Repetin (also known as RPTN), is a member of the "fused" gene family and localized in the epidermal differentiation complex on chromosome 1q21. Repetin contains 2 N-terminal EF hand motifs, a central domain containing 28 repeats of the consensus sequence QxDRQGQSSHYG, and a glutamine- and arginine-rich C-terminal domain(PMID: 15854042). Repetin is an extracellular epidermal matrix protein involved in forming keratinocyte envelope. Repetin is expressed in the epidermis and at high levels in eccrine sweat glands, the inner sheaths of hair roots, and the filiform papilli of the tongue(PMID: 20448178).