The importance of epidemiological studies for genetic concepts: examples from pediatric cardiology

Abstract

Examples from pediatric cardiology are used to illustrate the importance of epidemiological studies in understanding genetic basis of heart defects. The introduction presents fundamental understandings in the genetics of congenital heart defects, followed by the most signifi cant epidemiological studies in the last 30 years. Two major Croatian studies are compared with these investigations. Considerable variability of results is a consequence of unequal criteria and sensitivity in diagnostics. Echocardiography is the fundamental method for determining the criteria for inclusion and exclusion. The reader is introduced into the basic principles of Clark’s etiopathogenic theory, which is based on genetic evidence that a small number of etiopathogenic factors cause a large number of phenotypic expressions of heart defects. The validity of this theory is confi rmed by comparing the outcomes of epidemiologic analysis of the Croatian and Bavarian study. In the fi rst stage, the relative relation between particular etiopathogenic groups is compared, followed by comparison of frequency of simple (isolated) and complex defects within the same etiopathogenic group. Both methods confi rm genetic basis as well as the importance of epidemiological research in clarifying the etiology of congenital heart defects.