A discussion paper
Included here with permission from the author
POLYGENES, AND HOW BREEDERS (UNKNOWINGLY ?) USE THEM
by Fitz Usmany
Rainbow Warriors, Holland
(Received 3rd may 2002)
First, to all people who are not Sphynx breeders, you need
to understand that the working of polygenes is applicable
to every trait breeders are trying to improve. So, simply
replace 'Sphynx' by your own breed and
'hairlessness' by the trait you're after and
it will have meaning for you. Polygenes is what I - as a
Sphynx breeder - would call the secondary (genetic)
conditions. "Secondary" because we are breeders
with a breed specific gene - caused by a mutation.
The primary (genetic) conditions are the breed typical
genes: in Sphynx this is the hr-gene, in Cornish
Rex this is the r-gene, in Devon Rex this is the
re-gene, in Siamese this is the cs-gene, in
Burmese this is the cb-gene, in Persians and all
semi-long-haired breeds this is the long-hair gene. Some
varieties of breeds might have several breed specific
genes, like the Himalayan (the long-hair gene and the
A pedigree cat is a cat in which its (poly)genetic
structure conforms to a certain breed standard. Nothing
more, nothing less, although some want to believe that a
pedigree containing purely the cats of that breed is holy
ground. That's why I have to smile at people who
believe that an F6 is better and more pure than an F2. I
have seen F6's which looked less "pedigreed"
than certain F2's; the latter couldn't be shown in
certain associations since "rules forbid".
Polygenes are what make the difference between the
"pet quality" and the "top show
"POLYGENES: genes that have little or no noticeable
effect by themselves, but in groups are able to produce
So polygenes are a group of genes which operate next to
the breed specific genes. We know that they are there, but
we don't know where they are located on which
chromosome, with how many are supporting a certain trait;
if they are dominant, recessive or incomplete dominant.
And we'll probably never know.
To give you an illustration, I will give you some
examples, using the breeding of Sphynx to illustrate
things. The nakedness of the Sphynx is caused by the known
recessive gene for hairlessness of a North American
mutation, which occured around 1963/1966, indicated with
the code "hr" .
Normal hair has code "Hr" ->
a Sphynx is therefor [hrhr] û
a normal coated Sphynx hybrid is [Hrhr]
In this example I shall assume that the hair genes are
supported by 4 pairs of polygenes (could be 3 pairs, could
be 100 pairs!). I shall assume that they are incomplete
dominant. I will give 'downy' the mark
"+" and I will give "balder" the mark
"-" consequently: the more "-" in the
polygenetic structure, the balder the Sphynx will be.
So lets take a pet Sphynx with an inferior polygenetic
structure which is completely and totally covered in down.
This Sphynx will have the genetic code: [hrhr ++ ++ ++
We breed this Sphyx to a top quality Sphynx with a
superior polygenetic structure, which is slicky bald and
stays bald the whole year, no matter how cold it gets.
This Sphynx will have the genetic code: [hrhr -- -- --
This pair of Sphynx will get a litter of Sphynx kittens
which will all have the genetic code: [hrhr +- +- +-
These Sphynx will have a mediocre polygenetic structure
for hairlessness and therefore their hairlessness will be
acceptable for showing, but their hairlessness will
fluctuate under the influence of the third condition
(hormonal influences due to weather; open/fixed state;
male/female; sickness etc etc).
Most of the breeders will have started with such kinds of
(( The tertiary conditions which influence the level of
hairlessness are the hormonal levels within the Sphynx.
Cats with inferior or mediocre polygenetic structure for
hairlessness will undergo changes in their hairlessness
whenever their hormonal level changes; Sphynx with a
superior polygenetic structure will always be naked, the
whole year through. ))
Well, if you breed two 'mediocre' Sphynx to each
[hrhr +- +- +- +-] X [hrhr +- +- +- +-]
you will get a diversity of qualities:
Some will be balder than their parentage:
[hrhr +- +- +- --] a Sphynx with some down and a
fluffy lion tail, or
[hrhr -- +- +- --] a Sphynx with a lion tail, or
[hrhr -- +- -- --] a Sphynx with a little hair on
the nose bridge,
or when the breeder is lucky
[hrhr -- -- -- --] a sticky sticky bald one.
Others will be more downy or hairy than their parents:
[hrhr -- ++ ++ --] a Sphynx with long hairy ears,
[hrhr ++ +- +- --] a Sphynx with hairy feet and a
bushy tail, or
[hrhr -- +- ++ +-] a Sphynx with a hairy mask, or
'oh-my-gawd', [hrhr ++ ++ ++ ++]
If you understand the working of polygenes you can
understand why two downy Sphynx parents can
"suddenly" produce a completely naked litter; or
why two 'top quality' Sphynx, can produce a
complete downy litter. Or why in a litter the quality can
vary between a totally downy one, to a top quality, life
long bald Sphynx. Or why two parents will produce two
consecutive litters of extremely different qualities
"This is a gorgeous litter, the best I ever had! I am
going to repeat this breeding". Next litter .......
"oh-my-gawd!! this can't be true, they are all
Polygenes is what breeders use to develop their breeds:
that is, selective breeding. Sphynx breeders will always
continue with the 'better' kittens and hopefully
place the worst quality as neutered pets (and don't
sell these to other breeders as top quality.)
If a breeder has a decent breeding programme you will see
a certain progress in its line over the years.
He/she will start with [hrhr +- +- +- +-] quality
He/she will continue with a kitten with [hrhr -- -- +-
+-] quality and the next year
He/she will continue with a kitten with [hrhr -- -- --
Till finally most of his/her kittens will be of [hrhr
-- -- -- --] quality.
Every breeder will aim for uniformity in his/her litters.
Uniformity in type and - for Sphynx breeders - in
So in the beginning the litters will vary between
[hrhr ++ ++ ++ ++] to
[hrhr +- +- +- +-] and later on
[hrhr +- +- +- +-] to
[hrhr -- -- -- --] till finally all kittens are
[hrhr -- -- -- --].
If you look at pictures of the 'ancient'
Persians, their faces were not as extreme and their coats
not as silky and long as the ones of today. If you look at
photo's of the applehead Siamese, their heads were not
as long as they are today. Breeders of those breeds always
picked the kittens with their desired (poly)genetic
structure to the point that their cats breed true. Look at
pictures of the first Sphynx; they weren't that bald.
Over time we developed our breed and "improved"
the level of hairlessness.
Fitz Usmany´s website
(The source code for this web reproduction is copyright,
Tony Batchelor, 2002)