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How to Read DNA Test Results

written by: efrontiers•edited by: lrohner•updated: 1/13/2011

Reading a DNA test result may seem complicated for the general public but this skill may be learned with a few instructions. Learn how to read DNA test results with this information.

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    A strand of DNA provides the information about your identity like height and physical attributes. It is made up of different building blocks referred to as A, T, G, C. The sequence of these building blocks determines one’s identity. No sequence is the same for one individual. In analyzing a DNA test result, the sequences from two people are compared based on certain guidelines.

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    Types of DNA Testing

    There are two main categories of DNA tests. These include mtDNA and the Yline DNA test. The mtDNA, or mitochondrial DNA test, is the type of DNA testing that finds traits that are inherited through the mother’s genes. This type of test is conducted in both male and female. Meanwhile, the Yline DNA testing is a type of test that finds traits passed from the father to the son.

    In reading the results of mtDNA test, a match means that the two people have a common maternal ancestor. On the other hand, the Yline DNA test helps determine the distance of these two individuals with respect to the common ancestor.

    How to read DNA test results? In a DNA test report, the DNA markers are provided with chart-type readout. This does not mean anything, however, to the ordinary person without the interpretation of a DNA specialist.

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    mtDNA Test

    The mtDNA test is normally conducted with two specimens for comparison. If the report shows that the two specimens are a match, it can be concluded that both of these individuals came from the same side of the maternal ancestry.

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    Yline Test

    The Yline test, more commonly known as the paternity DNA test, determines the chances that two males are related to each other. When the two male individuals have more matching alleles, there is a higher chance of finding the most recent common ancestor.

    The most common application of the Yline test is to establish a father-son relationship.

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    Reading the Paternity Test Result

    A DNA paternity test result contains the DNA profile of each person in a one-page report. The report reflects the combined parentage index or CPI and the probability of paternity.

    For the alleged father to be considered as the child’s biological father, the CPI must be at least 100 and this corresponds to a probability of at least 99.0%. When the results do not provide at least 99.0% probability of paternity, the alleged father is not the biological father. The CPI can, however, determine the distance between the two individuals with respect to a common ancestor. Unfortunately, it cannot determine how related the two males are.

    The results of the paternity test is very important in legal issues. This information will certainly provide the answer for any doubts regarding paternity.

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    The Limitations

    A DNA test may provide information on one’s identity but it has its limitations. One of the major limitations is that the results may verify that two individuals are related but it cannot identify exactly how. Hence, one cannot establish an accurate family tree based on DNA tests alone.