How to Diagnose Genetic Diseases Using Karyotypes

DNA is a molecule made up of smaller groups of molecules called genes. Genes tell cells what proteins to produce. The proteins act on the cells' functions, from how to divide and grow to how to use energy. Genetic diseases occur when there is an error in the genes and DNA. Karyotyping is a technique used to evaluate the structure of DNA for any errors.

Things You'll Need

• Cell sample
• Glass slides
• Supravital stain
• Microscope
• Digital camera
• Printer
• Computer software
• Karyotype reference images

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Instructions

Viewing the Chromosomes

• 1

  Smear the cells on the glass slide from the sample you receive in the lab. The sample may be from a swab of a person's cheek, a sample of blood, a skin scraping. Basically, any cell from the body may be used since all cells share the same number and structure of chromosomes.

• 2

  Stain the cells on the glass slide with supravital stain per the stain manufacturer's instructions.

• 3

  Place the stained slide under the microscope and adjust the microscope to view the cells. Make sure you can see the DNA bands on the chromosomes.

• 4

  Identify cells with the best differentiated chromosomes (DNA strands). They will be long and arranged in different patterns.

• 5

  Take a digital picture of the cells with the best chromosomes and print out the picture. Next, you will assemble the chromosomes and look at the karyotype.

Karyotyping

• 6

  Arrange the chromosomes according to their size. Twin chromosomes will be the same size and have the same band patterns. You should have 23 pairs of chromosomes. This is the karyotype.

• 7

  Use a reference image of a normal karyotype to compare with your karyotype.

• 8

  Identify the number of pairs and the total number of chromosomes. If there are extra chromosomes (more than 46), then the person has a genetic condition known as Polysomy. If there are not enough chromosomes (less than 46), then the person has a genetic condition known as Monosomy.