MDR1 / Multidrug sensitivity (ABCB1-related) - Cat

MDR1 / multidrug sensitivity in cats

This genetic test examines the ABCB1 variant c.1930_1931delTC. The trait is also known as MDR1, Multi Drug Resistance 1, multidrug sensitivity, ivermectin sensitivity or P-glycoprotein deficiency. ABCB1 encodes P-glycoprotein, a transport protein that helps keep certain substances out of vulnerable tissues, including the central nervous system.

Cats with two copies of the variant produce insufficient functional P-glycoprotein. As a result, certain medicines, especially P-glycoprotein substrates such as macrocyclic lactones, can penetrate more strongly and cause more severe adverse effects. Neurological signs may include lethargy, ataxia, tremors, salivation, vomiting, dilated pupils, breathing problems, seizures, blindness, coma or death.

What is tested?

• The gene: ABCB1, also known as MDR1.
• The variant: c.1930_1931delTC.
• The inheritance pattern: autosomal recessive.
• The scope: cats of all breeds.

Practical value of this test

The result shows whether a cat carries zero, one or two copies of the tested ABCB1 variant. This helps owners, breeders and veterinarians make better informed medication and breeding decisions. For cats with two copies, the result is especially valuable because MDR1 status is relevant when using drugs that depend on P-glycoprotein transport.