186: Non-invasive prenatal testing (NIPT) versus diagnostic testing for evaluation of fetal structural anomalies
American Journal of Obstetrics and Gynecology(2017)
摘要
Fetal structural anomalies are associated with whole chromosome aneuploidy and sub-chromosomal copy number variants (CNVs) in approximately 3-6% of cases. Although the recommended evaluation of a fetus with an anomaly is diagnostic testing with microarray analysis, many physicians are offering non-invasive prenatal testing (NIPT) in cases where patients wish to avoid an invasive diagnostic procedure. This analysis evaluates the hypothetical performance of NIPT in this scenario. This is a secondary analysis of 2 NICHD funded prospective studies evaluating the frequency of aneuploidy and CNVs diagnosed in utero. We determined the frequency of cytogenetic abnormalities in fetuses with structural anomalies (including NT ≥3.5mm). We calculated the ability of either single nucleotide polymorphism (SNP) based NIPT or massively parallel sequencing (MPS) based NIPT to identify these abnormalities. We assumed that SNP-based NIPT could identify all cases of trisomies 13, 18, 21, sex chromosome abnormalities, triploidy and deletions of 1p36, 4p, 15q11, and 22q11.2. MPS-based expanded NIPT was assumed to detect all trisomies and CNVs ≥7Mb as well as deletions of 1p36, 4p, 5p, 8q24, 11q23, 15q11.2, 17p11.2, and 22q11.2. There were 1,724 fetuses with structural anomalies, 317 (18.4%) of which had an abnormal karyotype, and 106 (3.5%) of which had a pathogenic CNV. Among these, 1,294 had an isolated structural anomaly and 430 had multiple anomalies. Table 1 shows the cytogenetic abnormalities. SNP-based NIPT would identify 79.1% of the abnormalities and MPS-based would identify 87.4%. Detection rates vary by specific organ system, as shown in Table 2. An expanded MPS-based and a SNP-based NIPT could potentially identify 87.4% and 79.1%, respecitively, of cytogenetic abnormalities among fetuses with structural anomalies. However, this assumes that NIPT has 100% detection of all intended anomalies. Accordingly, its detection in clinical practice will be less. Patients choosing NIPT as their primary genetic test for a structural abnormality must be informed of his limitations.View Large Image Figure ViewerDownload Hi-res image Download (PPT)
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关键词
fetal,diagnostic testing,non-invasive
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