GENETICS in cats as applied to the Burmilla

Genetic chart on this page
Charts genetics of Colour and Pattern on this page
Simon Twigge on genetics  - this is on this page
Horizons on Genetics Notes and Genetics discussion - this goes to Horizons pages and is a detailed discussion with illustrations


Genetic chart


symbol
name/s
recessive
name/s
A/-
agouti
a/a
non agouti, self
B/-
black
b/b
brown, chocolate
C/-
full colour, full expression
cb/cb
sepia, Burmese restriction (in Burmese), pointed
D/-
dense (pigmentation)
d/d
dilute, maltesing
I/-
inhibitor, silver
In the self cats [d/d]  this gene can be seen as a lighter colour and is called Caramel in blue tones, Taupe in lilac, and Apricot in cream tones.  They are sometimes talked of as the powder coats.  In  the dense [D/-] cats that are also  sepia [cbcb]  is is sometimes called the Berrington gene . It is most often identified in  b/b, cb/cb,  (champagne)cats. We suggest these terms not be used.
i/i
golden, not silver, rufosed, rofused
L/
short hair
l/l
longhair, semi longhair (there are 4 genes that add up to deliver the very long hair)
O/-(X)
orange, tortie (F only)
o/o
not orange (usually not noted)
Ta/-
abbytabby (our term)
ta/ta
not abbytabby, macheral tabby, classic tabby, spotted tabby
Wb/-
wide band,  shaded (in A/-), smoke (in a/a)
wb/wb
 narrow band, ticked, non smoke, (usually not noted)
Swb/-
narrow band, not tipped,  ticked (usually not noted) swb/swb
tipped or superwide band
ta/ta requires that we consider Mc and Sp.
Mc/
mackerel tabby
mc/mc
classic tabby
Sp/-
spotted tabby (this spotting can vary in name and apperance depending on if the cat is a mackerel or classic by bckground)
sp/sp
non spotted, (usually not noted)
updated mar '09
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There are Mackerel/classic tabby and Spotting/non. Unless we are dealing with ta/ta we will leave then out of the genetic string. We take our understanding of these characteristics from Robinson’s.
We do not discuss R (re) - normal coat not Rex;  s/s - normal colour not piebald; w/w  - normal colour not dominant white; and wh/wh - normal coat not wirehair at this time. We assume all cats are R/R, s/s, w/w, wh/wh, bu---ut  who knows!!  The b1b1 gene is not in the gene pool. Therfore, the terms Cinamon [b1b1,  D/-] and Fawn [b1b1,  d/d] are not used.

Wide band is new, hypothesized by Robinson’s, and recently accepted by Ms Stephens in her latest edition. We accept it as fact as you see. We are beginning to think of very wide band cats as in the Chinchilla as super wide band (swb), normal/not being SWB. This is our descriptor, as we know of no other. We could use the term Tipped but there does appear to be some assocaition with wide band.
We have discounted Dm, Dilute/non modifier (from Robinson’s 4th ed  p141) after running it for some time. Thus the terms Caramel, Taupe and Apricot are not used. We do not dispute their existance rather we understand these are the minor colour variations one does see (in the solid cats -most particularly the "dilutes") due to the underlying golden /silver variable that becomes clearly visible and is identified in the tabby [agouti] cats.

For those interested in such things the mathematical possibilities are 2X each combination: ie A has  two possibilities(A/- and a/a), A and B have 2X2 possibilities giving 4  Thus there are about  2 to the 9th+  power of possibilities(> 500) + for the extra in the sex link and - in the epistatics (A gene is said to be epistatic when it masks other genes i.e. they are there but can not be seen, i.e. O ,  see Robinsons p 40 ).

Genetics of colour and pattern
Below are two charts that integrate the information above. Hopefully they will help with an understanding of the varieties of Colors and Patterns in cats. They are in a form that would be familiar to cat breeders.
Patterns are separate from Colors but certainly play on what the eye sees, particularly when I, Wb, and swb, come into play (the polygenetic cop out). Torties and long hair are not considered for this exercise. 
The color terms used are generally those used in CCA; different fancies may use others (we have shown 2). These are the terms we will use, for now, when talking of "genetic color".
The reader will note there are effectively 11 colors. 12 if one can identify full expression Red ???.
Given 12 colors, 4 - 6 patterns, I, Wb,  swb, L, and O,   - that should give a rather large number of possibilities.
The reader will begin to understand why a number of Cat Fancies are slowly coming to the realization that cat coat can only truly be described by genetic terminology.
These charts also provide a mathematical distribution of the possibilities -  - - the reader will note a number of errors and omissions in the standards that have been provided.
we are trying to update that as of mar.'09



gen&colour

gen& pattern



Simon Twigge on genetics. Simon is a senior member of the Breed Society in England. ( if I have stated that correctly)
We make the following comments to this very sound document.
1) The reader will note it is marked as copywritten and dated.
2) The chart format that he uses is particularly good and we have presented it above with additions and modifications as we see them - We do not use superscript as it makes typing more difficult and for no other reason. We separate nomenclature with slash and comma as in [ [ a/a,]  .and we have placed the symbols in alphabetical order.
3) We hope the reader is not intimidated by the large numbers and mathematics- they are not necessary to the use and understanding for applied breeding.
4) We do not agree that DM exists and have stated our reasons on our Genetics pages.The recessive of O/- is o/o or o/y.
5) Simon's table 2 is very useful to the understanding however we do not agree on his definition of Smoke. We see it as a/a, Wb/-. The issue of a smoke's  i/i is still open for us.  BUT time will tell. - -variants genotype has an extra b. Perhaps Simon has updated since '99.


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