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Feline Multidrug Resistance 1 (MDR1)
| Acronym: | MDR1 |
| Gene: | ABCB1 |
| Mutation: | c.1930_1931del |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Multidrug Resistance 1 is a genetic condition where an animal cannot efficiently efflux drugs and toxins from the body. MDR1 was firstly described in dogs but has now been identified in cats too and it is caused by a mutation within the MDR1 gene also known as the ABCB1 gene. ABCB1 encodes for a protein that acts as the multidrug efflux transporter P-glycoprotein (P-gp). Its main role is to protect the brain from potentially neurotoxic compounds while restricting the entry of drugs and toxins into the central nervous system (CNS). Affected cats that carry a mutation in the ABCB1 gene have P-gps with abolished function which is associated with increased drug susceptibility and drug accumulation in the CNS. Cats often start to show signs of neurological toxicity such as ataxia, temporary blindness, hypersalivation, tremors, lethargy, coma, and sometimes even death.
Multidrug Resistance in cats is inherited as an autosomal recessive trait meaning both mutated ABCB1 genes are required for this condition to develop. Cats that carry only one mutated gene will not develop the disease or show signs of neurological toxicity but may act as carriers of the specific mutation and potentially pass it to their offspring. Early genetic testing can help identify carriers and help prevent the disease from developing by proper selection of future 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:
Nürnberger, D., Wagner, L., Müller, S. F., Leiting, S., Leidolf, R., Alber, J., Hamann, M., Geyer, J. (2022). Detection of the ABCB11930_1931del TC Mutation in Two Suspected Ivermectin-Sensitive Cats and Their Relatives by a Novel TaqMan Allelic Discrimination Assay. Frontiers in veterinary science, 8, 808392. https://doi.org/10.3389/fvets.2021.808392
Mealey, K. L., Burke, N. S. (2015). Identification of a nonsense mutation in feline ABCB1. Journal of veterinary pharmacology and therapeutics, 38(5), 429–433. https://doi.org/10.1111/jvp.12212