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Autoimmune Lymphoproliferative Syndrome (ALPS)
| Acronym: | ALPS |
| Gene: | FASLG |
| Mutation: | c.418dup |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Autoimmune Lymphoproliferative Syndrome (ALPS) is a part of a diverse group of genetic conditions involving abnormal lymphocyte proliferation also referred to as lymphoproliferative diseases (LPDs). Few forms of ALPS have been identified in humans so far, but recently a new form has been identified in cats, in British shorthair (BSH) cats. Cats with ALPS have a decreased ability to trigger lymphocyte apoptosis due to insertions of an adenine within exon 3 in the FAS-ligand gene which results in a frameshift and premature stop codon that leads to a severely truncated protein. FAS-ligand gene encodes a tumor necrosis factor ligand superfamily member 6 that plays an important role in the activation of FAS mediated apoptosis pathway. Affected cats start to show progressive symptoms early at age, at approximately 6 weeks, and they include abdominal distension, hemolytic anemia, progressive lethargy, and weight loss that ultimately results in euthanasia.
This type of lymphoproliferative disease found in British shorthair cats is inherited as an autosomal recessive trait meaning both mutated FASL genes are required for the disease to develop. Cats with only one copy of the mutated gene will not develop the disease but may act as carriers and pass the mutation to their offspring. Early genetic testing can help identify cats that carry the gene with the specific mutation and help breeders in the proper selection of mating pairs.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Aberdein, D., Munday, J. S., Gandolfi, B., Dittmer, K. E., Malik, R., Garrick, D. J., Lyons, L. A., 99 Lives Consortium (2017). A FAS-ligand variant associated with autoimmune lymphoproliferative syndrome in cats. Mammalian genome : official journal of the International Mammalian Genome Society, 28(1-2), 47–55. https://doi.org/10.1007/s00335-016-9668-1
Aberdein, D., Munday, J. S., Fairley, R. A., Vernau, W., Thompson, K. G. (2015). A Novel and Likely Inherited Lymphoproliferative Disease in British Shorthair Kittens. Veterinary pathology, 52(6), 1176–1182. https://doi.org/10.1177/0300985815586224