Linkage of chromosome 5q and 11q gene markers to asthma-associated quantitative traits in Australian children

Asthma is a genetically complex disease, and the investigation of putative linkages to candidate loci in independent populations is an important part of the gene discovery process. This study investigated the linkage of micro satellite markers in the 5q and 11q regions to asthma-associated quantitati ve traits in 121 Australian Caucasian nuclear families. The families were r ecruited on the basis of a child proband: a cohort of 95 randomly recruited families of unselected probands (n = 442 subjects) and a cohort of 26 fami lies of probands selected on the basis of severe symptomatic asthma (n = 13 4 subjects). The quantitative traits assessed included serum levels of tota l IgE and specific IgE to house dust mite and mixed grass, blood eosinophil counts, and the dose-response slope (DRS) of FEV, to histamine provocation . Multipoint linkage analysis using Haseman-Elston sib-pair methods provide d evidence of significant linkage between the chromosome 5q markers and log , total serum IgE levels, specific serum IgE levels, and log, blood eosinop hil counts. The chromosome 11q markers showed evidence of significant linka ge to specific serum IgE levels. Neither region demonstrated significant li nkage to the log, DRS to histamine. Phenotypes were residualized for age an d sex. These data are consistent with the existence of loci regulating asth ma-associated quantitative traits in both the 5q31-33 and 11q13 chromosomal regions.