Ancestry DNA Test: Procedure, Reliability and Availability in Perspective for a Social Scientist
Is DNA based ancestry a solution to ambiguous history book ancestry? The cell is the basic structural and functional unit of all humans. In the nucleus, an important part of the cell, Deoxyribonucleic acid (DNA), a chemical, is found. DNA has four types of building blocks (beads) which are called Adenine (A), Guanine(G), Cytosine (C) and Thymine (T). These beads are arranged along the string of DNA ( Example: AGCTAGTCTTTGC…..). There are about 3 billion pairs of these beads in human DNA. 99.9 % of the arrangement of beads are common (same) in all human. Only 0.1 % are different. These 0.1% variations (differences) are called single nucleotide polymorphisms, or SNPs (pronounced “snip”).The more SNPs a person shares in common with another person, the more likely they share a similar, and more recent, ancestry. In Ancestry DNA Test (ADT) in the first step, the DNA of a person is extracted and the important SNPs are identified, amplified and sequenced (Means, the pattern of SNPs are explored). In the second step, the ancestry of that person is estimated by comparing the SNPs of that person with the SNPs of persons which have already been done and made the part of databases. So far ADT of 26 millions of people have been done and have been made part of various online databases. For example, the SNPs of a person A from a specific race from Chitral are first identified in laboratory and then matched with the SNPs in the online databases of people geographically located in Central Asia, Europe, and Africa. Inference, the more SNPs the person A from Chitral shares in common with another person of the mentioned geographical areas, the more likely they share a similar, and more recent, ancestry. Sometime, by application of algorithms and statistics in 3rd step, the ancestry of person A from Chitral may be reported for example as 76% Central Asian, 23 % European and 1% African. This step is not experimental rather actually computed with the application of algorithms comparing the SNPs of person A from Chitral with the various groups of biogeographical ancestries from databases. It doesn’t mean that the great-grandfather of person A was from Central Asia and great-grandmother was from Europe and so he/she has 76% Central Asian and 23% European SNPs similarity. Rather it means that 76% of SNPs seems to match with the people living in Central Asia and 23% SNPs seems to match with the people living in Europe.ADT is done in two areas; in research and conducted by genetic companies on the demand of “race-conscious person or groups”. The researchers are always in search of accurate findings so they make strict and tough “inclusion and exclusion” criteria. They check and recheck their findings for reproducibility. They have to pass through the editorial and review process for their publication. So they ultimately find quite good results after hard work. But the results of the companies might not be that much precise as that is quite impossible to make tough inclusion and exclusion criteria and thorough analysis for just 60-100$ from a US citizen or 500 $ from a Pakistani citizen.Genetic companies claim to do it in Pakistan and many foreign companies have “collection points” or collaboration with Pakistani companies. But the reliability of the data may be a problem due to technical expertise, inclusion and exclusion criteria and confounding factors.In another better technique, the SNPs of person A from Chitral is matched with the SNPs of a person from other parts of the world extracted directly in a laboratory and not from the database. It gives more precise results. Besides SNPs, other tools which are used for the exploration of personalized genetic histories are mitochondrial DNA based tests, autosomal marker-based test and other non-recombining Y chromosome test. Further subgroups of these categories include microsatellite-based tests and polymorphism based test. Based on these various techniques maternal lineage, paternal lineage, biogeographical ancestry analysis, siblings testing and other researches and explorations are done. Many organizations are doing work in this field in various sub-specialities. Some of the names of these organizations are African Ancestry, DNA heritage, DNA print, Oxford ancestors, Relative Genetics etc. The field is just 20 years old and in its rapid growth stage. So, on daily basis, novel discoveries are reported but still many questions have not been answered and many issues have not been resolved.Javeed Farooqi, MulkowNote: Some basic information about DNACell has three main parts. Cell membrane (outer membrane), nucleus ( centrally located solid mass) and cytoplasm ( the fluid part inside the membrane in which other cellular components are floating). The nucleus of the cell has again four main parts. These are nuclear membrane ( the membrane of the nucleus), nucleolus (it is located in the centre of the nucleus), nucleoplasm (the fluid part inside the nucleus) and chromatin ( this part is found inside the nuclear membrane). Chromatin is composed of two chemicals which are called proteins and DNA. DNA is composed of 3 billion nucleotides. These segments of nucleotides control all the biological characteristics. A segment of DNA which control a biological character is called a gene. Humans have about 25-30 thousands of biological characteristics which are controlled by segments of DNA (genes). For example, eye colour is a biological characteristic which is controlled by a segment of DNA and that segment is called Gene of eye colour. So, a major portion of DNA is found in the chromatin (in condensed form chromosome) of the nucleus of a cell. Besides, a very minor quantity of DNA is also found in the cytoplasm of the cell in mitochondria which is called mitochondrial DNA.