Secondary findings from non-invasive prenatal testing for common fetal aneuploidies by whole genome sequencing as a clinical service.

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.