ABSTRACT
OBJECTIVE: To report secondary or additional findings arising from introduction of non-invasive prenatal testing (NIPT) for aneuploidy by whole genome sequencing as a clinical service. METHODS: Five cases with secondary findings were reviewed. RESULTS: In Case 1, NIPT revealed a large duplication in chromosome 18p, which was supported by arrayCGH of amniocyte DNA, with final karyotype showing mosaic tetrasomy 18p. In Case 2, a deletion in the proximal long arm of chromosome 18 of maternal origin was suspected and confirmed by arrayCGH of maternal white cell DNA. In Case 3, NIPT was negative for trisomies 21 and 18. In-depth analysis for deletions/duplications was requested when fetal structural anomalies were detected at routine scan. A deletion in the proximal long arm of chromosome 3 was found and confirmed by karyotyping. In Case 4, NIPT correctly predicted confined placental mosaicism with triple trisomy involving chromosomes X, 7 and 21. In Case 5, NIPT correctly detected a previously unknown maternal mosaicism for 45X. CONCLUSION: Non-invasive prenatal testing is able to detect a wide range of fetal, placental and maternal chromosomal abnormalities. This has important implications on patient counseling when an abnormality is detected by NIPT.
Subject(s)
Aneuploidy , Chromosomes, Human, Pair 21/genetics , Down Syndrome/diagnosis , High-Throughput Nucleotide Sequencing/methods , Prenatal Diagnosis/methods , Trisomy/diagnosis , Adult , Chromosomes, Human, Pair 18 , Chromosomes, Human, X/genetics , Clinical Laboratory Services , DNA/blood , DNA/genetics , False Negative Reactions , Female , Fetus/metabolism , Humans , PregnancyABSTRACT
Non-invasive prenatal screening for fetal Down syndrome (NIFTY) by maternal plasma sequencing was performed in 12 subjects with twin pregnancies, including 11 with normal fetuses and 1 with discordant fetal Trisomy 21. For every sample, it was processed, sequenced and reported as soon as it was collected as other clinical samples for singleton pregnancies. The NIFTY test was negative in the 11 pregnancies carried normal fetuses, and was positive (high risk) in the case with discordant fetal Trisomy 21. The sensitivity and specificity were both 100%. This small case series suggested the NIFTY as a screening test for fetal Trisomy 21 is feasible in twin pregnancies.
Subject(s)
DNA/blood , Diseases in Twins/diagnosis , Down Syndrome/diagnosis , Fetal Diseases/diagnosis , Pregnancy, Twin , Prenatal Diagnosis/methods , Adult , Biomarkers/analysis , Chorionic Villi Sampling , Diseases in Twins/genetics , Down Syndrome/genetics , False Positive Reactions , Female , Fetal Diseases/genetics , Humans , Karyotyping , Maternal Age , Nuchal Translucency Measurement , Pregnancy , Sequence Analysis, DNAABSTRACT
OBJECTIVE: To report the initial experience of noninvasive prenatal diagnosis of fetal Down syndrome (The NIFTY test) in a clinical setting. METHODS: The NIFTY test was offered as a screening test for fetal Down syndrome to pregnant women with a singleton pregnancy at 12 weeks of gestation or beyond. A satisfaction questionnaire was sent to the first 400 patients. RESULTS: During a 6-month period, 567 NIFTY tests were performed. Over 90% of those studied were ethnic Chinese, and the mean age of the women studied was 36 years. The test was performed at 12-13 weeks of gestation in 49.21%. The median reporting time was 9 days. The test was positive for trisomy 21 in eight cases, and for trisomy 18 in 1 case; all were confirmed by fetal karyotyping. There was no false-positive result. Of the questionnaires, 182 completed responses were received. Over 95% had complete or almost complete resolution of anxiety. Except for one, all were satisfied with the NIFTY test, and all indicated that they would recommend the test to their friends. CONCLUSION: The NIFTY test was a highly specific test. Unnecessary invasive tests and associated fetal losses could be avoided in almost all women who have a normal fetus.
