How is the Diagnosis of Genetic Diseases in the Womb?

Many expectant parents wonder whether genetic diseases can be diagnosed in the womb. Today, thanks to the developing technology, there are different methods and tests to diagnose genetic diseases in the womb. If you are wondering how to diagnose genetic diseases in the womb, you can read the rest of our article.

What is Risky Pregnancy Status?

It is important to determine the risk of the baby in the mother’s womb in terms of genetic diseases. It is important to screen all pregnant women with detailed ultrasonography and to determine their risks by using special screening methods for special risk groups.

From this point of view, we can list the situations that may pose a risk as follows:

• Expectant mothers who are older than 35

• Mothers with recurrent miscarriages

• Couples with known carriers of genetic diseases such as cystic fibrosis, SMA (spinal muscular atrophy), chromosomal translocation carriers.

• Couples with a hereditary disease in their family, such as osteogenesis imperfecta, that is, glass bone disease.

• Pregnancies with anomaly detected in detailed ultrasound, such as heart diseases such as tetralogy of Fallot or tumoral diseases such as Neurofibromatosis

• Identical twins

• Pregnant women with metabolic diseases such as phenylketonuria

• Couples who lost their previous baby with an undiagnosed anomaly

Down syndrome is the most common chromosomal numerical disorder in pregnancy among genetic diseases. It occurs in 1 in 660 live births. After Down syndrome, Edwards, Patau and Turner syndromes can be counted. There are 46 pairs of chromosomes in every human cell, in other words, 23 pairs of chromosomes. An increase or decrease in this number creates a genetic disease. For example, in Down syndrome, there should be two of the 21st chromosomes, but there are three.

DiGeorge Syndrome is one of the most important examples of diseases that occur with the deterioration of structural changes of chromosomes. The most common chromosomal breakage disorder is DiGeorge Syndrome and occurs in 1 in 4000 births. 22. It is caused by a small break in the long arm of the chromosome, namely the loss of DNA. Another common chromosomal fracture disease is Angelman, or Happy Puppet disease. It is the long arm fracture of the 15th chromosome and occurs once in 12000 births.

An example of single gene diseases is SMA, Spinal Muscular Atrophy, which is better known in Turkey recently. Another example is cystic fibrosis.

Genetic Diseases Are More Passed From Whom?

It can be passed on from parents who are carriers of genetic diseases (autosomal recessive diseases). It can only be passed from surrogate mother to male offspring (X recessive diseases). It may occur for the first time in a fetus of healthy parents (De Novo mutation). There are many other forms of inheritance like this.

What are the Methods Used to Diagnose Genetic Diseases in the Womb?

We can list the common methods used to suspect and diagnose genetic diseases in the womb as follows:

• Family History (Anamnesis): Family history provides information about the genetic diseases or genetic risk factors that have existed in the past generations of the parents. Thus, the family tree is extracted. This information also makes it easier to identify possible genetic diseases.

• Detailed Ultrasound: Existing structural and functional disorders and anomalies are detected thanks to the detailed ultrasound performed by the Perinatology specialist for the baby in the mother’s womb. The risk of genetic disease in six due to the detected anomaly is explained to the family.

• Screening tests made from maternal blood: Screening tests made from maternal blood, such as double test, triple test, quadruple test and fetal DNA test, investigate the presence of genetic diseases, especially Down Syndrome in the fetus.

• Free Fetal DNA Test in Maternal Blood (also known as extracellular fetal DNA test, NIPT, NIFTY): It is another test that can be used to examine the genetic structure of the baby by taking blood from the mother, which has been developed and used in recent years. It is the test known as “free fetal DNA or cffDNA in maternal blood or non-invasive prenatal test, NIPT test” and can screen for Down syndrome with a success rate of 99%. It is the most successful of the screening tests.

• Amniocentesis: Amniocentesis is the process of genetic analysis by taking a sample from the fluid in the baby’s womb. It is possible to conduct genetic examination for all kinds of genetic diseases in the removed baby.

• Chorionic Villus Sampling (CVS): Chorionic villus sampling is done by taking a small tissue sample from the placenta of the baby in the womb. This tissue sample contains the baby’s genetic material and can be examined for any genetic disease.

• Cordocentesis: Cordocentesis is performed by taking a small amount of blood (usually 1-2 cc) from the baby’s umbilical cord in the later stages of pregnancy. With this test, which is performed after the 20th week of pregnancy, it is possible to diagnose various diseases. Examination of the baby’s blood is one of the most valuable methods. It enables the determination of many blood diseases and blood groups as well as genetic diseases.

You can contact Prof Dr Ali Ekiz for all genetic screening tests and diagnostic tests that should be done in the womb.