Molecular diagnosis of children with unexplained intellectual disability/ developmental delay by array-CGH / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To analyze the potential pathogenic genomic imbalance in children with unexplained intellectual disability (ID) and/or developmental delay (DD) and its association with phenotypes, and to investigate the value of array-based comparative genomic hybridization (array-CGH) in clinical molecular genetic diagnosis.</p><p><b>METHODS</b>The whole genome of 16 children with ID/DD was scanned by the array-CGH for detection of genomic copy number variations (CNVs), and the revealed genomic imbalance was confirmed by multiplex ligation-dependent probe amplification.</p><p><b>RESULTS</b>G-band karyotyping of peripheral blood cells showed no abnormalities in the 16 children. The results of the array-CGH revealed that 6 (38%) of the 16 patients had genomic CNVs, and 3 cases of CNVs were normal polymorphic changes; 1 CNV was a microdeletion of 4p16.3, which was the critical region for Wolf-Hirschhorn syndrome, and 1 CNV was a microdeletion of 7q11.23, which was the critical region for Williams-Beuren syndrome. Moreover, a CNV was identified with two duplications at 2q22.2 and 15q21.3 in a boy, which proved to have a clinical significance due to its association with ID, brain DD, unusual facies, cryptorchidism, irregular dentition, etc.</p><p><b>CONCLUSIONS</b>Array-CGH allows for the etiological diagnosis in some of the children with unexplained ID/DD. As a high-throughput and rapid tool, it has a great clinical significance in the etiological diagnosis of ID/DD.</p>

Congenital central hypoventilation syndrome, report of three cases / 中华儿科杂志

<p><b>OBJECTIVE</b>To evaluate clinical characteristics and PHOX2B gene mutations in congenital central hypoventilation syndrome (CCHS) and to facilitate the early diagnosis and management of CCHS and reduce the misdiagnosis.</p><p><b>METHOD</b>Clinical data of 3 infants with CCHS who had recurrent respiratory failure episodes and dependent on mechanical ventilation support in 3 from March 2008 to April 2012 were analyzed, and blood gas analysis was performed respectively in the awaken and sleeping status. Gene sequencing was used for detection of PHOX2B gene mutation.</p><p><b>RESULT</b>All the three patients had adequate ventilation during awaken time, but they presented with abnormal frequency and shallow breathing associated with alveolar hypoventilation after falling asleep. Blood gas analysis showed hypercapnia and CO2 partial pressure was consistently over 60 mm Hg (1 mm Hg = 0.133 kPa) after falling asleep, which is in accordance with the clinical features of CCHS. The PHOX2B gene sequencing showed that 6 GCN repeats were inserted at exon3 of PHOX2B in case 1, at same position, 5 GCN repeats were inserted in case 2 and 3.</p><p><b>CONCLUSION</b>Normal ventilation in awaken status while shallow slow breathing accompanied with hypercapnia in sleep are the main clinical characteristics of CCHS, which requires mechanical ventilation. Acquired mutation in exon 3 of PHOX2B gene encoding repeated GCN sequence seems to be the molecular etiology of these three patients.</p>

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>

Clinical application of proportional assist ventilation in very low birth weight infants with ventilator dependence / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the effect of proportional assist ventilation (PAV) on physiology and respiratory mechanics in very low birth weight (VLBW) infants with ventilator dependence by comparison with conventional assist/control (A/C) ventilation.</p><p><b>METHODS</b>Forty-six infants with ventilator dependence were randomly divided into two groups according to the ventilation model: PAV (n=23) and A/C (n=23). The gain of resistive and elastic unloading was set based on the runway method in the PAV group. Ventilation parameters were set based on the conventional method in the A/C group. Infants were observed for 30 minutes three times per day for three consecutive days. Arterial gas analysis results, transcutaneous saturation of oxygen (SPO2), heart rate, blood pressure (BP), respiratory rate (RR), mean airway pressure (MAP), peak inspiratory pressure (PIP), tide volume (VT), minute volume (MV) and oxygenation index (OI), were compared between the two groups.</p><p><b>RESULTS</b>Compared with the A/C group, PaO2 and OI in the PAV group were significantly higher while PIP and MAP were significantly lower. There were no significant differences in FiO2, SPO2, pH, PaCO2, PEEP, VT, MV and RR between the two groups. Although mean arterial blood pressure and heart rate in the PAV group were not different from the A/C group, beat-to-beat variabilities in systolic and diastolic arterial blood pressure were significantly lower in the PAV group than in the A/C group.</p><p><b>CONCLUSIONS</b>PAV may safely maintain gas exchange at lower airway pressures compared with A/C ventilation in VLBW infants. It can also improve oxygenation and infant-ventilator synchronization.</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>

Application of Plasma Exchange Therapy on Critical Diseases in Children / 实用儿科临床杂志

Objective To explore continuous renal replacement therapy(CRRT) machine for plasma exchange in critical disease in children.Methods Retrospective study of 8 patients(8 month to 14 years,mean 5.7 years) and 32 plasma exchange treatments,after(adowble) lumen catheter inserted into the subclayian venous,using the Baxter BM25 machine with commercially available plasma filters.Results Five patients(3 ABO-incompatibility in bone marrow transplantation,1 thrombotic thrombocytopaenic purpura TTP,1 sepsis) gained full recovery.One systemic lupus erythematosus(SLE) and 1 sepsis experienced moderate improvement while 1 case of acute disseminated encephalomyelitis failed PE treatment.The average total exchange volume was 80-100 mL/kg,achieved at a blood flow rate of 5-10 mL/(kg?min) and a turnover rate of 60-120 mL/(kg?h) over a 3-hours duration.Thirty-one PE treatments were finished smoothly,one of which experienced the serious complication involving plasma filter.Conclusion Plasma exchange therapy is a safe and effective procedure for severe autoimmune abnormalities and pathogen removal in children.