ABC | Volume 111, Nº4, Octuber 2018

Original Article Luo et al Genetic testing analysis of fetuses with CHD Arq Bras Cardiol. 2018; 111(4):571-577 At present, only a few studies have reported genetic testing among large groups of fetuses with CHD in China, 20-24 the genotype-phenotype relationship has not yet been fully established. The Laboratory of Genetics and Metabolism from the Maternal and Child Health Hospital in Guangxi is one of the largest Perinatal Diagnostic centers in South China. This study aimed to analyze the chromosomal abnormalities and pregnancy outcomes in 362 fetuses with CHD. Methods Subjects Fetal ultrasound anatomy scans were routinely performed for pregnant women at the Prenatal Diagnosis Center of Guangxi Zhuang Autonomous Region in China. The anatomy scans were conducted between 20 and 28 weeks of gestation by senior sonographers using GE E8 ultrasoundmachines (General Electric Healthcare, USA). If CHDwas suspected, the echocardiography was subsequently performed for confirmation. A total of 8,430 pregnancies between June 2012 and June 2016 were screened for fetal cardiac defects, and 362 fetuses were identified with CHD. The Medical Ethics Committee of the Guangxi Maternal and Child Health Hospital approved the study protocol (Approval no.160220), and the parents of all selected fetuses with CHD gave their written consent. Testing of SNP microarray All samples of amniotic fluid or fetal cord blood were collected from the pregnant women, and genomic DNA was extracted using the QIAamp DNA Blood Mini Kit (Qiagen, Germany) according to themanufacturer’s protocol. SNP (Single Nucleotide Polymorphism) microarray testing was performed using Illumina HumanCytoSNP-12 v2.1 BeadChip (Illumina, USA). The laboratory policy at the time of testing was not to report well‑established polymorphisms, CNVs that do not contain genes and CNVs smaller than 0.20 Mb. However, stretches of homozygosity larger than 10 Mb were reported. Karyotyping All samples of amniotic fluid or fetal cord blood were used to perform G-banding according to the standard procedure as described previously. 25 Results Clinical data Among the 8,430 pregnancies, 362 cases of CHD were diagnosed using fetal echocardiography, for a frequency of 4.2%. The mean age of the pregnant women was 31.1 ± 5.1 years, and the mean gestational week at diagnosis was 24.4 ± 3.8 weeks. The 5 most common types of CHD were, in order, ventricular septal defect (51.9%, 188/362), persistent left superior vena cava (13.0%, 47/362), endocardial cushion defects (0.9%, 33/362), single umbilical artery (0.9%, 32/362) and right-sided aortic arch (0.8%, 29/362) . Etiology In total, 362 fetuses were diagnosed with CHD. The genetic tests found 111 cases with aneuploidy, 10 cases with abnormality of chromosome structure, and 19 cases with pathogenic or likely pathogenic CNVs (Table 1). The remaining 222 cases showed no abnormal genetic findings. The abnormalities of chromosome numbers consisted of trisomy 18 syndrome (61 cases), trisomy 21 syndrome (31 cases) and trisomy 13 syndrome (19 cases). CMA identified 19 CNVs, including DiGeorge syndrome (8 cases), Jacobsen syndrome (2 cases), Angelman/Prader-Willi syndrome (1 case), 16p11.2-p12.2 microdeletion syndrome (1 case), 16q24-triplication syndrome (1 case), Thrombocytopenia-absent radius (TAR) syndrome (1 case), 3q29 microduplication syndrome (1 case), 22q11 duplication syndrome (1 case), Cri du chat syndrome (1 case) and 2 likely pathogenic CNVs (Table 2). Occurrence of fetal cardiac malformations Of the 362 CHD, 181 fetuses were found with single cardiac malformations, and 181 were found with multiple cardiac abnormalities; 220 were found with an isolated CHD; and 142 had CHD with extracardiac anomaly. Table 3 lists the etiology of the various types of fetal cardiac malformations observed. Pregnancy Outcomes Among all 140 cases with a positive genetic testing result, only one woman chose to continue her pregnancy, and the rest of them chose to induce labor. The fetus was diagnosed with trisomy 18 syndrome, presenting difficulties in feeding, and died 4 days after birth. Among the remaining 222 negative cases, 56 were subjected to labor induction, and most of these cases were deemed incurable or had poor prognostic cardiac malformations (including single ventricle, left or right ventricular dysplasia and tetralogy of fallot) or were complicated with extracardiac anomalies (Figure 1). Mothers of 77 fetuses with mild or curable cardiac malformations chose to maintain their pregnancies. Of these cases, 66 were found with no abnormality after birth, 8 cases needed surgery, one presented delayed development, one was found with clubfoot, one was identified with hypomyotonia, and the pregnancy outcomes of the remaining 89 cases were uncertain (Figure 1). Discussion In this study, 362 cases of fetal CHD were identified in a total of 8,430 pregnancies at a single Maternal and Children’s hospital from the Southern region of China from June 2012 to June 2016, with an incidence of 4.2%. This incidence was similar to that reported in Xi’an, in Northwestern China, 26 and higher than the rate of 2.3% reported in Guangzhou, In southern China. 23 Among the 362 CHD fetuses, ventricular septal defect (51.9%, 188/362) and persistent left superior vena cava (13.0%, 47/362) were the most prevalent cardiac abnormalities detected by ultrasound scans. Many factors such as genetic factors (including chromosomal abnormalities and gene mutations) and risk factors associated 572