What is cell line karyotyping?

cell line karyotyping

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The set of chromosomes that each cell of a species has is called a cell line karyotype. It is a very common term in clinical genetics, but not well known outside the field of medicine. The term karyotype is usually related to the term karyogram, which is a picture of the morphology of the chromosomes in a cell. In this blog post, we’ll tell you more about chromosomal variations or abnormalities and tell you everything you need to know about cell line karyotyping, what it’s for and how it’s done.

The karyotype of cell lines

The karyotype performs a chromosomal analysis of cells and it is expressed through a formula established by the International System of Nomenclature for Human Cytogenetics. The chromosome formula records the total number of chromosomes, followed by a comma, and then the sex chromosomes. In the case of a chromosomal abnormality, this is written next, after another comma.

Each species has a certain number of chromosomes. However, there may be variation in karyotype within the same species. For example, humans have 23 pairs of chromosomes, of which 22 are autosomal and 1 is sexual, i.e. 46 chromosomes in total, but people with Down’s Syndrome have one extra chromosome, which is equivalent to 47 chromosomes in total. This variation, among other factors, is caused by a break in the DNA strands that was not repaired.

What is it used for?

Karyotyping is performed to detect any chromosomal, structural and/or numerical abnormalities. It is even possible to detect the abnormality early. One of the best known studies is the so-called early prenatal diagnosis of chromosomal abnormalities. It can detect abnormalities such as Patau syndrome (trisomy of chromosome 13), Turner syndrome (monosomy of chromosome X), Klinefelter syndrome (XXY males) and Edwards syndrome (trisomy of chromosome 18). Numerical abnormalities, known as genomic mutations, are variations in the number of chromosomes in the genome that can lead to genetic diseases. Generally, in cases of numerical abnormalities, an individual has either one chromosome too many or one too few. At the same time, the numerical abnormality can often be observed in cancer cells. Structural abnormalities, on the other hand, are related to chromosomal breakage, as they affect the structure of chromosomes by adding or removing genetic material. In this way, they can undergo large-scale translocations, deletions, duplications or inversions.

In addition to prenatal testing of pregnant women, there are tests performed on infants, children and adults. In the case of infants and children, karyotyping is done to find the cause of developmental problems, or in the case of a baby who was not born alive, to find out if the death was related to a genetic problem. In adults, karyotype testing is often done to find out if you have a disease that can be genetically inherited by a child, because when abnormalities affect the germ cells, they are often passed on genetically. The tests can also help in obtaining appropriate treatment for cancer, because cancer can cause changes in chromosomes.

It should also be noted that karyotyping does not detect small genetic alterations. For this purpose, there are other tests that do detect small genetic alterations, such as CGH-arrays and the MLPA test.

How is karyotyping performed?

Karyotyping is performed by taking a blood or bone marrow sample. In cases of prenatal testing, a sample of amniotic fluid, which contains fetal cells, is obtained. The sample is then cultured and cell division, also known as mitosis, is obtained. The division, which occurs due to the presence of mitosis-inducing products in the incubation of the sample, allows the chromosomes to be observed. The chromosomes are arranged by size and stained with different dyes in each region of their structure so that they can be identified, properly viewed under the microscope and photographed.

Chorion biopsy, also known as chorionic villus sampling or chorionic villus sampling, is a test in which a needle is used to remove a sample of fetal cells from the placenta, which are then sent to a laboratory for further testing. Prenatal tests can only be performed during certain weeks of pregnancy. Chorion biopsy can be performed between 10 and 13 weeks of gestation. It should be noted that there is a risk that the biopsy may lead to miscarriage, which is why the doctor orders it only in cases where the pregnant woman has another child or family member with a chromosomal abnormality, or if she has a history of miscarriages, or if she has had a baby die before birth.

In cases where chromosomal analysis tests are needed because of blood disorders or cancer, the doctor may order an amniocentesis to be performed between the 15th and 20th week of pregnancy. The test involves the aspiration and biopsy of bone marrow, usually taken from the hip bone, through a special needle. The chance of miscarriage with this test is lower than with chorion biopsy, but it can cause heavy bleeding or infection.
The laboratory results of karyotype tests are certain and definitive regarding the existence or not of a chromosomal abnormality. As we have seen throughout this blog post, performing a karyotype study of cell lines is very useful for detecting any abnormality. Contact us if you have any questions and visit our blog to keep up to date with all the latest news in the clinical field.

At Ambar Lab we offer more than 3,000 laboratory tests, support in business management and the development of new projects. We work to ensure that our wide and growing catalogue of tests is tailored to your needs, as we know that knowledge is the key to making our clients’ work easier.

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