| Background:The22q11.2region is prone to chromosomal rearrangement because of the existence of low copy repeat (LCR) sequences. The rearrangement finally lead to the gene copy number variations (CNVs), which can be divided into ones proximal and distal to LCR22-4. Among these CNVs, the microdeletion proximal to LCR22-4is one of the most common genetic factors known to cause congenital heart desease and it’s incidence is about1/4000in the neonatal. In general, the phenotypes of genomic disorders are a consequence of the dosage imbalance of TBX1or other genes within the22q11.2region. The phenotype variety is a remarkable feature of22q11.2CNVs related syndrome. Children may exhibit heart defects only, or present other malformations simultaneously, such as pulmonary artery hypoplasia, immune deficiency, feeding difficulties, behavioral and psychological disorders. Identifing the children with malformations and chromosomal abnormalities and assessing the risk of surgery are of great significance for the treatment of children with congenital heart disease and the22q11.2region CNVs. Althought there have been some studies of the proximal22q11.2microdeletion in children with congenital heart disease, they can’t provide clinical guidance because of the limited sample size and using fluorescence in situ hybridization, which is costly and typically ordered in conjunction with a karyotype analysis that takes several days. In this study,642children with congenital heart disease are screened using quantitative real-time PCR technology with probes located to TBX1. Confirmation analysis was performed with the Illumina Human660W-Quad SNP Array. As a result, we can obtain the prevalence of22q11.2CNVs in the children with congenital heart disease, and explore the correlation between genotype and phenotype. Compare the preoperative evaluation index of the children with tetralogy of Fallot and22q11.2proximal CNVs to that of children with tetralogy of Fallot,but not CNVs, in order to assess risk factors which affect the early outcome of the radical surgery for tetralogy of Fallot. Chapter1The Prevalence and Phenotypic Analysis of22q11.2Proximal CNVs in Children with Congenital Heart DiseaseObjective:The aim of this research is to study the prevalence of22q11.2proximal CNVs in the children with congenital heart disease and try to discover phenotypic differences among patients with different22q11.2proximal CNVs in order to explore the relationship between genotype and phenotype.Method:642congenital heart defects cases, including340male and302female, were screened for22q11.2proximal CNVs. Genomic DNA was isolated from peripheral blood leukocytes using a QIAamp DNA Blood Mini Kit (Qiagen, Valencia, CA) according to the manufacturer’s instructions. The ABI StepOne quantitative PCR instruments produced by Applied Biosystems were used to implement real-time quantitative PCR using SYBR (?) Green I chimeric fluorescent method. The Human660w-Quad and Human Omni1-Quad Chip (illumina Inc, CA,USA) and the illumina BeadScan genotyping system (Beadstation Scanner) were employed to obtain the signal intensities of probes (SNP) following the manufacturer’s instructions and information of CNVs.Result:Among642cases of congenital heart disease,52cases (8.1%) of22q11.2proximal microdeletion and five cases (0.8%) of microduplication were found.43cases have a3Mb deletion from LCR22-2to LCR22-4and9cases have a1.5Mb deletion from LCR22-2to LCR22-3a. Five cases founded have a3Mb microduplication extending from LCR22-2to LCR22-4. The52cases with deletion included truncus arteriosus (2/5,40%), tetralogy of Fallot with pulmonary atresia, patent ductus arteriosus (3/8,37.5%), interrupted aortic arch (1/3,33.3%), tetralogy of Fallot (16/53,30.2%), partial anomalous pulmonary venous connection (1/5,20%), abnormal origin of the pulmonary artery (1/5,20%), pulmonary atresia with ventricular septal defect (1/7,14.3%), double outlet right ventricle (1/15,6.7%), ventricular septal defect (26/415,6.3%). The nine cases with1.5Mb microdeletion were tetralogy of Fallot (44.4%), ventricular septal defect (44.4%) and truncus arteriosus (11.1%). Among the five cases with duplication, three were tetralogy of Fallot. The rest were one case of hypoplastic left heart syndrome and one case of interrupted aortic arch.Conclusion:1. The real-time PCR technology with the probe located in the TBX1gene is a rapid and sensitive screening method for22q11.2proximal CNVs in the children with congenital heart disease.2. In the children with congenital heart disease, the prevalence of22q11.2proximal CNVs is about8.9%. The children with truncus arteriosus, tetralogy of Fallot with pulmonary valveatresia and patent ductus arteriosus, interrupted aortic arch and tetralogy of Fallot are prone to have22q11.2proximal CNVs. 3. The heart malformations in the children with3Mb microdeletion are more diverse than those with1.5Mb deletion. Chapter-2The Impact of22q11.2Proximal CNVs Genotype on Perioperative Outcome in Primary Repair for Tetralogy of Fallot.Objective:Compare the preoperative evaluation index of the children with tetralogy of Fallot and22q11.2proximal CNVs to that of children with tetralogy of Fallot, but not CNVs. Investigate the impact of22q11.2proximal CNVs genotype on perioperative outcome in primary repair for tetralogy of Fallot.Method:The19children with tetralogy of Fallot and22q11.2proximal CNVs discovered by RT-PCR screen were considered as research group. The children with tetralogy of Fallot, but not22q11.2proximal CNVs were randomly selected to be the control group. The information of each child was collected, including age (months), gender, height, weight, McGoon index, left ventricular end-diastolic volume index(LVEDVI), transcutaneous oxygen saturation, hematocrit, surgery, bypass duration, aortic cross-clamping duration, intubation duration, vasoactive-inotropic score, postoperative complications, and ICU duration. The differences of these data between two groups were compared using t test, rank-sum test and the chi-square test. Multivariable regression models were used to assess the independent associations between22q11.2proximal CNVs genotype and length of intensive care, vasoactive-inotropic score, postoperative complications and CPB time, adjusting for potential confounders.Result:Between the research group and the control group, left ventricular end-diastolic volume index, transcutaneous oxygen saturation, hematocrit differences were not statistically significant. The McGoon value of the study group was lower than the control group (p<0.05).17patients with22q11.2proximal CNVs and TOF children underwent a radical surgery, compared with the control group, they had longer cardiopulmonary bypass time (95.35vs85.48, p=0.04),higher vasoactive-inotropic score (10.91vs7.38, p=0.03),longer intubation time (82.58vs56.23, p=0.02) and longer duration of intensive care (138.47vs103.24, p=0.03).Conclusion:1. The development of pulmonary artery in the children with tetralogy of Fallot associated22q11.2proximal CNVs is poorer than the children with tetralogy of Fallot, but not CNVs.2.22q11.2proximal CNVs genotype affects early operative outcomes in tetralogy of Fallot resulting in longer duration of intensive care particularly, higher vasoactive-inotropic score and longer intubation time. |
