Patent ID: 6010912
Filing Date: 2000-01-04
Classification: G01N,G16H,Y10S

Abstract:
A method for antenatal screening for a chromosomal abnormality in a fetus, comprising:A) calculating a pregnant patient's a priori risk of carrying a fetus having said chromosomal abnormality,B) measuring said pregnant patient's blood in the first trimester for a concentration of free beta hCG, its precursors and metabolites, or a mixture thereof,C) measuring said pregnant patient's blood in the first trimester for a concentration of pregnancy associated plasma protein A, its precursors and metabolites, or a mixture thereof,D) calculating a normalized value for each of said concentrations from steps B) and C) by dividing said concentrations by a median value found in a population of women with unaffected pregnancies and same gestational age as said pregnant patient,E) calculating a first probability that the normalized values are part of a bivariate Gaussian distribution of values found in pregnancies with said chromosomal abnormality,F) calculating a second probability that the normalized values are a part of a bivariate Gaussian distribution of values found in unaffected pregnancies,G) calculating a likelihood ratio, said likelihood ratio being the ratio of said first probability and said second probability, andH) modifying the a priori risk by the likelihood ratio.