Header Ads

DNA Testing : How and What ?

DNA is the single source of information of our existence, it contains the data of our history and our present. It has answers to unrequited questions pertaining to our healthcare and even our ancestors. In school, we were taught that there is a dominant gene for brown eyes and a recessive one for blue. Talking about reality, it is not that straightforward for human traits to pass from generation to generation. Most traits develop under influence of several genes each having its own small effect.

Before the year 2000, we have relied on oral and written communications to trace family trees. But year 2000 came with the age of genealogical DNA testing. This provided genealogists an opportunity to use scientific methods to prove relationships using the ancestry DNA test.

As computing power increased, researchers have been able to link the molecular differences in DNA with specific human characteristics including behavioral traits such as education. Each of these genetic variants may explain a small amount of variation in the population, but when summed up together, they can explain more about why we see differences in people around us.

The DNA testing is done to gather such information and the umbrella of DNA testing is huge! For testing, DNA is extracted from cells and is sent to a laboratory for study. The scope of DNA testing is enormous; if we get answers to our healthcare, we can get information on any future diseases and take corrective actions in present to curb the disease. Further, the DNA of a newborn child can be sequenced to calculate the polygenic score and this can be used to predict how the kid will do in school for academic achievement or sports.

These days there are numerous companies for DNA testing who can help you learn what your DNA contains. Largely, there are three types of DNA tests, let us have a look at each of these.

1) Autosomal DNA

This is the most popular DNA testing technique and looks at the DNA that a person has inherited from his family tree. The results of this test provide an estimate of ethnicity or the regions in the world where one’s ancestors have lived in past few years. Autosomal DNA examines hundreds of natural DNA spelling variations called SNP nucleotide polymorphisms (SNPs). The overall pattern of these SNPs is then compared with those of people around the world to determine the DNA that has been inherited from a particular ancestor. But, the further you go back, the less DNA you have inherited from a particular ancestor. Inferring this, the test can link you with relatives as distant as third or fourth cousins and not more distant than that.

2) Mitochondrial DNA Testing

Mitochondrial DNA is the genetic material inside mitochondria and this is generally passed from mother. The test looks at only specific portions (16000 base pairs) of the mtDNA and compares them to established samples. Also, because it does not contain DNA from both parents it does not change with every generation and hence gives precise results for maternal ancestry.

3) Y-DNA

We have the 23rd chromosome, that has two versions, the X and Y DNA. Women have 2 X chromosomes while men have an X and a Y. The Y-DNA test examines only Y chromosome and thus gives the information of paternal line.

There are two-subsets of Y-DNA testing, the first one is a Short Tandem Repeat (STR) test that categorizes section of DNA according to their pattern of repetition. The second is Single Nucleotide Polymorphism (SNP) that works similar to Autosomal test and test about 30,000 SNPs.

All the three types of DNA tests give information about your ancestors but you have to identify what information you are looking for before signing up for these tests. As more and more companies are collecting data the accuracy of data is constantly improving. If you have read this far, chances are that you are too thinking of having a DNA test but don’t forget DNA testing have much more advanced capabilities.