The potential father and child swab the inside of their cheeks for buccal (cheek) cells. You mail the cotton swab applicators to our lab. Once all samples have arrived at the lab, DNA is extracted from the swabs and the testing begins.
The genetic loci that are analyzed contain DNA sequences known as short tandem repeats (STRs)—short, repeating units of DNA. For each person, the number of repeats present at each genetic locus is variable and is inherited from their biological parents. For each genetic locus, each person has two genetic markers, or alleles (alternate forms of the DNA sequence): one allele is inherited from their biological mother and one allele is inherited from their biological father.
The test result report lists the allele sizes (number of repeats) for the mother (if tested), child, and alleged father at each genetic locus.
If only the child and alleged father are tested, and they do not share any alleles in common at three or more loci, then the alleged father is a excluded (ruled out). When the alleged father possesses the obligate or possible paternal alleles at all loci tested, then he is not excluded (not ruled out) as the biological father. Based on these genetic findings, a probability of paternity is calculated and reported.