Autosomal DNA Testing

Human genetic make-up is the most 'authentic' part of the body. The characteristics of a DNA (deoxyribonucleic acid) structure, for any individual or family consist of similar pattern which helps identify the relation and the ancestry. A DNA retains some of its features as it passes from one generation to the other while some parts of it change drastically. The components that are unhindered, help in verifying the family history. Though it is difficult to establish the exact family tree of an individual, a DNA test can conclusively prove whether a person is related to another, determine whether they have the same ancestor, trace people with same surnames and assist in finding the ethnic origin.

Autosomal DNA Testing
There are three different tests that are used to gather information about one's ancestry-

• Mitochondrial or mt DNA (maternal line)
• Y-chromosome (paternal line)
• Autosomal DNA (common)

The human body consists of 23 pairs of chromosomes which are organized DNA structures found in the cells. Out of these, 22 pairs are non-sex chromosomes contained in the nucleus. The last pair can be an X or a Y chromosome or a combination of both which determines whether the major inherited features are from the mother or the father. The other 22 chromosomes are associated with the physical traits of an individual like hair, eye color or height. The genetic history of a person is ascertained through a complete scan of all the chromosomes. It gives an idea of all the characteristics of an individual contributed by both the parents. Autosomal DNA tests are not limited by the gender of the concerned family line. Hence, it is easier to verify nuclear relationships with family members like a grandmother, brother or a sister.

Applications of Autosomal DNA Tests
Paternity testing is the one field where autosomal tests find large scale application. The extended family can also be tracked using these tests. The FBI's crime-solving database contains 14 markers, that are standard for conducting these autosomal tests. These 'CODIS' markers are used for crime detection in DNA fingerprinting and also in paternity tests. Biogeographical ancestry mapping is another area of human genetics where autosomal DNA testing is used. The geographic heritage of a person can be determined, based on this test. The application of this test is limited because chances of an error are high, although, a rough idea about the family's origins can be deduced from the test. The cost of conducting a basic autosomal tests can range anywhere between $200 to $300. This test gives a classification as a percentage of European, Native American, Sub-Sahara African or East Asian genes, present in a person. The specification of the region can be traced exactly to a limited area, as one pays more money, but the authenticity cannot be guaranteed.

Constraints
The limitations of an autosomal DNA test are

• It can trace the origins back to only a couple of generations, though research on enhancing its scope is being carried out.
• In case of siblings, one may inherit more genetic component than the other, from the same parent. For instance a boy may inherit 40% African genetic structure form his mother whereas his sister may get only 20% from the same mother. Therefore, the percentage of the original ancestry cannot be established with certainty.
• Autosomal DNA tests fade in its authenticity as the ancestry deepens, since the DNA that is passed on, gets diluted with each passing generation. It can be used with the mitochondrial or the Y-chromosome tests with higher degree of reliability.

Although, the current status of DNA research is a contentious issue, there is hope that in the future, autosomal tests may lead us into the depths of human ancestry.