B Locus
Lesson #3 will be based on the B Locus. The B Locus attained it's name from the word Brown.
Red and White Boston Terriers, also known as Liver and White, have become the most well known of the
non-traditional colors.  These Boston Terriers are self colored, having matching pigmented nose/paw
pads/and iris, as well as coat color.  There are many varying shades of red and white Boston Terriers, from
brightly colored orange/copper red Boston Terriers to very vivid/bright red.  

Puppies born of the red coloring have differing colors of eyes. Just like when human babies are born and
appear to have blue eyes, young Bostons pups can sometimes have a "puppy blue" color of the eyes that
dissipates over time.  The iris can be various shades of green or brown after the puppy blue fades. It is not
normal for the eye to remain a green coloring into adulthood and is something of the puppy stage to be
cherished. The eyes will change usually at around 4-6 months, the iris becoming a hazel color. There have
been instances of red/brown Boston Terrier iris' to a rich amber color.  

A true red and white Boston Terrier (b/b) has no black hairs or pigmentation. This means a Boston Terrier
with a black nose can NOT be termed as a red/brown.  Though the red Boston Terrier has a reputation for
being named the "seal" Boston Terrier by many uneducated breeders, they are two entirely different colors.

Nose Color: Self Colored Red
Eye Color: Amber, Hazel
Red and White
Genetically Known As:  b/b
***These Boston Terriers are NOT Seal and White***
Brown and White Boston Terriers, also known as Chocolate and White, are genetically the same as red
Boston Terriers.  They are a much deeper and darker coloring.  There have been 3 mutations of the b gene
found in Boston Terriers:
bs, bd, bc.  The superscripts stand for the following: (s)top, (d)eletion, and
(
c)ysteine.  The first mutation creates a premature stop codon in the gene.  The second has a small
segment of DNA missing from the gene, and the third mutation causes the normal amino acid to be replaced
by different one (cysteine).  The three mutations are found in most breeds that are recessive for b/b brown,
and no genetic differences between the various combinations from breed to breed have been found. This
is different from the feline species, as different b mutations correlate to brown and red. Researchers have
yet to pinpoint precisely why in the canine breed there are differing hues of coat color from red to brown as
the mutations do not seem to be the reason in all cases. There are no known health issues linked with any
of the brown mutations.

Nose Color: Self Colored Brown
Eye Color: Amber, Hazel
Brown and White
Genetically Known As:  b/b
***These Boston Terriers are NOT Seal and White***
-  Although brown has been defined in some articles and literature as being a "dilute" of black, this
terminology is not correct. A proper way to describe the effects of the B locus in regards to black
is actually a FADING of black to brown.  Understanding it this way causes less confusion when considering
the role of the D locus.  When those who are not well versed in color genetics read that brown is a
"dilute" of black they tend to assume that ALL brown Boston Terriers must carry the dilute gene and are
then able to produce dilute colorings which is NOT the case. Calling it a fading instead of dilution also helps
to clarify when talking about lilac Boston Terriers which will be explained later in the tutorial. Though in
short, lilac is by genetic definition "dilute brown" because like blue is a dilute of black, lilac is a dilute of
brown having two recessive copies of D (d/d b/b).

-  There has yet to be a litter produced from two b/b Boston Terriers of true lineage, purebred, and DNA
verified parentage that has resulted in any puppies with dominant coloring of black/brindle/seal. There is
no genetic possibility of two brown nosed Boston Terriers producing a puppy with a black nose. If this ever
happens there is a double sire to blame.
***Important Facts To Note About Red/Brown Boston Terriers***
I am ready to move onto Lesson #4: A Locus
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