therefore can tell you definitively
if the baby is affected with a
genetic disorder or not. As these
are invasive tests, there is a risk of
miscarriage associated with the
procedures.
NON-INVASIVE PRENATAL
TESTING (NIPT)
A simple test using the mother’s
blood can now tell doctors more
about the pregnancy than ever
before. Did you know that pieces
of the baby’s DNA circulate in the
maternal bloodstream?
DNA is the blueprint of life—it
holds all of the genetic information
required for our bodies to
function. DNA carries this genetic
information on chromosomes.
Healthy humans have 23 pairs of
chromosomes. Any more or less
can lead to problems.
NIPT is a screening test that
analyzes the fetal DNA (cell-free
or cfDNA) that circulates in the
maternal blood to determine the
baby’s risk for a number of genetic
abnormalities.
WHAT CONDITIONS CAN
THE TEST DETECT?
The test screens for the most
common chromosomal
abnormalities, which can cause
serious birth defects, intellectual
disability, or other problems in the
baby. The test can also tell you the
sex of your baby, if you wish to
know.
THE TEST CAN ALSO
DETECT ABNORMALITIES OF
THE SEX CHROMOSOMES:
Turner syndrome (Monosomy
X), which is caused by a missing
X chromosome in females.
The disorder may cause heart
defects, hearing problems,
stunted growth, infertility and
minor learning disabilities.
Many pregnancies with Turner
syndrome miscarry before
delivery.
Klinefelter syndrome (XXY),
which is caused by an extra
X chromosome in males. The
disorder may cause delayed
or absent puberty, learning
A NON-INVASIVE PRENATAL
TEST CAN SCREEN FOR
Down syndrome (Trisomy 21), which is caused by
an extra copy of chromosome 21. The disorder is the
most common genetic cause of intellectual disability,
and it may also cause heart defects, other organ
defects, and hearing or vision problems.
Edwards syndrome (Trisomy 18), caused by an extra
copy of chromosome 18. The disorder causes severe
intellectual disability along with serious defects
of the heart, brain and other organs. Babies with
Edwards syndrome usually survive less than one year.
Patau syndrome (Trisomy 13), caused by an extra
copy of chromosome 13. The disorder causes severe
intellectual disability and many serious birth defects.
Babies with Patau syndrome usually survive less than
one year.
difficulties and tall stature. Most
males with Klinefelter syndrome
are infertile.
XYY or XXX syndrome,
which is caused by an extra Y
chromosome in males or an
extra X chromosome in females.
Individuals with this disorder
may have tall stature and an
increased risk for learning
difficulties or delayed motor
skills. Fertility is not usually
affected and some individuals
have no symptoms at all.
IF YOUR HEALTHCARE
PROVIDER RECOMMENDS
IT, THE TEST CAN
ALSO SCREEN FOR THE
FOLLOWING CONDITIONS,
WHICH ARE NOT
ROUTINELY TESTED:
Trisomy 9, an extra copy of
chromosome 9
Trisomy 16, an extra copy of
chromosome 16
Common micro-deletions
such as DiGeorg e syndrome,
Angelman syndrome, PraderWilli syndrome, WolfHirschhorn syndrome and Cridu-chat syndrome— which are
all caused by the loss of a small
piece of a chromosome.
WHAT WILL THE RESULTS
REPRESENT?
If your results are normal, this
means that the disorders tested
for were not detected, which can
provide significant reassurance.
In the case of an abnormal
result, your healthcare provider
will discuss what that means for
your pregnancy and will offer a
diagnostic test such as CVS or
Amniocentesis to confirm the
result.
WHEN CAN THE TEST BE
DONE?
The test can be performed from
week 10 onwards of the pregnancy.
(Written by Sonika Sachanandani-Phulwani-Genetic Counselor)
Contact: [email protected]
Mar/Apr 2016
19