Genes direct the synthesis of proteins in our bodies, which determines how we look and function.
All humans typically have 46 chromosomes, 23 of which we inherit from our mothers and fathers, respectively.
The first 22 pairs are calledautosomes, which determine our unique biological and physiological features.
DEPT. OF CLINICAL CYTOGENETICS, ADDENBROOKES HOSPITAL / Science Photo Library / Getty Images
Any error in genetic coding may affect development and the way our bodies work.
A karyotype allows healthcare providers to detect these errors.
Chromosomal defects occur when a cell divides during fetal development.
Any division occurring in the reproductive organs is called meiosis.
Any division occurring outside of the reproductive organs is called mitosis.
If there are more than two chromosomes where there should only be two, this is called a trisomy.
If there is a missing or damaged chromosome, that is a monosomy.
Some, in fact, may be beneficial.
One such example issickle cell disease (SCD)brought on by a defect on chromosome 11.
While inheriting two of these chromosomes will lead to SCD, having just one can protect you against malaria.
Finally, a karyotype may be used to confirm chronic myeloid leukemia in association with other tests.
(The presence of the Philadelphia chromosome on its own cannot confirm the cancer diagnosis.)
The process begins by growing the collected cells in a nutrient-enriched media.
Doing so helps pinpoint the stage of mitosis in which the chromosomes are most distinguishable.
Once the images are correctly positioned, they are evaluated to determine whether any chromosomes are missing or added.
These findings will be accompanied by “possible,” “likely,” or “definitive” interpretations.
Some conditions can be definitively diagnosed with a karyotype; others cannot.
Results from a prenatal karyotype take between 10 and 14 days.
Others are usually ready within three to seven days.
American College of Obstetricians and Gynecologists.Prenatal Genetic Diagnostic Tests.
Leukemia & Lymphoma Society.Blood and Bone Marrow Tests.
National Human Genome Research Institute.Chromosome Abnormalities Fact Sheet.
Centers for Disease Control and Prevention.Facts about Down Syndrome.
National Library of Medicine.Karyotype genetic test.
Thompson PA, Kantarjian HM, Cortes JE.Diagnosis and Treatment of Chronic Myeloid Leukemia in 2015.Mayo Clin Proc.
2015;90(10):14401454. doi:10.1016/j.mayocp.2015.08.010
American College of Obstetricians and Gynecologists.Amniocentesis.
American College of Obstetricians and Gynecologists.Prenatal genetic diagnostic tests.
