Genetic diseases with simple modes of inheritance
X-Linked Severe Combined Immunodeficiency Disease (X-SCID)
What is X-SCID?
This genetic disease affects the immune system and is carried on the X chromosome.
What are the symptoms?
Puppies with this genetic disease are normally identified by the time that they are 6 to 8 weeks old. They do not grow properly, lose weight, are lethargic, and may have diarrhea and vomiting.
Is there a treatment?
Most affected dogs die by 4 months of age due to their immune system not being able to fight off infections.
Genetic testing & our breeding program
We test ALL of our breeding dogs for X-SCID.
We have no dogs who carry genes for this disease.
What genetics are involved?
The gene involved is IL2RG Exon 1 on the X chromosome. This is a recessive sex linked disease.
This condition is sex linked. The gene is carried on the X chromosome. Remember that females have two X chromosomes while males have only one. The possible outcomes are explained below.
1. A female dog may inherit an X chromosome with the normal gene from both parents.
These dogs are normal and are not at risk of developing this disease themselves nor can they pass on this disease to their offspring.
2. A female dog may inherit an X chromosome with the normal gene from one parent and an X chromosome with the mutation from the other parent.
These dogs are carriers. These dogs will be normal however they may pass this mutated X chromosome on to their offspring.
3. A female dog may inherit 2 X chromosomes with the mutated gene.
These dogs will develop the disease and probably die before reproducing.
1. Males only have one X chromosome so if they inherit an X chromosome with the mutation (X chromosomes are inherited from females) they will be affected and die.
2. Males who inherit a normal X chromosome will be normal.