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Ventricular Arrythmia (RRIVA) - Rhodesian Ridgeback Type
| Acronym: | RRIVA |
| Gene: | QIL1 |
| Mutation: | g.54343438G>A |
| Inheritance: | Possibly dominant with incomplete penetrance |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Ventricular Arrhythmia (RRIVA) is a genetic abnormality of the cardiac electrical system that can cause the development of abnormal heartbeats which can lead to sudden juvenile death in some dogs. Sudden death associated with ventricular arrhythmias has been previously reported in young German Shepherd Dogs and English Springer Spaniels, but this type of PRIVA is specific for Rhodesian Ridgeback dogs. PRIVA is caused by a specific missense mutation within the QIL1 gene that produces a component of the Mitochondrial Contact Site and Cristae Organizing System (MICOS). MICOS forms and stabilizes mitochondrial cristae junctions and is important in cellular energy production and a dysfunctional protein would have a likely impact on organs with the highest energy needs, including the liver, brain, skeletal muscle, and heart.
The mode of inheritance for this type of Ventricular Arrhythmia specific to Rhodesian Ridgeback is still yet to be defined. There are two possible modes – an autosomal recessive one and an autosomal dominant one with incomplete disease penetrance. The latter is more likely to be correct which means that dogs with two copies of the mutated gene will develop the disease and it is very likely that even dogs with only one mutated gene develop a mild form of the disease. Early genetic testing can help identify affected dogs that carry the 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:
Meurs, K. M., Friedenberg, S. G., Olby, N. J., Condit, J., Weidman, J., Rosenthal, S., Shelton, G. D. (2019). A QIL1 Variant Associated with Ventricular Arrhythmias and Sudden Cardiac Death in the Juvenile Rhodesian Ridgeback Dog. Genes, 10(2), 168. https://doi.org/10.3390/genes10020168
Meurs, K. M., Weidman, J. A., Rosenthal, S. L., Lahmers, K. K., Friedenberg, S. G. (2016). Ventricular arrhythmias in Rhodesian Ridgebacks with a family history of sudden death and results of a pedigree analysis for potential inheritance patterns, Journal of the American Veterinary Medical Association, 248(10), 1135-1138. https://doi.org/10.2460/javma.248.10.1135