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MINI-INTRO TO GENTICIST’S PEDIGREES
(See link
below to extensive article.)
By Judy
Huston
The
Geneticist’s Pedigree is the foundation of Dr. George
Padgett’s work. Detailed information can be found in
his book, Control of Canine Genetic Diseases.
Using a geneticist’s pedigree is a very important step
after the establishment of an Open Registry. The
White Shepherd Genetics Project has the Open Registry
which includes reports of diseases and symptoms
submitted by breeders and White Shepherd owners. Now,
we need geneticist’s pedigrees to help us use this
registry in the best possible way.
Think of
Progeny as visual tracking.
When you
look at a GenPed, you will see one dog with an arrow by
the name. This is called the Proband. It is most often
indicating that this is the dog you are building the
pedigree around. In these “disease” GenPeds, it is
simply the first dog I entered on the pedigree, not the
first one affected, nor the most important dog. Squares
indicate males. Circles indicate females. A diamond
indicates sex unknown. A line through any of them
indicates deceased. A symbol filled in black means
affected. Half-filled in means a proven/defined or
obligate carrier. The percentage underneath the call
name means this is the risk factor for the dog carrying
the trait being tracked on this pedigree. A hook
through a line means they are not related. A line over
the top of a name is called a Shadow and is used when a
dog is on the pedigree more than one time, but they are
only counted once. All related affected dogs will
appear on one pedigree so they can become quite large.
When, as in the case of the EPI pedigree, there are dogs
reported that do not connect to the majority of the dogs
on the pedigree, they will be shown separately. With
the Megaesophagus pedigree, they are all on the same
GenPed.
For now, we
are doing pedigrees that track one disease at a time.
Later, we will try pedigrees that show up to four
diseases on one GenPed. Each disease will be in a
different color and take up ¼ of the symbol. This
process can help us identify linking diseases. On one we
are tracking eyes, hearts, and hernias. On another, we
would track IVDD, LS, DM, and IBD – because this is the
way we can see if they are associated. So we would
track those together and could see that this usually
goes with that. That’s the type of helpful linking
information we can get.
For now, I
have a Progeny software program and the WSGP recently
bought one for Lynda Proulx. We will be working on
these pedigrees so you can contact either of us with
questions.
To read an
extensive interview I did with Dr. Melissa Cox, our
former White Shepherd Genetics Consultant, on the use of
a Geneticist’s Pedigree, click on the following link.
Interview with Dr. Melissa Cox
These
pedigrees will be updated at least as often as the
charts are updated.
Spreadsheet
You will
notice that the GenPed has the call names of dogs. Look
at the spreadsheet to see not only the registered names
of the affected dogs, but the call names and registered
names of almost every dog on this pedigree. (A dog that
doesn’t seem implicated in the disease may not be on the
spreadsheet since there is no risk associated with that
dog.) Since the spreadsheet is in Excel, you can sort
it any way that suits your research. Right now, it is
sorted in descending order by the percent of risk each
dog carries for Megaesophagus. All the affected dogs
are listed with their sires and dams on the same line,
but each dog is also listed individually with degree of
risk and shows which affected dog(s) determined their
degree of risk.
Important fact to keep in mind, the pecentages are based
on reported affected dogs. We know we cannot
assume we have all the dogs that were/are affected on
this pedigree, but this gives us a pretty good idea
where the carriers are.
You must factor in that this pedigree only shows four
sibling relationships to affected dogs that I was
personally aware of, but every sibling of every
affected dog has a 66.6% risk of being a carrier, so you
need to know about siblings. Keep in mind that we are
showing 26 affected dogs and if each of them had only
four littermates, that would be another 104 carriers at
the 66.6% risk factor. And, for every carrier you see
on this pedigree, their siblings are also carrying a
risk for being a carrier. The approximately 50 parents
all have siblings and if you assume each have only four,
you would have another 200 possible carriers. You need
to do your homework to find these dogs. (Obviously, only
a small percentage of the potential carriers I just
mentioned would be in the breeding pool, but they are
important to know about.) You can also ask any of us
who have the Breeder’s Assistant Pedigree Program to
help identify siblings, half-sibs, etc.
So, good
luck with your research.
Intuitively, I think these GenPeds will make a huge
difference for all of you breeders and White Shepherd
enthusiasts once you become familiar with them.
IMPORTANT
NOTICE/DISCLAIMER: Every effort was made to make this
pedigree and spreadsheet as accurate as possible. If
you see an error, or what you think is an error, just
e-mail me at
hustonjudy@gmail.com and I will explain it or change
it as the case may be. This is an evolving process.
Right now, these are complicated and time-consuming and
I think it will take all of us working together to make
them as accurate and as powerful a tool as they can be.
In my opinion, they are the stepping stone to the next
level of health for our breed.
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TABLE 5.6*
RISK OF BEING A CARRIER IF
RELATED TO AN
AFFECTED DOG
(AUTOSOMAL RECESSIVE
TRAIT**)
Degree of Minimum
Relationship
Carrier Risk
1 = Parent,
progeny
1 100.0%
2 = Full
brother/sister
1 66.6%
3 = Grandparents, aunts,
uncle,
2 50
half-brothers
or sisters, grand-children
4 = Niece,
nephew
2 33.3%
5 = Great-grandparent,
first cousins
3 25.0
half-aunts
and uncles, great grandchildren
6 =
Great-great-grandparents, first
- 12.5%
cousin once
removed, second cousins
7 = Great-great-great
grandparent, first
- 6.25%
cousin twice
removed, third cousins
*This chart can be found on
page 63 in George Padgett’s book, “The Control
of Canine Genetic Disease.
**This chart is used for
Autosomal Recessive Traits as well as Polygenic
Traits—the risk for the Polygenic Trait will be
“at least” this percentage.
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GenPed Megaesophagus
- for download (revised
October - 2007)
Spreadsheet Megaesophagus - Excel for
download (revised October -
2007)
Spreadsheet Megaesophagus
- for
download (revised March 8 -
2007)
GenPed EPI
- for download (May
1 - 2007)
List of
Dog names EPI GenPed (Words
Document)- for download (May 1 -
2007)
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