View Full Version : 23andme Upgrading to NCBI Build 37 Coordinates

Scarlet Ibis
08-05-2012, 09:48 PM
Supposedly, 23andme is updating to the NCBI Build GRCh37 assembly. It was announced back in July, but as far as I understand, they only started doing the updating a few days ago. Has anyone seen any changes in your relative finder, or ancestry finder results yet?


The 23andMe genotyping results currently indicate SNP positions and alleles based on the NCBI Build 36 human genome assembly. On Aug. 1, we plan to upgrade the site to report SNP positions and alleles based on the newer, more accurate NCBI Build GRCh37 assembly.

* What is a genome assembly and why is the upgrade important?
While the reference human genome has been called “finished” since 2004 (ref. 1), it contains a small number of regions of unknown sequence and incorrect sequence. When these inconsistencies are discovered, the reference genome is updated to reflect the more accurate genome sequence. Each of these updates is called a “genome assembly”. NCBI Build 37 is the current gold standard upon which many public datasets are reported, so this upgrade will make it easier for users to compare their 23andMe data to other data sets.

* How does this affect my results?
The most noticeable change from the upgrade occurs in the “Browse Raw Data” feature, where reference coordinate positions are displayed. The coordinates of most SNPs will change, though the genomic sequence each SNP represents remains the same.

Small numbers of SNPs change strand information (e.g. A/G will be called C/T), change their name (e.g. from rsXXXX to iYYYY), or are not mapped in Build 37. In total, < 0.2% of all SNPs are affected by these changes.

Users may see small changes in Relative Finder and/or Ancestry Painting results, since changes to the relative positions of SNPs can influence inheritance predictions. This may result in some changes to your matches, because the shared DNA segment lengths can change. Although the segment lengths typically change by very little, this can result in distant matches being lost or gained, or in changes to a predicted relationship. No health and trait reports will be affected by the upgrade.

* What if I want to keep my Build 36 data?
Since Build GRCh37 is the gold standard human genome assembly, 23andMe will only support the Build GRCh37 data after the upgrade. If for some reason you want to keep your Build 36 data, you should download it from the Browse Raw Data ( http://www.23andme.com/you/download ) and Relative Finder ( http://www.23andme.com/you/relfinder ) pages prior to the upgrade. Additionally, in the week following the upgrade, raw data downloads will be temporarily disabled.

1 http://www.nature.com/nature/journal/v431/n7011/full/nature03001.html

08-09-2012, 04:53 AM
I'm not sure about my relative or ancestry finder results, however my ancestry painting changed by a few percentage points along with some of my compare genes scores.

08-15-2012, 04:54 PM
No apparent change, but nobody new has shown up in over a week, either.


PS. I forgot ... one 3rd cousin suddenly now appears as a first cousin!