Family Tree DNA prefixes kit numbers with one or more letters depending on their source.
Background The Ancestry V2 chip is Ancestry.com's second microarray chip. It is a custom version of the Illumina OmniExpress Plus Genotyping BeadChip. Its their current chip. Microarray chips test a small percentage of SNPs on the human genome. Each letter the DNA code for the human genome (A, C, T, or G) is called a base [...]
The Ancestry V1 chip was Ancestry.com's first microarray chip. It was a standard version of the Illumina OmniExpress chip Genotyping BeadChip.
The 23andMe V4 chip is 23andMe’s fourth microarray chip and is the one now in use. It replaced their V3 chip in November 2013. It is a completely custom Illumina Genotyping BeadChip.
The 23andMe V3 chip was 23andMe's third microarray chip. It replaced their V2 chip in January 2011. It was a custom version of the Illumina OmniExpress Genotyping BeadChip. One of its key features was backwards compatibility with their V2 chip.
The 23andMe V2 chip was 23andMe’s second microarray chip. It is almost surely the Illumina HumanHap550 Genotyping BeadChip.
Runs of Homozygosity (ROH) are places in autosomal DNA where every position sampled in a length of DNA is homozygous. 3rd Party tools for Runs of Homozygosity (ROH) There are two 3rd party tools available to check your results for ROH. They are Dr. David Pike’s tool and the ROH tool at GEDMatch. Checking for [...]