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.