In vitro fertilization (IVF) is used when couples with infertility problems have no other options. To increase the chances of success, IVF genetics testing is employed to determine which embryos have better quality and more likely to result to a successful pregnancy. IVF genetics screening is also performed to help reduce the risk of passing to the embryo the parent's genetic disorders.
The following are the different techniques of IVF genetics screening.
Comparative Genomic Hybridization or CGH
Comparative genomic hybridization or CGH is a method used to evaluate every chromosome of each cell. CGH is also known as comprehensive chromosome screening. CGH helps the doctors determine which embryo has chromosomal abnormalities and helps them decide which egg will most likely succeed.
Preimplantation Genetic Diagnosis/Screening or PGD/PGS
PGD/PGS is a technique used to determine and examine embryos which maybe carrying an inherited disease.
There are two steps to determine the genetic makeup of an embryo.
Embryo Biopsy
Embryo biopsy procedure is similar to assisted hatching where a laser is used to create a hole through the outer shell of an embryo. The hole would be slightly bigger than that of an assisted hatching for easy access to the cells inside the embryo. Two or more cells will be removed and biopsied. Once completed, the embryo is given 48 hours before it is returned back to the uterus or stored in a refrigerator.
Determination of the Genetic Information
Determining the genetic information of the embryo is done in two ways. First is finding out the chromosomal composition of the embryo or also known as aneuploidy screening. Aneuploidy screening is done to identify if an embryo has normal or abnormal chromosomal composition. Second is recognizing the absence or presence of a specific gene. This type of genetic information is useful when one of the parents is a carrier of a genetic disease. The most common genetic diseases are Tay-Sachs, Cystic Fibrosis, Sickle Cell Disease, and Hemophilia.
Preimplantation Genetic Haplotyping or PGH
PGH is a more advanced type of PGD as it employs DNA fingerprinting instead of determining the real genetic signature.
Compared to PGD, PGH:
- Allows identification of male embryos
- Has increased reliability
- Has higher success rate
Fluorescence in Situ Hybridization or FISH Analysis
FISH analysis allows identification of specific chromosomes with the use of fluorescent probes. These can be seen through a fluorescent microscope. Currently, only up to 9 chromosomes can be detected.
Polymerase Chain Reaction or PCR
Polymerase chain reaction is a method used to analyze the sequence of a DNA. PCR is used to amplify selected sections of the DNA. Amplification involves cloning a certain part of the DNA and making several copies. Applied in IVF genetics screening, PCR allows detection of embryos with mutated genes.
Before undergoing IVF treatment, it is better that couples know that there are options for IVF genetics screening. Couples must discuss these options with their doctor and determine which IVF genetics method will be more helpful to their case.