Genetic Testing Dna Test

When we think of DNA testing services, we often draw upon our memories of it in the latest CSI episode or on paternity tests in talk shows. We hear reports of paternity DNA testing in the news, and find references to ancestry DNA testing on genealogy Web sites. Prenatal DNA testing is now used regularly to screen unborn children for hereditary disorders.

It seems difficult to believe that a cotton swab of cells from our cheek or a tiny sample of blood is the only thing needed to convict a felon or find a relative. The fact that something so small could determine such important issues is astonishing, but obtaining a DNA sample is only a small part of the process of testing DNA.

What is DNA Testing

Before one uses a DNA testing kit, it is important to understand the structure of DNA. DNA is the blueprint to all living organisms and can be found in every cell in our bodies. It is made up of four chemicals called nucleotides that scientists nicknamed ‘A,’ ‘C,’ ‘G,’ and ‘T.’ From these four nucleotides, or bases, various patterns are created that make unique forms of DNA. These patterns of nucleotides are what determine your hair color, eye color and sex, among many other things.

When a scientist uses a DNA testing kit, he or she usually needs a hair, blood or skin sample, although DNA can be obtained from any tissue. This sample is mixed with chemicals called restriction enzymes, which cut long strings of DNA into smaller sections. The length of each set of cut DNA varies with each person.

After the DNA is cut, the pieces are placed at one end of a gelatin slab. Drawn through with an electric current, the small pieces of DNA in the gelatin move more quickly than the larger pieces, arranging the cut DNA pieces into ascending order. Once the DNA pieces are organized, the gelatin is replicated for further records.

With the DNA pieces organized and recorded, scientists then analyze and compare segments with other DNA samples in their records. They can use a variety of methods for comparison, including the sizes of the cut DNA segments. A more popular method is to look at the DNA’s STR, or Short Tandem Repeat. This is pattern of nucleotides repeated throughout the DNA that is unique to each individual.

Types of DNA Tests

There are many DNA testing kits available, each used for different purposes.

Some of the popular DNA tests are:

  • AmpFLP
  • Mitochondrial
  • PCR
  • RFLP
  • STR
  • Y-Chromosome.

RFLP, PCR and STR are commonly used in forensic testing, while Y-Chromosome and Mitochondrial DNA tests are used more frequently in ancestry DNA testing and paternity DNA testing.

Uses of DNA Testing Services

There are many reasons a person would use a DNA testing kit, including determining ancestry, relatives or solving a crime.

Ancestry and Paternity DNA Testing

Ancestry DNA testing can determine if two people come from the same ancestor and even help a person trace their ethnicity to an ancient origin, such as the ongoing National Geographic Genographic project. Similar to ancestry DNA testing is paternity DNA testing, which is often used to identify the father of a child.

Prenatal DNA Testing

Prenatal DNA testing is used to screen pregnancies for hereditary disease. For instance, prenatal DNA testing could reveal an unborn child has cystic fibrosis.

Prenatal DNA testing is not without controversy. Parents who discover their child has a hereditary disease may opt to abort the pregnancy. There are concerns that prenatal DNA testing could be also be used to select desired traits in a child, such as gender.

Perhaps the most common use for DNA testing is forensics, which uses traces of DNA found in crime scenes to determine the identity of the criminal.

Most DNA tests are done in laboratories by scientists; however, some people use home DNA testing kits to determine relationships which can be found in many pharmacies. Some health clinics also offer free DNA testing, mostly to solve paternity conflicts.

Resources

IDENTIGENE DNA Testing Center (2008). DNA paternity testing and other DNA tests. Retrieved August 26, 2008, from the DNATesting.com Web site: www.dnatesting.com/.

Medical Genomics (2004). How does DNA testing work? Retrieved August 25, 2008, from the Medical Genomics Web site: www.medicalgenomics.co.uk/howtestingworks.html.

Michigan State University (1995). What is DNA testing and how does it work? Retrieved August 25, 2008, from the Michigan State University Web site: www.pa.msu.edu/sciencet/ask_st/092795.html.

Riley, Donald E. (2005). DNA testing: An introduction for non-scientists. Retrieved August 25, 2008, from the Scientific Testimony Web site: www.scientific.org/tutorials/articles/riley/riley.html.

U.S. Department of Energy Office of Science (2007). Gene testing. Retrieved August 25, 2008, from the U.S. Department of Energy Office of Science Web site: www.ornl.gov/sci/techresources/Human_Genome/medicine/genetest.shtml.