GENEALOGY-DNA-L Archives

From:
Subject: Re: [DNA] significance of partial str repeats
Date: Sun, 01 Oct 2006 17:34:11 +0100

Rick

you are right that partial repeats should be passed from father to son and
so in an ideal world this should be included in the data available to
genetic genealogists. I don't think anyone has done a study investigating
how often a brand new partial repeat occurs but from the SMGF tables I would
assume it is a very rare event, which means it will be very useful
information in a small minority of family lines and irrelevant in the
remaining majority, although with 67 or more markers the number of
haplotypes with a partial repeat in at least one may not be insignificant.
It is similar in many ways to the way "null" values occur at particular
markers. Just as customers have pressed for more and more markers, there has
also been pressure for better reporting and understanding of quirky results
like nulls, recombinational effects and multi-step mutations. FTDNA is now
aiming to report null values accurately and recent posts have mentioned
sharing of information about possible recombinational issues.

Partial repeats are likely to be an issue in resolving inconsistencies
between data from different labs especially now that FTDNA will be offering
markers previously available from DNA-Fingerprint, which always reported
them (and for some markers like DYF399 they are useful in distinguishing
different copies). Perhaps this will be discussed at the Houston conference.
The main problem will be the adjustment of 5 years' worth of FTDNA results -
this is unlikely to happen quickly and may only be done in response to
requests from customers or project admins, so the databases may never been
completely consistent.

Gareth






----- Original Message -----
From: "Rick Arnold" <>
To: <>
Sent: Sunday, October 01, 2006 4:06 PM
Subject: [DNA] significance of partial str repeats


> Playing around with the smgf y database this morning I noted about half of the STR fields provide value entry options for partial repeat values (e.g., dys 388.....11, 12, 12.2, 13, ....). I recall reading somewhere - probably on this list - that some (most) labs round partial repeats off to the closest whole number of repeats. The question is, wouldn't partial repeats be just as heritable from generation-to-generation as are full sequences of repeats? Thus wouldn't a difference between values of 12 and 12.2 on a marker be just as significant as a difference between 12 and 13 on the marker? If so, the reporting of both 12 and 12.2 as 12 strikes me as ill advised, to say the least. I hope I'm wrong.!!!

This thread:

• [DNA] significance of partial str repeats by Rick Arnold <>
  • Re: [DNA] significance of partial str repeats by Doug McDonald <>

  • Re: [DNA] significance of partial str repeats by