Clinical outcomes of screen-positive genome-wide cfDNA cases for trisomy 20: results from the global expanded NIPT Consortium

Table 2 Diagnostic testing outcomes and obstetric outcomes for study cohort

Case	Diagnostic testing results	Pregnancy complications	Pregnancy outcome	Category^a
1	Amniocentesis: Normal microarray	Fetal macrosomia	Term livebirth	Discordant
2	Amniocentesis: Normal microarray and UPD studies	Preeclampsia	Term livebirth	Discordant with adverse outcome
3	Amniocentesis: Normal (unspecified testing)	Unavailable	Unavailable	Discordant with unknown outcome
4^b	Amniocentesis: Normal microarray and FISH POC (cord): Normal (unspecified testing)	Multiple anomalies on ultrasound and autopsy	Elective termination	Discordant with adverse outcome
5^c	Amniocentesis: Normal microarray	Fetal growth restriction, gestational diabetes; Emergency preterm birth	Livebirth	Discordant with adverse outcome
6^d	Amniocentesis: Normal karyotype	Gestational diabetes; Preterm delivery	Livebirth	Discordant with adverse outcome
7	Amniocentesis: Normal karyotype	None reported	Term livebirth	Discordant
8^e	Amniocentesis: Normal karyotype Postnatal placenta: Normal karyotype	None reported	Term livebirth	Discordant
9^f	Amniocentesis: Karyotype 46,XY, add (20)p13 [2]/46,XY [14]	None reported	Term livebirth	Discordant^f
10	No diagnostic testing	Spontaneous fetal demise	Fetal demise at 13 weeks	Adverse outcome, no testing

N/a, not applicable
^aCases 1–8 could possibly represent confined placental mosaicism. Case 9, although discordant, could likely be explained by the mosaic partial duplication being interpreted as a trisomy 20 by the assay. Case 10 could possibly represent confined placental mosaicism or full or mosaic fetal trisomy 20 as the explanation for the fetal demise
^bFeatures consistent with prolonged oligohydramnios, bilateral small kidneys, small bladder, normal ureters, bilateral small lungs, abnormal horizontal sulcus in occipital lobes of brain, small areas of haemorrhage and possible haemosiderin deposition in the brain, possible fibrin thrombus 19 weeks gestation
^cEmergency preterm birth (C-section) due to cord prolapse. Eight-week stay in the neonatal intensive care unit
^dSpontaneous preterm birth < 37 weeks
^ePostnatal testing carried out on placental tissue, 6 biopsy samples all 46, XY
^fBaby required breathing support initially at birth. Jaundice due to ABO incompatibility, doing well otherwise. Although listed as discordant, it is likely that the mosaic partial duplication (duplication at 20p13) observed was related to the high-risk NIPT result for a trisomy 20

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