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Putting a timeframe to BigY SNP mutations

McGinnis Y-DNA Case StudyIn June 2018 Irish Origenes was commissioned to do a Y-DNA Case Study report for a Mr David McGinnis from Oregon in the USA. In that report (based exclusively on his commercial Y-DNA test results) we pinpointed an origin for his McGinnis paternal ancestors within the farmland that lies to the east of the modern City of Derry/Londonderry in Northern Ireland an estimated 1,000 years ago.

At Irish Origenes we encourage customers to recruit locals (with the surname of interest) from the identified area to participate in commercial DNA testing; in order to confirm the ancestral origin and to reconnect with distant relatives. Recently, David successfully recruited a Patrick T. McGinnis from the Greysteel area of County Derry/Londonderry to participate in commercial Y-DNA testing; the results of which confirmed their shared paternal ancestry, and conclusively pinpointed the origin of their McGinnis Clan within County Derry. The Update McGinnis Case Study can be downloaded and studied by CLICKING HERE.

But their story does not end there! The added beauty of this story is that both David and Patrick have done extensive Y-DNA testing (Y-DNA111 STR and BigY SNP). By using the Scottish Origenes 'timeframe to a shared paternal ancestor based on genetic distance upon Y-DNA STR testing' (pictured, original article; click here), and by comparing David and Patrick’s Y-DNA STR and SNP results, we have, for the first time ever, successfully estimated the frequency with which Y-DNA SNP mutations appear (while STRs are repetitive sequences of DNA that can be amplified or deleted with each generation, the SNPs are far more permanent mutations that are passed intact through the generations). All 7 BigY testing McGinnis males share the BY48888 mutation, and differ on average in approximately 5 SNP mutations; which according to the Scottish Origenes STR timetable have appeared within the last 300 years. This indicates that each Y-DNA SNP mutation occurs on average every 60 years.

BigY Block displayThe average number of SNP mutations that have appeared between the McGinnis-Adam (R-BY12159) and each of the 7 BigY testing McGinnis is 12; which equates to a 720 year timeframe. These results indicate that the founder of the Derry McGinnis (the Derry McGinnis-Adam) was born in around 1300AD. For David and Patrick it also means that their shared McGinnis ancestor lived in Derry/Londonderry in around 1700AD. Surnames of InishowenThe Derry McGinnis are part of the Gaelic Irish R-M222 (Niall marker) group, and this study puts the appearance of their R-M222 mutation in a single male who lived on the Inishowen peninsula (pictured) to approximately 1,800 years ago (previously estimated at Irish Origenes at 1,500 years +/- 300 years).  

For the vast majority of human history life expectancy was short, averaging around 30 years, which means that Y-DNA SNP mutations have been relatively rare, appearing in every 3rd generation. In medieval times this would mean that a Grandson would expect to differ from his Grandfather in a single SNP mutation. The Derry McGinnis are tentatively making plans for a reunion in County Derry/Londonderry in the summer of 2021, a nice way for David McGinnis to celebrate his 70th birthday.  I hope to meet them there, give a presentation, and share a pint or 2!

You can contact Irish Origenes CLICK HERE for a FREE CONSULTATION on your DNA results (Y-DNA, Autosomal or mtDNA) or to find out which commercial ancestral DNA test is suitable for you. Remember folks, I am a trained Scientist with over 20 years’ experience in both Academic and Industrial Labs. Always check the scientific qualifications of the blogger offering DNA advice. An honorary qualification is no substitute for decades of genuine awards and practical experience.


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