Genetic Symbols

The majority of symbols shown here are taken from Dr. Willard F. Hollander’s book, "Origins and Excursions in Pigeon Genetics".   I have separated them into groups by their genetic effects and known linkage.   The groupings are Sex-Linked Color genes;  Autosome (non sex-linked) genes which effect basic color;   and Autosome genes that effect body and or feather structure.   Within each grouping  are also listed their mutant alleles.   Genes with the symbol + denote the original wild Rock Pigeon's genes or what we would call a wild type pigeon where no mutant genes are present.

All genes symbolized with an upper case letter are dominant to some degree.    All recessive genes are symbolized in lower case. This case distinction between the dominant and recessive types is a standard practice.  It serves as an aid in keeping them classified properly in your mind while you are working with them. 

Just remember, if its listed as beginning with a capital letter, it's a dominant gene.    A dominant gene will express when present.  The only exception to this rule is when it is being masked by another genetic condition.    Symbols beginning with lower case letters are always recessive.  A recessive gene can only be displayed when in their pure state.

Genetic Symbols

 

These are the Sex-Linked genes.  They occur on the sex or Z chromosome, of which a cock has two and a hen only one. Remember each Z chromosome will carry only one of these possibilities for each set.

The three basic or primary color genes, in their order of dominance are:


B
A - Ash Red Color
B
+ - Normal Wild Type for the color of Blue or Black
b    - Brown Color

The four Color Dilution possibilities are:
D+ -  Wild Type for Full color
dP -  Pale
d    -  Dilute
dex - Extreme Dilute

The three Color Reduction possibilities are:
R+ - Wild Type for nonreduction or Full Color
r     - Reduced
r
ru  - Rubella

There is also a Lethal Sex-Linked gene that occurs on the sex or Z chromosome which is known as Lethal Sex-Linked web foot or simply Weblethal.   It's two possibilities are:
Wl+ - Wild Type for non weblethal or Normal
wl   - Weblethal

We also have the Almond family (no I don't mean the singers but the genes that causes the scrambled, speckled patchwork of colors) which occurs on the Z chromosome. Originally known as gesprenkelt which means sprinkled in German is now known to consist of the following mutations:
St - Almond
St
H - Hickory
St
Q - Qualmond
St
Fr - Frosty
St
Sa - Sandy
St
F - Faded
st
+- Wild Type for non almond series or normal


Genes "not found" on the sex or Z chromosomes are known as Autosomal genes.   Since they occur on non-sex chromosomes every bird, both cocks and hens will carry two gene possibilities for each chromosome set.   In otherwords one gene for each chromosome in a set of two each.

During the replication process, genes which are located closely together on the same chromosome are sometimes pass along in groups like links in a chain.

Autosomal genes and their alleles which are known to be linked togather are the pattern series, spread and recessive opal. Their symbols are as follows:

The Pattern series in their order of dominance:


C
T  - T-pattern Check
C
D  - Dark Checker
C    - Checker
C
L  - Light Checker
C
+  - Normal Wild Type pattern or Barred
c     - barless

Pattern modifier linked to pattern:
S    - Spread
s
+  - Wild Type or normal non-spread / pattern

Color modifier linked to pattern
O
+ - Normal Wild Type or non recessive opal color effects
o    - recessive opal i.e. blue phase

o
ch - Cherry i.e. red phase recessive opal
 

Other Autosomal genes which effect the basic color but are not found on the same chromosome as the pattern series and therefore are not linked to pattern are listed below. Their wild type or normal alleles are not included:

al     - albino
An   - Anthrazit

ba   - Atlas Bronze
Bh   - Baldhead pattern

Bl    - Bleached
Drz  - Drizzle
e      - Recessive red
eE   - Ember
fs    - Frill Stencil  (Orient-Stencil)
G     - Grizzle
GT  - Tiger grizzle
gp   - Gimpel Pattern
ic     - Ice
ir      - Iridescence
In     - Indigo
K     - Kite bronze
ma   - Mahogany (Mondena Bronze)
my   - Milky
Od   - Dominant opal
pc    - Pencilled
pd    - Pink-eyed dilute
pl     - Platinum
Pst  - Pesudo tiger
ry     - Rusty
Sm  - Schmale Schwanzbinde (narrow tail bandage )
so   - Sooty
sy    - Smoky
tr      - Pearl iris
Ts    - Toy Stencil
Ug   - Undergrizzle
V     - Dirty (Verdunkel)
Wt   - White Tailed
Ws  - White sign factor
Ws
Rh - Red neck factor
z      - Gazzi
zwh - Recessive White

 



Other Autosomal genes which effect body or feather structure are listed below. Their wild type or normal alleles are not included:

  ac    - Lethal
  am   - Amputated
  at     - Ataxic
  aw   - Aberrant wing
  ca    - Cataract
  cl     - Clumsy
  cr    - Crest
  ru    - Shell crest (Rundkappe)
  Cu  - Curly
  cy  - Crazy
  da  -  Dark eyes (epistatic to both pearl and 
orange eye; and is similar to but not the same as, bull eye).
  dr    - Drumming
  ds   - Davis Syndrome
  dsc - Deutch Scraggly
  er    - Erratic
  F      - Frayed
  fb    - Feed  Blind (lining blindness)
  fr     - Frillneck
  fz    - Frizzy
  gr    - Grouse
  H     - Hosen or Grouse legged
  Ku  - Short beak
  L     - Lace or Silky
  mi   - Microphthalmia
  n     - no oil gland
  Nn   - Naked neck
  na   - Naked
  ofr  - Chinese Owl frill
  p     - Porcupine
  py   - Polydactyly
  ro    - Rolling
  ros  - Rose, beak crest
  Sb   - Sideburns
  sc    - Scraggly
 skpy- Show King Polydactyly
 Sl&  - Slipper
    t   -   Extra outer toes
  t
H    - Hasz' lethal
  w     - Web Foot
  Wr   - Warbling
  wo  - Wobbly

Genetic Symbol Usage

In genetics we use symbols to denote the various gene mutations for each chromosome locus.  Unfortunately, we do not know how many actual locus points there are.  Nor do we know all of the mutations that exist since not all mutations have something physical for us to point to as a means of identification.    We know that all genes act in one of three ways.

1)      If "recessive" they will not be express when in combination with a dominant allele.  

2)      If "partial dominate" or "codominant"  they will express themselves partially or to some degree when heterozygous.   When homozygous or pure they will be express completely.   Let me use grizzle to demonstrate what is meant by partial dominate or codominance.  A single gene for grizzle on a genetically blue bar bird would give the typical salt and pepper looking phenotype with black bars, black salt and peppery head, white salt and peppery body and black wing tips.  This same gene in its pure or homozygous state would be almost completely white with only a small amount of black peppery effect around the bird’s head and black wing tips.  Other examples of partial dominate codominant genes being, Almond, Indigo and Dominant Opal to name a few.

3)      If "dominant" they will be fully express regardless of heterozygous or homozygous states.   An example being Spread.

When we select a symbol to denote any new mutation we try to incorporate as much of this information into the symbol as possible.  To do this all mutations are given a letter or set of letters to denote their name.   In addition, this becomes the name of the chromosome's locus point where the mutant gene is to be found.  Next to we assign a upper or lower case first letter to denote whether the new mutant  is a recessive or a dominant gene. 

All recessive genes are assigned symbols in a lower case to denote their being a recessive, while all partial dominant, codominant and or dominant genes are assigned symbols beginnibg with upper case capitals to denote their being a dominant  form. 

Examples:   

  • All Wild Type alleles are denoted by the symbol +.    However should we want to be more specific and denote their locus and their degree of dominance, we would use the mutant's appropriate upper or lower case symbol and then add the superscript + to denote them as being wild type.  
  • Brown is a mutation from wild type.  This gene changes the basic color from blue/black pigment  to brown pigment but the brown phenotype is only displayed when in the hemizygous and or homozygous states.  This classifies it as being a recessive.  Therefore, the symbol for brown is a lower case letter b. 

  • Since the wild type allele for brown is a codominant, we would assign it the symbol B+.    Please keep in mind that the Capital B does not stand for blue but rather an allele at the b locus that is a dominant.  In this case a wild type dominant which would result in a blue/black phenotype should no other associated genes prevent its expression. 
  • BA or ash red is another mutant at this same b locus and since it is more dominant than wild type B+ we assign the superscript capital A for ash.  Keep in mind the use of the letter b, be it upper or lower case, is for the brown locus and since brown was the first of the mutations to be discovered at this locus it becomes the standard.  Had Ash red been the first, then these symbols would have been lower case a for brown, A+ for wild type blue and A for ash red.  But brown came first so the locus is known as the b locus, not the A locus.
  • Okay so what is the correct symbol for Ember?  First we know that ember is an allele of recessive red (e).   Secondly we know that Ember is also a recessive gene since it cannot be expressed in the presence of a wild type E.   Thirdly we know that in the order of recessive dominances, Ember is more dominant than its recessive red allele.   So how do we symbolize ember to reflect the known data for Ember?    Answer:   Since recessive red has been assigned e as a simple recessive, ember will also have to be assigned the lower case of e.  However, since ember is the more dominant of these two recessives it gets the superscript capital E.   In this case for ember, the proper symbol would then be eE.    This tells the reader that the gene is located at the e locus and is a recessive to wild type or normal factor E but more dominant than its other allele e at this same locus.
  • Okay so what do we assign, as a symbol for Wild Type, at this locus should we want to denote its state of dominance?    Simple, we would symbolize Wild Type at the e locus as E+.  This tells us that Wild Type or normal at the e locus is a dominant gene.

This same is true for all the other mutations.  Now one last question; What is the correct symbol for non spread, if spread is symbolized as being S?         Answer : Lower cass s with superscript + or in this case..... s+.    Now can you explain or figure out why it's a lower case s with the superscript +?     If you can, then you understand correctly the use of symbols in pigeon genetics.   It’s not a case of what I or someone else personally think works well.   It's simply a standardize format of rules.  Like all language, words must have set meanings.  The same is true in genetic science where standard symbols are used so that others can read and come to the same understanding.

 

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Copyright 1999 by Ronald Huntley.
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