Karyotype is a test to identify and
evaluate the size, shape, and number of
chromosomes in a sample of body cells.
Results of a karyotype test are usually available within 1 to 2
- There are 46 chromosomes that can be
grouped as 22 matching pairs and 1 pair of sex chromosomes (XX for a female and
XY for a male).
- The size, shape, and structure are normal for each
- There are more than or less than 46
- The shape or size of one or more chromosomes is
- A chromosome pair may be broken or incorrectly
What Affects the Test
If you are being treated for cancer, the results of a karyotype test may not be accurate. Chromosomes may be damaged by some types of cancer treatment.
What To Think About
- Sometimes a karyotype test is combined with
other genetic tests to provide more specific information about genetic
problems. For more information, see the topic
- If the results of karyotype
are abnormal, other family members may be advised to undergo testing.
- A sample taken by gently swabbing the tissues inside the cheek
(called a buccal swab) sometimes is used for a karyotype test. But results from
buccal swabbing are less accurate than other types of karyotype
- Since the information obtained from karyotyping can have a
profound impact on your life, you may want to see a doctor who specializes in
genetics (geneticist) or a
genetic counselor. This type of counselor is trained
to help you understand what karyotype test results mean for you, such as your
risk for having a child with a condition like
Down syndrome that is caused by a chromosome problem.
A genetic counselor can help you make well-informed decisions. Ask to have
genetic counseling before making a decision about a
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby?s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Primary Medical Reviewer
||Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer
||Siobhan M. Dolan, MD, MPH - Reproductive Genetics
||March 29, 2011