DNA testing is a group of techniques that provide information about genetic makeup. Most of the genetical information (about 99%) is identical to all human beings because biological processes like breathing and digestion, demand highly organised regulation that is coded by the genes. Most of the changes in those vital genes will result in serious developmental issues. However, there are some variations in less significant parts of DNA between individuals that can be used for parentage and lineage testing. DNA test can also identify hereditary diseases or be used for legal and immigration purposes.
There are three main parts of the genome (all the DNA of the cell) that are used for testing, depending on the client’s needs.
An autosomal DNA testing (atDNA test)
It uses DNA contained in 22 pairs of chromosomes out of 23 (all except sex chromosomes). Usually, autosomal testing is employed for the genetical diseases or disorders detection and DNA fingerprinting. But it also can be used for genealogical research. People that belong to the same family tree often have very similar regions of DNA called STRs (short tandem repeats) and also SNPs (single nucleotide polymorphisms). High percentage of similarity is an indicator of close genetic relationship. Microarray chip technology is the latest and most accurate method of detection matching DNA sequences between individuals that are tested for forensic purpose or the ancestry search. In addition, there are databases that collect information about SNPs and STRs of the people around the world. Comparing a client’s DNA with a database collection, geneticists can identify the particular world region of his or her ancestors.
Mitochondrial DNA (mtDNA) Testing
This method uses a particular molecule of DNA that is stored in mitochondria and gets inherited only through maternal line (from mother to her daughters and sons). Close relatives share very similar highly variable regions (HVR) on mtDNA. This method can be used to trace ancestry line many generations back. The origin of the whole nation can be determined using mtDNA testing.
Y chromosome (Y-DNA) Testing
This method uses one of the sex chromosomes that get inherited exclusively from father to son without much alteration, thus, enabling to trace paternal ancestry. Even though this test is not available for women, as they do not carry Y chromosome, an information can still be obtained through testing any male paternal relative (brother, paternal cousin, uncle or grandfather). Y chromosome testing similarly to the autosome test uses SNPs and STRs for the analysis.