Application Of Chromosomal Microarray Analysis In Fetuses With Neurodevelopmental Abnormalities

Objective:1.To explore the application value of Chromosomal Microarray Analysis(CMA)in fetuses with abnormal nervous system development.2.To analyze the differences in detection rates between fetuses with abnormal nervous system development using CMA technique and traditional g-banding chromosome karyotype analysis technique.3.To investigate the difference in the detection rate of CMA between the fetus group with simple and complex neurodevelopmental abnormalities.4.Discuss how to consult CMA techniques for the occurrence of unclear copy number variations(CNVs)in clinical prenatal diagnosis.Methods:1.The object of study: between January 2018 and June 2019 by prenatal ultrasound fetal performance for the abnormal development of the nervous system to the health care of women and children in jiangxi province prenatal diagnostics division line of non-invasive prenatal diagnosis of pregnant women,a total of 140 cases,according to whether the merger other system structure is unusual,it can be divided into pure abnormal fetal nervous system development group and composite abnormal fetal development of the nervous system.All pregnant women signed informed consent for prenatal diagnosis before the operation to clarify the surgical procedures,surgical risks and CMA technology,as well as the significance and limitations of chromosome karyotype analysis technology.CMA analysis and g-banding karyotype analysis were performed on all samples from different amniocentesis or umbilical venous blood samples during pregnancy.2.Sample collection: under the condition of signing the informed consent for surgery,all pregnant women were sterilized,the fetus and placenta were positioned by type B ultrasound,the needle was inserted into the position of the damaged fetusand placenta,and amniotic fluid or umbilical cord blood samples were sterile extracted.3.DNA extraction: DNA extraction was performed using the Qiagene DNA extraction kit.4.CMA: affy-metrix 750 K chip kit and Clontech DNA amplification kit were used.DNA of NspI enzyme was digested,ligated,purified after PCR amplification,fragmented,labeled,hybridized,washed and scanned to obtain data,and Chas v4 software was further used for analysis and interpretation of the results.The interpretation standards refer to relevant international public databases,such as DGV,DECIPHER,ISCA,UCSC,OMIM,ClinGen sensivity Map,Pubmed,etc.5.Statistical analysis: the t-test between the two groups was used to compare and analyze the samples of the two groups with the statistical software SPSS 19.3.P<0.05 was defined as statistically significant.Results:1.G-banded karyotype analysis of 140 fetuses showed 10 abnormal cases,including 1 case with trisomy 21,6 cases with trisomy 18,1 case with trisomy 13,1case with trisomy 46,XN,dup(12)(q24.3q24.3),1 case with 46,XN,del(1)(q43).The abnormal detection rate was 7.1%.2.CMA analysis of 140 fetal samples revealed 15 abnormal cases.There were 1case with trisomy 21,6 cases with trisomy 18,1 case with trisomy 13,1 case with arr(12q24.31q24.33)repeated 11.85 m,1 case with arr(12q43q24.33)missing679.64 kb,1 case with arr(1q43q44)missing 12.27 mb,1 case with arr(6q27)missing2.3mb,1 case with arr(1p36.23p36.33)missing 7.89 mb,and 23.47 mb with arr(7p22.3p15.3)missingArr(Xp22.2)duplication of 640.49 kb in 1 case,arr(1p36.31p36.33)deficiency of 7.89 mb in 1 case.The detection rate of abnormality was 10.7%,which was 3.6% higher than that of g-banding karyotype analysis.At the same time,8 cases of CNVs with unknown significance(VOUS)were detected,and the detection rate was 5.7%.3.The 140 abnormal fetuses were divided into the single group(112 cases)and the compound group(28 cases).Among the 15 cases of pathogenic CNVs,7 caseswere fetuses with simple dysplasia of the nervous system,and 8 cases were fetuses with complex dysplasia of the nervous system.The pathogenic detection rates were6.3%(7/112)and 28.6%(8/28),respectively.The latter was significantly higher than the former,but without statistical significance(Fisher's test,P > 0.05).4.Among 140 pregnant women with abnormal fetus,the CMA detection rate of112 cases was 5.4%(6/112),with 6 cases of VOUS.Two of the 28 cases in the composite group were VOUS in CMA,with a detection rate of 7.1%(2/28).Conclusions:1.The detection rate of CMA in fetuses with abnormal nervous system development was increased by 3.6% compared with that of karyotype analysis,indicating that there was a certain correlation between nervous system development and chromosomal microdeletions/microduplications.Therefore,it is suggested to carry out CMA detection at the same time for fetuses with abnormal nervous system development to improve the detection rate of abnormalities.2.There was no statistical difference in the detection rate of pathogenic CNVs of CMA in the fetus group with simple and complex neurodevelopmental abnormalities.3.In clinical,prenatal ultrasound prompted merge abnormal fetal development of the nervous system,suggest lines of invasive prenatal diagnosis(amniotic cavity puncture biopsy,and umbilical vein puncture),and at the same time line of the G banding karyotype analysis and CMA testing,eliminating abnormal chromosome and eliminate chromosome micro/micro repeat may missing,improve the quality of the population was born.4.With the progress of CMA technology,the resolution is gradually improved,and the clinical detection rate of VOUS is also gradually improved.In view of this result,we can extract the peripheral blood of parents for CMA detection and compare the results to help explain the nature of unclear CNVs.