Chromosome 22 microdeletion in children with syndromic congenital heart disease by fluorescent in situ hybridization (FISH)

Abstract

Congenital heart diseases (CHDs) are the most common of all birth defects. Congenital heart disease may occur as an isolated malformation or may be part of a syndrome. One of the most common syndromes associated with CHDs is the 22q11.2 microdeletion syndrome, the various conditions associated with del22q11 include DiGeorge syndrome (DGS), velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome (CTAFS), and others. The abnormalities associated with this syndrome include parathyroid hypoplasia, thymic hypoplasia, immune defect, cleft palate, and abnormal facies. The cardiac defects are usually derived from conotruncus. The aim of the study was to detect the prevalence and the most common or frequent clinical manifestations of chromosome 22q11.2 microdeletion among children with syndromic congenital heart disease. The study was conducted on 20 children with syndromic CHD presenting to the Menoufiya University Hospitals, Egypt. Their ages ranged from 10 days to 12 years. Cytogenetic study and fluorescence in situ hybridization (FISH) were performed in the patients. The study revealed that 2 patients were with chromosomal aberrations [one with 46,XY, add (13)(p13) & the other with 47,XX,+13]. In addition, FISH revealed 4 patients (20%) with 22q11.2 microdeletion syndrome. The congenital heart malformations detected in patients with 22q11.2 microdeletion were somewhat unexpected and included VSD, ASD, PDA, and double outlet right ventricle. The most frequent extracardiac features were hypocalcemia, microcephaly, brain atrophy, epicanthus, low set posteriorly rotated ears, micrognathia, and anemia. The extracardiac features were in some cases subtle. It is concluded that 22q11.2 microdeletion is not uncommon and its manifestations are highly variable. This entails that screening for the microdeletion by FISH should be performed in all patients with syndromic CHD especially those with hypocalcemia, microcephaly, brain atrophy, epicanthus, low set ears, posteriorly rotated ears, micrognathia, and anemia. In addition, patients with minor features and those with non-conotruncal heart disease should not be excluded from the screening for 22 microdeletion.

Keywords: Chromosome 22 microdeletion; Syndromic congenital heart disease; DiGeorge syndrome; Hypocalcemia; Velocardiofacial syndrome