While numerous familial studies of asthma have identified several distinct chromosomal regions, no linkage studies have been performed taking into account the age of onset of disease. Here, we performed a genome-wide scan to search for loci linked either to asthma or wheezing age of onset in a population of German asthmatic children by incorporating survival analysis techniques in the maximum-likelihood-binomial approach. In addition to several regions already reported in asthma, wheezing age of onset was found to be strongly linked to chromosome 6q24-q25 (lod score = 3.56). Interestingly, this region contains some candidates genes such as the gene coding for the IFN-gamma receptor ligand-binding chain.