SCHWANGERSCHAFTSPROTEIN-1 (SP1) AS A MATERNAL SERUM MARKER FOR DOWN-SYNDROME IN THE FIRST-TRIMESTER AND 2ND-TRIMESTER

The potential of the maternal serum concentration of schwangerschaftsp rotein 1 (MSSP1) as a marker for Down syndrome (DS) pregnancies was ev aluated in the fifth to the 20th gestational week using 156 DS pregnan cies and 546 unaffected control pregnancies. In DS pregnancies, the me dian of the multiple of the median (MOM) of MSSP1 was 0.27 [95 per cen t confidence interval (CI) 0.11-0.59] in weeks 5-9 (n = 25) and 1.28 ( CI 1.11-1.49) in;weeks 14-20 (n = 117), significantly different from c ontrols (P < 10(-6)). In weeks 10-12, the median MSSP1 MOM was 0.89 (C I 0.20-2.09) (n = 14), not different from controls (P = 0.42). Using M SSP1 alone as a marker for DS gave-in empirical receiver-operator-char acteristics (ROC) analysis-a detection rate of about 44 per cent for a false-positive rate of about 5 per cent in weeks 5-9 (using MSSP1 MOM less than or equal to cut-off), whereas a sensitivity of about 20 per cent was found for a false-positive rate of 5 per cent in weeks 14-20 (using MSSP1 MOM greater than or equal to cut-off). In parameterized ROC analysis, the detection rates were 38 and 18 per cent for a false- positive rate of 5 per cent in weeks 5-9 and 14-20, respectively. (C) 1997 by John Wiley & Sons, Ltd.