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Hereditary Cataract (HC) Australian Shepherd Type
| Acronym: | HC, PHC |
| Gene: | HSF4 |
| Mutation: | c.971delC |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Hereditary cataract Australian Shepherd type is a common genetic disease affecting eyes in the Australian Shepherds. It is one of the most common disorders in purebred dogs, affecting approximately 100 breeds and representing a leading cause of blindness in dogs. The dominant form of the hereditary cataract Australian Shepherd type is caused by a single nucleotide deletion in the HSF4 gene, encoding for a heat shock transcription factor that regulates the expression of heat shock proteins in response to different stresses, such as oxidants, heavy metals, elevated temperatures, and bacterial and viral infections.
HSF4 deletion is associated with bilateral, symmetrical cataract. Dogs carrying a single copy of a mutated gene have an increased risk of developing a milder cataract, whereas homozygotes are more likely to develop more progressive, debilitating cataract. About 23% of Australian Shepherds are carriers of the mutated gene responsible for the disease.
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:
Mellersh, C.S., Pettitt, L., Forman, O.P., Vaudin, M., and Barnett, K.C. (2006). Identification of mutations in HSF4 in dogs of three different breeds with hereditary cataracts. Veterinary Ophthalmology 9, 369–378.
Mellersh, C.S., McLaughlin, B., Ahonen, S., Pettitt, L., Lohi, H., and Barnett, K.C. (2009). Mutation in HSF4 is associated with hereditary cataract in the Australian Shepherd. Veterinary Ophthalmology 12, 372–378.