Norwegian Forest Cat HCM DNA Research Project
Genetics Review
Created by: Karen Fleming/Quinsigamond Cattery, USA
A = affected gene
a = normal gene
AA
= carrying affected gene (homozygous)
Aa = carrying affected gene (heterozygous)
aa = not carrying the affected gene (unaffected or normal cat)
Dominant gene vs. Recessive gene:
If A
is dominant, then a cat with AA
(homozygous), or Aa (heterozygous) will
exhibit the trait
A cat that is aa will not exhibit the trait
If A is recessive, then a
cat with Aa will be a carrier of the trait
A cat that is AA will exhibit the trait
A cat that is aa will not exhibit the trait
Example Table
In this case, if A is a dominant gene, each individual offspring would have a 100% chance (in the yellow section) of exhibiting the trait because Parent 1 passed the A (dominant) gene to them.
If A was a recessive gene, each individual offspring would have 50% chance of exhibiting the trait, and a 50% chance of carrying the trait because Parent 1 passed the gene to them (they would not exhibit the trait).
When using these Mendelian Charts, they are read as to the % of probability of each individual offspring being affected, not the % of offspring that will have the probability of being affected. The chart is applied to each individual.
|
Parent 1 |
|||
|
A |
A |
||
|
Parent 2 |
A |
AA |
AA |
|
a |
Aa |
Aa |
|
Table 1
(same as above)
|
A |
A |
|
|
A |
AA |
AA |
|
a |
Aa |
Aa |
Table 2
In this case, if A is a dominant gene, each individual offspring would have a 75% chance of exhibiting the trait because Parent 1 passed the A (dominant) gene to them.
If A was a recessive gene, each individual offspring would have 25% chance of exhibiting the trait (AA), a 50% chance of carrying the trait (Aa) and a 25% chance being unaffected (aa) (normal)
|
A |
a |
|
|
A |
AA |
Aa |
|
a |
Aa |
aa |
Table 3
In this case, if A is a dominant gene, each individual offspring would have a 50% chance of exhibiting the trait because Parent 1 passed the A (dominant) gene to them. Each individual offspring would have a 50% chance of being unaffected (aa)
If A was a recessive gene, each individual offspring would have a 50% chance of carrying the trait (Aa) and a 50% chance being unaffected (aa) (normal)
|
A |
a |
|
|
a |
Aa |
aa |
|
a |
Aa |
aa |
Table 4
In this case, if A is a dominant gene, each individual offspring would have a 100% chance of exhibiting the trait because Parent 1 passed the A (dominant) gene to them.
If A was a recessive gene, each individual offspring would have 100% chance of carrying the trait (Aa)
|
A |
A |
|
|
a |
Aa |
Aa |
|
a |
Aa |
Aa |
Table 5
In this case, neither parent carries the A gene, so each individual offspring would have 100% chance of being unaffected (normal)
|
a |
a |
|
|
a |
aa |
aa |
|
a |
aa |
aa |