A human epidermal differentiation factor polypeptide and DNA (RNA) encoding such polypeptide and procedure for producing such polypeptide by recombinant techniques is disclosed. Also disclosed are methods for utilizing such polypeptide for treating and/or preventing skin diseases. Diagnostic assays for detecting mutations in a nucleic acid sequence encoding a polypeptide of the present invention and for detecting altered levels of the polypeptide of the present invention are also disclosed.