Mechanisms of asthma and allergic inflammationMajor quantitative trait locus for eosinophil count is located on chromosome 2q
Section snippets
Methods
Twins were recruited as part of an ongoing study concerned with the development of melanocytic naevi (moles), the clinical protocol of which has been described in detail elsewhere.16., 17., 18. Twins were enlisted by contacting the principals of primary schools in the greater Brisbane area, by media appeals, and by word of mouth. It is estimated that approximately 50% of the eligible birth cohort was recruited into the study and was typical of the population with respect to eosinophil
Results
The results of the univariate variance components tests for linkage are displayed in Fig 1. Each plot displays LOD scores for all 3 ages so that it is possible to compare the consistency of results across measurement occasions. The strongest evidence of linkage occurred at age 12 years on chromosome 2q (LOD = 4.70; P = .000002). There was also a smaller peak in the same location at age 14 years (LOD = 1.0; P = .016), but not at age 16 years, at which there were far fewer twins tested and hence less
Discussion
The most promising result from this study is the large linkage peak on chromosome 2q33 for eosinophil count in 12-year-old twins. Several studies have reported suggestive linkages to asthma31 and asthma-related phenotypes in the 2q33 region, including circulating IgE,13 bronchial hyperresponsiveness,14 and reaction to a skin prick test.31 Several candidate genes are present within this region, including genes involved in T-cell signaling (CD28 and CTLA-4) and apoptosis (caspase 8).
A major
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Cited by (0)
Funding source: collection of phenotypes and DNA samples was supported by grants from the Queensland Cancer Fund, the Australian National Health and Medical Research Council (950998, 981339, and 241944) and the US National Cancer Institute (CA88363) to Dr Nick Hayward. The genome scans were supported by the Australian National Health and Medical Research Council's Program in Medical Genomics and funding from the Center for Inherited Disease Research (Director, Dr Jerry Roberts) at Johns Hopkins University to Dr Jeff Trent.