View Full Version : Usefulness of Higher Density SNP Testing in Autosomal Matching

01-03-2014, 07:13 PM
While reviewing the products offered on IrelandsDNA, I noticed that their autosomal tests cover 3-4x the number of SNPs as their competitors now that most of them have switched over to the V4 chips. What they don't offer is any form of tool to compare with others. This has me wondering... Is there a benefit for autosomal relative matching by testing out to this level if something like GedMatch allowed uploads and comparison? Would the higher density decrease or increase the likelihood of IBS on shorter shared segments?

If anyone has some pointers to some good papers on this, I'd love to take a look.

01-03-2014, 07:26 PM
Looking at several close relatives in combination, I can safely say that it's possible a fair proportion of current "matches" would not stand up to the scrutiny of denser testing and/or proper phasing, though this also depends on levels of endogamy, for example.

Whether the denser testing at IDNA/BDNA/SDNA would actually compensate for this meaningfully, I don't know; also, since Gedmatch.com has to allow for various platforms, I wouldn't think uploading denser results would eliminate any false matches there because you would still be matching at the resolution of the lowest level tested. In effect, this might be compared to upgrading your RAM to the highest level possible while keeping a primitive CPU and hard drive: you probably won't see benefits.