Prenatal diagnosis by FISH of a 22q11 deletion in two families.

We report on prenatal diagnosis by FISH of a sporadic 22q11 deletion associated with DiGeorge syndrome (DGS) in two fetuses after an obstetric ultrasonographic examination detected cardiac anomalies, an interrupted aortic arch in case 1 and tetralogy of Fallot in case 2. The parents decided to terminate the pregnancies. At necropsy, fetal examination showed characteristic facial dysmorphism associated with congenital malformations, confirming full DGS in both fetuses. In addition to the 22q11 deletion, trisomy X was found in the second fetus and a reciprocal balanced translocation t(11;22) (q23;q11) was found in the clinically normal father of case 1. These findings highlight the importance of performing traditional cytogenetic analysis and FISH in pregnancies with a high risk of having a deletion.