RSS Feed
June 7th, 2012 
FAKE NEWS for the Zionist agenda WEDNESDAY, June 6 (HealthDay News) — Researchers report they
have decoded the entire genome of a fetus using only a blood sample from
the mother and a saliva sample from the father.
The scientists said prenatal genome sequencing using the noninvasive
method could one day be used to determine if a fetus has any of the
thousands of genetic disorders that are caused by a single, often
devastating, mutation on one gene.
In pregnant women, bits of fetal DNA move through the mother’s body in
the plasma, a component of blood. Unlike a sample of DNA taken directly
from fetal tissue or from amniotic fluid — such as when expectant mothers
undergo amniocentesis to look for chromosomal disorders such as Down
syndrome — the DNA in plasma is in fragments.
That makes analyzing it complex, but increasingly possible given the
latest generation of gene-sequencing technology, explained study author
Jay Shendure, an associate professor of genome sciences at the University
of Washington.
“The chromosomes are shattered, but all the information is there,
represented in small fragments,” Shendure said.
In the current study, researchers used plasma from a woman who was 18
weeks pregnant and saliva from the dad to tease out which was fetal DNA.
Researchers confirmed the accuracy of their conclusions by mapping the
baby’s DNA using umbilical cord blood after birth.
Testing for genetic problems using a blood sample and saliva would be
an improvement over more-invasive tests such as amniocentesis, which can
pose risks to the fetus, Shendure said.
“This fits in quite well with what we do today, which is to provide
expectant mothers with as much information as we can,” Shendure said. “It
would simply be more comprehensive.”
Still, he noted, the paper should be viewed as a “proof of concept,” or
showing that noninvasive whole fetal genome sequencing was possible. More
research is needed before the technique is ready to be used in doctor’s
offices, he said.
The study is published in the June 6 issue of Science Translational
Medicine.
Until the last few years, whole genome sequencing has been
extraordinarily expensive. That began to change after the Human Genome
Project produced the first whole human genome in 2001 at a cost of about
$3 billion. By 2010, sequencing an entire genome cost around $50,000,
while experts now put the cost at a few thousand dollars and dropping.
“The study is the next logical step in beginning to figure out how to
use this amazing new technology we have that allows very robust sequencing
of the genome. We now are in a situation [where], for relatively
affordable and dropping prices, one can evaluate an individual’s whole
genome,” said Dr. James Evans, editor-in-chief of Genetics in
Medicine, the journal of the American College of Medical Genetics and
Genomics.
Already there are several commercial companies that sift through the
fetal DNA in plasma to look for an extra copy of chromosome 21 that
indicates Down syndrome, Evans said.
But there are some 3,000 other single-gene genetic disorders that
individually are rare, but collectively affect up to about 1 percent of
births, Shendure said. Those diseases include Tay-Sachs, Marfan syndrome,
cystic fibrosis, Huntington’s disease and Kabuki syndrome.
The fetal genome sequencing could tell parents before the baby is born
if the child has the mutation that causes the disease, informing their
decisions and helping them to prepare, Shendure said — not unlike what
amniocentesis and other prenatal tests such as ultrasound offer today.
But significant questions remain, including how early in the pregnancy
whole genome sequencing could be done. Research has found that there is
fetal DNA in the mother’s plasma between four and seven weeks, but
researchers have not yet determined if the technique would give an
accurate picture of a fetal genetic profile that early, Shendure said.
(Their analysis of maternal plasma at 8.2 weeks gestation turned up fetal
DNA in the mother’s blood.)
Levels of fetal DNA in the mother’s plasma fluctuate during pregnancy,
and disappear at birth. Because about 90 percent of the DNA in plasma is
from the mother, while only about 10 percent comes from the fetus,
researchers had to do complicated biostatistical analysis to determine
what belonged to baby and what belonged to mom.
And although babies inherit one copy of each gene from mother and
father, new mutations can arise that aren’t found in the mother or the
father’s genes, which further complicates the analysis.
However, perhaps the biggest challenge is how to interpret all of the
information, Evans said. Not only does it take time, researchers don’t
know what every mutation means as far as disease.
“When you do a whole genome sequence, you end up with millions of
variants. The biggest challenge facing our field is to understand which
variants are importantly clinically and which are meaningless,” Evans
said.
For example, Shendure noted, mutations on the BRCA1 and 2 genes are
known to be associated with a much higher risk of breast cancer. But even
after many years and tens of thousands of tests, researchers still come
across mutations on those genes that they haven’t seen before and
therefore aren’t sure if they really mean a heightened risk of breast
cancer.
“We have only begun to scratch the surface in our ability to interpret
the findings in a whole genome sequence,” Evans said. “This should been
seen as very much in the realm of research. It is not ready for clinical
application.”
What prenatal whole genome sequencing likely won’t be used for
anytime soon time is to predict a baby’s likelihood of going on to develop
common diseases such as heart disease and diabetes, experts said.
While there is plenty of research that links various mutations with a
heightened risk of various diseases, genetics remains a poor predictor,
Evans said. Instead, other, more obvious influences such as diet,
exercise and whether a person smokes remain the best bet for predicting
who’s going to develop the more common chronic diseases, Evans said.
“Measuring weight and asking them a few questions about activity and
lifestyle does a far better job of figuring out, for example, heart
disease risk,” Evans said.
Shendure agreed. “These single-gene disorders are the things we
understand the best, and even there it’s challenging,” he said.
More information
Read more about the Human Genome Project.
Related posts:
Views: 0
Posted in 
Tags: 
