Genetic Testing is a series of tools to decipher the codes in your DNA, which could be used for medical or other issues such as identity and forensics. In medical genetic testing we would be able to determine whether there are any known changes in your DNA sequence. These changes are called mutations and could potentially cause health problems if they are in regions that code for functional proteins.
There are several samples that could be tested for genetic disorders and they are cells from any part of the body including cheek cells, blood cells, hair cells and so on. Once these cells reach the laboratory experts extract the DNA from the cells and with sophisticated techniques they amplify the parts that represent the ordered test. After amplification the laboratory experts search for changes or mutations in the DNA by comparing it to a normal sequence. If there was not change then the results will be normal yet if there was a mutation then the results should be interpreted by a genetic expert and ultimately by your physician. Genetic testing is 99.9% accurate yet there is always a slight chance for errors during testing process.