Clear
Genotype: N / N [ Homozygous normal ]
The horse is noncarrier of the mutant gene.
It is very unlikely that the horse will develop FOAL IMMUNODEFICIENCY SYNDROME (FIS). The horse will never pass the mutation to its offspring, and therefore it can be bred to any other horse.
Carrier
Genotype: N / FIS [ Heterozygous ]
The horse carries one copy of the mutant gene and one
copy of the normal gene.
It is very unlikely that the horse will develop FOAL IMMUNODEFICIENCY SYNDROME (FIS) but since it carries the mutant gene, it can pass it on to its offspring with the probability of 50%. Carriers should only be bred to clear horses.
Avoid breeding carrier to carrier because 25% of their offspring is expected to be affected (see table above)
Affected
Genotype: FIS / FIS [ Homozygous mutant ]
The horse carries two copies of the mutant gene and
therefore it will pass the mutant gene to its entire offspring.
The horse is likely to develop FOAL IMMUNODEFICIENCY SYNDROME (FIS) and will pass the mutant gene to its entire offspring
