Frequently Asked Questions (FAQs) About Snapshot
- What is Snapshot?
Snapshot is a forensic analysis service developed by Parabon that can help law enforcement generate new investigative leads. Using modern SNP technology, Snapshot generates a physical profile from a DNA sample — a process known as DNA Phenotyping. A composite profile includes sex, ancestry, pigmentation (skin color, hair color, eye color, freckling), and even face morphology. A statistical confidence measure accompanies each phenotype prediction, and phenotype ranges that can be excluded with 95% confidence are also reported.
- What type of analysis/reporting does Snapshot provide?
We report sex, genetic ancestry — both on a global (e.g., European) and subcontinental (e.g., Scandinavian) scale — eye color, hair color, skin color, freckling, and face morphology. The data is presented in a report with a composite predicted profile of the individual and the detailed supporting information that goes into making that profile. You can request a sample report here.
- How does it work?
Snapshot takes advantage of modern SNP technology. Using bioinformatics pipelines and predictive models developed by Parabon, Snapshot reads genetic content from DNA, which in turn has allowed the creation of datasets that include both genotypic (genetic content) and phenotypic (trait) data for each of thousands of subjects. With the diligent and repeated application of data mining and machine learning processes to such data, Parabon produces statistical models that translate the presence of specific genetic biomarkers into forensically relevant trait predictions.
- What is the difference between STRs and SNPs and why do you think SNP analysis is better?
STR analysis is only useful for matching a sample to a known suspect or a database. The Snapshot technology uses the information about physical appearance encoded in SNPs to generate new leads about unknown suspects.
- How does my agency order a Snapshot analysis?
Once we determine what type of sample and laboratory service is required to process your sample, we will send you a specimen transmittal form.
- Do I ship the sample directly to you?
No, we would ask you to send the extracted DNA to one of our partner labs for genotyping.
If you do not have extracted DNA, please ask your crime lab if they can extract DNA from the biological evidence in the case. If they are unable to perform the extraction, we can refer you to a private forensic laboratory that can perform the extraction for your agency on a fee-for-service basis.
For more information, please see our Workflow of a Parabon Snapshot Investigation diagram.
- How much extracted DNA do you need?
Snapshot reports can be reliably produced from as little as 1ng† of DNA; however, if your case has more DNA available, we advise submitting more than 1ng to improve the likelihood of genotyping success. Before accepting a case, we will work directly with your DNA analyst to determine the quantity of DNA that will need to be consumed for a Snapshot analysis. A variety of factors go into this determination including, but not limited to, the total available quantity of extracted DNA, its quality, mixture level, the date and method of extraction, the age of the original biological evidence, and the availability of other biological evidence from which additional DNA might be extracted.
The genotyping assay used for Snapshot analysis calls for nuclear double-stranded DNA (dsDNA) either suspended in elution buffer, distilled water, or submitted as a lyophilized product. Depending on the sample quality, single-stranded DNA (ssDNA) may also be accepted on a case by case basis.
† The genotyping assay required for Snapshot has produced viable data using 50pg (0.05ng) of extracted DNA, however, at these levels we generally observe lower genotyping call rates, which results in phenotype predictions that have lower-than-normal confidence estimates. In some cases, where almost no information is available about the person of interest, these predictions may still be of value. Please contact us to discuss your case if you have < 1ng of DNA.
- Do you accept cases for which only partial profiles are available?
Yes, Parabon can accept DNA that has generated only a partial STR profile! Partial profiles are typically an indication that there is some sort of impairment to the DNA evidence — e.g., inhibition, mixture, contamination, degradation, etc. If the latter, Parabon is able to repair some level of DNA fragmentation. In addition, partial profiles serve as a warning that we may encounter data loss while genotyping these samples, resulting in lower confidence levels in our final phenotype predictions; the more partial the STR profile (i.e., fewer loci reported) the more risk we associate with the sample. In most cases, however, Parabon can accept samples with higher risk assessments at the agency's full understanding of the trade-off in confidence levels.
- Can mixed DNA samples be used?
Yes. Parabon can accept two-person mixtures as long as the unknown person of interest is the major contributor of the mixture. If the minor contributor is >10% contribution, a single-source DNA extract from the minor contributor will need to be provided to Parabon so that a mixture deconvolution process can be performed. In some instances, Parabon can accept three-person mixtures, as long as all of the above criteria are met and the third person in the mixture is a trace contributor or ≤10% contribution.
- What is the turnaround time (the time from when the sample is received to when the prediction is returned to the customer)?
The turn around time will largely depend upon the batch cycle of the laboratory. For economies of scale, the laboratories often like to run as many genotype samples as possible. So, the turnaround time can vary between four and six weeks. Once a decision is made by your organization to use Snapshot, we will coordinate with our partner laboratory and provide a more precise turn around time.
- Do you accept credit cards?
- We are a genotyping/forensic lab, can we partner with you?
We'd be happy to consider additional partnerships! We are interested in forensic labs who have experience evidence chain of custody, DNA extraction, and/or SNP genotyping capabilities.
- What type of file format do you require from the labs?
We request that labs use Illumina's GenomeStudio software to convert the raw data to Top Allele format, which reports the genotypes as A/C/G/T. We also ask for the results from the sex inference module in GenomeStudio.
- I'm unhappy with how law enforcement is handling my case. Can I send you a DNA sample of someone I suspect committed a crime, and have you analyze it?
At the present time, we are only providing this service to law enforcement and Federal government agencies. We'd be happy to speak with the detectives handling your case, if they express interest in learning more about the service.
- Who has used it so far?
For the past four years, the development of Snapshot has been funded by the United States Department of Defense (DOD), specifically the Defense Threat Reduction Agency. As part of the development and validation process, Snapshot has been tested on thousands of out-of-sample genotypes and has been shown to be extremely accurate. In addition to the DOD, Snapshot has been used by State and local police departments throughout the US, and private citizens seeking ancestry information.
Please see our gallery of Published Police Investigations for a number of publicly available Snapshot profiles.