PAPPA and Down syndrome: The 713 samples with abnormal results in the PAPP-A test were divided into four subgroups according to risk type: 615 cases (615/713, 86.3%) with high risk of Down syndrome, 36 cases (36/713, 5%) with high risk of Edwards syndrome, 20 cases (20/715, 2.8%) with high risk of Patau syndrome and 42 cases (42/713, 5.9%) with high risk of trisomy 21, 18 and 13.