Mosaic trisomy 5 in amniotic fluid in a live fetus with Ebstein anomaly and complete trisomy 5 in chorionic villus sampling.

Complete trisomy 5 is a rare and lethal abnormality. Mosaic trisomy 5 presents in various phenotypes, ranging from a clinically normal fetus to fetuses presenting uterine growth restriction, congenital heart anomalies, multiple dysmorphic features and psychomotor development abnormalities. Although rare, there are cases of a normal psychomotor development regardless of the associated low fetal growth frequently associated with mosaic trisomy 5. This is the first case report to date of a live fetus with complete trisomy 5 reported in chorionic villus sampling and mosaic trisomy 5 in amniotic fluid with a concomitant Ebstein anomaly. Diagnosis of mosaic trisomy 5 represents a challenge for the clinical team and patients, as the information regarding this syndrome is scarce and based mostly on case reports of liveborns, which may introduce a selection bias when counselling the parents.