Investigating Trends and Challenges in Prenatal Diagnosis of Monogenic Conditions in India-An LMIC Setting-Over Half...

To study the overall trends, indications, timing, mode of testing, geographical distribution of cases and challenges in prenatal diagnosis (PND) of single gene conditions using invasive fetal testing in India over half a decade. We also studied the clinical indications of pregnant women undergoing targeted and expanded testing.

This is a retrospective analysis of data of pregnant women who underwent an invasive procedure for diagnosis of single gene conditions at a perinatal care center in South India between January 2018 and December 2022.

Total 704 out of 1460 (48.2%) pregnant women underwent invasive testing for single gene conditions. Targeted testing was carried out in 636 cases (90.3%), while expanded testing comprised 68 cases (9.6%). The ratio of women undergoing targeted testing versus expanded testing was constant at 9:1 across the five years. While hemoglobinopathies (n = 331, 47%) continued to be the most common indication for testing, other indications such as neurodevelopmental conditions (n = 78, 11.1%) and inborn errors of metabolism (n = 76, 10.8%) have shown a rising trend in the recent years (p < 0.001). The number of women undergoing PND for single gene conditions has risen significantly across the study period (p = 0.003). Over the years, there was also a significant rise in the use of whole exome sequencing (n = 39, 57%) over clinical exome sequencing (n = 27, 40%) (p < 0.001).

Single gene conditions were major indications for prenatal invasive testing. Targeted testing was performed significantly more frequently than expanded testing. Although hemoglobinopathy continues to be the most common indication, others showed a rising trend in the recent years. For expanded testing, WES has been increasingly used over CES, especially in the recent years.