Prevalence of 22q11 deletion in fetuses with conotruncal cardiac defects: A 6-year prospective study

Objectives: Conotruncal malformations (CTMs) are a major feature of 22q11 microdeletion (22qdel). The prevalence of 22qdel in fetuses harboring these defects is unknown. We assessed the prevalence of 22qdel in a population of fetuses with conotruncal cardiac defects. Study design: Consecutive fetuses (n = 261) with a CTM and a normal karyotype were included in the study. All fetuses were screened for 22qdel by means of fluorescent in situ hybridzation. Results: A 22qdel was found in 54 fetuses (20.7%). The proportion of 22qdel for each CTM was: tetralogy of Fallot (14/100), pulmonary atresia with ventricular septal defect (11/61), tetralogy of Fallot with absent pulmonary valves (6/16), interrupted aortic arch (10/22), truncus arteriosus (9/29), and complex transpositions of the great arteries (4/33). Additional vascular anomalies were present in 75%. Typical abnormal facial appearance at birth or at autopsy was observed in 80%, and thymus hypoplasia, in 76%. The pregnancy was terminated in 41 of 54 cases, including an intrauterine death in one case. The 22qdel was inherited in 7.7%. Conclusion: Prevalence of the 22qdel is high in fetuses with CTMs. The risk of mental retardation associate; with the respective risk of cardiac surgery for each type of CTM may strongly influence prenatal counseling.