Eczema in early life: genetics, the skin barrier, and lessons learned from birth cohort studies.

czema is a chronic inflammatory disorder of the skin that affects as much as 30% of children. It often afflicts infants in the first few months of life and can be the first indicator of the atopic march. Recent results from birth cohort studies have uncovered novel information about genetic and environmental factors that promote the development of eczema. Birth cohort studies provide an optimal study design to elucidate these associations and prospectively track longitudinal data including exposure assessment and health outcomes from birth into early life and childhood. This is especially relevant for eczema because of the age-specific emergence of this disease. In this review, we will provide a general overview of pediatric eczema and discuss the important findings in the literature for genetics and environmental exposures, highlighting those derived from birth cohort studies. Additionally, we will review how these relate to the atopic march, the hygiene hypothesis, and the integrity of the skin barrier.