Featured Research

from universities, journals, and other organizations

Forensics: Developing a tool for identification -- even using very degraded DNA samples

Date:
April 12, 2011
Source:
Basque Research
Summary:
Frequently the only biological material available to identify persons is DNA in a very degraded state. In these cases, the kits usually employed to carry out DNA identifications do not produce accurate results, given that all the DNA is not available. Biochemists have now developed a tool for identifying persons from these small fragments of DNA.

Frequently the only biological material available to identify persons or find next of kin is DNA in a very degraded state. In these cases, the kits usually employed to carry out DNA identifications do not produce very positive results, given that all the DNA is not available, and that which is available is highly fragmented. Biochemist Adrian Odriozola has developed a tool for identifying persons from these small fragments of DNA.

His thesis, presented at the University of the Basque Country (UPV/EHU), is entitled "Developing molecular tools for analysis of highly degraded DNA samples."

In order to develop this tool, Dr Odriozola used sequences known as STR (short tandem repeat). These are sequences of small fragments of DNA that are continuously repeated and turn out to be highly useful for distinguishing between persons, due to the fact that the number of repetitions of the sequence varies according to the individual. Precisely, the kits that Odriozola investigated and that are currently employed in Forensic Genetics are based on STR analysis. However, they fail when the DNA is degraded, and so the researcher drew up a new route for analysing STRs, taking these conditions into account. Dr Odriozola has published a number of articles together with research colleagues at the UPV/EHU, in publications such as the International Journal of Legal Medicine. The University has also been granted two patents.

Working with shorter sequences

To carry out identification using DNA, it is first of all essential to undertake millions of copies of the fragment to be analysed (a process called amplification); in this case, of the STRs, which are obtained using the PCR (polymerase chain reaction) technique. So that PCR can function, primers have to adhere themselves to the two ends of each of the STR sequences. In this way, on undertaking PCR, copies are obtained of both the STR sequence and of the sequential fragments of the ends that have remained trapped between the two primers. With the tool he has developed, Dr Odriozola has enhanced the design of the current primers. Thus, the sequential fragments that have remained at the extremes of the STR are shorter than those with conventional techniques (they are called miniSTR, because there is an approximation of the focus on the STR), and an identification can be obtained despite the DNA to be analysed being fragmented.

The more STRs from the same sample analysed, the greater the precision when determining to whom the sample belongs. With regard to this, Dr Odriozola has managed to develop sufficient tools (primers) to study 14 and 11 mini STRs, employing two kits that are mutually combinable. Besides developing these kits, he has shown in the process of validation that, effectively, identifications can be undertaken even with very degraded DNA samples. This fact is of great relevance given that, to date, rarely has it been possible to validate a tool of this kind, and the Forensic Genetics equipment must be totally reliable to be valid.

Methodology for looking for mutations

The primers cannot be situated in any zone whatsoever: it is fundamental that there is no mutation in the fragments that remain at the STR ends. That is, they cannot adhere to sequential fragments that vary according to the person (they would thereby lose information that could be useful for discriminating persons, because it would be trapped by the primers). To avoid this kind of situation, Dr Odriozola also drew up a methodology in his thesis for seeking mutations at these locations, using DHPLC technology. Moreover, he developed a generic methodology, useful for looking for any kind of mutation. Thus, what is involved is a tool that can not only be applied to Forensic Genetics, but to other genetic disciplines also (for example, to hereditary disorders).

Given STR analysis and the mutations-seeking methodology drawn up in the thesis, more concrete data can be obtained in order to undertake positive identifications. Thus, according to Dr Odriozola, the combination of these two tools could also be effective in complex kinship tests.


Story Source:

The above story is based on materials provided by Basque Research. Note: Materials may be edited for content and length.


Cite This Page:

Basque Research. "Forensics: Developing a tool for identification -- even using very degraded DNA samples." ScienceDaily. ScienceDaily, 12 April 2011. <www.sciencedaily.com/releases/2011/04/110412065950.htm>.
Basque Research. (2011, April 12). Forensics: Developing a tool for identification -- even using very degraded DNA samples. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2011/04/110412065950.htm
Basque Research. "Forensics: Developing a tool for identification -- even using very degraded DNA samples." ScienceDaily. www.sciencedaily.com/releases/2011/04/110412065950.htm (accessed July 23, 2014).

Share This




More Health & Medicine News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Courts Conflicted Over Healthcare Law

Courts Conflicted Over Healthcare Law

AP (July 22, 2014) Two federal appeals courts issued conflicting rulings Tuesday on the legality of the federally-run healthcare exchange that operates in 36 states. (July 22) Video provided by AP
Powered by NewsLook.com
Why Do People Believe We Only Use 10 Percent Of Our Brains?

Why Do People Believe We Only Use 10 Percent Of Our Brains?

Newsy (July 22, 2014) The new sci-fi thriller "Lucy" is making people question whether we really use all our brainpower. But, as scientists have insisted for years, we do. Video provided by Newsy
Powered by NewsLook.com
Scientists Find New Way To Make Human Platelets

Scientists Find New Way To Make Human Platelets

Newsy (July 22, 2014) Boston scientists have discovered a new way to create fully functioning human platelets using a bioreactor and human stem cells. Video provided by Newsy
Powered by NewsLook.com
Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

TheStreet (July 21, 2014) New research shows Gilead Science's drug Sovaldi helps in curing hepatitis C in those who suffer from HIV. In a medical study, the combination of Gilead's Hep C drug with anti-viral drug Ribavirin cured 76% of HIV-positive patients suffering from the most common hepatitis C strain. Hepatitis C and related complications have been a top cause of death in HIV-positive patients. Typical medication used to treat the disease, including interferon proteins, tended to react badly with HIV drugs. However, Sovaldi's %1,000-a-pill price tag could limit the number of patients able to access the treatment. TheStreet's Keris Lahiff reports from New York. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins