Efficiency of Chromosome Microarray Analysis Combined with Karyotyping in Fetuses with Abnormal Down Syndrome Screening Results.

OBJECTIVE

We aimed to explore the value of chromosome microarray analysis (CMA) and karyotyping in fetuses with a high risk for Down syndrome (DS) by serological screening and prenatal cell-free DNA(cfDNA) screening in Southwest China.

METHODS

We performed CMA and karyotype in 3028 pregnant women at high risk of DS.

RESULTS

Among 2,830 individuals identified as high-risk through serological screening for DS, 280 (9.89%) returned positive results. Subsequent karyotyping confirmed 51 cases of DS, 13 cases of sex chromosome aneuploidy, and 11 cases of trisomy 18. Moreover, CMA revealed 45 cases of pathogenic/likely pathogenic copy number -variations (p/lpCNVs), 128 cases of uncertain significance(VOUS), and 32 cases of regions of homozygosity(ROH), with a 13.04% (205/280) increase in CMA yield compared to the karyotype analysis. Among 227 who had a high risk of prenatal cfDNA screening for DS, 181 (79.74%) exhibited positive results, including 179 cases with DS.

CONCLUSION

Serological screening cannot be replaced by prenatal cfDNA screening. CMA, combined with karyotyping, has a high diagnostic value for DS and should be promoted.