The human genome is believed to contain around 20,000-25,000 genes. A mutation in any one of these could cause anything from retardation to increasing your chances of cancer. The benefits of genetic testing is that it can find out if an individual is at risk of inheriting any of the diseases that are tested for.
There are many types of genetic testing and more are becoming available. The most well known is prenatal genetic testing to detect changes in a fetus’s genes before birth. This is most commonly done with an amniocentesis, but this process has been known to pose risks, such as miscarriages.
The most widespread use of genetic testing is screening of newborn infants. Millions of babies are tested each year in the U.S. for diseases such as phenylketonuria and congenital hypothyroidism. Other tests are diagnostic and carrier testing to either confirm a diagnosis or let people know if their children are at risk of inheriting a genetic disorder or being a carrier of a condition.
Genetic testing is also used in forensic science and to go back in time to determine ancestry. Unlike the traditional testing to detect gene mutations associated with disease, forensic genetic testing can identify crime victims, rule out suspects or establish biological relationships. Genealogical genetic testing allows one to trace their ancestry. It allows individuals to find out the probability that they are, or are not, related to another person within an estimated number of generations.
Cancer researchers have discovered gene mutations that could increase a woman's risk of getting cancer. For example those who carry a particular mutation on the BRCA1 gene have an increased risk of breast cancer and genetic testing informs women if they carry this mutation. This kind of genetic testing is called predictive or presymptomatic testing.