Only 3% of the human genome codes for protein. The rest does not and this non-coding region is composed of repetitive DNA sequences. Repetitive parts called satellites are named according to the number of bases found in this region. If the length of the repetitive bases is between 8 and 100, it is called minisatellite or VNTR (variable number of tandem repeats). If it changes between 2 and 7, it is called microsatellite or STR (short tandem repeats).
Why STR Is Used in DNA Profiling
Since repeat numbers are different between individuals, STR regions have become popular DNA markers and they are used in DNA profiling. The other important reason why STR regions have become popular is that they can be easily amplified by PCR method. To be able to perform successful DNA profiling when DNA amount is not enough, being easily amplified by PCR is very advantageous to increase DNA amount. Moreover, since it is compatible with technology, it provides rapid analysis opportunity.
Why STR Number Is Very Important
DNA shows 99.9% similarity within individuals. STR regions are used in DNA profiling because repeat numbers differ between individuals. Negative results (there is no relationship between individuals) do not cause any doubt; however, same thing is not valid for positive results (there is relationship between individuals) because there is no such thing that ‘all STR markers differ between individuals’. Let say, for example, tested 5 STR regions are matched between two individuals who are not relatives. This situation does not definitely say that tested individuals are relatives. This means that tested 5 STR regions are the same; however, there might still be difference in other regions. To get more accurate results, more STR regions should be tested.
Why You Should Prefer Us
Recently, for DNA profiling there is addition to 16 STR markers determined by FBI and totally 21 STR regions are chosen as standards. The reliability of tests performed in our laboratory is very critical for us because all our team members are aware of potential of influencing individuals deeply with the results of these tests. Because of this reason, instead of 21 STR regions, paternity and maternity tests are performed with 26 STR regions in our DNA laboratory.