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Baby's genome decoded from mom's blood,
pop's saliva
Friday June 08, 2012 09:12:20 AM,
IANS
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Washington: Using a
non-invasive technique, scientists for the first time have
successfully sequenced the genome of a foetus without tapping its
protective fluid sac.
Maternal blood sampled at about 18 weeks into the pregnancy and a
paternal saliva specimen had enough information for the scientists
to map the foetus' DNA.
This method was later repeated for another expectant couple closer
to the start of pregnancy. The researchers checked the accuracy of
their genetic predictions using umbilical cord blood collected at
birth, the journal Science Translational Medicine reports.
Jacob Kitzman and Matthew Snyder, working in the lab of Jay
Shendure, associate professor of genome sciences at the University
of Washington, US, led the study.
Scientists have long known that a pregnant woman's blood plasma
contains cell-free DNA from her developing foetus, according to a
Washington statement.
Foetal DNA appears in the mother's plasma a few weeks after
conception. It rises during gestation and normally vanishes after
the baby arrives. While the concentration varies among
individuals, about 10 percent of the cell-free DNA in a pregnant
woman's blood plasma comes from her foetus.
Based on this phenomenon, other research labs are designing
maternal blood tests for major aberrations in the foetus' genetic
makeup. The tests are considered a safer substitute for the more
invasive sampling of fluid from the uterus, a common procedure in
obstetrical practice.
These new tests search for just a few genetic disorders or
specific birth abnormalities. For example, a test targeted for
Down Syndrome would look for evidence of three copies of
chromosome 21.
Kitzman explained what distinguishes his team's latest methods is
the ability to assess many and more subtle variations in the
foetus' genome, down to a minute, one-letter change in the DNA
code.
"The improved resolution is like going from being able to see that
two books are stuck together to being able to notice one word
misspelled on a page," said Kitzman.
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