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Congenital ichthyosis (ICT) - American Bulldog type
| Acronym: | ICT |
| Gene: | NIPAL4 |
| Mutation: | c.744delC |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Congenital ichthyosis is a heterogeneous group of genetic diseases 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 skin scaling and bad coat quality in affected dogs on the entire body and is detected shortly after birth. This specific variant has been found only in American Bulldogs so far and it is caused by a deletion variant in the NIPAL4 gene yielding a premature stop codon and a truncated and defective ichthyin protein. Ichthyin is a transmembrane protein that plays an important role in epidermal lipid metabolism.
This type of congenital ichthyosis found in American Bulldogs is inherited as an autosomal recessive trait, requiring both copies of the mutated gene for the disease to develop. That means bulldogs with only one mutated gene copy will not develop the disease, but may potentially pass the mutation to their offspring. Early genetic testing can help identify dogs that carry the gene with the specific mutation and prevent their further breeding by 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:
Casal, M. L., Wang, P., Mauldin, E. A., Lin, G., & Henthorn, P. S. (2017). A Defect in NIPAL4 Is Associated with Autosomal Recessive Congenital Ichthyosis in American Bulldogs. PloS one, 12(1), e0170708. https://doi.org/10.1371/journal.pone.0170708
Briand, A., Cochet-Faivre, N., Reyes-Gomez, E., Jaraud-Darnault, A., Tiret, L. and Chevallier, L. (2019), NIPAL4 deletion identified in an American Bully with autosomal recessive congenital ichthyosis and response to topical therapy. Vet Med Sci, 5: 112-117. https://doi.org/10.1002/vms3.149
Mauldin, E. A., Wang, P., Evans, E., Cantner, C. A., Ferracone, J. D., Credille, K. M., & Casal, M. L. (2015). Autosomal Recessive Congenital Ichthyosis in American Bulldogs Is Associated With NIPAL4 (ICHTHYIN) Deficiency. Veterinary Pathology, 52(4), 654–662. https://doi.org/10.1177/0300985814551425