Gene Primer
Written By:
Katie Greer
This is the very basics of gene behavior.
Each individual receives two copies of each gene from
its parents,
one from the father and one from the mother.
Dominant Gene:
A gene is considered to be dominant when it only requires
one copy of the gene in order for the trait to be expressed. |
| Recessive Gene:
A gene which requires two copies in order to express itself in the
individual. |
Coat length is the most basic of dominant/recessive genetic schemes
to explain. The smooth coat gene is dominant and the long coat gene is
recessive. It only takes one dominant gene to express the trait, in this case smooth
dogs. It takes two recessive long coat genes in order to express the long coat trait.
Hence, smooth is considered to be a dominate gene. However, the dominant smooth
coat gene can be trumped by two recessive long coat genes. Remember,
each individual only gets 2 copies of each gene.
A graphic example is offered below for clarity of understanding. Capitol letters represent dominant genes and lower case represents recessive
genes. In using coat length as an example to demonstrate dominant and recessive
genes, "S" represents the smooth coats, and "l" represents the long coats.
The percentages offered below are average possibilities that could be
encountered. Actual numbers may vary.
Smooth to Smooth breeding.
Smooth to Smooth breeding.
Smooth to Long breeding:
Long to Long breeding:
A long coat to long coat breeding can only result in long coat puppies as
neither parent has a smooth coat gene to offer any of its young.
Vetgen offers a coat length determination DNA test.
"While it is not a color trait, the length of a dog's coat is of interest to
many. It has recently been demonstrated that in many breeds, the gene FGF5 is
responsible for whether a dog has a long coat (rough or fluffy), or a short
(smooth) coat. The test Vetgen offers detects the presence or absence of the
recessive allele that results in long coats when present in two copies, and as
such allows dogs with short coats that carry a hidden "long coat" allele to be
detected."
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