Autosomal DNA Testing

Autosomal DNA Testing

Autosomal DNA testing is a method to determine the parentage of an individual. DNA tests are the most authentic means of determining an individual's identity.
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, consists of similar patterns, which helps to identify their 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.

Description

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, height, etc. 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, which are 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 grandmother, brother, sister, etc.

Applications

Paternity testing is a field, where autosomal tests are applied on a large-scale basis. 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 tests. These "CODIS" markers are used for crime detection in DNA fingerprinting, and also in paternity tests. Bio-geographical ancestry mapping is another area of human genetics, wherein this type of testing is used. The geographic heritage of a person can be determined, based on this technique. Its applications are limited, because chances of an error are high; although, a rough idea about the family's origins can be deduced from this method. The cost of conducting a basic autosomal test can range anywhere between USD 200 to USD 300. This technique provides a classification as a percentage of European, Native American, Sub-Sahara African, or East Asian genes, which are 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 this 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 components than the other, from the same parent. For instance, a boy may inherit 40% African genetic structure from his mother, whereas his sister might inherit only 20% from the same mother. Therefore, the percentage of the original ancestry cannot be established with certainty.
  • Autosomal DNA tests fade in their 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, these tests may lead us into the depths of human ancestry.
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