What is DNA Test ?

What is DNA?

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.

DNA contains the genetic information that parents pass on to their children. Half of a person's DNA is received from their mother, and half is received from the father. Thus, DNA Testing is done to establish familial relationships. The genetic potential of an organism is carried in the base sequence of its DNA, according to the genetic code. Every nucleated cell in our bodies - from heart to skin, blood to bone - contains a complete set of our DNA.

What is DNA Test?

DNA testing is a powerful tool for identification and has many practical applications. Testing for similarities between DNA (deoxyribonucleic acid) samples from two people allows family relationships to be established - or disproved - to an extraordinarily high degree of certainty. A common use for a DNA test is to establish if a man is the biological father of a child, a paternity test. However, there are other uses for the science of DNA testing (also called genotyping), these include forensic analysis of human DNA samples, and tracking relationships amongst domesticated animals.

Each person is unique and just as people differ in their fingerprints, they also have a unique and slightly different DNA sequence. Half of a person's DNA is received from their mother, and half is received from the father. However, while fingerprints have no value for establishing family relationships, the minor variations in DNA sequence are extraordinarily useful for this purpose. All cells of our body contain DNA except RBC's therefore DNA is extracted from WBC's, likewise skin cells from the lining of the cheek provide a simple and convenient source of material. Indian Biosciences - DDC India Pvt. Ltd. is one of the most reliable DNA testing labs in India. We have best facilities for DNA Testing in India at affordable price.

Applications of a DNA Test

DNA testing is a powerful tool for identification and has many practical applications.
Common uses include:
• Parental testing
   To establish if someone is the biological parent of a child
• Relationship Testing
   To establish if someone is the biological relative (brother, sister, grandfather, grandmother) of a child
• Forensic testing
   To help identify suspects or victims in a criminal investigation
• Gene therapy
   To test parents or foetuses for genetic conditions or birth defects
• Health Wellness
   To test individuals for obesity, nutrition, heart diseases, other diseases
• Genetic genealogy
   To find out more about someone's ancestry

How to Interpret a DNA Paternity Test Report ?

The DNA Test Report shows the results of laboratory DNA tests that provide evidence regarding the alleged family relationship. This is a brief explanation of the meaning of the numbers (that is to say, the statistical certainty of the result) and other items that appear in a DNA test report: The laboratory analysis tests the DNA isolated from cheek swabs to locate certain regions of chromosomes that are known to vary in length between individuals. 22 of these sites are tested; each site is called a "locus", ("loci" – plural). Analysis of these 22 sites in a large population has revealed many different sized versions associated with each site. Versions of a DNA sequence or a gene are called “alleles”. These are the genetic markers* used in parentage analysis. Because each individual has two of each type of chromosome, one inherited from each parent, everyone has two alleles at each locus. These two alleles are sometimes identical (homozygous), but usually they are not the same size (heterozygous). During parentage DNA testing, the laboratory identifies the length of the two alleles found at each locus. The DNA test report you will receive shows numbers (in the first column) that indicate each of the 22 loci involved in the DNA testing process.

The columns marked "allele" on the DNA test report contain numbers indicating the two alleles found at each locus (or one number if they are the same size). If, for example, a child has two alleles that are designated 12.1 and 18, and if the mother has alleles 12.1 and 16, then the child inherited the 12.1 allele from the mother. The child has to have inherited the 18 allele from the father. The 18 allele is the "obligate paternal allele." Generally, the alleged father must have this allele if he is the biological father of the child.

21 different loci are used as genetic markers in the DNA tests, as well as one (Amelogenin) to confirm the gender of the person providing the DNA sample. If the alleged father does not have the matching allele at every tested locus, then he usually cannot be the biological parent. If he does have it, then he could be the father. A "relationship index" (called the "Paternity Index" in the report) for each locus is calculated based on information including the portion of the male population that has the obligate paternal allele at that locus. This index is reported for each DNA locus.

A combined relationship (or "Direct") index for all of the tested alleles is then calculated and appears below the chart. This number is used to calculate the "probability of relationship," which is the percentage likelihood that a man with the alleles of the alleged father is the biological parent of the child, as compared to an untested, unrelated man of the same race. If the DNA of the alleged father is consistent (to a degree of mathematical certainty) with that of the child, then the report will conclude that the alleged father cannot be excluded as the biological father of the child. If the DNA is not consistent however, it will conclude that the alleged father can be excluded as the biological father of the child.

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