Prenatal diagnosis of a 22q11 deletion in a second-trimester fetus with conotruncal anomaly, absent thymus and meningomyelocele: Kousseff syndrome

A 30-year-old nulliparous woman was seen for a detailed ultrasound scan at 20 weeks of gestation. The scan revealed a male fetus with truncus arteriosus, membranous ventricular septal defect, absent thymus and sacral meningomyelocele. A 46,XY karyotype with a 22q11 deletion was detected. The parents chose to terminate the pregnancy. The pathological autopsy showed normal facial structures, minimal ventricular dilatation in the brain and a sacral meningomyelocele. Overlapping toes and a left claw-hand were also noted. An aplastic thymus with absent parathyroid glands was detected. The cardiac examination was consistent with the ultrasound diagnosis. The parental karyotypes were both normal. Kousseff syndrome is caused by a chromosome 22q11 deletion. It includes sacral meningomyelocele and conotruncal heart defects, unlike DiGeorge syndrome. Obstetricians should consider this a not so rare entity when they detect conotruncal abnormalities and a meningomyelocele as part of a 22q11.2 deletion syndrome.