Prenatal phenotypic spectrum of full trisomy 18 in an Indian cohort

Trisomy 18 or Edward syndrome is a chromosomal disorder due to the presence of an extra chromosome 18. We describe the phenotype of five fetuses at different gestational ages, each highlighting a different aspect of trisomy 18. The clinical spectrum included increased nuchal translucency, fetal hydrops, congenital malformations of the central nervous system, congenital heart disease, radial ray defects, and characteristic facial gestalt. We made a comparison of prenatal ultrasonography and the autopsy findings. The fetal autopsy defined the craniofacial and digit anomalies better compared with sonography. The facial features of tall forehead, hypoplastic nares, microstomia, micrognathia, low set abnormal ears along with clenched hands, and short hallux are typical for trisomy 18 and help in planning the targeted cytogenetic or molecular tests. The diagnosis was established by either fluorescence in situ hybridization or quantitative fluorescent polymerase chain reaction or chromosomal microarray in the patients. This communication emphasizes the importance of detailed assessment for craniofacial and limb anomalies on prenatal ultrasonography which can prompt an early evaluation for trisomy 18.