Gene expression profile of trisomy 21 placentas: a potential approach for designing noninvasive techniques of prenatal diagnosis.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of the DNA microarray technology for the study of the differences in gene expression between placentas of pregnancies with trisomy 21 fetuses and placentas of fetuses with a normal karyotype. STUDY
DESIGN: Complementary DNA samples from 7 second-trimester placentas of fetuses with trisomy 21 was compared with 7 matched and 7 nonmatched complementary DNA samples from normal karyotype placentas as control samples. For gene expression comparison, a microarray that contained 8976 expressed sequence tags was used. Four experiments were performed: (1) the study samples were compared with matched control samples; (2) the study samples were compared with nonmatched control samples; (3) the study samples were compared with themselves; and (4) the matched and nonmatched control samples were compared. Gene overexpression and underexpression were defined as sample signal differences of >1.7 over each other. Gene overexpression and underexpression were confirmed by Northern blotting studies.
RESULTS: Seven expressed sequence tags of 8976 tags that were examined have met the selection criteria. Overexpression of 2 expressed sequence tags in placentas with trisomy 21 was confirmed by Northern blotting studies.
CONCLUSION: Our study demonstrates the feasibility of the microarray technique in the study of the differences of gene expression in trisomic placentas compared with placentas with a normal karyotype. This technique may contribute to the identification of additional maternal serum biochemical markers in aneuploid pregnancies.