How DNA tests can detect earlier signs of a genetic disorder in a fetus?

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Genetic disorders are very serious illnesses that are caused due to genetic disorders which are caused by a mutation in one gene, by mutations in multiple genes, by damage to chromosomes.


Aneuploidy is a chromosomal disease in where no. Chromosome decreases or increases than the normal no. Due to mutations.

In a trisomy, there is an extra chromosome.

In monosomy, a chromosome is missing.

Genetic disorders


Inherited disorders are diseases that are caused by changes in genes called mutations. Some of the inherited disorders include sickle cell disease, cystic fibrosis, etc. Usually, both parents must carry the same gene to give birth to an affected child.


A DNA test can find these abnormalities or mutations by comparing the DNA sequence of the parent with the DNA sequence of the fetus or by observing any kind of changes in the number, position, or size of chromosomes.


A genetic disorder can be tested by two methods:


  • Screening tests – these tests check the chances of your baby having certain genetic disorders
  • Diagnostic tests – these tests can determine if certain genetic disorders are present in the baby or not. Both the screening and diagnostic tests are optional and are available to all women,

Genetic disorders

Some additional advanced tests that are available include:


  • Percutaneous umbilical blood sampling (pubs): It uses a blood sample from the baby’s umbilical cord to determine genetic disorders. It is also known as fetal blood sampling.


  • Prenatal chromosome analysis (karyotype): In this, the sample collected from amniocentesis or CVS is used to detect large changes in the chromosomes like change in no. Of chromosomes or position of chromosomes.


  • Prenatal chromosomal microarray analysis (CMA): It is a very detailed test done with the samples obtained by amniocentesis or CVS. It detects if any pieces of chromosomes are missing or are extra in numbers.



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