Prenatal Diagnosis of Birth Defects by Exome Sequencing

Abstract

Prenatal screening and diagnosis are increasingly becoming a part of medical practice. Prenatal screening can reduce the incidence of birth defects which cause morbidity and mortality in newborns. With emerging technologies, now it is possible to diagnose the genetic basis of birth defects more accurately in the prenatal period for early management. Different approaches are available for detecting genetic defects at different levels like karyotyping, chromosomal microarrays and Sanger sequencing. However, many cases still remain undiagnosed. Next generation sequencing has revolutionized the field of genetics that can detect genetic defects at the level of a single base pair. It includes both whole exome sequencing (WES) and whole genome sequencing (WGS). WES has particularly accelerated the discovery of disease-causing variants in many monogenic anomalies postnatally. Research is being conducted on the use of whole exome sequencing in the prenatal diagnostics of genetic anomalies detected by ultrasound. It is a more efficient way of getting an insight into the molecular basis of birth defects compared with conventional genetic approaches. However, technical and ethical issues need to be addressed before introducing this technique into routine prenatal clinical practice. Fetal cell sampling is done by invasive medical procedures like amniocentesis or chorionic villus sampling. However, noninvasive strategy of collecting fetal DNA from maternal plasma is an exciting and emerging domain. It is evident that in the coming years, we shall be able to use these techniques in the routine clinical setting and to improve the diagnosis and management of birth disorders during prenatal period.