In comparing Chromo2 and FTDNA results there are several issues at play: 1. Which strand is reported? I found the following links usefull: https://customercare.23andme.com/entries/21272593-Which-DNA-strand-does-23andMe-report-for-SNP-genotypes- https://www.biostars.org/p/12026/ 2. What ancestral value is used as reference? For example, FTDNA says that the ancestral S2606 value is "T" while BritDNA says it is "C" (and "A" is derived). So one of the two must be wrong. It might explain though why all FTDNA results for S2606 turned out to be no-calls ... 3. Are we talking about a mutation or a back mutation? Chromo2 also makes a difference between an ancestral value (-), the mutated value (+) and the backmutated value (!) Best, Hans > Date: Wed, 4 Jun 2014 10:06:07 -0400 > From: vaeringi@gmail.com > To: I1-Z58andZ63@yahoogroups.com.au; y-dna-haplogroup-i@rootsweb.com > Subject: [yDNAhgI] S2078 Problem Corrected and PR683 Now Available for Testing > > This might be valuable to others. I requested that FTDNA add S2078 to the > catalog for the Z63 sector. S2078 occurs with robust frequency based on > Big Y and Chromo2 results. Unfortunately, FTNDA inverted the consensus and > reference alleles. This caused everyone who tested to get the opposite > result, that is to say those who were positive were showing negative and > vice versa. This naturally created much confusion. I think the take away > is to audit newly requested SNP results with care, if being done at FTDNA, > in case this is not an one time problem. As stated in the title, PR683 > which shows to be immediately downstream of S2078 is now available and > which has divided some Big Y kits already. > > Paul > > ------------------------------- > To unsubscribe from the list, please send an email to Y-DNA-HAPLOGROUP-I-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message