The Trps1 gene codes for an atypical member of the GATA type family of transcription factors. Mutations in human TRPS1 lead to the tricho-rhino-phalangeal syndrome types I and III, which are characterized by craniofacial and skeletal abnormalities and disturbed hair development. Correspondingly, during mouse embryonic development strong Trps1 expression is found in the cartilage condensations, the developing joints, the hair follicles and in the developing snout. In addition, Trps1 is expressed surrounding the skeletal condensations, in the trachea, the intervertebral disks, and in lung and gut mesenchyme. A complex pattern of expression is also found in the developing brain.