The prevalence of chromosome 22q11.2 deletions in 2,478 children with cardiovascular malformations. A population-based study.

Deletion of chromosome 22q11.2 is considered one of the most frequent genetic causes of cardiovascular malformations. It is frequently associated with conotruncal malformations, but may also be present among patients with nonconotruncal malformations. The aim of the present study was to establish the prevalence of the 22q11.2 deletion in an unselected population-based cohort of children with various cardiovascular malformations. The study population was defined as children born in 2000-2008 who were registered in the Danish National Patient Registry with a diagnosis of cardiovascular malformation from one of the two national departments of pediatric cardiology. Sensitive multiplex ligation-dependent probe amplification was performed on dried blood spot samples from each individual's neonatal screening test. Of 2,952 children with cardiovascular malformations, 2,478 were eligible for genetic testing. A total of 46 individuals (1.9% [1.4-2.5%]) carried the deletion, with the highest prevalence among individuals registered with interrupted aortic arch (22% [11-40]). The most frequent diagnoses among individuals carrying the deletion were tetralogy of Fallot (n = 15) and ventricular septal defect (n = 15). One in four cases had not been diagnosed in the usual clinical setting. The prevalence of 22q11.2 deletions in an unselected population-based cohort of children with cardiac malformations was 1.9% [1.4-2.5%]. Genetic testing of every individual registered with a conotruncal malformation would have achieved a diagnostic sensitivity of 70% in the present cohort. Prospective studies outlining testing recommendations in children with ventricular septal defect are warranted.