TDK conference 2016

The multidrug resistant gene 1 (MDR1 or ABCB1) codes for an adenosine triphosphate (ATP) driven P-glycoprotein functions as an efflux pump to extrude unrelated toxic compounds from inside a cell out into the capillary blood stream. A 4 base pair deletion at the nucleotide position 230 results in a severely truncated, nonfunctional P-glycoprotein. The ABCB1-1∆ polymorphism (previously nt230(4del) MDR1 gene defect) is known so far in 13 dog breeds: Collie, Australian Shepherd, Miniature Australian Shepherd. Shetland Sheepdog, Old English Sheepdog, Border Collie, Longhaired Whippet, McNab, Silken Windhound, Wäller, German Shepherd and White Swiss Shepherd. In dogs affected by the hereditary ABCB1-1∆ gene deletion severe neurotoxic phenomena after treatment with P-glycoprotein substances can lead to severe clinical symptoms up to lethal consequences.

The aim of our study was to measure the ABCB1-1∆ gene defect in British herding breeds in Hungary and to test the existing genotyping screening methods from the point of view of effectiveness and reliability.

Altogether 49 blood samples were collected from the Hungarian population of British herding dogs (forty Border Collies, six Shetland Sheepdogs, two Collies and one Australian Shepherd) and were investigated for the ABCB1-1∆ genotype. The extracted DNA samples were processed with three different PCR based diagnostic screening methods: 1. Detection of the 4 base pair deletion with fluorescent labeled PCR primer followed by length polymorphism analysis using capillary electrophoresis; 2. PCR amplification with two allele specific oligonucleotide primer pairs followed by agarose gelelectrophoresis; 3. 1-step real-time PCR based fluorogenic 5´nuclease TaqMan allelic discrimination.

Preexisting data from breeders supplemented these data for statistical analysis.

The prevalence of this genetic defect within the Hungarian population of British herding breeds was compared to that of similar dog populations worldwide.

This work is done in order to increase the awareness of this genetic defect in the above mentioned breeds and refer the high number of unpredicted carriers (mixed breed) for the MDR1 gene defect.