Genotype: N / N [ Homozygous normal ]
The horse is noncarrier of the mutant gene.
The horse will never develop SCID (Severe Combined Immunodeficiency) and therefore it can be bred to any other horse.
Genotype: N / SCID [ Heterozygous ]
The horse carries one copy of the mutant gene and one
copy of the normal gene.
The horse will never develop SCID (Severe Combined Immunodeficiency) 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)
Genotype: SCID / SCID [ Homozygous mutant ]
The horse carries two copies of the mutant gene and
therefore it will pass the mutant gene to its entire offspring.
Affected horses usually die before reaching the breeding age.
The horse will develop SCID (Severe Combined Immunodeficiency) and will pass the mutant gene to its entire offspring