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Single Gene Defect
Analysis
PGD for single gene defect (SGD) uses
gene amplification to reveal serious genetic conditions that
couples may wish to avoid. Using PGD with SGD, the IVF team
will transfer only embryos diagnosed as unaffected, greatly
increasing the chances of having unaffected children.
Partial List of conditions
that PGD/FISH and PGD/SGD can detect:
- Cystic
Fibrosis
-
Duschenne Muscular Dystrophy
- Retinitis
Pigmentosa
- Charcot-Marie-Tooth
disease
- alpha-1-antitrypsin
deficiency
- Down's
Syndrome
- Fragile
X syndrome
- Lesch-Nyhan
syndrome
- Turner
Syndrome
- Huntington's
Chorea
- Phenylketonuria
(PKU)
- Gaucher's
disease
- Hemophilia
How
is PGD preformed?
PGD is preformed on embryos that result
In Vitro Fertilization. Multiple eggs are retrieved from the
ovaries and fertilized with the husband's sperm in our lab.
Three days after in vitro fertilization, when each embryo
contains 6 to 8 cells, one cell is removed from each embryo
through a procedure called Embryo Biopsy. These cells are
then sent to a specialized lab for genetic analysis. During
the analysis on the single cell, the embryos are kept in culture
and allowed to continue to develop. It takes about 48 hours
to get the results, and embryos are then transferred at the
day-5 blastocyst stage. These technologies identify which
embryos are mostly likely to produce a normal, unaffected
pregnancy. The embryos identified as normal or non-affected
are then replaced in the uterus. Generally this takes place
6 days after the eggs are retrieved. The number of embryos
replaced follows standard IVF protocol. The post procedure
treatment follows the same routine as a standard IVF case.
Who
should have PGD?
There are two distinct
groups of patients who can benefit from PGD. The first group
of patients is those couples at risk for passing on an inherited
genetic disease due to a single gene defect. PGD dramatically
improves the odds of having a baby without the disorder since
affected embryos are identified and not transferred. Some
disorders only affect male offspring, so that female embryos
may be selected to avoid the condition even if the exact defect
isn't understood. The second group of patient is those couples
with advanced maternal age, multiple pregnancy losses, or
multiple failed IVF pregnancy attempts. In these instances
PGD can be used to select embryos with a normal number of
chromosomes. This will increase the likelihood of a normal
pregnancy. Please
call our office to learn more about these exciting new
clinical tools.
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