Genetic testing
examines a person's DNA and looks for the presence of mutations.
Diagnostic genetic testing describes procedures performed to answer questions about an individual's genetic makeup. Physicians will sometimes suggest genetic testing to confirm or rule out suspected disease conditions or to determine if a person is a carrier of a disease gene. This information may also be used by genetic counselors to determine the risk of other family members or future offspring developing these diseases. Diagnostic DNA testing procedures are also used to screen for genetic defects prenatally on fetuses or on embryos to be used for in vitro fertilization.
DNA
Deoxyribonucleic acid (DNA) is the genetic blueprint for cells. It is made up of long chains of molecules called nucleotides, and the sequences of nucleotides form individual's genes, according to the National Institute of Health's Genetics Home Reference. Each person's DNA sequence is unique to them. The only exception to this rule is in the case of identical twins, whose DNA is also identical.
How It Works
Some diagnostic testing involves looking directly at DNA molecules themselves and searching for the presence of mutated genes. Other tests look at gene products such as enzymes or proteins to see if they are present and/or functioning normally. These tests can be performed with dyes, restriction enzymes that will cut DNA at known spots or probes that will bind to known DNA sequences. The Human Genome Project states that a DNA sample can be obtained from any tissue, including hair or blood.
Legal Issues
Legal concerns need to be considered with regards to genetic diagnostic testing. Issues arise when considering who does and does not have the right to the individual's genetic information, and how it may be used. Employers, schools, the military, adoption services and insurance companies are all examples of groups that may be better able to serve an individual given their genetic information, however in the wrong hands this could easily lead to discrimination. In 2008 the Genetic Information Nondiscrimination Act (GINA) was ratified by President G.W. Bush to protect an individual's privacy with regards to genetic, information according to the Human Genome Project.
Ethical Issues
Many ethical issues arise when considering genetic testing. With regards to the presence of genes contributing to certain behaviors, questions arise as to an individual's responsibility for their actions. In the case of prenatal testing, the results of diagnostic tests may lead parents to a decision to terminate a pregnancy.
Other Uses
Genetic testing is also used in non-diagnostic fields, including forensic science and the determination of parentage. Forensic scientists use genetic testing as a means placing individuals at crime scenes in much the same way that fingerprinting has been used; if a suspect's DNA is found on or near a victim this is very good evidence that the individual was at the scene of the crime.
Parentage determination, most often paternity testing, is another application for DNA testing. According to Genetic Home Reference offspring carry 50 percent of each of their parents' genes, so in the case of paternity testing a match is determined if the two individuals in question share half of their genes.
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