Abstract
Asthma, allergic rhinitis (AR) and atopic dermatitis also called eczema are allergic co-morbidites, which are likely to depend on pleiotropic genetic effects as well as on specific genetic factors. After a previous genome-wide linkage screen conducted for asthma and AR in a sample of 295 French EGEA families ascertained through asthmatic subjects, the aim here was to search for genetic factors involved in eczema and more particularly the ones shared by the three allergic diseases using the same EGEA data. In this sake, eczema and phenotypes of "allergic disease" accounting for the joint information on the presence/absence of the three diseases were examined by linkage analyses using the maximum likelihood binomial method. A fine mapping was carried out in regions detected for potential linkage, followed by association studies using the family-based association test (FBAT). Evidence for linkage to 11p14 region was shown for "allergic disease" and eczema. Linkage was also indicated between eczema and 5q13 and between "allergic disease" and both 5p15 and 17q21 regions. Fine mapping supported the evidence of linkage to 11p14 and FBAT analyses showed the association between "allergic disease" and a marker located at the linkage peak on 11p14. Further investigations in this region will allow identifying genetic factor(s) which could have pleiotropic effect in the three allergic diseases.