Genealogical DNA Test

DNA and Chromosomes

Before understanding the concepts of the genealogical DNA testing, it is very important to understand the concepts of the DNA and the chromosomes. Read on to know more...

Deoxyribonucleic acid (DNA) is the name given to the chemical that is present on the inside the nucleus of all cells and carries the genetic instructions for making living organisms. A normal DNA molecule consists of two strands that are tightly wrapped around each other and resemble a twisted ladder. The 'rungs' of the DNA are made of chemicals that contain nitrogen and are called bases while the sides are composed of sugar and phosphate molecules. The four different types of bases present in the DNA are the adenine (A), cytosine (C), guanine (G) and the thymine (T). The DNA sequence is defined by the particular order of the bases that are arranged along the sugar - phosphate backbone.

Chromosomes are the thread like paired packages consisting of long segments of DNA that is contained inside the nucleus of each cell. In the human beings, there are about 23 pairs of chromosomes. While, 22 pairs of chromosomes are essentially identical in the males and females. The 23rd pair is different. In the females, this particular pair has two similar chromosomes known as the X chromosome while in males, this pair of chromosome contains and X strand and a Y strand which are very different from each other. It is this pair of chromosome that determines the sex of the individual.

What is Genealogical DNA Test?

A genealogical DNA test is performed to examine the nucleotides present on specific locations on an individual's DNA. The results of this test have no medical information. Neither does it have any information regarding the specific genetic disorder or disease that the individual is suffering from. These tests only provide genealogical information and are usually performed when you want answers to the following questions:

• Do you want to validate or invalidate your genealogical records?
• Do you believe that the spelling of your surname has been changed or somebody has been adopted into your family?
• Do you want to verify your relationship with a family that may have lived or is living in a region that you think you belong to?
• Do you think that you share a common ancestor with another individual or group?

If your answer to any of the questions above is 'yes', then you will need to undergo a genealogical DNA test along with the person in question.

Types of Genealogical DNA Tests

The general procedure involved in genealogical DNA test requires a buccal swab which is a painless cheek scrap. These days, mouth wash or chewing gum too can be provided for testing purposes. The most common genealogical tests are as follows:

• Y Chromosome Testing - is used when a man's paternal ancestry is to be traced. This procedure is also known as the Y-DNA or the Y-STR testing as the tests are performed on the Y chromosome of the men. The Y chromosome is used as it passes from the father to the son. Women who want to determine their parental ancestry will have to request their father, brother or any other male relative who share the same parental lineage to take the test for them. In this test, segments of DNA on the Y chromosome are examined where the nucleotides segments are repeated. These segments are known as the 'genetic markers'.
• Mitochondrial DNA Testing: is used to trace an individual's maternal ancestry. The DNA present in the human mitochondria is passed down from the mother to the child without any changes. This procedure is also known as mtDNA testing. mtDNA is divided into three regions as per the current conventions and the results of the tests are compared with the results of another person to determine the time frame when the two people shared a most recent common ancestor (MRCA).

It is imperative that the reason behind getting a genealogical test done be a valid one. The outcome of these results have been known to upset people as they can prove if the father of a particular generation is not the same one as the one mentioned in the birth records. However, they are an excellent means for genealogical research.