Karyotype Lab The Steps To Determine Down Syndrome

Karyotype LabThe Steps To Determine Down Syndrome

By: - Science - August 29, 2011
karyotype lab the steps to determine down syndrome

A karyotype is an image of chromosomes in a cell. It will show the actual number and shape of chromosomes showing exactly what they look like including banding, size and exact number. Normal humans with no chromosomal disease will have 23 chromosomes in their karyotype that will show during a karyotype lab or karyoptype test. One of the most common ways a karyotype lab is used is to determine if a person has Down syndrome.

A person who has Down syndrome will show a karyotype with trisomy, or a third part of their 21st chromosome. A karyotype test is done to actually diagnose Down syndrome. It can be done via a blood test, amniotic fluid or occasionally bone marrow cells. Once the sample is collected, the lab can begin and usually the karyotype is done on white blood cells in a new born, which will be our example.

A karyotype lab is typically found in larger hospitals and is or can be called a cytogenetics lab. The sample is examined by highly trained doctors and scientists by examining and separating the actively dividing white blood cells from the ones who have not yet divided. The dividing cells are placed in a culture that mimics the body and contains chemicals and hormones in order for them to divide naturally. It generally takes 3-4 days for blood cells to be cultured in this way.  In order for the chromosomes to be seen in a microscope, the cells actually have to be stopped partway through the dividing process as to see them at a specific point.

At this point, the scientist or doctor will chemically separate the chromosomes from the dividing cells. Once the chromosomes are split from the cell remains, they will be stained with a special dye that will show different parts of the chromosome in different shades that can be seen under a microscope. When dyed, a picture will be taken of the chromosomes and will be analyzed.

Analysis will begin by counting the chromosomes. A human should have 46 total, 22 pairs plus their sex chromosomes, two X’s in females and an X and Y in males. When doing a test for Down syndrome, the focus will be on the number of chromosomes. A diagnosis will be positive when there is extra genetic material on the 21st chromosome. Approximately 1 in 733 births will have the karyotype lab showing Down syndrome. Many of these children can have a normal life, even graduating from high school, college and are able to enter the workforce. Often it is up to the parents and the treatment that the children receive when they are young. Given the right support, people with Down syndrome thrive.