What is Karyotyping?

A test to look at the chromosomes in a cell sample, karyotyping can help count the number of chromosomes and will look for any structural changes. It can identify genetic problems for disease or disorder.

Performing the Test

Nearly every type of tissue can be typed for this, including blood, placenta, amniotic fluid, or bone marrow. Tissue samples are put into a dish and let grow. Cells are taken from that sample and stained to look at under a microscope. It is photographed. Abnormalities can be seen through the arrangement of the chromosomes or by the number of them. No preparation for this test is needed.

Who Takes This Test

It can be done by blood or bone marrow to check for the Philadelphia chromosome. This is seen in about 85 percent of those with chronic myelogenous leukemia. Amniotic fluid can be tested for chromosomal abnormalities of a fetus. It can be done for those with a history of miscarriage or for babies that have signs of a genetic abnormality. Other conditions that may result in this test include ambiguous genitalia, multiple birth defects, multiple developmental delays, or leukemias.

The Test Results

Normal results are 44 autosomes for males or females plus 2 sex chromosomes, either XX for females, or XY for males. Abnormal results can be a sign of a genetic condition such as Turner syndrome, Trisomy 18, Down syndrome, or Klinefelter syndrome.

Test Risks

There can be risks depending on the procedure used to get the tissue sample. Your doctor will go over any risks before you undergo the procedure. The test should be repeated if there is an abnormality found, to negate the chance that it occurred in the lab and not the patient.

Chemotherapy can cause alterations of this test. There can be other tests done with this test including telomere studies, fluorescent in situ hybridisation, and microarray.

Source: A.D.A.M.