Karyotype and Chromosome Disorders

Karyotypes help us to increase our knowledge about human genetics. By looking at them scientists can see many informations of the person. But what else is so special about a so called karyotype? 


Structure of a karyotype
A karyotype can be seen as a picture of all the chromosomes in the cell of a person. Chromosomes carry all the genetic information, which is required for various functions and development. Typically, every human has 46 chromosomes. These are 23 pairs and contain genetic information from both mother and father. The last pair of chromosomes decides if the person is a boy or a girl as they are called the sex chromosomes. Scientists can see possible abnormalities by looking at these karyotypes.




How can we see those chromosomes?
During the process of meiosis cells are encouraged to divide and you can see those chromosomes if you take a close look under a microscope. Chromosomes are very tiny so you are not able to see them with the naked eye - you need a microscope. By looking at these chromosomes we can tell if the person has any chromosome disorders.

Disorders in chromosome nondisjunction
During the process of meiosis, pairs of homologous chromosomes or sister chromatids are supposed to separate. If that is not the case and these fail to separate, it is called a nondisjunction. The likelihood of nondisjunction is getting higher as the parents are getting older.

What are chromosome disorders?
Chromosome disorders are caused when the cells fail to separate correctly during the process of meiosis or behave abnormally. There are two categories of chromosome disorders: abnormalities in chromosome numbers and chromosome structural rearrangements. 

Abnormalities in chromosome number: chromosomes are too many or some are missing
An example for this one is Trisomy 21, also known as Down syndrome. Down syndrome occurrs when there is an extra copy of the 21st chromosome. This disorder is affecting the development of the child and could also be noticeable by typical facial features. It is diagnosed before the birth or shortly after the birth of the child.

Chromosome structural rearrangements: the structure of chromosome changes due to rearrangements in its genetic material
An example for this is translocations and it can cause development delays. Another example for chromosome structural rearrangements are inversions or duplications.


During the pregnancy you can go through a karyotype analysis, if there is an elevated risk of chromosome disorders, to find out if there are any abnormalities. Doing this analysis can help by making an early diagnosis, as family history and the age of the mother are very important at this point.





In conclusion it is fascinating that we are able to see the general structure and number of chromosomes just by looking at the karyotype and chromosomes of the baby. Karyotypes are very valuable in today´s knowledge about human genetics, and they give us several information about a human body. You are able to identify abnormalities such as chromosome disorders. This knowledge helps us understand and manage genetic health.




  • Cleveland Clinic (2023). Down Syndrome. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/17818-down-syndrome evelandclinic.org)
  • Todd Nickle and Isabelle Barrette-Ng. Chanes in Chromosome Structure. LibreTexts Biology.  https://bio.libretexts.org/Bookshelves/Genetics/Online_Open_Genetics_(Nickle_and_Barrette-Ng)/09%3A__Changes_in_Chromosome_Number_and_Structure/9.02%3A__Changes_in_Chromosome_Structure mosome Structure - Biology LibreTexts
  • Amalia Dutra, Ph.D. (2024). Karyotype. National Human Genome Research Institute. https://www.genome.gov/genetics-glossary/Karyotype

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