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Raw Data Technical Details

Important: The raw data provided by 23andMe is an advanced view of all the uninterpreted raw genotype data, including data that is not used in 23andMe reports. This data has undergone a general quality review however only a subset of markers have been individually validated for accuracy. As such, the data from 23andMe's Browse Raw Data feature is suitable only for research, educational, and informational use and not for medical or other use.

 

What topic would you like to learn more about?

  • Reference Genome and Strandedness
  • Not Determined/ Not Genotyped
  • rs numbers (rsids)
 
Reference Genome and Strandedness

23andMe results indicate SNP (Single Nucleotide Polymorphism) positions and alleles based on the NCBI human reference genome (a standard version of the nucleotide sequence of the human genome). Both the raw data as well as site features and reports currently use human genome assembly GRCh37 (build 37).

DNA consists of two strands that are complementary to each other. The DNA nucleotide "A" always pairs with "T" and "G" always pairs with "C" across these two strands. One strand is called the positive (+) strand and the other is called the negative (-) strand.

The genotypes displayed on the 23andMe website, including in the Browse Raw Data tool, always refer to the positive (+) strand on build 37 of the human reference genome. This is sometimes different from how other websites or publications refer to a genotype.

If the possible genotypes reported by 23andMe and another source do not match, it is likely that we are referring to complementary DNA strands rather than the same strand. For example, 23andMe might report that a SNP has two versions, G and A. But other sources may report that the versions for that SNP are C and T. Because G pairs with C on the opposite DNA strand, while A pairs with T, both ways of reporting the SNP are correct

 
Not Determined/Not Genotyped

In some cases, a user will not have data for a particular SNP (Single Nucleotide Polymorphism). There are two different ways this could occur in 23andMe raw data: Variant Not Determined or Not Genotyped.

Not determined: In some cases, we are not able to provide a result for a particular SNP. If results cannot be provided, you will see “variant not determined.” In the Raw Data tool, the entry for any uncalled SNP displays '--' instead of a two-letter genotype. If you see this result, our algorithm may not have been able to confidently determine your genotype at that marker. This can be caused by random test error or other factors that interfere with the test. Some “not determined” variants are expected in the raw data and are not a cause for concern.

Not genotyped: 23andMe periodically updates its DNA genotyping platform to take advantage of improvements in technology. Not all genotyping platforms include the same SNPs. Results for SNPs that are not included on the genotype platform you used will appear as "not genotyped" in the Browse Raw Data tool.

 
RS numbers (rsids)

The rsID number is a unique name ("rs" followed by a number) used by researchers and databases to refer to a specific SNP (Single Nucleotide Polymorphism). It stands for Reference SNP cluster ID and is the naming convention used for most SNPs.

If a probe on our genotyping platform doesn't correspond to a SNP with a clear rsID, or the probe is assaying a DNA change that is not a SNP, that SNP or change is usually assigned an "internal" id ("i" followed by a number). Our researchers may have selected some of these SNPs to maximize the number of actionable 23andMe features available to customers as well as to offer flexibility for future research.

In general, any SNP within your 23andMe raw data named with an "internal" id will not have a corresponding rsID in outside scientific literature or any third party services.

 

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