Satin is a gene found in many animals and proposed to be found in some breeds of horses, most notably the Akhal Teke. Satin animals have mostly hollow hair shafts with a missing medulla (innermost layer of the hair shaft). The hair is instead filled with air pockets. This causes light to refract differently on satin coats then normal coats. Satin hair is also finer and more delicate then normal hair. Satin may be located at the Foxq1 gene (Forkhead box, subclass q, member 1).