Rex mutation
（重定向自Rex Cat）
The rex mutation is a genetic variation in mammals that results in soft curly fur. These effects are due to changes in the structure of groups of hairs and cross-section of individual hairs. The Rexed coats are unusual but occur (and have been preserved) in cats, rabbits, horses, and dogs. The mutations, infrequent and spontaneous, occur in a variety of genes and genetic regulatory structures. The diversity of genetic factors results in variable coat thickness/density and fur length.