Prenatal Diagnosis

Prenatal diagnosis with the QF PCR method is the fastest and most reliable way to establish chromosome abnormalities during pregnancy.

The need of future parents to find out in the early stages of
pregnancy whether a risk exists for the regular development of
their child, can be satisfied with the most contemporary QF –
PCR prenatal diagnosis, which is applied in the Helix
Laboratory.

The majority of genetic disorders lead to miscarriages during the
first months of pregnancy, however, certain chromosome anomalies
will not have a fatal outcome, but will cause serious mental
disorders in children – the Patau syndrome (change to 13 chromosomes),
the Edwards syndrome (18 chromosomes), Down syndrome (21
chromosomes), as well as anomalies of the sex chromosomes XY
such as Turner’s and Klinefelter’s syndromes.
With rapid DNA diagnosis which our biologists and doctors use,
it is possible to establish changes on the chromosomes during the
first weeks of pregnancy, when an eventual decision about an abortion
is medically justified and safe as far as the woman is concerned.
The first DNA analysis of the fetus is performed in the eight week
of pregnancy by taking a sample from the chorionic villus sampling
(one of the three embryonic membranes), and this is also a way to find
out which sex the baby is as early as possible, together with the existence
of chromosome aberrations. If the DNA analysis is performed in the 16th to
18th week of pregnancy, a sample from the amniotic fluid is taken
(amniocentesis), and for testing the baby’s condition after the
21st week of pregnancy, a sample of the fetus’s blood from the
umbilical cord (cordosynthesis) is used.
The advantages of the QF-PCR technology in comparison to the
classic cytogenetics which are otherwise used in the health
institutions in the country for the above stated analysis, are manifold.

•    The time spent waiting for results of prenatal diagnosis with the
DNA method is 24 hours, while waiting for the results for classic cytogenetics can last up to a few weeks. This is especially important after the 16th
week of pregnancy, where during this the 20th week of pregnancy
commences, together with greater complications as far as intentional
abortions are concerned (one has to receive the unanimous approval of the
Ethic Board of the health institution, while abortions in advanced
pregnancies increase the risk of serious psychological and physical
traumas for the woman).

•    Contamination of the sample – when in doubt that the mother’s and
the baby’s chromosomes have been mixed, which is possible when
analyzing the fetus in the later weeks of pregnancy. In those cases,
classic cytogenetics cannot differentiate the one from the other chromosomes
and cannot issue valid results, while the QF-PCR method is the only one
that can do that.

International statistics are relentless and according to them, almost a fourth
of all pregnancies carry a risk of chromosome abnormalities.
The most frequent being trisomy (the existence of one surplus chromosome) 21,
i.e. the Down syndrome. The possibility of mongoloidity of the baby
increases with the mother’s age, and according to clinical studies one
out of 360 pregnancies, in pregnant women over 35, carries that risk.
The Helix laboratory is the only institution in Serbia which applies this
DNA testing method, while in the UK, where this technology
originates from, this manner of testing gene abnormalities in the
prenatal stadium – is the golden rule.

Risk Factors

•    Pregnancies of women over 30
•    Women who have already had a miscarriage or a premature child
•    Women who have previously given birth to children with genetic disorders
•    Families with known hereditary diseases
•    Women with high blood pressure, diabetes, asthma, epilepsy

Incidents for trisomy 21 (Down syndrome) depending on the age group of the
pregnant woman:
25 years 1/1.200
30 years 1/800
35 years 1/360
40 years 1/100
45 years 1/32

•    Incidents for trisomy 13 (Patau syndrome) 1/20.000
•    Incidents for trisomy 18 (Edwards syndrome) 1/10.000

RESEARCHING THE CAUSES OF MISCARRIAGE:

The DNA method enables and establishes the causes of miscarriages, i.e.
checks whether the miscarriage occurred due to chromosome abnormalities.
This service is mostly required by doctors/obstetricians, while results
can be received in a day. Beside chromosomes which are tested within
prenatal diagnosis in this case tests are also carried out on 15, 16 and 22
chromosomes whose abnormalities can lead to miscarriages. These analyses
are important for pregnant women who have difficulty conceiving, i.e.
maintaining the fetus, in order to find the causes in an easier manner.