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How Does SPARK Analyze Study Participants’ DNA?
See the journey your DNA takes from saliva sample to genetic results.
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See the journey your DNA takes from saliva sample to genetic results.
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Five to ten percent of samples can't be processed. This may be because the samples were not labeled properly. Or because there was not enough saliva to isolate DNA. In these cases, SPARK will send you another saliva kit.
Scientists isolate DNA from saliva
This process used to take much longer, 3 to 9 months. This was because SPARK had to collect batches of 15,000 DNA samples before the DNA could be analyzed. This is no longer the case.
DNA samples are gathered for analysis
- About two to three percent of samples cannot be sequenced. This may be because the samples were not labeled properly or contaminated. In these cases, SPARK will send you another saliva kit.
- The type of sequencing is called exome sequencing. This means that scientists read the parts of DNA that produce proteins.
DNA is read letter by letter, a process known as sequencing
- Changes in the DNA can include new or inherited changes. These changes may involve a single letter of DNA or span many letters, known as copy number variations.
- Computer programs analyze DNA for different types of changes. The process involves huge amounts of data – a petabyte, or a million gigabytes. This can be time-consuming. For comparison, it would take 2,000 years to listen to a petabyte of music on MP3 files.
- SPARK staff and scientific experts who collaborate with SPARK search for different types of changes. SPARK then compiles the results.
- Automated tools can find about half of the DNA changes. Scientists analyze more difficult cases by hand, a process that can require many hours.
SPARK receives sequence data from an external lab and analyzes the data, searching for changes in the DNA sequence
Learn more about SPARK's gene list and "What Makes an Autism Gene?"
Scientists narrow down the list of DNA changes to genes or regions that are on SPARK’s gene list. Genes on this list have been linked to autism in multiple unrelated people.
- Some gene changes result in a non-working copy of the gene. Other gene changes alter how well the gene works. Some changes affect many genes.
- Early results suggest that about 10 percent of participants will get a genetic result. That number will grow as more genes that are linked to autism are discovered.
If a gene change is found that is linked to autism, a clinical genetics lab reanalyzes your DNA and confirms the result.
In these cases, scientists consult the medical genetics committee, which regularly reviews new research and adds to SPARK's list of autism-related genes.