Results for marker CDYa and CDYb

[morvoren]

Results for the marker CDYa and CDYb - recorded in a possible 4-way match:

37-40
36-40
33-40
33-40

How significant are the unusual 4-step and 3-step mutations in CDYa, when the number for CDYb is the same for all 4 results?

Does the 37 and 36 count as a 4 and 3-step mutation from 33 - or simply as a 1-step? FTDNA seems to reckon it as only 1 - whereas ysearch counts it as 4 and 3.

Is this amount of mutation usual for this particular marker - and why might it have occurred?

[Araminta]

Following ...

I have same type of question on DYS464.

A: 15-15-15-15
B: 13-13-16-16
C: 13-13-14-14
What are the mutation counts when calculating GDs?

Also is 40 -> 42 one or two mutations?
What about: A:29, B:30, C:31

These are all actual values in my comparison. Thank you for any enlightment on this!

[Darren]

Hello all,

CDY A and B are some of the faster moving markers we test. It uses what is called the infinite allele method for counting mismatches. So whether it is a 35-40, 37-40, 39-40, these three would all be considered a genetic distance of 1 at this marker. The system will always list the lowest numeric value allele first. So you would not see one listed as 40-37 for example.

As for DYS 464 you don't count the number of steps that the values are off, but just one for each mismatching value.

In the first comparison:

A: 15-15-15-15
B: 13-13-16-16

This would be a genetic distance of four. Since none of the markers match up.

B: 13-13-16-16
C: 13-13-14-14

In this second comparison above, this would be a genetic distance of 2, as would the following example:

13, 13 , 16, 17

14 , 16, 17, 18

-Darren

[Araminta]

Thank you Darren! So we follow the minimum variation route.

[morvoren]

CDYa ad CDYb mutations

Thank you Darren. That's all very clear and helpful.