Molecular Analysis of Duchenne muscular dystrophy / 中华实用儿科临床杂志

Objective To detect the mutation type and size variation of the dystrophy gene in Duchenne muscular dystrophy(DMD) patients,and discuss the strategy of molecular genetic diagnosis for DMD.Methods Multiplex ligation-dependent probe amplification(MLPA) and next-generation sequencing(NGS) were applied for genetic detection in patients with clinical suspected DMD.Sanger sequencing was performed to confirm the results.Results Pathogenic mutations were found in 28 cases with DMD.Twenty-two of the 28 cases were found to be positive with MLPA analysis,16 cases with deletion mutations,4 cases with duplication,and 2 cases with both deletion and duplication mutations.Then,NGS technology was performed to detect 5 cases with MLPA positive and 1 case with MLPA negative,which were chosen optionally,and 3 cases showed deletion (exon51 del,chrX:31779857-31795289; exon53 del,chrX:31685440-31747548; exon51-55 del,chrX:31632504-31827732) and 2 cases of duplication (exon45 dup,chrX:31970766-32023816 ; exon55 dup,chrX:31540860-31649750),which were consistent with MLPA analysis.Meanwhile,NGS could determine the location of break point and the size of DNA segments accurately and also detect one point mutation which was MLPA negative.In the end,Sanger sequencing was performed to confirm this point mutation.Conclusions The mutational spectrum of the DMD gene is complex,including deletion/duplication and point mutations,and MLPA is an efficient method for detecting paternal deletion and duplication of DMD,while NGS can not only detect both deletion/duplication and point mutations,but also determine the location of break point and the size of gene segments accurately.Next-generation sequencing may be a powerful technology for early clinical diagnosis,prognostic judgment and prenatal diagnosis of DMD.

Clinical and molecular genetic analysis for a patient with glycogen storage disease Ⅰa / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the mutation of glucose-6-phosphatase gene (G6PC gene) in a patient with glycogen storage disease Ⅰa.</p><p><b>METHODS</b>PCR was used to amplify all five exons of G6PC gene. The PCR products were directly sequenced to detect the mutations.</p><p><b>RESULTS</b>A heterozygous 743G>A mutation was found in the patient and his mother, resulting in the substitution of glycine (G) by arginine (R) in codon 222(G222R) in the putative membrane-spanning domain in human G6Pase, but not in his father and his sister.</p><p><b>CONCLUSIONS</b>G222R mutation in G6PC gene was first identified in a patient with glycogen storage disease Ⅰa in mainland China.</p>

Genetic analysis of a supernumerary derivative chromosome 15 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect and analyze a supernumerary derivative chromosome 15 with combined cytogenetic and molecular techniques, and to discuss the correlation between genomic copy number variations (CNVs) and clinical phenotypes.</p><p><b>METHODS</b>G-banded chromosome analysis and multiplex ligation-dependent probe amplification (MLPA) were carried out. The whole genome of the patient was also analyzed with array-comparative genome hybridization(array-CGH).</p><p><b>RESULTS</b>G-banding analysis indicated that the patient has a karyotype of 47, XY, + mar, with the supernumerary chromsome derived from 15q11-13 region spanning 9.8 Mb from locus 20477397 to 30298155.</p><p><b>CONCLUSION</b>CNVs of 15q11-13 are associated with mental retardation, language development delay and autistic disorder. Conventional cytogenetic analysis with array-CGH may provide a platform for accurate detection of chromosomal aberrations, which can faciliate the study of genome rearrangement underlying various diseases.</p>

Value of methylation-specific mutiplex ligation-dependent probe in the diagnosis of Prader-Willi syndrome / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Prader-Willi syndrome (PWS) with different pathogenesis has different clinical manifestations, prognosis and genetic risks. Pathogenesis of the disease cannot be explained by conventional diagnostic method MS-PCR. This study employed methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) for the diagnosis of PWS in order to explore the role of this method in the diagnosis and assessment of pathogenesis of PWS.</p><p><b>METHODS</b>A system antithetical method was employed. Peripheral blood samples were collected from 30 children for MS-PCR. Of the 30 children, 16 were diagnosed with PWS by MS-PCR and the other 14 showed negative MS-PCR. MS-MLPA kit Me028 was used to detect DNA extracted from the 30 samples.</p><p><b>RESULTS</b>The results showed by MS-MLPA and MS-PCR were identical. MS-MLPA demonstrated that 4 cases were maternal uniparental disomy and 12 cases were paternal dfeletion in 15q11-q13 region.</p><p><b>CONCLUSIONS</b>MS-MLPA is a reliable method of genetic testing for PWS which can distinguish pathogenesis of PWS.</p>

Chromosome analysis in 92 children with congenital mental retardation / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To explore the chromosome karyotypes in children with mental retardation.</p><p><b>METHODS</b>The peripheral blood lymphocytes from 92 children with congenital mental retardation were cultured and analysed by the G-band technique.</p><p><b>RESULTS</b>Of the 92 cases, 43 cases (47%) showed chromosome abnormalities. Autosomal abnormalities were found in 35 cases (38%) and sex chromosome abnormalities were found in 8 cases (9%). A novel abnormal karyotype 45, XX, psu dic (11;9) (p15;p24) was found in a child.</p><p><b>CONCLUSIONS</b>Chromosome abnormalities may be important cytogenetic factors for congenital mental retardation. Cytogenetic chromosome karyotypic analysis appears to be an important method for genetic screening of congenital mental retardation.</p>

Association of alpha 2-Heremans-Schmid glycoprotein gene polymorphisms with its serum levels / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the single nucleotide polymorphisms (SNPs) of the alpha2-Heremans-Schmid glycoprotein (AHSG) gene and assess their association with the AHSG serum level.</p><p><b>METHODS</b>The SNPs of the AHSG gene were identified from 30 unrelated Han individuals from Guangzhou area by resequencing. Linkage disequilibrium(LD) was performed to observe the linkage disequilibrium pattern. Then tagSNPs were genotyped in 192 Han individuals from Beijing and 424 Han individuals from Guangzhou area. Finally, luciferase reporter gene assay was performed to determine whether the SNPs affected the promoter activity. Serum AHSG concentrations were measured in the 192 subjects from Beijing using ELISA.</p><p><b>RESULTS</b>Eight SNPs were detected in total. The linkage disequilibrium profile in the Guangzhou Han population was different from that in the Beijing Han population. However, the allele and genotype frequencies of tagSNPs between the two Han populations were not significantly different. The reporter gene assay showed that the -799A allele had significantly higher promoter activity than the -799T allele. Multiple regression analysis revealed that only the rs2248690 SNP was an independent contributor to serum AHAG concentration.</p><p><b>CONCLUSION</b>The rs2248690 SNP in the promoter region of the AHSG gene might affect the AHSG gene transcription.</p>

Electromyogram Characteristics and Gene Diagnosis in Child Type of Spinal Muscular Atrophy / 实用儿科临床杂志

Objective To explore the importance of gene diagnosis and prenatal diagnosis of spinal muscular atrophy(SMA),and improve the clinical diagnosis of SMA by analyzing the electrophysiological and gene characteristics of SMA.Methods Fifteen cases with SMA including 9 male and 6 female were enrolled in this study.The age was 5 months to 12 years.The 15 cases were subdivided into 3 clinical types,5 cases of type Ⅰ including 3 male and 2 female aging 5-18 months;7 cases of type Ⅱ including 4 males and 3 females aging 5 months-3 years;3 cases of type Ⅲ including 2 male and 1 female aging 3-12 years.They were all characterized by symmetric muscle weakness(more proximal than distal)associated with atrophy,absence or marked decrease of deep tendon reflexes,loss of voluntary movement and inability to sit or stand.The clinical characteristics and changes of electromyography(EMG)and nerve conduction velocity were assessed in all cases by using Danish Medoc Keypoint myoelectricity and evoked potentials inducer.The survival of motor neuron(SMN)gene was detected by PCR and restriction endonuclease spectrum analysis in 10 cases.Results EMG analysis found 94% patients had spontaneous potential,90% patients had increased duration of motor unit,and amplitude increased in 89% patients.Motor nerve conduction velocity was determined in 78 nerves.Motor nerve compound action potential wave amplitude decreased in 52 nerves,among them,distal latent period prolonged and motor conduction velocity reduced slightly in 36 nerves.Sensory nerve conduction velocity was determined in 45 nerves and remained normal.The SMN gene detection revealed deletion of exon 7 and 8 in 9 cases,deletion exon 7 in 1 case.The SMN gene detection in 10 patients and their parents didn't find any deletion of exon 7 and 8.Conclusions The definite diagnosis of SMA will rely on the typical clinical characteristics,changes of EMG and gene deletion analysis.Gene diagnosis of SMA lays a basis for prenatal diagnosis.