Chromosome 11q13 and atopic asthma

Asthma is a complex syndrome in which bronchial inflammation and smooth mus cle hyperactivity lead to labile airflow obstruction. The commonest form of asthma is that due to atopy, which is an immune disorder where production of IgE to inhaled antigens leads to bronchial mucosal inflammation. The ult imate origins of asthma are interactive environmental and genetic factors. The genetics is acknowledged to be heterogeneous, and one chromosomal regio n of interest and controversy has been 11q13. To clarify the nature of the chromosome 11q13 effect in atopy and asthma, we conducted a genetic associa tion study in subjects with marked atopic asthma and matched controls, whic h incorporated the study of 13 genetic variants over a distance of 10-12 cM and which took account of detailed immune and clinical phenotyping. Associ ation with high IgE levels was limited to the interval flanked by D11S1335 and CD20 in a 0.8-Mb interval and was greatest for variants of Fc epsilon R I beta and HTm4; these variants also associated with asthma (recurrent whee ze with labile airflow obstruction and need for regular inhaler treatment). At the more telomeric marker, D11S480, variants associated with asthma, bu t not with high IgE levels. The data might support the possibility of multi ple loci relevant to atopic asthma on chromosome 11q13.