Chromosomal Abnormalities Through Amniocentesis


Aghdas Pourahmad 1 , Nasrin Saadati 2 , Mojgan Barati 1 , Farideh Moramezi 1 , Razieh Mohamadjafari 1 , *

1 Fertility, Infertility and Perinatology Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

2 School of Medicine, Department of Social Medicine, Fertility, Infertility and Perinatology Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

How to Cite: Pourahmad A, Saadati N, Barati M, Moramezi F, Mohamadjafari R. Chromosomal Abnormalities Through Amniocentesis, Jentashapir J Cell Mol Biol. Online ahead of Print ; 10(2):e90949. doi: 10.5812/jjhr.90949.


Jentashapir Journal of Health Research: 10 (2); e90949
Published Online: July 23, 2019
Article Type: Research Article
Received: February 23, 2019
Accepted: June 23, 2019


Objectives: The study aimed to assess the frequency and type of abnormal karyotype in Khuzestan, Iran by amniocentesis before 22 weeks of gestation.

Methods: We conducted a retrospective analysis of 1197 amniotic fluid specimens in Khuzestan province, before 22 weeks gestations for fetal karyotyping.

Results: The incidence of abnormal aneuploidies was 4.9% (59 of 1197) for all specimens. The highest chromosomal abnormality was Down syndrome (64.4%).

Conclusions: The rate of chromosomal abnormalities was higher than other reports from Iran and all over the world. The detection rate of Down syndrome similar to other reports remains high.

1. Background

In recent years, in addition to a decrease in birth rate, the number of mothers ≥ 35 has been increasing (1). Based on this fact, and also the high incidence of Down syndrome with maternal age, as well as some other chromosomal anomalies, the efforts for prenatal diagnosis of these disorders have risen (2). In spite of introducing non-invasive prenatal tests, including prenatal aneuploidy screening program combined with NT (nuchal translucency), invasive antenatal test is yet widely being used around the world (3)). Amniocentesis is the gold standard and most commonly an invasive antenatal test for diagnosis of fetal chromosome abnormalities (4). Most of these abnormalities are numerical, and minority are structural and mosaicism (about 86%, 6%, and 8%, respectively) (5, 6). Various clinical indications affect the distribution of prenatal chromosome abnormality identification 4. Introduction of non-invasive prenatal testing changed the frequency of chromosomal abnormalities. However, cell-free fetal DNA testing, as the best screening test for common chromosomal abnormalities, failed to be a universal prenatal aneuploidy screening due to its high cost and false positive rate (7). Trisomy 21, known as Down syndrome, is the most prevalent chromosomal abnormality, which is associated with intellectual disability. The rates of fetal chromosomal aneuploidies in central Iran, Tehran, and north of Iran is 5.2%, 3.1%, and 1.5% - 1.7%, respectively (6).

2. Objectives

In this study, we determined the incidence and the type of chromosome abnormalities in the first and second trimester of pregnant women using amniocentesis in Khuzestan, south of Iran.

3. Methods

3.1. Subjects

This retrospective study was conducted on 1197 pregnant women undergoing amniocentesis for chromosomal abnormality detection at second trimester (18 - 24 weeks of gestation). The study population was recruited from the Prenatal Care Clinic at Imam Khomeini Hospital from 2012 to 2013. The amniotic fluids specimens were analyzed at Narges Medical Genetic Lab, Ahvaz, Iran.

3.2. Data Analysis

The data were analyzed using SPSS version 20.

4. Results

The incidence of abnormal aneuploidies was 4.9% (59 of 1197) for all specimens (Table 1). The highest chromosomal abnormality was Down syndrome (64.4%).

Table 1. The Incidence of Abnormal Aneuploidies
Chromosomal AbnormalityNo. (%)
Down syndrome38 (64.4)
Edward syndrome5 (8.5)
Klinefelter syndrome6 (10.2)
Turner syndrome6 (10.2)
Triploid syndrome1 (1.7)
Triple X2 (3.4)
Patau syndrome1 (1.7)
Total59 (100)

5. Discussion

We reported an analyses of chromosomal aneuploidies identified among 1197 pregnant women undergoing amniocentesis within second trimeste. We found the rate of chromosomal abnormalities in 4.9% of amniocentesis specimens. The rate of chromosomal abnormalities in central Iran, Tehran and north of Iran were 5.2%, 3.1% and 1.5% - 1.7%, respectively (8-10). Studies in other countries reported lower rate, between 2.7% - 3.1% than our study (11-13). However, a study in Japan reported the rate of 6% (1).

According to our studies and previous reports the trisomy 21 remains the most common chromosomal abnormalities. We detected that 64.4% of chromosomal abnormalities were Down syndrome. In a study in Tehran, Iran the detection rate of Down syndrome at second trimester was 81%, which was higher than our study (6). Some other studies from other countries reported much lower rates of trisomy 21 detection including 46%, 35.6% and 36.9% of all chromosomal abnormalities (2, 13, 14). These varieties may be attributed to differences in maternal age of populations evaluated in different studies.

5.1. Conclusions

The rate of chromosomal abnormalities was higher than other reports from Iran and all over the world. The detection rate of Down syndrome similar to other reports remains high.




  • 1.

    Nishiyama M, Yan J, Yotsumoto J, Sawai H, Sekizawa A, Kamei Y, et al. Chromosome abnormalities diagnosed in utero: A Japanese study of 28 983 amniotic fluid specimens collected before 22 weeks gestations. J Hum Genet. 2015;60(3):133-7. doi: 10.1038/jhg.2014.116. [PubMed: 25566756].

  • 2.

    Ocak Z, Ozlu T, Yazicioglu HF, Ozyurt O, Aygun M. Clinical and cytogenetic results of a large series of amniocentesis cases from Turkey: Report of 6124 cases. J Obstet Gynaecol Res. 2014;40(1):139-46. doi: 10.1111/jog.12144. [PubMed: 24033845].

  • 3.

    American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 88, December 2007. Invasive prenatal testing for aneuploidy. Obstet Gynecol. 2007;110(6):1459-67. doi: 10.1097/01.AOG.0000291570.63450.44. [PubMed: 18055749].

  • 4.

    Sago H. Prenatal diagnosis of chromosomal abnormalities through amniocentesis. J Mamm Ova Res. 2004;21(1):18-21. doi: 10.1274/jmor.21.18.

  • 5.

    Goddijn M, Leschot NJ. Genetic aspects of miscarriage. Baillieres Best Pract Res Clin Obstet Gynaecol. 2000;14(5):855-65. doi: 10.1053/beog.2000.0124. [PubMed: 11023805].

  • 6.

    Seyyed Kavoosi E, Younessi S, Farhud DD. Screening of Fetal Chromosome Aneuploidies in the First and Second Trimester of 125,170 Iranian Pregnant Women. Iran J Public Health. 2015;44(6):791-6. [PubMed: 26258091]. [PubMed Central: PMC4524303].

  • 7.

    Amorim Costa C. Non‐invasive prenatal screening for chromosomal abnormalities using circulating cell-free fetal DNA in maternal plasma: Current applications, limitations and prospects. Egypt J Med Hum Genet. 2017;18(1):1-7. doi: 10.1016/j.ejmhg.2016.07.004.

  • 8.

    Sereshti M, Banaeyan S, Kazemeyan A. [Prevalence of apparent major congenital malformations and some associated factors, in terminated pregnancies in hajar hospital of Shahrekord, 2005-2006, Iran]. J Shahrekord Univ Med Sci. 2008;10(1). Persian.

  • 9.

    Shajari H, Mohammadi N, Aghai MK. [Prevalence of congenital malformations observed in neonates in Shariati Hospital (1381-1383)]. Iran J Pediatr. 2006;16(3):308-12. Persian.

  • 10.

    Golalipour MJ, Ahamadpour M, Vakili MA. [Gross congenital malformations in 10000 births (Gorgan Dezyani Hospital 1997-99)]. J Gorgan Univ Med Sci. 2002;4(2):42-7. Persian.

  • 11.

    Mademont-Soler I, Morales C, Clusellas N, Soler A, Sanchez A, Group of Cytogenetics from Hospital Clinic de B. Prenatal cytogenetic diagnosis in Spain: Analysis and evaluation of the results obtained from amniotic fluid samples during the last decade. Eur J Obstet Gynecol Reprod Biol. 2011;157(2):156-60. doi: 10.1016/j.ejogrb.2011.03.016. [PubMed: 21492994].

  • 12.

    Chang YW, Chang CM, Sung PL, Yang MJ, Li WH, Li HY, et al. An overview of a 30-year experience with amniocentesis in a single tertiary medical center in Taiwan. Taiwan J Obstet Gynecol. 2012;51(2):206-11. doi: 10.1016/j.tjog.2012.04.007. [PubMed: 22795095].

  • 13.

    Han SH, An JW, Jeong GY, Yoon HR, Lee A, Yang YH, et al. Clinical and cytogenetic findings on 31,615 mid-trimester amniocenteses. Korean J Lab Med. 2008;28(5):378-85. doi: 10.3343/kjlm.2008.28.5.378. [PubMed: 18971619].

  • 14.

    Zhang YP, Wu JP, Li XT, Lei CX, Xu JZ, Yin M. [Karyotype analysis of amniotic fluid cells and comparison of chromosomal abnormality rate during second trimester]. Zhonghua Fu Chan Ke Za Zhi. 2011;46(9):644-8. Chinese. [PubMed: 22176986].

  • Copyright © 2019, Jentashapir Journal of Health Research. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License ( which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.