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Genetic Variation in the Promoter Region of Chitinase 3-Like 1 Is Associated with Atopy

¹ Department of Pediatrics and Institute of Allergy, Brain Korea 21 Project for Medical Sciences, and ² Department of Pharmacology, Pharmacogenomic Research Center for Membrane Transporters, Yonsei University College of Medicine, Seoul, Korea; ³ Section of Pulmonary and Critical Care Medicine, Yale University School of Medicine, New Haven, Connecticut

Correspondence and requests for reprints should be addressed to Dr. Min Goo Lee, Department of Pharmacology, Yonsei University College of Medicine, 134 Sinchon-Dong, Seoul 120-752, Korea. E-mail: mlee{at}yuhs.ac

Rationale: Atopy or atopic syndrome is an allergic hypersensitivity subject to hereditary influences. Aberrant expression of chitinase 3-like 1 (CHI3L1), also known as YKL-40 or HC gp-39, is involved in the pathogenesis of inflammatory and allergic diseases.

Objectives: The genetic contribution of CHI3L1 gene to atopic susceptibility was investigated using an integrated population genetic and molecular analysis.

Methods: Genetic variations in CHI3L1 were identified and genotyped in 295 unrelated patients with atopy and 180 control subjects. Serum YKL-40 and IgE levels were analyzed according to genotype. The effects of a promoter polymorphism (g.-247C/T) on promoter activity were examined in reporter and protein binding assays.

Measurements and Main Results: In the case-control association analysis, the g.-247C/T polymorphism at the promoter region (rs10399805; P = 0.0062) and the IVS7+82C/T polymorphism at intron 7 (rs2275353; P = 0.0056) of CHI3L1 showed a significant association with atopy. Subjects with the g.-247T risk allele had significantly higher serum YKL-40 (P < 0.0001) and IgE (P = 0.012) levels. An in vitro promoter assay using THP-1 human monocyte cells revealed that the C to T conversion at g.-247 induced a more than twofold increase of reporter gene expression. Moreover, the g.-247T allele showed an increased affinity for CCAAT enhancer-binding protein, a well known transcriptional activator, by electrophoretic mobility shift assay. Accordingly, subjects with the g.-247TT genotype showed a 2.5-fold increase in CHI3L1 mRNA expression in peripheral blood cells compared with those with the g.-247CC genotype.

Conclusions: These results strongly suggest that the g.-247C/T polymorphism in the CHI3L1 promoter region is associated with the risk of atopy.

Key Words: chitinase-like proteins • genetic association • YKL-40 • hypersensitivity

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject Atopy is a common childhood allergic hypersensitivity subject to hereditary influences. Aberrant expression of chitinase 3-like 1 (CHI3L1), also known as YKL-40 or HC gp-39, is involved in the pathogenesis of inflammatory and allergic diseases. What This Study Adds to the Field Data from genetic and molecular analyses show that a promoter polymorphism in CHI3L1 is associated with atopy and the g.-247T allele is a risk factor of atopy.