The growing genetic links and the early onset of atopic diseases in children stress the unique role of the atopic march: a meta-analysis.

Allergic asthma and rhinitis, atopic dermatitis, urticaria and food allergy are genetic diseases present in infants and children. Several investigators have provided evidence for a genetic localization for atopy. Babies of atopic parents are at high risk of developing atopic diseases; however, the phenotypic expression of such diseases varies widely in that it can be very mild in some infants and children, severe and frustrating in many, even life-threatening in others, as well as also being common, disabling and chronic. A meta-analysis of all available studies on the age of onset of atopic march was carried out by selecting what appeared to be the most relevant articles in the literature rather than aiming for a comprehensive selection. It was found that in the first year of life, there is the onset of atopic dermatitis in 79.8% (60.2-100%) of babies, of cow's milk allergy in 72.7%, egg allergy in 71%, and fish allergy in 51.3%. Asthma starts in the first year of life in 41.8%, in the second in 49.3%, and within the eighth year in 92.5% of children. Allergic rhinitis begins in 35% of babies in the first year of life, and in 59% or 13-19% in those aged 2-5 years. It seems therefore that up until now the role of pediatric allergy and immunology has been somewhat obscured, as can be witnessed by atopic march. Instead, pediatric allergy and immunology have a substantial, unmatched role, focusing on the early and often very early onset of atopy, which requires strategic intervention in the very first months of life or even before birth. As the main goal of modern medicine is prevention of chronic and severe diseases, the possibility of preventing such disorders in predisposed children has stimulated the imagination of researchers since the beginning of the century, when atopic diseases were not as common as they are now.