Frequently Asked Questions: DNA

Family Reference Samples

Q: What is a Family Reference Sample?: Family members of missing persons are asked to provide DNA samples that are profiled and uploaded to the National DNA Index System, in an effort to locate missing persons through DNA database searches. These samples, known as Family Reference Samples, are voluntary DNA submissions that are used only in the search for a missing loved one.

Q: What is the National DNA Index System?: The National DNA Index System, or NDIS, is part of the Combined DNA Index System (CODIS). NDIS contains profiles contributed from federal, state, and local participating DNA laboratories across the country. The DNA profiles uploaded to NDIS are organized into indices, such as the Convicted Offender index. Direct profiles from a missing person, which are derived from items such as toothbrushes or tissue samples, are uploaded to the Missing Person index of CODIS. Profiles for unidentified decedents are uploaded to the Unidentified Human index of CODIS. Profiles from family members are uploaded to the Relatives of Missing Persons Index.

Q: How are Family Reference Sample DNA profiles searched in CODIS?: Individuals who provide Family Reference Samples in an effort to locate a missing loved one will have their DNA profiles uploaded to the Relatives of Missing Persons index of CODIS, which is searched only against the Unidentified Human index of CODIS. Family reference profiles are not searched against any of the criminal indices, such as those containing profiles of convicted offenders or unknown suspects.

Q: Can a family member collect or submit his/her own DNA sample?: A family member cannot collect or submit his/her own DNA sample for profiling and upload to CODIS. All samples must be collected by criminal justice personnel who verify the DNA donors' identity, collect the samples, and submit samples to the UNT Center for Human Identification under proper chain of custody. The UNT Center for Human Identification DNA collection kit includes all necessary submission paperwork, including the chain of custody.

Q: How do I collect a Family Reference Sample?: A Family Reference Sample must be collected by a law enforcement officer, medical examiner, coroner, or other medicolegal investigator employed by a criminal justice agency. Samples submitted to the UNT Center for Human Identification can be collected utilizing a prepackaged collection kit that can be obtained through a NamUs Regional System Administrator or by calling 1-855-626-7600. Please note that these kits are specific to the UNT Center for Human Identification's DNA laboratory and should not be used for other purposes. If another laboratory will be utilized, please contact that agency for instructions, submission paperwork, and/or collection kits that are specific to their laboratory.

Q: Which family members are best for collection?: First-degree relatives (parent, full sibling, or child) are most beneficial for Short Tandem Repeat (STR) DNA comparisons. Second-degree relatives (half-sibling, aunt, uncle, grandparent, etc.) may be useful for limited STR comparisons, as well as for Y-STR or mitochondrial DNA comparisons; however, first-order relatives are always preferred when available.

Q: How many family members should provide DNA samples?: In order for proper searching to take place in CODIS, and for potential associations to be identified, DNA profiles from at least two family members should be collected for every missing person case. If no first-degree relatives are available, additional family reference collections may be required. If you have questions regarding DNA collections in a particular case, contact your NamUs Regional System Administrator or the NamUs toll-free line at 1-855-626-7600.

Q: Does it matter how half-siblings are related?: It is important to note on the DNA submission paperwork if siblings share only one parent, and if they are half-siblings, it is important to note if they are paternally or maternally related, as this information will allow the laboratory to ensure that proper searching takes place within CODIS. For instance, half-siblings who share the same mother will be utilized as both a nuclear and mitochondrial DNA reference.

Q: How long does it take to get results?: Processing time varies depending upon the volume of samples received by the laboratory at any given time; therefore, it is not possible to provide a standard turn-around time on family reference DNA samples processed by the UNT Center for Human Identification. Updates on specific cases may be requested by the submitting agency by contacting the Laboratory for Molecular Identification's Technical Leader, Dixie Peters, at 817-735-2749.

Q: Does the UNT Center for Human Identification accept charred remains?: Charred remains may be examined on a case-by-case basis. For a case consultation, please contact the Laboratory for Molecular Identification's Technical Leader, Dixie Peters, at 817-735-2749.

Q: Does the UNT Center for Human Identification accept samples that have previously been tested at another laboratory?: Provided enough sample remains for re-testing, the UNT Center for Human Identification may analyze a sample that has previously been tested at another laboratory. It is recommended that the investigating agency contact the Laboratory for Molecular Identification's Technical Leader, Dixie Peters, at 817-735-2749 for a consultation prior to submission.

Q: How long does it take to get results?: Processing time varies depending upon the condition of remains, how many attempts are required to extract DNA from a particular sample, and the volume of samples received by the laboratory at any given time. For these reasons, it is not possible to provide a standard turn-around time on unidentified remains samples processed by the UNT Center for Human Identification. Updates on specific cases may be requested by the submitting agency by contacting the Laboratory for Molecular Identification's Technical Leader, Dixie Peters, at 817-735-2749.