Karyotyping is a type of genetic test prescribed during the special pregnancy cases to evaluate chromosomes.
A type of genetic test- karyotyping is prescribed during the pregnancy and some cases of having a history of genetic abnormalities.
A karyotyping, popularly known as a karyotype test is usually employed to evaluate chromosomal abnormalities. Unfortunately not so popular.
Reasonly, it is time-consuming, tedious and not so accurate. Though, it’s use in prenatal genetic testing is so common.
The karyotyping technique is a common cytogenetic practise performed on metaphase chromosomes. Genes are located on chromosomes. If either chromosome’s structure or number changes, it causes abnormality to a person.
Usually, the chromosomal abnormalities are congenital and not curable.
Structural chromosomal abnormalities and numerical chromosome alteration are two common aberrations associated with it. In one the structure of chromosomes changes while in another the number of chromosomes changes, respectively.
Henceforth, if we study the chromosome correctly, we can identify any abnormality associated with it.
Karyotyping technique or a karyotype test facilitate evaluation and characterization of chromosomes via the cell culture technique.
In this technique, the cells are isolated and cultured using the culture media and under the aseptic conditions, while using the cell harvesting technique, the metaphase cells are harvested to get metaphase spread.
The chromosomes are observed under the microscope to identify anomalies associated with the sample, if any.
This is the whole process of karyotyping but the question arises in mind in which conditions the karyotyping technique or the karyotype test is prescribed by the doctor.
Should i have to go for a karyotyping? Or who can test for karyotyping? What are the criteria based on when a doctor prescribed the karyotyping?
In the present article, we will try to answer all the questions and make you understand in which condition the karyotype test is preferred.
Read more: What is karyotyping?
In which conditions a karyotyping or a karyotype test is preferred?
Commonly, in normal conditions, no genetic testing either DNA test or karyotyping is preferred. But there are several conditions in which a patient has to go for karyotyping. Some of these conditions are,
- Maternal age above 35
- Abnormal pregnancy screening or marker test
- Previous history of chromosomal disorders
- In case of cancer or inherited cancer
- Person suffering from genetic or congenital abnormalities
- Infertility
- Reccurant abortion
Maternal age above 35:
If the age of the pregnant lady is more than 35 then she is considered in the high risk pregnancy and prescribed for karyotyping normally.
There is a reason behind that, studies indicated that the women above the age of 35 have a higher chance of birth defects and premature birth. Their children have higher chance of genetic abnormalities and hence genetic tests and karyotyping is preferred by a doctor.
Abnormal screening test or marker test:
The process of sample collection and karyotyping is tedious and time-consuming process and consumer as well hence several pre-testing like triple or double marker tests and indications of sonography are taken into consideration before advising someone on a karyotype test.
For instance, if the nasal bone is not visible during the sonographical analysis, the gynecologist advises karyotyping.
The other example is the triple marker test in which the abnormal range of results indicate that the patient should have to go for further genetic testing, preliminarily the karyotyping.
Previous history of chromosomal disorder:
This must be something serious, in your family or near by siblings if anyone has any type of genetic abnormalities you should have to tell it to your doctor.
And during the pregnancy you must have to go for karyotyping first.
Some chromosomal abnormalities are inherited hence that there might be a change your baby may have that type of condition.
Though in most of the cases, the chromosomal conditions are non-inherited, still, one has to go for karyotyping testing.
Note that if one of your children or any child of your family is suffering from down syndrome for instance, there is not a single percent chance that your child may have the same condition.
The event of occurrence of trisomies like the Down syndrome is totally a random process, though, it occurs by the inherited translocation, there is surely a chance.
So on the safe side, should go for karyotyping or follow your doctor’s advice.
In case of cancer of inherited cancer:
Cancer is a life threatening condition occurring by abnormal cell division conditions. Polymorphism at chromosomal level also causes several types of cancer. For example a myeloid leukemia occurs by the translocation of chromosome 9 and 22.
If you or any of your family members have these types of conditions, immediately contact your doctor and go for karyotyping. Several cancer indication by karyotyping are enlisted here:
Table
A person suffering from chromosomal or genetic abnormality:
If you or any of your family members have any type of congenital abnormalities ask them to go for karyotyping.
Deletion, duplication, translocation and inversion like copy number variations are involved in so many different conditions are many of them are still unknown to us.
Infertility:
Several chromosomal aberrations are involved in infertility both in male and females. However, the role of chromosomes in male infertility is common.
For instance, a portion of the Y chromosome known as the TDF- testis determining regions at where the SRY and other genes are located, it causes infertility typically azoospermia in Male.
Other microdeletions and duplications are also involved in various types of infertility in male but the Y chromosome microdeletion is one of the most common reasons.
Besides karyotyping (which can only detect major deletions or big deletions), PCR amplification is also used to determine how much portion is deleted.
Recurrent abortion:
One of the major role of chromosomal aberrations are in the recurrent abortions. Due to some of the deletions or duplication, a female suffers from condinueous miscarriage.
However, it can be treated by using some medications.
We have discussed so far in which conditions karyotyping is preferred but you also have to know in which conditions the test is not required!
See there are clear reasons for that, first, the test is not so easy and there are risk factors with it, the pregnancy may prematurely terminate. A person may break down with the stigma of getting the genetic abnormality or some disease which is not curable.
Also, the test is so costlier as the other genetic test! And after all in normal condition it is not needed.
If your age is below 35, don’t have any family history of genetic disorders or cancer, do not have infertility and stillbirth you no longer need to go for either DNA or karyotyping testing.
But keep in mind that if any of your or your wife’s pregnancy is terminated prematurely or if you have any previous history of stillbirth, go for karyotyping. Even if your doctor doesn’t prescribe it, take advice from a genetic counsellor or concern some other gynecologist.
Read more: How to prepare a karyotype?
Conclusion:
A karyotype test or karyotyping technique is an invasive sample collection technique, so a patient has to bear pain. Aslo, in case of pregnancy there are chances of miscarriage hence it is not process as commonly as the DNA test.
Also, the sample requirement is high, can’t be repeated and change of culture failure and connotation are high.
Besides having so many limitations, the karyotype test or karyotyping is a must need in the case listed above.
Although in normal condition or normal pregnancy it is not needed.
