We start testing 15 loci as they are enough to get a good paternity result for most cases. Testing more locations on your DNA (between 20 or 25 loci) will incur a higher fee and the testing times will be longer. All tests are done in batches, the largest and most common batches are for 15 loci. Testing more loci takes more time and because they are fewer, they are scheduled less frequently. Testing more loci also requires more reagents, hence the higher testing fee.

When we receive your samples at our laboratory, we obtain DNA profiles from a single sample from each individuals tested in a single case. These profiles are compared and if the result is negative, ie 0% probability of paternity, another set of samples are tested a second time on either the same day or second day. Results are then issued on the third day. This is why we say it usually takes up to 3 working days for a test. Please note that samples from all individuals involved in a test must be received at our laboratory before testing may commence.

Are testing times guaranteed?

Testing times are not guaranteed, even for the Express Testing option. This is because we do not know your genetic makeup. We provide a minimum guarantee of 99.99% probability of paternity for positive tests and 0% for negative tests. If we are unable to obtain a conclusive result on 15 loci, we will continue testing more loci (up to 26) at no additional cost to satisfy our guarantee. If testing the maximum number of loci does not provide a conclusive result, samples will be subjected to other tests, including Y-Chromosome, mtDNA and even RFLP. This means that testing times could be extended by 1-4 weeks.

However, cases where testing takes 2 weeks or more to complete are very rare.

Why does this happen?
There are many reasons why testing times may be longer than 3 days. Below, we list the 3 main reasons:
1. Mother’s profile not available
2. Mutation in child’s DNA
3. Samples are contaminated

1. Mother’s profile not available

Testing times are almost always shortest when we have samples from Mother, Alleged Father and Child. If the mother is not available, then testing times MAY be longer. Each parent provides 50% of the child’s genetic makeup, and if her profile is not available, there are cases where the combined paternity index is not high enough.

In the sample results below, the initial set of loci tested (in green box) only gives a Combined Paternity Index of 2,350, which gives a Probability of Paternity of 99.9575%. Since this is below our guarantee of 99.99%, additional testing is carried out with more loci. After the additional testing, the Probability of Paternity is 99.99935%.

2. Mutation in child’s DNA

Mutations occur when a Child’s alleles at a specific loci differ from what we expect it to be. Remember, Child’s alleles occur in pairs – one from Mother and another from Father. Sometimes, the child’s alleles at a few loci will differ from either Father’s alleles, Mother’s alleles or both. Below is a sample report where the Child has mutations at loci FGA and TPOX. (Please read our previous FAQ – PART 3: Understanding a PTC Paternity Test Report). You will notice that there are no matching paternal alleles at these 2 loci, but a paternity index is still given to accommodate the mutations.

Can I ask for you to start testing 20 loci instead of 15?

We do not recommend this because more than 90% of the time, only 15 loci are required to obtain a conclusive result. Also, if we are unable to obtain a conclusive result on 15 loci, we will continue testing more loci at no additional charge to you.

I would like to pay more to get my results quickly.

We have an Express Testing Option for an additional fee of THB 4,500 where we guarantee results will be available the day after testing commences. If samples arrive at the lab before 10 am, testing starts on the same day. If not, testing commences the following day.

If we are unable to give you results in time, we refund the Express fee and continue testing until we reach our minimum guarantee of 99.99%. However, this rarely happens.