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Ichthyosis (ICT)– German Shepherd Type
| Acronym: | ICT |
| Gene: | ASPRV1 |
| Mutation: | c.1052T>C |
| Inheritance: | Autosomal Dominant |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
| Method: | Sanger sequencing |
Genetics and characteristics
Ichthyosis (ICT) is a heterogeneous group of cornification disorders characterized by abnormal differentiation (cornification) of the epidermis. In dogs, several forms of ichthyosis have been described so far and all of these disorders share an inability to correctly form the outermost layer of the epidermis – the stratum corneum. Ichthyosis is characterized by generalized dry skin, scaling, and bad coat quality in affected dogs on the entire body. This specific variant has been found only in German Shepherd dogs so far and it is caused by a deletion variant in the ASPRV1 gene encoding a retroviral-like protease playing an essential role in skin barrier formation.
This type of congenital ichthyosis found in German Shepherd dogs is inherited as an autosomal dominant trait meaning even dogs with only one mutated gene will develop the disease, not only dogs that carry two mutated genes. Other types of ichthyosis found in dogs usually have an autosomal recessive mode of inheritance. Early genetic testing can help identify dogs that carry the gene with the specific mutation and prevent their further breeding by 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. |
AFFECTED HETEROZYGOTE |
Tested mutation was detected in animal with „affected heterozygote“ result. Animal tested as affected heterozygote has one wild-type and one mutation allele, it is in heterozygous state. It is likely to 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.
**Penetrance of tested mutation, and potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Bauer, A., Waluk, D. P., Galichet, A., Timm, K., Jagannathan, V., Sayar, B. S., Wiener, D. J., Dietschi, E., Müller, E. J., Roosje, P., Welle, M. M., Leeb, T. (2017). A de novo variant in the ASPRV1 gene in a dog with ichthyosis. PLoS genetics, 13(3), e1006651. https://doi.org/10.1371/journal.pgen.1006651
Mauldin, E. A., Elias, P. M. (2021). Ichthyosis and hereditary cornification disorders in dogs. Veterinary dermatology, 32(6), 567–e154. https://doi.org/10.1111/vde.13033