The American Curl is a breed of cat characterized by its unusual ears, which curl back from the face toward the center of the back of the skull. An American Curl's ears should be handled carefully because rough handling may damage the cartilage in the ear. The breed originated in Lakewood, California, as the result of a spontaneous mutation
Due to its large genetic pool with non-pedigree cats, the American Curl is generally a healthy breed. These cats' ears however require frequent cleaning to prevent infections, and needs gentle handling to prevent damage. Various matings between curled cats and normal cats revealed a dominant inheritance of the curl gene. Sex linked distribution was not found. The mutant gene was designated as curl and is symbolized by Cu. Another mutation of the ear pinna was found in Scottish Fold cats. In these cats anomalies were rarely found when heterozygous, however in homozygous (FdFd) cats, animals suffer from dysplasia of the lower limbs and tail. So the question arises if homozygous curls (CuCu) could also be affected by cartilage formation defects and bone abnormalities. However observations of a CuCu cat over two years showed no sign of anomaly.