A karotype blood test is used to determine and evaluate the shape, size, and number of chromosomes that may be in a sample of specific body cells. If there are extra or missing chromosomes based on the results of this test, then it can explain some of the problems an individual may be having with body functions, growth, or development.
Although any cells can be used for the karotype blood test, in adults the test is typically performed on lymphocytes. Some people may have white blood cells taken from a bone marrow aspiration if a hematologic or a lymphoid disease is suspected.
If a fetus is being examined for karotype testing, the amniotic fluid and chorionic villi will be collected through sampling and amniocentesis.
How Is the Karotype Blood Test Performed?
The karotype blood test is a multi-step process to obtain results. The first step involves acquiring a sample of cells and then culturing them to promote cell division. This allows the laboratory to choose a specific time to analyze the cells so that the chromosomes are easy to distinguish in the sample. Then the chromosomes must be isolated from the nucleus of the cell. They will be placed on a slide and then treated with a stain.
Once this process is complete, microphotographs of the chromosomes can be taken, The analyst will then arrange the images of the chromosomes so that pairs can be matched up. They will be arranged from largest to smallest and show vertical orientation to determine if there are differences that may be causing health issues. Any abnormalities discovered will then be noted to create the test results that are reported to the patient.
What Do the Karotype Blood Test Results Mean?
A karotype blood test can be used to determine the presence of some chromosomal disorders. This includes Trisomy 21, or Down Syndrome, Trisomy 18 [Edwards Syndrome], Trisomy 13 [Patau Syndrome], Klinefelter syndrome, Turner syndrome, and a specific type of leukemia.
Because of this, it will often be ordered if an infant is suspected of having a congenital abnormality or a fetus is believed to have a potential chromosomal abnormality. Some women may also have this test ordered if they experience frequent miscarriages or to seek out an explanation for infertility. Adults with suspected genetic disorders may also have the karotype blood test ordered, especially if there is a family history of certain conditions.
Depending on the health issues being experienced, the test may be used to look for translocations, deletions, duplications, or even genetic rearrangements. Each of the specific results that are sought after will often be communicated in a positive or negative fashion. The condition is either there and can be detected or it is not.
Because certain cancers can also be detected with this type of test, it can be diagnosed and the clinical course of the disease predicted. These results are usually based on a patient’s individual medical history, so how they are communicated will depend on the medical professional.
Here’s What You Need To Know About the Karotype Blood Test
For those having this test completed on a fetus, the gender of the developing child will be determined by this test as the sex chromosomes are identified during analysis. New parents may wish to speak with their doctor about not having this result communicated to them if they wish to keep the gender of their child a surprise.
There are some alterations to chromosomes that are extremely subtle that cannot be detected by the karotype blood test, but still may cause bothersome signs and symptoms. In these situations, a microarray or FISH [fluorescent in situ hybridization] may be used to keep investigating the possibility of a chromosomal abnormality.
It is also possible for an individual to have cells with different genetic material in their body. This is called mosaicism and occurs early in the development of a fetus through the cell lines. As a result, some samples may have a third chromosome present while others may not. In this instance, multiple test samples may be taken and compared to one another to determine the extent of the patient’s condition.
The karotype blood test has several uses and the outcomes are usually definitive. If you suspect leukemia or other cancers, have a family history of genetic health issues, or are expecting a child that a doctor is concerned about, then this test may be ordered. Use this guide to ask questions so that you have a complete picture of what is going on with your health or the health of your family.