(toc)
1. Explanation:
The chromosomal karyotyping is defined as the cytogenetic process of arranging the chromosomes in terms of its structure and number. It plays a significant role in a human being as a little mistake in the arrangement will lead to a defect in their bodies.
2. Process of chromosomal karyotyping:
This process involves seven major steps.
They are:
● Collecting the sample
● Culturing of cells
● Arresting the Metaphase
● Treatment of hypotonicity
● Chromosomal staining and banding
● Analysis using Microscope
● Generating the karyotype
● Collecting the sample :
The required cell sample is collected from the amniotic fluid, blood, placental tissue or bone marrow.
● Culturing of cells:
The collected cell sample is cultured in a laboratory with the help of a medium to enhance the replication and division of the chromosomes and cells respectively, which are later used for observation.
● Arresting the Metaphase:
The cell division and chromosomal replication is arrested in the metaphase using a chemical and the condensation of chromosomes takes place.
● Treatment of hypotonicity:
This state is achieved by treating the metaphase arrested cells with a hypotonic solution which in turn results in the swelling of cells and the separation of the chromosomes.
● Chromosomal staining and banding:
After this, the staining of the chromosomes occur with the aid of giemsa stain which forms a unique pattern of banding in the chromosomes and is later used for identifying the chromosomal structures and abnormalities.
● Analysis using microscope:
Now, the stained chromosomes are visible under the microscope forming an arrangement called karyotype.
● Generating the karyotype:
The last step involves the ordering of the chromosomes according to their number and structure. This arrangement is called a karyotype and is photographed for later analysis.
3. Importance of karyotyping:
The karyotyping results in the diagnosis of genetic disorders, cancer, detecting the abnormalities in the chromosomes and the miscarriage investigations.
● Diagnosis of genetic disorders:
It can be used to detect genetic disorders like Klinefilter’s syndrome, Turner’s syndrome and Down’s syndrome.
● Diagnosis of cancer:
Cancer conditions, such as leukemia are diagnosed by chromosomal karyotyping.
● Detecting the abnormalities in the chromosomes:
Karyotyping aids in the detection of chromosomal abnormalities like structural aberrations of deletions, duplications etc., and also the detection of the extra or missing chromosomes.
● Miscarriage investigations:
Sometimes, recurrent pregnancy losses can lead to chromosomal abnormalities.
4. Types of karyotyping:
There are three major types of karyotyping namely, Fluorescence-in-situ hybridization (FSH), Conventional karyotyping and Comparative Genomic Hybridization (CGH).
● Fluorescence-in-situ hybridization:
This process functions with the fluorescent probes to detect smaller abnormalities in the chromosomes by targeting certain DNA sequences.
● Conventional karyotyping:
It is the usual and complete examination of chromosomes using a microscope.
● Comparative Genomic Hybridization:
It is a technique of molecular cytogenesis that requires the comparison of reference DNA with a DNA tumor sample.
