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Old 1st February 2018, 05:51 PM
talleymd talleymd is offline
FTDNA Customer
Join Date: Sep 2015
Posts: 1
Question SNP disappeared with update of BigY

An SNP that was an important link between two branches in my project disappeared after the BigY update:

BY6658 13715897 (hg19) 11560221 (hg38)

Can anyone explain why it disappeared and is it possible to get it back. Out of five four BigYs that were taken before the update, two were positive as novel variants. I was able to get it named and now it is gone. It was an important subclade as this is a multisurname project.

Michael Talley
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Old 2nd February 2018, 07:53 AM
Jim Barrett Jim Barrett is offline
Join Date: Apr 2003
Location: Timpson, TX
Posts: 2,279
Which test(s) had been used to determine this SNP?
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Old 3rd February 2018, 02:35 PM
dtvmcdonald dtvmcdonald is offline
mtDNA: | Big Y Pending
Join Date: Mar 2011
Posts: 264
Could you post the entries for that SNP in the VCF files
if they are there? What do the BED files look like at that location and vicinity?

Does that SNP show up in the chromosome browser? None
of my files show it.
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Old 4th February 2018, 08:06 PM
wkauffman wkauffman is offline
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Join Date: Feb 2011
Posts: 161
Wait for the BAM

When one remaps sequences against a new reference not all of the sequences may get mapped to back to the "same" location. Changes in the new reference sequence will drive how the sequence fragments are mapped. The vast majority in the good regions will get mapped correctly but the presence of the new/updated regions may siphon away enough fragments to lower the coverage/quality in a region to a point where a positive call is no longer made. You should wait for the BAM files and look at all of the expected positive calls and a couple of the known negatives to see if there is sufficient evidence to support a positive call under the new mapping.

Of course results from individual SNP testing can also support the presence of the level.
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