Autosomal Kit Analysis

Analysis of raw autosomal kit files has been undertaken for a group of Y-DNA related Johnston relatives, other Johns(t)on(e) participants, and a small group of non-related control subjects. These raw autosomal kit files have been provided by participants from Ancestry, FTDNA, and 23andme autosomal tests.

The purpose is to determine whether it is possible to determine genealogical relationships between these individuals for distant relationships (5th/6th cousins).

• Build 36 tests use the HapMap 2008-03_rel22_B36 recombination rates for calculating centimorgans
• Build 37 tests use the HapMap 2011-01_phaseII_B37 recombination rates for calculating centimorgans
• Build 36 tests use the Human Genome hg18-GRC36 autosomal gene position files to determine which gene the SNP resides in
• Build 37 tests use the Human Genome hg19-GRC37 autosomal gene position files to determine which gene the SNP resides in
• No call results (– in FTDNA and 00 in Ancestry) are ignored; treated as if the SNP was not tested in either kit
• Only SNPs that were tested in both test participants are compared
• Where a participant has tests from Ancestry and FTDNA the results are combined before performing matching (version 3)
• Segment lengths are for Half Identical Region (HIR) matching
• No allowances are made for mutations
• Kits from different companies (Ancestry vs FTDNA) are difficult to compare and can lead to incorrect matching results
• Weighting is used to filter out false positives; weighting is calculated as the multiplication of SNP count times cMs for each segment
• Thresholds are used for each segment before it is considered genealogically relevant
• Thresholds for each segment are set at: 5.0 cMs, 500 SNPs, and 3000 SNP-cMs weighting
• Thresholds for the total of all segments passing their threshold levels is set at 3000 SNP-cMs weighting

Version 3 - 10th December 2017

Version 3 includes:

• Logic to combine test results for the same person from Ancestry and FTDNA to perform more accurate matching
• Estimation of relatedness using parameters derived from the Shared cM project August 2017 histograms
• Adjustment to the cutoff and weighting parameters

Version 3 - Build 36 FTDNA autosomal files analysis

Version 3 - Build 37 FTDNA autosomal files analysis

Version 3 - Build 37 Ancestry autosomal files analysis

Version 3 - Build 37 Combined Ancestry & FTDNA autosomal files analysis

Version 3 - Build 37 Combined Ancestry & FTDNA 3-way match analysis

Version 2 findings