CLINICAL ANALYSIS OF 194 CASES OF AMNIOTIC FLUID CHROMOSOME MICROARRAY DETECTION

Xu Cao^*, Qingmei Wang, Bin Liu, Yu Liang, Hui Song

Department of Prenatal Diagnosis, Wanbei Coal-Electricity Group General Hospital, Suzhou, PR China

Objective: To explore the clinical significance of chromosome microarray analysis (CMA) in prenatal diagnosis. 

Methods: 194 amniotic fluid specimens that underwent chromosome karyotype analysis and chromosome microarray technique in the prenatal diagnosis centre of our hospital from August 2016 to November 2018 were selected, including 61 cases with abnormal ultrasound, 50 cases with high risk of non-invasive prenatal testing (NIPT), 56 cases with high risk of prenatal screening, and the other 27 cases were aged 18 to 42 years old with a gestational age of 17 to 26 weeks. The results of chromosome karyotype and chromosome microarray detection were analyzed.

Results: Among the 194 cases of amniotic fluid specimens, a total of 47 cases were found to be abnormal, in which 27 cases were detected abnormal by chromosomal karyotype analysis with the detection rate of 13.91% (27/194), including 22 cases of aneuploidy, 1 case of translocation, 1 case of inversion, and 2 cases of chimerism. 44 cases were detected by CMA with a detection rate of 22.68% (44/194) including 22 cases of aneuploidy, 2 cases of chromosome chimerism, and 20 cases of microdeletion and microduplication. In the population with normal karyotype analysis (167 cases), an additional 7.78% (13/167) of pathogenicity copy number variation with clinical significance was found by CMA technology. The karyotype analysis and CMA results of one case were normal, and the patient was diagnosed with monogenic genetic disease methylmalonic acidemia after delivery. In the 50 patients with abnormal NIPT results, 23 cases were detected as abnormal by CMA technology, and the complete consistency rate of the two results was 30% (15/50). Only one case was completely inconsistent, with a basic consistency rate of 44% (22/50).

Conclusion: 1. CMA technique is a necessary tool in prenatal diagnosis as it has higher sensitivity and specificity than karyotype analysis, but there are still some technical limitations which need to be supplemented by the results of karyotype analysis. 2. NIPT is a screening test, and its abnormal results are not of diagnostic significance so it can be used as a clear clinical indication for CMA analysis. 3. In this study, 3 cases of 22q11.2 deletion/distal deletion syndrome were detected, and the cardiac system structure abnormality was an indication of the abnormal ultrasound detected by CMA. 4. Karyotype analysis and CMA technique cannot detect monogenic disease and genetic metabolic disease. In the future, prenatal diagnosis still needs to integrate a variety of detection methods in order to further reduce birth defects.