A new diagnostic test employing fetal DNA could reduce
invasive procedures such as amniocentesis and chorionic
villus sampling (removal of tissue from the uterus) to
determine if birth defects exist.
In "A Non-invasive Test for Prenatal Diagnosis Based
on Fetal DNA Present in Maternal Blood: A Preliminary
Study," now available online in The Lancet, School of Nursing
baccalaureate student Kara Franz and other members of a
research team at the private biotech firm where she once
worked describe a new methodology for isolating fetal DNA
to diagnose chromosomal abnormalities.
Franz and her former co-researchers note in the study
that "such testing has been hindered by the inability to
distinguish fetal DNA from maternal DNA and distinguish the
number of fetal chromosomes in the mother's blood sample."
The study focused particularly on trisomy 21, the
chromosomal abnormality associated with Down Syndrome. In a
test of 60 pregnant women, with a median age of 34 and an
average length of pregnancy of 17-plus weeks, the test
results in 58 of 60 samples were correctly established
through amniocentesis or newborn reports. One of the
incorrectly identified samples was a false positive and the
other, a false negative. With further refinement, the
researchers said, the test could become a useful complement
to available prenatal tests.
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