ySTR Counts

[AJAskey]

Take a look at http://www.kerchner.com/dnamutationrates.htm

Note the marker changes are not very common , thus we are able group similar STR markers together to form clusters. If the participants are in the same haplogroup (confirmed with SNPs) then we can make estimates for the ages. You may see references MRCA (Most Recent Common Ancestor).

Thank you for the link. It is very interesting information.

[thetick]

Take a look at http://www.kerchner.com/dnamutationrates.htm

Note the marker changes are not very common , thus we are able group similar STR markers together to form clusters. If the participants are in the same haplogroup (confirmed with SNPs) then we can make estimates for the ages. You may see references MRCA (Most Recent Common Ancestor).

[AJAskey]

OK, I misunderstood your question. There are several studies on the mutation rate of Y-STRs. Most involve thousands of father-son pairs, and they've found varying rates among different markers. This article in the Journal of Genetic Genealogy (JoGG) is a good discussion of the methodology and links to two such studies. The handiest reference for mutation rates is this color-coded diagram.

For DYS456, the average observed mutation rate is 0.00735/generation, i.e. about once every 136 generations. For more detail, this page at YHRD shows the allele frequencies for DYS456, and links to more recent studies that included it.

Nathan - Thanks again for the links. I have seen the diagram but have not read the article. What I really want may not be available due to lack of data as of today. If this were my field, I would research the information when a mutation does occur.

• What percentage of the time does a mutation of a specific marker produce a GD of +1?
• What percentage of the time does a mutation of a specific marker produce a GD of -1?
• What percentage of the time does a mutation of a specific marker produce a GD of +2?
• What percentage of the time does a mutation of a specific marker produce a GD of -2?
• When any mutation occurs, what percentage produces at total GD of +1?
• etc..

The utility of this information will increase as the database increases. At some point, it will be possible to make a family tree with only information derived from DNA samples.

[nathanm]

Thanks Nathan. I reread the FAQ and still did not see the answer to my question. But it may be in there and I missed it. I'll take your answer unless someone tells me different. I would think someone would have done a statistical study on counts between known close generations. If I find one online I will post it here.

OK, I misunderstood your question. There are several studies on the mutation rate of Y-STRs. Most involve thousands of father-son pairs, and they've found varying rates among different markers. This article in the Journal of Genetic Genealogy (JoGG) is a good discussion of the methodology and links to two such studies. The handiest reference for mutation rates is this color-coded diagram.

For DYS456, the average observed mutation rate is 0.00735/generation, i.e. about once every 136 generations. For more detail, this page at YHRD shows the allele frequencies for DYS456, and links to more recent studies that included it.

[AJAskey]

Yes, STR counts can mutate up or down, and when it happens, the GD between father and son will be > 0. I'd recommend reading the Y-STR FAQ on this website. It'll answer many questions you might have, and questions you hadn't thought of yet.

Thanks Nathan. I reread the FAQ and still did not see the answer to my question. But it may be in there and I missed it. I'll take your answer unless someone tells me different. I would think someone would have done a statistical study on counts between known close generations. If I find one online I will post it here.

[nathanm]

Is it possible for a son to have a lower count for a marker than a father or grandfather? For example, one father has a DYS456 of 16 while the son has a 15. Is this possible? Rare? Can't happen?

Are there any rules for STR counts? General guidelines? I just need an expert or links to information please.

Thanks.

Yes, STR counts can mutate up or down, and when it happens, the GD between father and son will be > 0. I'd recommend reading the Y-STR FAQ on this website. It'll answer many questions you might have, and questions you hadn't thought of yet.

[AJAskey]

Is it possible for a son to have a lower count for a marker than a father or grandfather? For example, one father has a DYS456 of 16 while the son has a 15. Is this possible? Rare? Can't happen?

Are there any rules for STR counts? General guidelines? I just need an expert or links to information please.

Thanks.