Atopic dermatitis (AD) is a genetic disorder which has 70~80% of family history. The prevalence of AD in children is about 50% when one parent has AD, while it may be as high as about 80% when both parents have the disease. AD is a complex genetic disorder influenced by environmental factors. Nowadays, there are abundant studies about genes and markers associated with AD, but appropriate biomarkers which are adaptable tools for diagnosis, treatment and prognosis are relatively poor. Recently, FLG mutations were found to be an important predisposing factor for AD, and attention has focused on impaired epidermal barrier function, which is a hallmark feature of AD. The fact that FLG mutations have been reported as important predisposing factors for AD and atopic asthma suggests the these mutations also predispose to atopic march, the early onset of AD that persists into adulthood, as well as more severe asthma. In the near future, biomarkers like FLG for AD is not only helping new classification of the atopic patients but also affecting the response to early detection and individualized therapy, which is important in personalized medicine.