Congenital Disorder is a disorder that triggers cats to where they have more than 4/5 toes on each foot. It's also called polydactyl.
The famous Hemingway Cats were the first or second known cats to have polydactyl claws. They reside now at Ernest Hemingway's house in Key West Florida. There resides 50-60 sixtoed cats. The House was designated as a U.S National Historic Landmark on Nov 24, 1968.