Table 6.

Invasive test results of 3 false-negative NIPT samples

Sampling site				Karyotype
Placenta				case 1		case 2		case 3
Fetal surface		0		T21 (10% mos)		46, XN		T18 (40% mos)
		3		T21 (23% mos)		46, XN		T18
		6		T21		46, XN		T18
		9		T21 (58% mos)		46, XN		T18
		Central		T21		46, XN		T18
Maternal surface		0		T21		46, XN		T18 (37% mos)
		3		T21 (31% mos)		46, XN		T18 (56% mos)
		6		T21		46, XN		T18 (41% mos)
		9		T21		46, XN		T18 (49% mos)
		Central		T21		46, XN		T18 (46% mos)
Fetus		Muscle		T21		T21		T18
		Skin		T21		T21		T18

Mos Mosaic, N X or Y, T21 Trisomy 21, T18, Trisomy 18; 0, 3, 6, 9, and central: the tissue sampling sites according to the Clock face notation