Schwangerschaftsprotein 1 (SP1) as a maternal serum marker for Down syndrome in the first and second trimesters

Abstract

The potential of the maternal serum concentration of schwangerschaftsprotein 1 (MSSP1) as a marker for Down syndrome (DS) pregnancies was evaluated in the fifth to the 20th gestational week using 156 DS pregnancies and 546 unaffected control pregnancies. In DS pregnancies, the median of the multiple of the median (MOM) of MSSP1 was 0.27 [95 per cent 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 controls (P < 10(-6). In weeks 10-12, the median MSSP1 MOM was 0.89 (CI 0.20-2.09) (n = 14), not different from controls (P = 0.42). Using MSSP1 alone as a marker for DS gave--in empirical receiver-operator-characteristics (ROC) analysis--a detection rate of about 44 percent for a false-positive rate of about 5 per cent in weeks 5-9 (using MSSP1 MOM < or = cut-off), whereas a sensitivity of about 20 percent was found for a false-positive rate of 5 percent in weeks 14-20 (using MSSP1 MOM > or = cut-off). In parameterized ROC analysis, the detection rates were 38 and 18 percent for a false-positive rate of 5 per cent in weeks 5-9 and 14-20, respectively.