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Ency. home > Test > K > Karyotyping

Karyotyping   

Overview | Risks | Results

Alternative names:

Chromosome analysis

Definition:

The process of performing a karyotype which is a test to identify chromosome abnormalities as the cause of malformation or disease.  This test can both count the number of chromosomes and look for structural changes in chromosomes that may indicate genetic changes associated with increased risk for disease.

How the Test is Performed

The test can be performed on a sample of blood, bone marrow, amniotic fluid, or placental tissue.

Chromosomes contain thousands of genes that are stored in DNA, the basic genetic material. The specimen is grown in tissue culture in the laboratory; and then the cells are harvested, chromosomes are stained, and viewed under the microscope. They are photographed to provide a karyotype which shows the arrangement of the chromosomes. Abnormalities can be identified through the number or arrangement of the chromosomes.

How to Prepare for the Test

There is no special preparation for the blood test. To test amniotic fluid, an amniocentesis is performed. Testing on placental tissue is done after a chorionic villous sampling or after a miscarriage. A bone marrow specimen requires a bone marrow biopsy.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

How the Test will Feel

How the test will feel depends on the sample procedure, that is, a venipuncture, amniocentesis, or bone marrow biopsy.

Why the Test is Performed

The blood test is usually performed to evaluate a couple with a history of miscarriages or to evaluate an abnormal appearance of the body that suggests a genetic abnormality. The bone marrow or blood test can be done to identify the Philadelphia chromosome that is present in 85% of those with Chronic myelogenous leukemia (CML). The amniotic fluid test is done to evaluate a developing fetus for chromosome abnormalities.

Ency. home > Test > K > Karyotyping

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