Description
Paternity testing is based on amplification and detection of short tandem repeat (STR) loci. STRs are microsatellite DNA consisting of tandem repeating sequence elements that are each 2-7 base pairs in length. These abundant repeats are distributed throughout the human genome and are a rich source of highly polymorphic genetic markers. Thousands of STR loci have been identified in the human genome to date. The number of repeats at a STR locus is highly variable among individuals, resulting in length polymorphisms that can be detected by polymerase chain reaction (PCR) amplification. STR analysis is currently the most powerful genetic method for accurately determining parentage and is replacing older and less sensitive techniques such as serology and restriction fragment length polymorphism. PCR amplification products are detected using state-of-the-art fluorescent multicolour dye technology and the capillary injection ABI 310 Genetic analyzer. Additional applications include sibship analysis, grandparentage studies, maternity testing, twin testing (zygosity), genetic disease, DNA banking, and forensic analysis.

Accuracy
DNA paternity testing through PCR analysis of STR loci is the most accurate method for parentage testing currently available. The accuracy/power of a DNA test is dependent upon the number of different STRs examined. The power of the test increases as the number of STRs tested increases. Many laboratories in North America examine 9 or less STRs to cut costs. Genex Diagnostics examines all 16 STRs for all tests to ensure the greatest accuracy for all tests. The DNA test will demonstrate either 0% probability of paternity or greater than 99.99% for paternity inclusion.