Genetic Health Markers

By looking at your complete genetic code, geneticists can identify slight variations, known as genetic markers. By studying these genetic markers, scientists have found links between certain genetic traits and particular inherited diseases or conditions.

Genetic markers provide valuable information and can also be used in genetic engineering, which allows defective DNA sequences to be replaced with healthy, normal DNA sequences. Genetic markers are also useful in pharmaceutical research. By looking at genetic markers in cancer cells for example, researchers are able to predict how well a cancer treatment drug will work.

What are Genetic Markers

Genetic markers are DNA sequences that can be used to understand the relationship between a disease and a cause, specifically when the disease is inherited. Inherited diseases, also known as genetic disorders, are caused by certain abnormalities in chromosomes or genes. Some disorders are specifically identified depending on whether genetic markers are paternal or maternal.

How Researchers Understand DNA Genetic Markers

Certain abnormalities at specific locations in your genetic makeup may indicate a genetic disposition for an inherited disease that runs in your family. DNA collected may be from any human sample suitable for testing, including blood, semen, urine or saliva. Scientists have identified DNA genetic markers in the blood which indicate a predisposition for autism and mental retardation.

Identifying Genetic Disorders with DNA Genetic Markers

Some genetic disorders or inherited diseases you may have heard of include:

  • achondroplasia
  • Aicardi syndrome
  • cystic fibrosis
  • Huntington’s disease
  • Klinefelter syndrome
  • Rett’s syndrome
  • sickle-cell anemia
  • spinal muscular atrophy
  • Tay-Sachs disease.

For a genetic marker to be useful, the marker must be polymorphic, with two or more different alleles at the same gene locus. An allele is a version of a gene that can have several alternative versions that are responsible for different characteristics, called phenotypes. For example, different alleles are responsible for various eye colors.

Genetic disorders may be caused by something that went wrong during meiosis, the process in which DNA divides and the number of chromosomes per cell is cut in half. Defective genes can also simply be inherited from the parent, either when a defective gene is dominant or two healthy carriers both reproduce with a defective recessive gene.

Genetic Markers Indicate Increased Risk of Breast Cancer

In May 2008, researchers at the Memorial Sloan-Kettering Cancer Center discovered a genetic marker for breast cancer. Although the findings do not have immediate treatment implications for women with cancer, the research may indicate additional DNA sequences linked to the disease. Women with the DNA genetic marker are 1.4 times more likely to develop breast cancer over the course of their life than women who do not have the genetic marker present.

Privacy and Discrimination Issues and DNA Genetic Testing

Some critics of DNA testing do not believe that receiving information about genetic predisposition for diseases is positive and empowering. Instead, privacy and discrimination issues are the heart of their concern. Could an insurance company deny you insurance because you have a high likelihood of developing cancer? Could you be denied a job because your mother and all three of your sisters had breast cancer?

The impact of distributing such information could be much more complicated than receiving depressing news or putting preventative lifestyle changes into place. Unfortunately, until genetic researchers know how to prevent all genetic conditions and inherited diseases discovered by genetic markers, privacy and discrimination issues will continue to be a concern.

Resources

Godfrey, M. (n.d.). Ways to protect people from discrimination based on genetic information. Retrieved September 21, 2008, from the Gene Forum Web site: http://www.geneforum.org/node/538.

National Institute of Neurological Disorders and Stroke Staff. (2008). Blood markers associated with autism and mental retardation. Retrieved September 21, 2008, from the National Institute of Neurological Disorders and Stroke Web site: http://www.ninds.nih.gov/news_and_events/press_releases/pressrelease_autism_042501.htm.

NPR Staff. (2008). Genetic marker linked to breast cancer. Retrieved September 21, 2008, from the NPR Web site: http://www.npr.org/templates/story/story.php?storyId=87984350.