Atopy is an immediate-onset allergic reaction ( type 1 hypersensitivity reaction ) as asthma, food allergies, AD or hay fever.[6][7] In 2006 it was discovered that mutations in the gene for the production of filaggrin strongly increased the risk for developing atopic dermatitis. Most importantly two mutations were found that affect approximately 5% of people in Western Europe that may disrupt the production of filaggrin. Filaggrin is a protein that plays an important role in the retention of water in the stratum corneum.