Observation on results of chromosomal karyotype analysis and chromosomal microarray analysis of 1 600 fetuses with abnormal prenatal ultrasonography
Objective To observe the results of chromosomal karyotype analysis and chromosomal microarray analy-sis(CMA)in 1 600 fetuses with abnormal prenatal ultrasonography.Methods A total of 1 600 fetuses exhibiting ultra-sonic abnormalities,including 789 cases with structural anomalies and 811 cases with non-structural anomalies,were se-lected for concurrent chromosomal karyotype analysis and CMA detection.The results and detection rates of the two meth-ods were compared,and the molecular characteristics and ultrasonic findings of 46 cases of pathogenic chromosomal micro-deletion/microduplication syndrome identified through CMA were analyzed.Results Among the 1 600 fetuses with ab-normal ultrasound findings,68 cases were identified through chromosomal karyotype analysis,resulting in a detection rate of 4.25%(68/1600).A total of 147 abnormal cases were identified through CMA,comprising 58 cases of copy number variations of unknown clinical significance(VOUS CNVs)and 89 cases of pathogenic copy number variations(pCNVs),resulting in a detection rate of 9.19%(147/1600).Significant difference was found in the detection rate between the two methods(P<0.05).Among the 789 cases exhibiting ultrasonic structural abnormalities,41 cases were identified through chromosome karyotype analysis,resulting in a detection rate of 5.20%(41/789);among the 811 cases presenting ultra-sonic non-structural abnormalities,27 cases were confirmed via chromosome karyotype analysis,yielding a detection rate of 3.33%(27/811);significant difference was found in the detection rate between the two groups(P<0.05).Among the 789 cases exhibiting ultrasonic structural abnormalities,45 cases of pCNV were identified through CMA,resulting in a de-tection rate of 5.70%(45/789).Among the 811 cases with ultrasonic non-structural abnormalities,44 cases of pCNV were detected via CMA,yielding a detection rate of 5.43%(44/811).No significant difference was found in the detection rate between the two groups(P>0.05).Two methods were employed to identify 48 cases with identical abnormalities.Karyotype analysis additionally detected 15 cases of balanced structural abnormalities,and CMA additionally detected 39 cases of pCNV.The use of CMA increased the detection rate of pathogenicity by 2.44%(39/1,600).A total of 46 in-stances of pathogenic chromosomal microdeletions and microduplications were identified through CMA,of which 15 cases exhibited fetal ultrasound phenotypes that correlated with the detected pCNVs.Specifically,this included 9 cases of 15q microdeletion/microduplication syndrome,7 cases of 16p11.5 microdeletion/microduplication syndrome,4 cases each of 1q21.1,7q11.23,and 16p13.11 microdeletion/microduplication syndromes,while the remaining 18 cases were CNVs with a relatively low detection rate.Conclusions The analysis of chromosome karyotype offers advantages in the identifi-cation of balanced structural abnormalities and low-proportion chimera abnormalities.Conversely,CMA provides advantag-es in detecting small structural abnormalities,particularly microdeletions and microduplications,thereby significantly en-hancing the detection rate of pCNV and reducing missed diagnoses in prenatal testing.Chromosomal karyotype analysis and CMA can complement each other to provide more precise data for prenatal diagnosis and genetic counseling.
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