Publication

Abstract :

Background: About 3-5% of pregnancies are complicated by chromosomal aberrations and birth defects. In the past prenatal genetic testing is identified to be largely restricted to the detection of chromosomal abnormalities like aneuploidy. With advances in the field of medical genetics, there has been substantial rise in use of prenatal genetic testing and we wanted to find out the same in our cohort of patients.

Methods: Study design was retrospective, single-center observational study. Pregnant patients who underwent invasive testing for prenatal genetic disorder at fetal medicine specialty were considered for inclusion in the study. The invasive procedures that were performed in our study were amniocentesis, chorionic villous sampling (CVS) and cordocentesis.

Results: Total 515 pregnant women underwent prenatal testing. Amniocentesis was the most common procedure to be performed accounting for about 74% of total cases. In our cohort, abnormal aneuploidy screening was the most common indication for performing prenatal diagnosis (64% of cases), while 12.8 % underwent prenatal diagnosis due to abnormalities/genetic disorder in previous child. Abnormalities in antenatal ultrasonography accounted for 16% of cases. Quantitative fluorescene polymerase chain reaction, rapid aneuploidy testing (QFPCR) was performed in all the cases. Karyotype was performed in 273 cases while chromosomal microarray was performed on 92 samples. Multiplex ligation dependent probe amplification (MLPA) was done for 15 patients. Targeted mutation testing (Sanger sequencing) was done on 121 prenatal samples. Exome sequencing was performed on 14 fetuses. Out of 515 a total of 79 fetuses (15.3%) were found to have genetic disorder. Aneuploidies were identified in 11 fetuses (2.1%), 12 fetuses (2.3%) were found to have pathogenic CNVs (Copy number variants). Single gene disorders were found in 56 fetuses (10.8%).

Conclusions: We have moved very rapidly from Karyotyping to chromosomal microarray to exome sequencing. There has been rapid change in the indications for prenatal Diagnosis from yesteryears with coming of new era of genetics.