Our newly established non-invasive prenatal test allows detection of fetal trisomies 13, 18, and 21 with high accuracy in a population in Germany and Switzerland.
Objective
About 3% of newborns show malformations, with about 20% of the affected having genetic causes. Clarification of genetic diseases in postnatal diagnostics was significantly improved with high‐throughput sequencing, in particular through whole exome sequencing covering all protein‐coding regions. Here, we aim to extend the use of this technology to prenatal diagnostics.
Method
Between 07/2018 and 10/2020, 500 pregnancies with fetal ultrasound abnormalities were analyzed after genetic counseling as part of prenatal diagnostics using WES of the fetus and parents.
Results
Molecular genetic findings could explain ultrasound abnormalities in 38% of affected fetuses. In 47% of these, disease‐causing de novo variants were found. Pathogenic variants in genes with autosomal recessive or X‐linked inheritance were detected in more than one‐third (70/189 = 37%). The latter are associated with increased probability of recurrence, making their detection important for further pregnancies. Average time from sample receipt to report was 12 days in the recent cases.
Conclusion
Trio exome sequencing is a useful addition to prenatal diagnostics due to its high diagnostic yield and short processing time (comparable to chromosome analysis). It covers a wide spectrum of genetic changes. Comprehensive interdisciplinary counseling before and after diagnostics is indispensable.
Background: Epignathus is a rare form of congenital teratoma, originating from the base of the skull, most commonly the hard palate, or mandible. It has been associated with a poor prognosis due to complications including polyhydramnios and respiratory compromise at birth as a consequence of upper airway obstructions. It is usually not associated with chromosomal aberrations. We present a case of prenatally diagnosed epignathus associated with a gonosomal pentasomy 49,XXXXY. Case: A 34-year-old gravida 1, para 0 was referred to our unit with a sonographically suspected gastroschisis at 26+6 weeks’ gestation. A detailed ultrasound scan revealed a large mixed echogenic mass seen in continuation with the mouth in the midline. Based on the appearance, an epignathus was suspected. No other fetal anomalies were detected. Karyotyping showed a 49,XXXXY karyotype of the fetus. The couple decided to continue the pregnancy after detailed counseling about results and prognosis. A cesarean section was necessary and performed at 29+0 weeks’ gestation due to a pathological Doppler and cardiotocogram. Because of the enormous epignathus intubation of the newborn was not possible. A tracheostomy was performed for ventilation and oxygenation, which failed and the newborn died 30 min after birth. Conclusion: Prenatal diagnosis by ultrasound has improved perinatal management. This should include assessment of the tumor size and spread in order to establish an accurate prognosis and to anticipate likely problems which are to be encountered during pregnancy or at the time of delivery. To our knowledge, this is the first reported case of a prenatally diagnosed epignathus with a gonosomal pentasomy 49,XXXXY.
Structured ultrasound training courses based on an ultrasound simulator system seem to be useful for defining a basic standardized quality of training and significantly improving examiners' skills. This is a suitable additional instrument to improve the education in obstetric ultrasound.
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