Hum. Reprod. Advance Access originally published online on June 21, 2007
Human Reproduction 2007 22(8):2267-2272; doi:10.1093/humrep/dem154
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Elevated levels of total (maternal and fetal)
-globin DNA in maternal blood from first trimester pregnancies with trisomy 21
1 Department of Obstetrics and Gynecology, Baylor College of Medicine, 2450 Holcombe Blvd, Houston, TX 77054, USA 2 Department of Obstetrics and Gynecology, Columbia University, New York City, NY, USA 3 Department of Obstetrics and Gynecology, University of Bologna, Italy 4 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, USA
5 Correspondence address. Tel: +1-713-798-8885; Fax: +1-713-798-5575; E-mail: bischoff{at}bcm.tmc.edu
BACKGROUND: Elevated levels of circulating fetal DNA have been observed in maternal plasma when a trisomy 21 fetus is confirmed. However, these studies have been limited to pregnancies carrying a male fetus. We sought to quantify total (fetal and maternal) DNA from dried blood spots (DBS) for use as an additional factor in multi-parameter prenatal screening for aneuploidy.
METHODS: Maternal DBS were obtained from the NICHD-sponsored multi-center cohort (BUN) study. Seventeen confirmed trisomy 21 (mean gestational age 12.23 ± 0.77 weeks) cases were each matched by gestational age to euploid controls (n = 30). DNA was extracted and quantitative PCR was performed to measure four non-chromosome 21 loci, including glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (12p13),
-globin (11p15.5),
-actin (7p15–12) and p53 (17p13.1).
RESULTS:
-Globin DNA levels were significantly elevated (P = 0.003) in 13 of 17 trisomy 21 cases (4.08 ± 1.78 Geq/ml x 105) compared with matched controls (2.35 ± 1.84 Geq/ml x 105). Following conversion of
-globin concentrations into multiples of the median (MoM), MoM for trisomy 21 cases was 2.8 compared with 1.0 in euploid cases. No significant differences in levels of circulating GAPDH,
-actin and p53 sequences were detected.
CONCLUSIONS: This work demonstrates differential levels of circulating
-globin DNA in maternal blood of euploid and trisomy 21 cases. Sequence-specific quantification could provide an additional measure to improve non-invasive methods of prenatal screening to detect trisomy 21 using dried blood.
-Globin in particular is an attractive biomarker that could contribute to enhance multiple serum parameter testing in the first trimester.
Key words:
-globin/cell-free fetal DNA/maternal dried blood spot/non-invasive prenatal diagnosis/trisomy 21
Submitted on February 23, 2007; resubmitted on April 20, 2007; accepted on May 10, 2007.