Alternate hypotheses regarding the origin of pruritus have included high serum immunoglobulin (Ig)E levels (3,24), concurrent filaggrin mutations leading to atopy (7), high expression of matrix metalloproteinase 1 (MMP1) causing imbalance of collagen degradation (16,18), and high cytokine interleukin (IL)-31 levels (10). This evidence concerns the gene MMP1 and Pruritus.