Indian Journal of Obstetrics and Gynecology Research 2023;10(3):374–378 Content available at: https://www.ipinnovative.com/open-access-journals Indian Journal of Obstetrics and Gynecology Research Journal homepage: www.ijogr.org Case Report Detection of 22q11.2 deletion syndrome by single-nucleotide polymorphism based non-invasive prenatal test Angela Devanboo 1, *, Dhriti Chendil Nathan 1 , Shweta Kannan Mahalingam 1 , Vishalakshi Apparaya Prabhu 2 , Hema Purandarey 2 , E Venkataswamy 1 , V. L. Ramprasad 1 , Priya Kadam 1 1 MedGenome Labs Ltd, Narayana Nethralaya, Bangalore, Karnataka, India 2 MedGenome Centre for Genetic Health Care, Mumbai, Maharashtra, India ARTICLE INFO Article history: Received 23-01-2023 Accepted 07-04-2023 Available online 24-08-2023 Keywords: Prenatal screening SNP -NIPT Microdeletions 22q112DS Chromosomal microarray ABSTRACT Non-invasive prenatal test (NIPT) has become a popular screening test worldwide for screening common trisomies. In addition, the test can also sex chromosomal aneuploidies (SCAs) with similar sensitivity. In recent years, the scope of NIPT has extended to screen pregnancies for clinically significant microdeletions (MDs), rare autosomal aneuploidies, and subchromosomal abnormalities. The clinical utility of NIPT screening beyond trisomies 21,18,13 and SCAs are still being evaluated because of low positive predictive value which in turn leads to an increase in invasive procedures. Here, we present a case where SNP - NIPT correctly identified a microdeletion syndrome, i.e., 22q11.2DS in a pregnant woman with normal ultrasound findings. This NIPT finding was further confirmed in the chromosomal microarray study and FISH. This is an Open Access (OA) journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: reprint@ipinnovative.com 1. Introduction The introduction of non-invasive prenatal testing (NIPT) in 2011 has transformed the prenatal screening scenario. The test utilizes cell-free DNA obtained from maternal plasma to screen for common whole chromosomal abnormalities such as Trisomy 21, Trisomy 18 and Trisomy 13 in addition to sex chromosomal aneuploidies (SCAs) such as Turner syndrome (MX), Klinefelter syndrome (XXY), Triple X syndrome (XXX) and Jacobs syndrome (XYY) in the fetus. This superior screening test is the most sensitive for screening these conditions compared to conventional maternal serum screening. Furthermore, international committees such as American College of Medical Genetics and Genomics (ACMG) and the American College of * Corresponding author. E-mail address: angela.devanboo@medgenome.com (A. Devanboo). Obstetricians and Gynecologists (ACOG) agree that the cell-free DNA based test is the most sensitive and specific screening test that can be offered to pregnant women. 1,2 Different NIPT methodologies are being used in clinical practice, these include whole genome-based approach or targeted based approach. With further developments, the clinical utility of NIPT is being expanded to screen for other chromosomal conditions such as rare autosomal aneuploidies, microdeletions/microduplications and monogenic disorders. Single nucleotide polymorphisms- based (SNP-based) NIPT is one such targeted NIPT that can screen for clinically significant common microdeletions such as 22q11.2 deletion syndrome, 1p36 deletion syndrome, cri-du-chat, Prader-Willi, and Angelman microdeletion syndromes along with whole chromosomal aneuploidies i.e. common trisomies and SCAs. https://doi.org/10.18231/j.ijogr.2023.073 2394-2746/© 2023 Innovative Publication, All rights reserved. 374