Gene Cell Tissue. 2019 July; 6(3):e89849. Published online 2019 July 24. doi: 10.5812/gct.89849. Letter The Clinical Indications and Cytogenetic Analysis of Genetic Amniocentesis Cases Seyed Mehdi Tabatabaei 1, * and Zahra Metanat 2 1 Pregnancy Health Research Center, Zahedan University of Medical Sciences, Zahedan, Iran 2 Provincial Clinical Genetic Counseling Center, Ali-Asgahr Pediatric Hospital, Zahedan, Iran * Corresponding author: Pregnancy Health Research Center, Zahedan University of Medical Sciences, Zahedan, Iran. Email: zu.healthdeputy@gmail.com Received 2019 January 24; Revised 2019 March 05; Accepted 2019 July 14. Keywords: Prenatal Screening, Genetic Amniocentesis, Genetic Counseling, Iran Dear Editor, Prenatal genetic screening tests are planned to screen for structural abnormalities, aneuploidy, and genetic dis- eases in the prenatal period. The prevalence of genetically modified disorders in neonates is estimated to be 4%, and the risk increases with increasing maternal age (1). Down syndrome is one of the most prevalent genetic diseases af- fecting about 1 in 400 - 1500 newborns, and the risk in- creases with increasing maternal age (2). Screening for this syndrome is recommended to all pregnant women, espe- cially in women 35 years of age and older. Prenatal genetic screening tests of pregnant woman include first-trimester screening, second-trimester screen- ing, and combined first- and second-trimester screening tests. First-trimester screening (FTS) for common chro- mosomal aneuploidies is based on a combination of maternal age and biochemical serum measurements of free beta-human chorionic gonadotropin (B-HCG), pregnancy-associated plasma protein-A (PAPP-A), and ultrasonographic evaluation of nuchal translucency (NT). These tests are usually performed between 11 weeks and 13 weeks of pregnancy. Second-trimester screening (STS) includes biochemical serum measurements of triple- markers (alpha-fetoprotein, unconjugated estriol, and B-HCG) or quad-markers (alpha-fetoprotein, unconju- gated estriol, B-HCG, and inhibin A), and ultrasound exams that screen the fetus for anomalies. The tests are usually done between 15 weeks and 22 weeks of pregnancy. However, in Iran, because of legal constraints for thera- peutic abortions after the 20th week of pregnancy, STS is mostly recommended before the 17th week of pregnancy. The detection rate of down syndrome for the first- trimester screening at earlier stages of pregnancy is higher than the second-trimester screening (approximately 87% versus 81%) (3). The screening tests that involve two mark- ers, specifically PAPP-A, free β-hCG, in combination with maternal age have a considerably better performance than those involving single markers with and without mater- nal age, and they can detect 70% of down syndrome af- fected pregnancies (4). However, underutilization of the first-trimester screening shows that the advantage of ear- lier diagnosis associated with FTS has been overlooked by clinicians providing genetic counseling. The risk of fetal loss and other complications associ- ated with amniocentesis is very low, and the risks of inva- sive procedures have also decreased over time (5). How- ever, not all women with abnormal screening test results agree to undertake such an invasive procedure. Offering pregnant women the relatively new noninvasive prenatal screening (NIPS) tests that use cell-free fetal DNA sequences isolated from a maternal blood sample may provide reas- surance to women who have concerns about undertaking an amniocentesis (6). GA is recommended for pregnant women with abnor- mal screening tests. FTS has acceptable performance for detection of pregnancies with chromosomal abnormali- ties; however, this method has been hardly recommended by clinicians. Some pregnant women who are GA candi- dates refuse invasive prenatal diagnosis. Moreover, a large fraction of pregnant women have a delayed diagnosis or recommendations for therapeutic abortion. Training of the clinicians on the principles of genetic counseling and increasing public awareness regarding prenatal genetic screening tests and providing pre- and post-test genetic counseling is of great importance. Copyright © 2019, Gene, Cell and Tissue. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.