UNDERSTANDING DNA - A PRIMER
by Jeanette Knight FTDNA / World Families Admin.
Predicted Haplotypes
Unless additional SNP’s are ordered to test for haplogroup, the haplogroup assignment for YDNA tests are “predicted” based on the STR markers tested . Family Tree [DNA] explains the difference between STR and SNP markers this way: Y-Chromosome DNA (Y-DNA) tests trace both recent and distant generations. The number of generations traced by a Y-Chromosome DNA test depends on the type of test taken, short tandem repeat (STR) or single nucleotide polymorphism (SNP).
STR tests are able to trace a male lineage within genealogical times and into historic times. Your genealogical connections will be shown on the Y-DNA – Matches page of your myFTDNA account. The Y-DNA – Ancestral Origins page of your myFTDNA account will point towards possible countries of origin.
On the other hand, Y-DNA SNP tests are able to trace both ancient anthropological migrations and more recent prehistoric movements. A Y-DNA SNP test also identifies the haplogroup, which represents your deep ancestral origins (tens of thousands of years ago).
https://www.familytreedna.com/learn/y-dna-testing/y-str/generations-y-str-test-trace/
Many project members are interested in tracing their more recent family lineage while some are more focused on their deep ancestral origins. There are a few whose interest includes both. STR marker results are used to predict the haplogroup, based on comparison of the SNP results of others who have already tested. Since this is a dynamic field, there are frequent changes based on new technology and research. The only way to really follow the SNP results and significance now is to look at the SNP tree.
I frequently get questions regarding the “meaning” of specific markers. This is always hard to explain. The real value in DNA testing is in comparison with other results. The larger the pool, the better. From FTDNA:
By themselves, Y-Chromosome DNA (Y-DNA) short tandem repeat (STR) markers from a Y-DNA test do not have any particular meaning. The value of testing Y-DNA STR markers comes from creating a Y-DNA signature (haplotype) with them and comparing that Y-DNA signature to others in a database. They are useful for genetic genealogy because your Y-DNA signature distinguishes your paternal lineage from others. They can then be used with Family Tree DNA’s comparative database to discover genealogical connections or historic ancestry.
The haplogroups are color coded on FTDNA site; amber/brown is Predicted. Tested positive is green. The haplogroup may indicate where your ancestors lived thousands of year ago. While this is interesting, it is of little benefit for identifying more modern relations; therefore, the importance of SNP and haplogroup depends on your research goals.
This article will be expanded upon soon. . .
Unless additional SNP’s are ordered to test for haplogroup, the haplogroup assignment for YDNA tests are “predicted” based on the STR markers tested . Family Tree [DNA] explains the difference between STR and SNP markers this way: Y-Chromosome DNA (Y-DNA) tests trace both recent and distant generations. The number of generations traced by a Y-Chromosome DNA test depends on the type of test taken, short tandem repeat (STR) or single nucleotide polymorphism (SNP).
STR tests are able to trace a male lineage within genealogical times and into historic times. Your genealogical connections will be shown on the Y-DNA – Matches page of your myFTDNA account. The Y-DNA – Ancestral Origins page of your myFTDNA account will point towards possible countries of origin.
On the other hand, Y-DNA SNP tests are able to trace both ancient anthropological migrations and more recent prehistoric movements. A Y-DNA SNP test also identifies the haplogroup, which represents your deep ancestral origins (tens of thousands of years ago).
https://www.familytreedna.com/learn/y-dna-testing/y-str/generations-y-str-test-trace/
Many project members are interested in tracing their more recent family lineage while some are more focused on their deep ancestral origins. There are a few whose interest includes both. STR marker results are used to predict the haplogroup, based on comparison of the SNP results of others who have already tested. Since this is a dynamic field, there are frequent changes based on new technology and research. The only way to really follow the SNP results and significance now is to look at the SNP tree.
I frequently get questions regarding the “meaning” of specific markers. This is always hard to explain. The real value in DNA testing is in comparison with other results. The larger the pool, the better. From FTDNA:
By themselves, Y-Chromosome DNA (Y-DNA) short tandem repeat (STR) markers from a Y-DNA test do not have any particular meaning. The value of testing Y-DNA STR markers comes from creating a Y-DNA signature (haplotype) with them and comparing that Y-DNA signature to others in a database. They are useful for genetic genealogy because your Y-DNA signature distinguishes your paternal lineage from others. They can then be used with Family Tree DNA’s comparative database to discover genealogical connections or historic ancestry.
The haplogroups are color coded on FTDNA site; amber/brown is Predicted. Tested positive is green. The haplogroup may indicate where your ancestors lived thousands of year ago. While this is interesting, it is of little benefit for identifying more modern relations; therefore, the importance of SNP and haplogroup depends on your research goals.
This article will be expanded upon soon. . .
