Why Scottish Fold Cats' Ears Fold

The forward-folded ears that give the Scottish Fold cat its name are not just a cosmetic trait. They are a visible sign of a mutation that affects cartilage throughout the animal's whole body. In 2016, researchers identified the specific genetic cause. It is a single change in a gene called TRPV4. This gene normally helps control how cartilage cells develop. In cats with this mutation, cartilage forms abnormally soft and bendable. This is why the ear, an organ made almost entirely of cartilage, folds forward instead of standing up. Cartilage supports joints and bones throughout the body, not just the ears. So the same mutation also disrupts skeletal development elsewhere. Veterinarians call this condition osteochondrodysplasia. Cats need only one copy of the mutated gene to develop folded ears. However, even one copy makes cats prone to thickened, stiff tails, misshapen toes, and worsening joint pain over time. This happens because cartilage throughout their skeleton fails to develop normally. Every Scottish Fold with visibly folded ears carries this mutation to some degree. The resulting joint disease is both painful and incurable. Because of this, breeding the trait has become a serious controversy. Several countries, including the Netherlands, Austria, and Belgium's Flanders region, have restricted or banned breeding Scottish Folds. They did this specifically because of the condition the folded ear represents.