27 August 2010

A circle of suspects the size of a biochip

A biochip has been developed that allows to establish a person's identityNews of Science
Specialists of the V. A. Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences and the Moscow Institute of Physics and Technology (State University) have developed a biochip that allows you to identify a person by trace amounts of DNA with a probability of 99.6%.

The biochip can be used in forensic medical practice in examinations that narrow down the circle of suspects, or in identifying the bodies of the deceased. The work of scientists was partially supported by the Federal Agency for Science and Innovation.

The biochip contains characteristic DNA sequences of three genes: ABO, AMEL and HLA-DQA1. The ABO gene determines a person's blood type, there are 90 possible variants of its sequence. HLA-DQA1, the gene of the main histocompatibility complex of the second class, has 34 variants. The AMEL gene encodes a protein that is involved in the development of tooth enamel. It is located on the sex chromosomes, and the sequences on the X and Y chromosomes are slightly different, which makes it possible to determine the sex of a person. Analysis of the diversity of sequences of three selected genes allows us to divide people into 1350 groups and assign each individual to a specific group.

Traditional examination has been determining the blood type by immunological methods for almost 100 years. But bloodstains don't always stay at the scene. In addition, the stain may be too old, dirty or very small, that is, unsuitable for traditional examination. DNA sequence analysis allows you to do with a much smaller amount of material. The creators of the biochip used cigarette butts with a filter on which saliva remained, and crumpled laboratory paper napkins with traces of sweat in their hands. The participants of the experiment were also asked to drink water from a disposable glass, after which lip prints were removed from the edge of the glass with a napkin soaked in sterile water. The DNA of the necessary genes was isolated from this material and applied to a biochip. The biochip, created on the basis of polyacrylamide gel, contains characteristic DNA fragments of all three studied genes.

The donor DNA is labeled with a fluorescent dye, and the human genotype is determined by the position of the fluorescent dots on the biochip. The creators of the chip used material obtained from 422 volunteers. The probability of a random coincidence of genotypes for three genes is 0.4%. This probability is too high to prove involvement in the commission of a crime, but it allows you to narrow down the circle of suspects and restore the picture of the incident if several people left traces.

Scientists hope that the inclusion of additional genetic loci in the biochip can significantly increase the informative value of the test. This is reported by Informnauka.

Portal "Eternal youth" http://vechnayamolodost.ru27.08.2010

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