Breeds Affected: Basset Hound
Samples Accepted: Blood, Buccal Swabs
Disease Information: The immune systems of XSCID affected pups fail to develop properly, thus the pups do not grow well, often have diarrhea and occasional vomiting, and are susceptible to many opportunistic infections. Because of these recurrent infections, affected pups usually die around 4 months of age.
Inheritance Information: XSCID is X-linked recessive, because the IL2RG gene is located on the X-chromosome. Male animals with the mutation (which have only one X chromosome) are affected. Females may have one normal and one mutated version and be asymptomatic carriers.
The possible genotypes are:
XX This dog is a normal female.
XXXSCID This dog is a carrier female. She is clinically normal, but will pass the mutation (XXSCID) to 50% of her offspring. When bred to a normal male, she can have pups of all four genotypes: normal female (XX), carrier female (XXXSCID), normal male (XY), and affected male (XXSCIDY).
XY This dog is a normal male.
XXSCIDY This dog is an affected male.
– Female offspring of a carrier female should be genetically tested to determine if they are normal or carriers (XX or XXXSCID).
– Carrier females (XXXSCID) should not be bred, because affected males can be produced.
Test Information: This mutation test identifies a 4 base deletion in the IL2RG gene.
Henthorn, P.S., Somberg, R.L., Fimiani, V.M., Puck, J.M., Patterson, D.F., Felsburg, P.J.: IL-2R gamma gene microdeletion demonstrates that canine X- linked severe combined immunodeficiency is a homologue of the human disease. Genomics 23:69-74, 1994. Pubmed reference: 7829104. DOI: 10.1006/geno.1994.1460.
Further information is available at the Online Mendelian Inheritance in Animals website