03.09.2018

Relationship testing

What is relationship testing?

Relationship testing is done to determine various types of biological relationships.
For example, a grandparentage test can be conducted to determine if a biological relationship exists between the alleged grandparent and the child, in cases where the alleged father is not available to do the test. Other types of relationship tested include twins, sibling, aunt/uncle, cousin, and nephew/niece.

How is it done?

To carry out the test, all we need are genomic DNA from the two test subjects. Genomic DNA can be obtained from buccal swab and whole blood. We then compare the lengths of specific repeated DNA sequences in the chromosomes of the two test subjects. From there, we will be able to accurately determine the existence of a biological relationship between them.

Test method and theory

Short Tandem Repeat (STR) DNA typing is used to conduct the relationship testing. STRs are short repeated DNA sequences found in the chromosome of every individual. An individual inherits one copy of an STR from each parent, and unrelated people almost certainly have different repeat units. Thus, STR is an effective marker of biological relationships.