DNA-Fingerprint Reference STR Database(728 total words in this text)(25536 Reads)
This on-line data base allows scientists to synchronize their DNA ladders. This is particularly important, if new DNA systems are developed. By exactly typed cell culture lines it can be guaranteed that each laboratory calls the same alleles and the results of DNA expertís reports can be compared directly.
Unfortunately it is not obvious that every laboratory world-wide calls the same alleles for one and the same person in a DNA expertís report. Most of the STR loci are well standardized and can be clearly recognized in commercial analysis kits, but sometimes there is disagreement, in which way the repetition units are to be counted. A prime example for this is e.g. the Y-chromosomal locus Y-GATA-H4: Depending on whether one counts the GATA repetition units on one strand, or the TCTA the repeats on the opposite, complementary DNA strand, the result differs by one unit. Therefore some scientists call the same marker Y-TAGA-H4. (Click here for an example of Y-GATA-H4)
Things get very complicated if complex repeats have to be typed. E.g. if 3 deviating bases are inserted in a tetrarepeat (= 4 bases in each repetition unit). In these cases it is very helpful for a scientist, if he can rely on a well-known DNA, whose alleles are known and neednít be sequenced. The DNA-fingerprint data base (http://www.dna fingerprint.com) is helpful exactly for this.
High-quality DNA extracts of EBV immortalized cell lines are commercially available for several years now. These are often included in commercial DNA typing kits as a control DNA. Therefore they are available in practically every DNA laboratory, that is involved in human DNA identification. At present the DNA fingerprint data base contains four of these cell lines: K562, 9947A, 9948 and ABI 007 control DNA. Of course further control DNAs can be added at any time if necessary.
The individual alleles can be sorted and filtered to gain fast access to the needed information. In the first draft version there are already more than 200 alleles registered with the four DNA templates. Constantly new entries will follow, as soon as the laborious literature research will supply new facts. Particularly Professor Dr. R. Szibor of the University of Magdeburg has to be thanked, who made a long list of autosomal and gonosomal STR alleles of three of the four control DNAs available to us.
Of course the creators of the DNA fingerprint database have not eaten the whiteness with the spoon to expect all laboratories in the world to follow only the content of this database. Indeed the allele entries offer the possibility to discuss alternative counting methods and classification possibilities in detail in a large dimensioned comment field. It should be possible however, that in scientific papers and in the communication between different working groups one only has to refer to an entry of the DNA fingerprint data base, in order to make a clear and unmistakable description of the laboratoryís own standard.
In the near future a web-form will be provided, where every scientist can suggest his own loci and alleles (e.g. from a newly developed DNA typing system) to include into the DNA fingerprint database. At present an email to the system administrator is still necessary for this.
The reference data base is developed in a way that the entries can be extended and corrected later if necessary. A completely retraceable version control is however always stored in the system, which can be queried at any time later on.
To be sure that nonsense and false information is not registered with the data base, the Administrator tries to arrange a team of experienced scientists who constantly verify the plausibility and correctness of the new entries. In a later version of the DNA fingerprint database the user will be able to see whether the entry was examined by the review-team or if it is just virginally registered.
The developers of the DNA fingerprint database hope that the scientific community will find the new website useful and they are grateful for every feedback and constructional criticism. By the way one can find a multiplicity of external links on the web-page to all the things, that a human genetics scientist is interested in.
If you are working with DNA-fingerprints or if you are interested in DNA analysis then feel free to contact us:
Webmaster: Thomas Krahn