DNA Parentage test
The DNA parentage test is most often requested for determining paternity. A child’s DNA is inherited from the biological parents with half from the mother and half from the father. We are able to identify the child’s maternal DNA when the mother is tested and then compare what we know to be the child’s paternal DNA with the putative father. If the putative father is the biological father, then he will have DNA that matches the child’s paternal DNA and he cannot be excluded from paternity. If the putative father is not the biological father then he will have DNA that does not match the child’s paternal DNA and he can be excluded from paternity.
A Negative Result
If the putative father is excluded at more than 2 of the 15 DNA regions routinely investigated, then the putative father’s DNA does not match the child’s paternal DNA and the case is reported as negative. A statistical analysis is not necessary for negative cases.
Positive Cases and the Likelihood of Paternity – The Paternity Index Value
If the putative father’s DNA matches the child’s paternal DNA at all 15 regions analysed, then a paternity index value is calculated. The paternity index value is only calculated when the putative father can not be excluded from paternity of the child. The paternity index provides a value for the strength of the DNA evidence. Values of greater than 10,000 are usually obtained (the threshold value for reporting a case as positive) and often many orders of magnitude greater when the putative father and child have matching DNA at the 15 regions routinely investigated. With a paternity index value of 10,000, the DNA evidence is 10,000 times more likely if the putative father is the biological father rather than if a man unrelated to the putative father is the biological father.
The paternity index value is not as high for positive cases and fewer exclusions are identified for negative cases when the mother is not tested.
Requirements and helpful information
- Formal identification is required at the time of sample collection
- Samples are collected at one of the designated collection centres throughout New Zealand
- Sample required - typically a mouth swab sample; more information on the DNA Sample procedure and requirements can be found on our Getting Started page
- Who should be tested:
- putative father (s)
- child
- mother (not necessary, but preferable and strongly recommended); testing of the mother helps to identify the child’s paternal DNA by exclusion of the maternal DNA and the possibility of chance matching is reduced
- Cost:
| Two or three people |
1125.00 including GST |
| Each additional person processed at the same time |
281.25 including GST |
| Repeat test with a new putative father |
725.00 including GST |
| Repeat test with a new mother and child |
925.00 including GST |
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Twin Zygosity Test
The Twin Zygosity test will establish whether or not twins or other multiples are identical. Individuals have unique DNA excepting identical twins and other identical multiples. Thus, we expect that identical twins will have an identical DNA profile. Twins who are not identical will have different DNA. This test is sometimes undertaken to satisfy a parent’s, or the adult twins’ curiosity or for health reasons.
Collecting the sample
Mouth swab samples are collected at home and then sent by post to DNA Diagnostics Ltd. A sample collection kit is provided upon request. The kit contains instructions, sterile swabs and a form for completion and return to us with the samples and the payment. A pre paid return envelope is supplied.
Cost: $168.75 incl GST (based on 1 set of twins)
Please contact us for other multiples.
DNA extraction, profiling and Storage
DNA is extracted and saved for possible future use, such as availability for future family studies when a genetic disease needs investigation, an estate claim, when the claimant can be requested to undergo parentage testing to prove their relationship to the deceased. A DNA profile is obtained from a small fraction of the saved DNA and is provided to the client.
Samples are collected at designated collection centres throughout New Zealand and formal identification is required at the time of collection.
Cost: DNA extraction, profiling, storage (5 years) $350.00 including GST
Independent Review of DNA Evidence
We are able to provide an independent review of DNA profiling work that is to be presented as evidence in Court. We have over 20 years experience in DNA profiling and have appeared in Court as an expert witness for the defence and for the prosecution.
Cost: Consultancy $168.75, including GST, per hour (elapsed time)
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