Prevalence of 22q11.2 microdeletion in children with sporadic non-syndromic conotruncal heart defects

Abstract

Objective Congenital conotruncal heart defects were commonly found in DiGeorge (DGS) and velocardiofacial (VCFS) syndromes. The deletion of chromosome 22q 11.2 (del22q) has been demonstrated in sporadic or familial cases of conotruncal heart defect (CTD). The aim of this study was to investigate the frequency of del22q and clinical phenotypic analysis in patients with nonsyndromic CTD at a pediatric thoracic and cardiovascular surgical centre. Methods Seventy-seven non-syndromic CTD children (42 male, 35 female, aged 0-10 years) were recruited. History, physical examination and medical records were reviewed. Venous blood was collected for genomic DNA after informed consent. Chromosome 22q 11.2 microdeletion was screened with Multiplex Ligation-dependent Probe Amplification (MLPA) and Fluorescence in situ hybridization (FISH). Genotype phenotype correlations were performed using Fishers exact test. P values less than 0.05 on a 2-tailed test were considered significant. Results We examined 77 non-syndromic CTD patients for a 22q 11.2 deletion.55 patients presented with tetralogy of fallot (TOF), 4 with pulmonary atresia with ventricular septal defect (PA-VSD), 8 with double outlet right ventricle (DORV) and 10 with transposition of the great arteries (TGA). Six children (7.8%) were found to have a del22q; including four TOF, one DORV and one PA-VSD. Interestingly, none of the ten TGA children had the deletion. Conclusions Chromosome 22q 11.2 microdeletion is detected in 7.9% of children with non-syndromic CTD. There was a tendency of higher 22q11.2 microdeletion prevalence in those with PA-VSD, DORV and TOF. Molecular genetic screening of non-syndromic CTD children may be important for diagnosis and genetic counselling. Key words: Truncus arteriosus,abnormalities; Chromosomes