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Last revised January 31, 2023

What is a karyotype, and why should I do karyotype testing?

Karyotype testing is a type of genetic testing that looks for abnormalities in your chromosomes to identify genetic issues. Karyotyping tests include checking for causes of infertility.

Karyotyping tests may help if you’re having difficulty growing your family. You should do karyotype testing if you’ve had multiple miscarriages or are experiencing infertility, to determine if there’s a genetic cause. Karyotyping tests can also reveal your risk of passing a genetic disorder on to your child, and check a fetus or baby for chromosome abnormalities.

Here, we explain what a karyotype is, how karyotyping tests work, what you can learn from karyotype testing, and who should consider doing it. We also talk about other tests that can help you understand your fertility.

Key takeaways

  • Human cells usually have 46 chromosomes, which are made up of DNA. Extra, missing, or broken chromosomes can cause a variety of health conditions.
  • Karyotype testing looks for abnormalities in your chromosomes to help diagnose genetic disorders and potential causes of infertility.
  • Karyotyping tests may help you if you’re having trouble conceiving a child or are concerned about passing a genetic disorder down to your offspring. It can also check for chromosome abnormalities in a fetus or a baby.
  • Besides karyotype testing, a semen analysis can also help you understand and improve your fertility.

What is a karyotype?

A karyotype is an image of all of a person’s chromosomes arranged in numerical order. Chromosomes are structures inside cells that are made from protein and DNA. People usually have 23 pairs of chromosomes in each cell, with half coming from each of their parents.

Since your chromosomes hold genetic information, abnormalities or changes to your chromosomes may cause various medical conditions.

What is karyotype testing?

Karyotyping tests, also called chromosome testing, examine the number, shape, and size of chromosomes in a cell sample to look for abnormalities.

Specifically, it checks to see whether you have the normal number of 46 chromosomes, as extra or missing chromosomes can cause certain health conditions. Karyotype testing can diagnose disorders like Down syndrome and Turner syndrome.

Karyotyping tests also check the structure of your chromosomes. Chromosomes that are broken or have additional parts can lead to other health conditions.

How are karyotyping tests done?

Karyotyping tests may be performed on tissue samples including blood, bone marrow, and a cheek swab, as well as amniotic fluid when performing the test on a fetus.

Your doctor will collect the sample by drawing your blood, conducting a bone marrow biopsy (inserting a needle into the bone) to withdraw bone marrow, rubbing a swab across the inside of your cheek, or performing an amniocentesis (inserting a thin needle through your stomach and into your uterus) to obtain amniotic fluid during pregnancy.

Scientists stain the cells from the sample, then create an image of all the pairs of chromosomes from one of the cells. This image, showing the number and arrangement of the chromosomes, can help identify some genetic disorders.

Who should consider karyotype testing?

Karyotyping tests may be done when:

  • a couple is experiencing infertility
  • a couple is planning to get pregnant and wants to determine their risk of passing abnormal chromosomes to their child
  • a person has had multiple miscarriages
  • a baby shows signs of delayed development
  • an unborn baby may have chromosome abnormalities, particularly if the parents are over age 35 or a genetic disorder runs in the family
  • a person has a family history of a genetic disorder
  • a person shows symptoms of a possible genetic disorder
  • a doctor is determining the best treatment for diseases like leukemia and anemia

What can karyotype testing tell me?

Karyotype testing looks for changes in chromosomes to help diagnose certain medical conditions along with reasons for infertility. These conditions include:

  • Down syndrome, which is caused by an extra copy of chromosome 21 and results in developmental delays
  • Turner syndrome, which occurs in females when parts or an entire X chromosome (one of the sex chromosomes) is missing, leading to developmental issues
  • Klinefelter syndrome, which happens when a male has an extra X chromosome, resulting in small testicles and low or no sperm production
  • Edwards syndrome, which is caused by an additional copy of chromosome 18 and often leads to children dying before their first birthday
  • leukemia, a bone marrow cancer where certain sections of chromosomes are swapped
  • multiple myeloma, a blood cancer where sections of chromosome 17 may be absent

Karyotyping tests can also reveal your chances of passing abnormal chromosomes to your children.

Since using a karyotype test or other genetic test can impact both you and your family, it may help you to consult a genetic counselor before undergoing karyotyping testing.

Interpreting karyotyping test results

Normal results from a karyotype test would show exactly 46 chromosomes, including two sex chromosomes: XX for females and XY for males. As a result, the normal result for people with ovaries is 46, XX, while the normal result for people with testes is 46, XY. In addition, there would be no chromosome structural changes, such as extra or missing sections of the chromosomes or rearranged segments of chromosomes.

Potential abnormalities detected in a karyotyping test

Your results would be considered abnormal if the karyotyping test showed a different number of chromosomes or any unusual shapes. The specific changes determine the effect on your health, such as whether you have a genetic condition related to the chromosome abnormality.

Benefits of karyotype testing

As with other genetic tests, karyotype testing has a range of benefits. These may include:

  • giving you and your family more knowledge about your health
  • helping you understand the risk of passing a genetic condition down to your children
  • identifying a genetic condition so it can be monitored or treated
  • helping determine the cause of infertility
  • informing you of genetic disorders present in a fetus

On the other hand, karyotype testing may also have drawbacks, such as potentially causing anxiety for you and your family. Karyotyping tests are also unable to identify or diagnose all genetic disorders, and in some cases may be costly.

Karyotype testing costs

The cost of a karyotyping test, like other genetic testing, can be anywhere from $100 to over $2,000. Karyotyping test costs are sometimes covered by insurance, particularly when they’re ordered by a doctor. It’s best to check with your insurance provider prior to undergoing the test so you understand the cost in advance.

Karyotyping test costs may also increase if you need multiple tests or if any of your family members need to be tested to determine the result.

Other testing that can help you learn more about your fertility and overall health

Karyotype testing and other genetic tests can help you understand conditions that may affect your fertility or the health of your child. When you’re trying to improve or preserve your fertility or grow your family, other tests are important too.

A semen analysis is the primary test for understanding your sperm health and fertility. It reveals your semen volume, along with your sperm count, concentration, motility (how your sperm moves), and morphology (the shape of your sperm) — all factors that could affect your chances of success in conceiving a child.

Legacy offers an at-home semen testing kit that allows you to quickly and conveniently understand your sperm health. Combining a semen analysis with genetic testing will help provide the tools you need to improve your health and fertility and have a healthy pregnancy.

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