Background: Asthma and atopy are complex genetic traits, influenced by the interaction of multiple genes and environmental factors. Linkage of these traits to chromosome 5q31-33 has been shown in other populations, but has not been well studied in the Chinese. We studied linkage between asthma and atopy with markers on chromosome 5q31-33 in the Singapore Chinese. This region contains many candidate genes, including the cytokine gene cluster.
Methods: We recruited 88 Chinese families with at least two affected offspring, totaling 373 subjects, with 125 and 119 sib-pairs for atopy and asthma, respectively. All individuals were genotyped with 19 polymorphic microsatellite markers spanning a distance of 41 cM along chromosome 5q31-33. Affected sib-pair and multipoint linkage analysis was performed.
Results: There was evidence for linkage of the asthma and atopy phenotypes with three markers, D5S2110, D5S2011, and D5S412 (P values of 0.001 to 0.00001). Multipoint analysis further substantiated this (nonparametric linkage scores of 1.8-2.9). These findings suggest that susceptibility genes for asthma and atopy are found in this region in the Chinese.
Conclusion: This study has shown linkage of atopy and asthma to chromosome 5q31-33 in a heterogeneous Chinese population. These findings further substantiate the notion that chromosome 5q31-33 contains "universally" important susceptibility genes for these traits.