagnosis of myotonic dystrophy or dystrophia myotonia (DM) families.@*METHODS@#Clinical data of 2 DM families were collected based on the probands. The number of trinucleotide CTG repeat in the 3' untranslated region of myotonic dystrophy protein kinase (DMPK) gene on chromosome 19 was determined by DNA sequence and repeat fragment.@*RESULTS@#Except for 1 subclinical patient, another 5 patients progressed slowly with the features of myotonic muscular weakness and atrophy. One patient had hatchet face, 1 had cataract and diabetes mellitus, and the other 3 were bald. Electromyologram showed 3 patients had myotonic discharge and myopathic abnormalities. The number of trinucleotide CTG repeat in the 3' untranslated region of DMPK gene of 5 patients exceeded 50.@*CONCLUSION@#DM can be anticipated. Gene analysis can verify the disease and identify subclinical patients. It helps to prevent the DM births by hereditary consultation performing prenatal diagnosis.