[The epidemiology and genetics of asthma. I. Descriptive epidemiology and analysis of environmental factors]

Asthma is regarded as a disease with a complex interaction between genetic and environmental factors. Since the end of the 1970s and during the 80s the world has seen an increase in the prevalence, morbidity and mortality linked to asthma. The rapidity of progress of this phenomenon means that it cannot be explained only by modification of genetic factors and stresses the preponderance of exogenous factors. The purpose of this review is to examine the epidemiological knowledge of these environmental factors and of the genetic factors in asthma in order to underline how these genetic and exogenous factors interact and modulate the occurrence of the asthmatic disease. In the first part of this general review we will discuss the epidemiology of asthma in terms of prevalence, incidence, mortality, cost and socio-professional and scholastic repercussions and will underline for each environmental factor its causal role and/or exacerbation in asthma as well as its contribution in the increased prevalence and severity of asthma. In the second part of this general view we touch on the epidemiological knowledge of the genetics of asthma and of atopy.