[Data analysis of non-invasive prenatal testing based on special loci in cell-free fetal DNA].

OBJECTIVE To analyze the data of non-invasive prenatal testing based on specific loci of circulating cell-free fetal DNA (cffDNA). METHODS Selected loci of target chromosomes were analyzed by sequence capture and sequencing. Meanwhile, 600 loci were selected from other chromosomes for determining the concentration of cffDNA. RESULTS A total of 768 specific loci were captured on chromosomes 21 and 18, and used to determine whether the two were abnormal. When the minimum concentration of detected cffDNA was set at 3% and the threshold of Z score was set to [-6,6], the specificity of the analysis was 99.37% and the sensitivity was 100%. CONCLUSION A reliable, convenient and low-cost analytical method has been developed. The method requires less sequencing data for non-invasive prenatal testing, and can accurately detect abnormalities of fetal chromosomes 21 and 18, and simultaneously determine the concentration of cffDNA.