The discovery of free fetal DNA in plasma of pregnant women has opened a new avenue for non-invasive prenatal diagnosis. We hypothesized that epsilon (ɛ)-globin gene expression could serve as a positive control for the presence of fetal nucleic acid.
We measured ɛ-globin mRNA in human fetal tissues and compared concentrations with that measured in adult non-pregnant and pregnant samples. Total RNA was isolated from fetal marrow, liver, blood, and placenta (10–24 weeks gestation), from adult peripheral blood mononuclear cells, and from maternal plasma. RNA was reverse transcribed and quantitative polymerase chain reaction performed for ɛ-globin expression.
ɛ-globin gene expression was detected in all fetal samples, was detected in plasma of pregnant women, but was negligible in non-pregnant samples. Relative ɛ-globin gene expression was significantly greater in fetal blood compared to fetal liver, and was minimally expressed in placenta. ɛ-globin gene expression decreased at the highest gestational ages in fetal blood, while expression was greatest at 15–19 weeks in fetal marrow.
Fetal ɛ-globin gene expression is significantly greater than adult expression and is increased in maternal plasma compared to non-pregnant samples. ɛ-globin gene expression might serve as a positive control when determining the presence of fetal nucleic acid in total nucleic acid isolated from maternal plasma.