Behind every expectant mother, regardless of age, origin or course of pregnancy, lies a risk of about 2-3% for giving birth to a child with congenital anomalies.
The standard examination that every pregnant woman undergoes is the familiar fetal morphology.
Fetal morphology
Fetal morphology is an ultrasound examination that is performed around the twentieth gestational week of pregnancy. Through the examination, structural abnormalities of the fetus are detected - cranial box, orbits, lips, spine, heart, lung, diaphragm, stomach, kidneys, bladder, abdomen, umbilical cord, limbs, sex organs.
Some genetic abnormalities give early manifestations in structural development, but others remain hidden despite the chromosomal defect. Fetal morphology provides information about severe congenital structural abnormalities, but cannot detect all possible fetal malformations and does not guarantee the birth of a completely healthy child.
More and more couples are taking the IVF route for reasons of various origins, with an undiagnosed genetic problem being an increasingly common reason.
Fortunately, specialists have good helpers in this not easy task to create life. The procedures require precision and maximum knowledge of the organism of the future parents. This is a query to create a quality and healthy embryo, the wear and birth of a healthy child.
Some investigations are recommended in parents, especially when there is uncertainty about which of the two parents is the carrier of a chromosomal abnormality that has manifested in a first-born child.
FISH (fluorescence in situ hybridization) is a laboratory technique for detecting and locating a specific DNA sequence on chromosomes. It is performed using a probe to which a fluorescent molecule is attached that stains a specific part of the DNA. The piece of DNA has a corresponding segment on one of the chromosomes viewed under the microscope. The fluorescent staining makes it possible to trace to which segment of the chromosome the piece of DNA is attached. In this way, it can be determined from which parent the carrier of a genetic disease or chromosomal defect comes.
The test is performed by taking a sample of peripheral blood, fixed tissue or a bone marrow smear. The disadvantage of FISH is that it can only detect common genetic abnormalities as it is run through a template. Specifically, it is primarily used to detect the presence or absence of a particular chromosomal abnormality. For example: Detection of chromosomal translocation in a patient with chronic myelogenous leukemia. In this case, the defect is in a segment of the 9th chromosome, i.e. a probe specimen is inserted for the 9th chromosome.
PGT pre-implantation genetic tests
The purpose of these genetic tests is to increase the chance of selecting a healthy embryo that will develop into a healthy baby. Poor quality embryos almost never fail to implant, and if they do most often only result in a biochemical pregnancy or miscarriage. In some cases, the process evolves to the birth of a child with serious abnormalities.
For ease of understanding and grouping the reason for testing, preimplantation testing is broken down into several smaller groups:
- PGT-A
Embryos with an incorrect number of chromosomes (also called aneuploid embryos) usually do not result in a successful pregnancy or may result in the birth of a child with a genetic disorder. PGT-A identifies embryos with the correct number of chromosomes. This allows the geneticists involved in your procedures to select the embryo with the best chance of success. - PGT-M is suitable for people who are at high risk of transmitting a specific single gene disorder.
PGT-M is recommended if:
- You and your partner are carriers of the same autosomal recessive condition (e.g. cystic fibrosis)
If any of you suffer from:
- Duchenne dystrophy or an autosomal dominant condition such as Huntington's disease
- Mutation associated with hereditary carcinoma syndrome /BRCA 1 and 2/
- If you have had a pregnancy or a child with a genetic disability - PGT-SR
Translocations of chromosomes can be inherited or can occur spontaneously. Many carriers of balanced chromosome translocations are healthy and do not suspect a problem until they try to have children. Carriers of balanced translocations can create embryos with an irregular structure of chromosomal material or a missing part of the chromosomes. PGT-SR can be used to identify embryos with correct chromosome integrity that are most likely to result in a successful pregnancy and a healthy child.
Pre-implantation genetic diagnosis /PGD/ and pre-implantation genetic screening /PGS/. These terms are used interchangeably, but they are actually different.
Preimplantation genetic screening PGS
Preimplantation genetic screening PGS examines the chromosomes in an embryo created by Invitro or ICSI. It determines whether the set of chromosomes in the future organism is correct.
The correct set of chromosomes is 23 pairs of chromosomes (i.e. 46 chromosomes). As the last pair of chromosomes in males and females is different. Accordingly: women - XX, men - XY.
Preimplantation genetic diagnosis PGD
Preimplantation genetic diagnosis PGD is commonly used by couples with a family history of a serious or deadly disease that they can pass on to their future child. They look for markers of a particular disease, such as cystic fibrosis or sickle cell anaemia, or a familial burden of a sex-linked disorder such as 'broken X chromosome syndrome', or muscular dystrophy.
PGD is also used to detect matched stem cells when bone marrow transplants are needed.
Comparative genomic hybridization CGH
CGH - Comparative genomic hybridization is a genetic testing method that identifies chromosome breaks /deletions/ or duplications at the microscopic level, invisible to other tests.
The main advantage of CGH is that it detects changes in DNA copies throughout an organism's hereditary information in a single test. The results are available in a few weeks.
However, CGH did not detect balanced chromosomal abnormalities that did not result in altered DNA copies. For this reason, the method is often combined with FISH.
Comparative genomic hybridization is used both prenatally and in pediatrics or in adult patients with specific indications.
In connection with the Comparative Genomic Hybridization (CGH) technique, a more specific form of testing, the aCGH (microarray technique), has been developed. DNA microarrays examine the contents of two different DNA samples using higher resolution. Through this optimized technique, it is possible to discover the etiology of rare conditions, as well as to explain different phenotypic variations in similar symptoms - for example, similar manifestations in Wolff-Hirschhorn syndrome and Turner syndrome.For more information, we at Medical Karadje are at your service.
Call us on the following numbers "Medical Karaj": 0879 977 401 or 0879 977 402.
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