Cardiac phenotype in the chromosome 22q11.2 microdeletion syndrome

Chromosome 22q11.2 deletions are present in 88% of patients with DiGeorge syndrome, 76% of patients with velocardiofacial syndrome, and 80% of patients with conotruncal anomaly face syndrome. In addition, haploinsufficiency at chromosome 22q11 has been noted with Opitz GBBB and CHARGE syndrome. The major features of these syndromes include congenital heart disease, aplasia or hypoplasia of the thymus and/or parathyroid glands, palatal abnormalities and learning difficulties. Overall, 75-85% of patients with a chromosome 22q11.2 microdeletion have some type of congenital heart disease. Conotruncal malformations, ventricular septal defects and aortic arch defects represent the most common cardiac phenotype. In this article, we review the most common cardiac anomalies associated with the deletion, the mechanism(s) underlying the pathogenesis of congenital heart disease due to chromosome 22q11.2 deletion, and the association of chromosome 22q11.2 deletion with cardiac defects in non-syndromic patients.