Polymorphisms in the 5-lipoxygenase activating protein (ALOX5AP) gene are not associated with asthma in an Australian population

BACKGROUND: The cysteinyl-leukotrienes (cys-LTs) are important pro-inflammatory mediators in asthma, and have been shown to have a role in specific disease subtypes, including asthma severity. Few studies have investigated the role of polymorphisms in the ALOX5AP gene, encoding 5-lipoxygenase activating protein (FLAP), and asthma. We hypothesized that polymorphisms in this gene are associated with asthma and in particular, with asthma severity, in an Australian population. OBJECTIVE: To screen the coding region of the ALOX5AP gene for polymorphisms and to determine the association between previously described polymorphisms and asthma and asthma severity in an Australian population. METHODS: We used PCR-SSCP and PCR-RFLP analysis to examine a previously described promoter polyA variable repeat polymorphism and two intronic polymorphisms (IVS2+12C>A, IVS2+105T>C), and to screen all five exons of the gene for new polymorphisms, in a large Australian population of randomly selected, non-asthmatic controls (n=457), mild asthmatics (n=274), moderate asthmatics (n=231) and severe asthmatics (n=79). RESULTS: We confirmed the presence of two polymorphisms in intron 2 and found no association between these polymorphisms and asthma or asthma severity, nor between a promoter polymorphism in the ALOX5AP gene and asthma or asthma severity. Gene fragment analysis of the promoter polymorphism revealed novel, conserved repeat numbers in our population, and no new polymorphisms were found in the coding region of the gene. CONCLUSION: These findings in a large, well characterized asthma population, reveal that, while FLAP is an important enzyme in cys-LTs biosynthesis, polymorphisms in the ALOX5AP gene are not likely to be functionally associated with the asthma phenotype.     

5-Lipoxygenase (ALOX5) and FLAP (ALOX5AP) gene polymorphisms as factors in vascular pathology and Alzheimer's disease

We first hypothesized in 2000 that a polymorphism of the human gene encoding the enzyme 5-lipoxygenase (5-LOX) might be associated with Alzheimer's disease. Only a little progress has been made in directly testing our proposal. However, additional important new data lead us to hypothesize that genetic variability not only in the 5-LOX gene, i.e., ALOX5, but also in polymorphism of the five-lipoxygenase activating protein (FLAP) gene, i.e., ALOX5AP, may be associated with Alzheimer's pathology. Studies in mice followed by several extensive clinical studies have identified ALOX5 and ALOX5AP polymorphisms as strong risk factors for atherosclerosis and cerebrovascular pathologies. New data point to a significant aggregation of vascular risk factors and risk of Alzheimer's disease. Preliminary findings in postmortem brain of Alzheimer's patients identified elevated 5-LOX immunostaining in this disease. We suggest that our hypothesis of a link between the ALOX5 and ALOX5AP gene polymorphisms and Alzheimer's disease could be tested in a clinical setting and in animal models, i.e., transgenic mice could be produced by crossing the available 5-LOX-deficient mice with the available transgenic mice models of Alzheimer's disease.     

Association between arachidonate 5-lipoxygenase-activating protein (ALOX5AP) and lung function in a Korean population

Arachidonate 5-lipoxygenase-activating protein (ALOX5AP) plays a role in the 5-lipoxygenase (LO) pathway, which includes the LTC(4), LTD(4), LTE(4) and LTB(4). These leukotrienes are known causative factors of asthma, allergy, atopy and cardiovascular diseases. ALOX5AP lacks enzyme activity and acts by helping 5-LO function. In this study, healthy and general subjects who live in rural and urban areas of Korea were tested for the association of ALOX5AP polymorphisms with lung function. Lung function was also estimated by calculating the predicted values for forced expiratory volume in one second (FEV(1) _%PRED) and the proportion of the forced vital capacity exhaled in the first second (FEV(1) /FVC_PRED). The linear regression was adjusted for residence area, gender, age, height and smoking status. The analysis revealed associations between FEV(1) and the single-nucleotide polymorphism (SNP) rs9506352 and the haplotype TCAC (permuted P-value < 0.05). The linkage disequilibrium block that included the significant SNPs overlapped with SNPs that were revealed previously to associate with myocardial infarction and asthma and to affect lung function. This study is the first to demonstrate the association between lung function and ALOX5AP polymorphisms in a healthy and general population.     

The role of LTA4H and ALOX5AP genes in the risk for asthma in Latinos

Background Leukotrienes play an important role in allergic and inflammatory diseases, but reports on the involvement of arachidonate 5‐lipoxygenase‐activating protein (ALOX5AP) and leukotriene A₄ hydrolase (LTA4H) in asthma have been inconclusive. Objective To determine whether polymorphisms in ALOX5AP and LTA4H genes are risk factors for asthma in two different Latino groups: Mexicans and Puerto Ricans. Methods The LTA4H gene was sequenced in individuals from both groups to identify novel polymorphisms. Single‐nucleotide polymorphisms (SNPs) in the ALOX5AP and LTA4H genes were analysed for associations with asthma and asthma‐related phenotypes in 687 parent–child trios of Mexican and Puerto Rican origin. Results In LTA4H, five previously unknown polymorphisms were identified. Two SNPs within LTA4H (rs17525488 and rs2540493) were protective for asthma in Latinos (P=0.007 and 0.05, respectively). Among the Mexican patients, LTA4H polymorphisms were associated with baseline lung function and IgE levels. For ALOX5AP, the minor allele at SNP rs10507391 was associated with protection from asthma (odds ratio=0.78, P=0.02) and baseline lung function (P=0.018) in Puerto Ricans. A gene–gene interaction was identified between LTA4H (rs17525488) and ALOX5AP (rs10507391), (P=0.003, in the combined sample). Conclusion Our results support the role of LTA4H and ALOX5AP variants as risk factors for asthma in Latino populations. Cite this as: M. Via, A. De Giacomo, H. Corvol, C. Eng, M. A. Seibold, C. Gillett, J. Galanter, S. Sen, H. Tcheurekdjian, R. Chapela, J. R. Rodríguez‐Santana, W. Rodríguez‐Cintrón, S. Thyne, P. C. Avila, S. Choudhry and E. González Burchard on behalf of the Genetics of Asthma in Latino Americans (GALA) Study, Clinical & Experimental Allergy, 2010 (40) 582–589.     

ALOX5 variants associated with susceptibility to human pulmonary tuberculosis

The 5-lipoxygenase (ALOX5)-derived lipid mediators leukotrienes and lipoxins have regulatory functions in inflammation by modulating activities of immune cells and cytokine production. Recently, it was shown in ALOX5-/- mice that host control of Mycobacterium tuberculosis is regulated by 5-lipoxygenase (5-LO). ALOX5 polymorphisms were genotyped in 1916 sputum-positive patients with pulmonary tuberculosis (TB) from Ghana and in 2269 exposed, apparently healthy controls. Polymorphisms of a variable number of tandem repeats (VNTR) of the ALOX5 promoter and of the exonic non-synonymous variant g.760G>A were analysed by fragment length determination and fluorescence resonance energy transfer, respectively, and DNA sequencing. Mycobacterial lineages of >1400 isolates were differentiated biochemically and genetically. Carriers of one variant (n repeats not equal 5) and one wild-type VNTR allele (n = 5) or of the exonic allele g.760A had a higher risk of TB [P(corrected) = 0.026, odds ratio (OR) 1.19 (95% CI 1.04-1.37) and P(corrected) = 0.026, OR 1.21 (95% CI 1.04-1.41), respectively]. The association of the exonic variant was stronger in infections caused by the mycobacterial lineage M. africanum West-African 2 [P(corrected) = 0.024, OR 1.70; (95% CI 1.2-2.6)]. Determination of haplotypes revealed the strongest associaton with TB for the 'non-5/760A' haplotype compared with the 'non-5/760G' haplotype (P = 0.003, OR 1.50). Our observation of an association of ALOX5 variants with susceptibility to TB contributes evidence of the importance of 5-LO products to the regulation of immune responses to M. tuberculosis.     

Effect of Genetic Polymorphism of ALOX15 on Aspirin-Exacerbated Respiratory Disease

Background: Aspirin-exacerbated respiratory disease (AERD) is a clinical syndrome associated with chronic inflammation in the airways coincident with chronic rhinitis, sinusitis, recurrent polyposis and asthma. Eosinophils are the key inflammatory cells in the development of AERD. AERD has been attributed to abnormalities of the arachidonic acid metabolism, but the pathogenesis of AERD is not fully understood. Our aim was to investigate the genetic contribution of the arachidonate 15-lipoxygenase gene (ALOX15) to the development of AERD. Methods: We enrolled 171 patients with AERD, 229 patients with aspirin-tolerant asthma, and 195 normal healthy controls in a Korean population. Three polymorphisms (-427G/A, -272C/A, -217G/C) in the promoter region of ALOX15 were genotyped. The functional variability of the promoter polymorphisms were analyzed by luciferase reporter activity assay. Result: No significant difference in the genotype frequency of the ALOX15 genetic polymorphism was found. Peripheral total eosinophil count was significantly higher in the patients carrying the GG genotype of the -427G/A polymorphism (p = 0.016). Similarly, the patients carrying haplotype 1 (ht1) (GCG) of -427G/A, -272C/A and -217G/C showed a significantly higher total eosinophil count compared to the other haplotypes (p = 0.008) in the AERD group. The promoter activity of the ht1 (GCG) construct was significantly higher compared to that of the ht3 (AGG) construct in A549 and U937 cells (both p < 0.001). Conclusion: These results suggest that the promoter polymorphisms of the ALOX15 gene affect ALOX15 activity leading to increased eosinophil infiltration in AERD patients.     

No association of ALOX5AP polymorphisms with risk of MRI-defined brain infarcts

The arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene has been associated with stroke. The majority of the reported ALOX5AP associations have considered non-radiologically confirmed infarcts as the stroke phenotype. We assessed the association of genetic variants in ALOX5AP with stroke defined by the presence of infarcts on brain magnetic resonance imaging (MRI). We studied 202 persons with MRI-defined brain infarcts and 487 healthy individuals of Caribbean Hispanic ancestry. Another sample of European ancestry comprised 1823 persons with MRI-defined brain infarct and 7578 control subjects. Subjects were genotyped for the 4 single nucleotide polymorphisms (SNPs) that define ALOX5AP HapA haplotype. No association was found between SNPs and MRI-defined brain infarcts. Our data do not support the hypothesis that variants in ALOX5AP are associated with risk of MRI-defined brain infarcts.     

ALOX5AP gene variants and risk of coronary artery disease: an angiography-based study

The aim of this study was to explore the role of variants of the gene encoding arachidonate 5-lipoxygenase-activating protein (ALOX5AP) as possible susceptibility factors for coronary artery disease (CAD) and myocardial infarction (MI) in patients with or without angiographically proven CAD. A total of 1431 patients with or without angiographically documented CAD were examined simultaneously for seven ALOX5AP single-nucleotide polymorphisms, allowing reconstruction of the at-risk haplotypes (HapA and HapB) previously identified in the Icelandic and British populations. Using a haplotype-based approach, HapA was not associated with either CAD or MI. On the other hand, HapB and another haplotype within the same region (that we named HapC) were significantly more represented in CAD versus CAD-free patients, and these associations remained significant after adjustment for traditional cardiovascular risk factors by logistic regression (HapB: odds ratio (OR) 1.67, 95% confidence interval (CI) 1.04-2.67; P=0.032; HapC: OR 2.41, 95% CI 1.09-5.32; P=0.030). No difference in haplotype distributions was observed between CAD subjects with or without a previously documented MI. Our angiography-based study suggests a possible modest role of ALOX5AP in the development of the atheroma rather than in its late thrombotic complications such as MI.     

Genetic mechanism of aspirin-induced urticaria/angioedema

PURPOSE OF REVIEW: Aspirin-induced urticaria/angioedema is a major aspirin-related hypersensitivity often associated with aspirin-intolerant asthma. Genetic studies on aspirin-intolerant asthma have shown chronic overproduction of cysteinyl leukotrienes. The genetic analysis of aspirin-induced urticaria/angioedema is limited, however. RECENT FINDINGS: A recent study on HLA genotypes has suggested that the HLA alleles DRB11302 and DQB10609 may be genetic markers for aspirin-induced urticaria/angioedema. A polymorphism study that examined nine single-nucleotide polymorphisms of five leukotriene-related genes [ALOX5 (encoding 5-lipoxygenase), ALOX5AP (5-lipoxygenase-activating protein), PTGS2 (cyclooxygenase 2), LTC4S (leukotriene C4 synthase), and CYSLTR1 (cysteinyl leukotriene receptor 1)] found that promoter polymorphisms of ALOX5 (-1708A>G) and CYSLTR1 (-634C>T) were significantly different between aspirin-intolerant asthma and aspirin-induced urticaria/angioedema, suggesting different contributions to the lipoxygenase pathway. A second polymorphism study, conducted on histamine-related genes, did not find any significant associations with aspirin-induced urticaria/angioedema for the genes HNMT (encoding histamine N-methyltransferase), HRH1 or HRH2 (encoding histamine receptor types 1 and 2 respectively), or the gene encoding high-affinity IgE receptor Ibeta (FcepsilonRIbeta); however, the FcepsilonRIalpha gene promoter polymorphism was significantly associated with aspirin-induced urticaria/angioedema. This finding has been supported by in vitro functional studies. SUMMARY: The HLA alleles DRB11302 and DQB10609, and the ALOX5 and FcepsilonRIalpha promoter polymorphisms, may contribute to the pathogenesis of aspirin-induced urticaria/angioedema. Further investigation to identify candidate genetic markers would help to elucidate the pathogenic mechanism of this condition.     

Leukotriene-related gene polymorphisms in patients with aspirin-intolerant urticaria and aspirin-intolerant asthma: differing contributions of ALOX5 polymorphism in Korean population

The pathogenesis of aspirin (acetylsalicylic acid, ASA)-intolerant urticaria (AIU) is still poorly understood but it has recently been suggested that it is associated with the overproduction of leukotriene (LT). This is supported by evidence that cyclooxygenase 2 inhibitor is given safely to patients with AIU. The present study was designed to investigate the role of genetic polymorphism of LT related genes in the pathogenesis of AIU via a case-control study. We screened single nucleotide polymorphisms (SNPs) in genes encoding enzymes involved in leukotriene synthesis in the Korean population with AIU (n = 101), ASA-intolerant asthma (AIA, n = 95) and normal healthy controls (n = 123). Genotype was determined by primer extension reactions using the SNapShot ddNTP primer extension kit. Among 8 SNPs of four LT related genes, the polymorphism of ALOX5 at positions of -1708 G > A showed significant difference in genotype frequency between AIU and AIA (p = 0.01). Furthermore, there were significant differences observed in the frequencies of two ALOX5 haplotypes between the AIU group and AIA group (p < 0.05). However, there were no differences in allele, genotype, or haplotype frequencies of ALOX5 between the AIU group and the normal control group. These results suggested that ALOX5 has a differing contribution in two major clinical pathogenesis related to ASA-sensitivity.     

A novel promoter polymorphism in the gene encoding complement component 5 receptor 1 on chromosome 19q13.3 is not associated with asthma and atopy in three independent populations

BACKGROUND: The inflammatory functions of complement component 5 (C5) are mediated by its receptor, C5R1, which is expressed on bronchial, epithelial, vascular endothelial and smooth muscle cells. A susceptibility locus for murine allergen-induced airway hyper-responsiveness was identified in a region syntenic to human chromosome 19q13, where linkage to asthma has been demonstrated and where the gene encoding C5R1 is localized. OBJECTIVE: The aim of this study was to screen for novel polymorphisms in the C5R1 gene and to determine whether any identified polymorphisms are associated with asthma and/or atopy and whether they are functional. METHODS: Single-nucleotide polymorphism (SNP) detection in the gene encoding C5R1 was performed by direct sequencing. Genotyping was performed in three populations characterized for asthma and/or atopy: (1) 823 German children from The Multicenter Allergy Study; (2) 146 individuals from Tangier Island, Virginia, a Caucasian isolate; and (3) asthma case-parent trios selected from 134 families (N=783) in Barbados. Functional studies were performed to evaluate differences between the wild-type and the variant alleles. RESULTS: We identified a novel SNP in the promoter region of C5R1 at position -245 (T/C). Frequency of the -245C allele was similar in the German (31.5%) and Tangier Island (36.3%) populations, but higher in the Afro-Caribbean population (53.0%; P=0.0039 to <0.0001). We observed no significant associations between the -245 polymorphism and asthma or atopy phenotypes. Upon examination of the functional consequences of the -245T/C polymorphism, we did not observe any change in promoter activity. CONCLUSION: This new marker may provide a valuable tool to assess the risk for C5a-associated disorders, but it does not appear to be associated with asthma and/or atopy.     

ALOX5AP基因SG13S114A/T多态性与颈动脉粥样硬化斑块稳定性的相关性

目的 探讨花生四烯酸5-脂氧合酶激活蛋白(arachidonate 5-lipoxygenase acttvating protein,ALOX5AP)基因SG13S114 A/T的多态性与颈动脉粥样硬化斑块稳定程度的关系.方法 应用聚合酶链反应-限制性片段长度多态性分析法检测132例颈动脉易损斑块及152例稳定斑块的急性脑梗死者ALOX5AP基因SG13S114 A/T基因型,比较两组间该位点多态性的差异.结果 易损斑块组ALOX5AP基因SG13S114 AA基因型和A等位基因频率高于稳定斑块组,两组差异有统计学意义(P＜0.01),其中男性和女性上述基因型和等位基因频率的比较,易损斑块组均高于稳定斑块组,两组差异有统计学意义(P＜0.01).结论 ALOX5AP基因SG13S114 A/T多态性可能与动脉粥样斑块的稳定性有关,其中SG13S114 A等位基因可能是易损斑块的风险因素.     

The role of LTA4H and ALOX5AP polymorphism in asthma and allergy susceptibility

Background: Leukotrienes (LTs) have been identified as central mediators in asthma and allergy. Pharmacological inhibition of cysteinyl‐LT activity improves asthma symptoms and control. Accumulating evidence suggests a role for the dihydroxy leukotriene LTB₄ in airway disease. LTA₄ hydrolase and 5‐lipoxygenase activating protein have key roles in LTB₄ production. Single nucleotide polymorphism (SNPs) and haplotypes spanning the LTA4H and ALOX5AP genes have been associated with LTB₄ production and myocardial infarction (MI). Objective: To assess the contribution of LTA4H and ALOX5AP polymorphism to asthma and allergy susceptibility. Methods: Three hundred and forty‐one Caucasian families (two asthmatic siblings) were genotyped for eight SNPs spanning ALOX5AP and five SNPs spanning LTA4H. Association analyses of asthma and related phenotypes (total IgE, atopy, bronchial hyper‐responsiveness, FEV₁) were undertaken using the Family Based Association Test. Results: Single point analyses identified association (P < 0.05) between SNPs SG13S114, SG13S89, SG13S41 (ALOX5AP), rs1978331 (LTA4H) and asthma and/or related phenotypes. Haplotype analyses using all LTA4H SNPs identified a single key risk haplotype for the development of asthma (P = 0.006) and related phenotypes (P = 0.042–0.005). Haplotype analyses using all ALOX5AP SNPs identified several asthma and atopy risk and protective haplotypes. There was limited correlation with previously identified MI risk haplotypes in both genes. Carriers of both ALOX5AP SG13S41 and LTA4H rs1978331 alleles had an increased risk of developing asthma (OR 2.17, CI 1.41–3.32). Conclusions: These data provide evidence for the role of SNPs spanning the ALOX5AP and LTA4H genes in asthma and atopy susceptibility in the Caucasian population and support a role for LTB₄ in disease pathogenesis.     

Genetic variation in the lipoxygenase pathway and risk of colorectal neoplasia

Arachidonate lipoxygenase (ALOX) enzymes metabolize arachidonic acid to generate potent inflammatory mediators and play an important role in inflammation‐associated diseases. We investigated associations between colorectal cancer risk and polymorphisms in ALOX5, FLAP, ALOX12, and ALOX15, and their interactions with nonsteroidal anti‐inflammatory drug (NSAID) use. We genotyped fifty tagSNPs, one candidate SNP, and two functional promoter variable nucleotide tandem repeat (VNTR) polymorphisms in three US population‐based case‐control studies of colon cancer (1,424 cases/1,780 controls), rectal cancer (583 cases/775 controls), and colorectal adenomas (485 cases/578 controls). Individuals with variant genotypes of the ALOX5 VNTR had a decreased risk of rectal cancer, with the strongest association seen for individuals with one or more alleles of >5 repeats (wild type = 5, OR>5/≥5 = 0.42, 95% CI 0.20–0.92; P = 0.01). Four SNPs in FLAP (rs17239025), ALOX12 (rs2073438), and ALOX15 (rs4796535 and rs2619112) were associated with rectal cancer risk at P ≤ 0.05. One SNP in FLAP (rs12429692) was associated with adenoma risk. A false discovery rate (FDR) was applied to account for false positives due to multiple testing; the ALOX15 associations were noteworthy at 25% FDR. Colorectal neoplasia risk appeared to be modified by NSAID use in individuals with variant alleles in FLAP and ALOX15. One noteworthy interaction (25% FDR) was observed for rectal cancer. Genetic variability in ALOXs may affect risk of colorectal neoplasia, particularly for rectal cancer. Additionally, genetic variability in FLAP and ALOX15 may modify the protective effect of NSAID use against colorectal neoplasia. © 2013 Wiley Periodicals, Inc.     

支气管哮喘易感区域5q31-33内Tim-3基因单体型分析

目的： 探讨染色体上支气管哮喘易感区域5q31-33内Tim-3基因多态性与支气管哮喘的关系。方法：应用限制性片段长度多态性技术方法,分析了118个儿童变应性哮喘核心家系Tim-3基因4个SNPs(rs10053538、rs10515746、rs13170556和rs9313441)的基因型;采用基于家系传递不平衡检验（TDT）,分析基因分型数据;应用TRANSMIT软件构建单体型并进行单体型关联分析。结果：①基于家系的TDT分析显示,Tim-3基因的4个SNPs由杂合子父母传递给患病子代的等位基因频率不比预期值高,与哮喘无关（P>0.05）。②Transmit多个位点单体型分析结果显示由Tim-3基因rs10053538、 rs13170556、 rs9313441构建的单体型与支气管哮喘有关联（Global 2=10.83,P<0.05）。父母传递给患病子女GGG单体型的观察值小于期望值,差异显著（2=8.24,P<0.01）。结论：中国汉族人群中,位于染色体5q31-33区域的Tim-3基因本身或其附近的基因可能与儿童变应性哮喘的易感性相关。     

Association of ALOX5AP gene single nucleotide polymorphisms and cerebral infarction in the Han population of northern China

ABSTRACT: BACKGROUND: To explore the association of ALOX5AP single nucleotide polymorphisms (SNPs) and haplotype with the occurrence of cerebral infarction in the Han population of northern China. METHODS: Blood samples were collected from 236 patients of Han ancestry with a history of cerebral infarction and 219 healthy subjects of Han ancestry with no history of cerebral infarction or cardiovascular disease. Applied Biosystems(R) TaqMan(R) SNP Genotyping Assays for SNP genotyping were used to determine the genotypes of 7 ALOX5AP SNP alleles (rs4073259, rs4769874, rs9315050, rs9551963, rs10507391, rs9579646, and rs4147064). RESULTS: One SNP allele (A) of rs4073259 was significantly associated with development of cerebral infarction (P = 0.049). In comparison to control groups, haplotype rs9315050&rs9551963 AAAC [OR (95 % CI) =1.53 (1.02-2.29)], and genotypes rs4147064 CT [OR (95 % CI) =1.872 (1.082-3.241)], and rs9551963 AC [OR (95 % CI) = 2.015 (1.165-3.484)] increased the risk of cerebral infarction in patients with hypertension. Genotype rs9579646 GG [OR (95 % CI) = 2.926 (1.18-7.251)] increased the risk of, while rs4073259 GG [OR (95 % CI) = 0.381 (0.157-0.922)] decreased the risk of cerebral infarction in patients with diabetes. CONCLUSION: These results suggest the ALOX5AP SNP A allele in rs4073259 and genotype rs9579646 GG, rs9551963 AC, and haplotype rs9315050 & rs9551963 AAAC were associated with an increased risk of ischemic stroke in the Han population, while rs4073259 GG was associated with a decreased risk.     

TNF-alpha (-308 G/A) and CD14 (-159T/C) polymorphisms in the bronchial responsiveness of Korean children with asthma

BACKGROUND: TNF-alpha is a pivotal proinflammatory cytokine increased in asthmatic airways. The TNF-alpha gene family might be linked to asthma or bronchial hyperresponsiveness (BHR), and TNF-alpha production might be modulated by CD14(+) cells. OBJECTIVE: We investigated the association between asthma susceptibility or asthma-related phenotypes and TNF-alpha (-308G/A) polymorphism and examined the combined effect with CD14 (-159T/C) polymorphism in Korean children. METHODS: Asthmatic (n = 788) and control (n = 153) children were evaluated for asthma phenotypes. Genotypes were determined by using the single-base extension method and PCR-restriction fragment length polymorphism. RESULTS: There was no difference between asthmatic children and control subjects in terms of the allele frequencies of TNF-alpha (-308G/A) and CD14 (-159T/C). Significantly lower PC(20) values were seen in asthmatic (P = .016) children with the TNF-alpha risk allele (-308A). Higher frequencies of 1 or 2 copies of the risk allele were found in asthmatic children with moderate-to-severe BHR to methacholine and exercise compared with control children (adjusted odds ratio of 2.57 [95% CI, 1.30-5.08] and adjusted odds ratio of 2.04 [95% CI 0.99-4.20], respectively). In addition, asthmatic children with risk alleles at both loci had significantly greater BHR than those homozygous for the common alleles (P = .018). CONCLUSION: The TNF-alpha promoter polymorphism (-308G/A) might be associated with severe BHR in Korean children with asthma. In addition, these children show a synergistic effect between the TNF-alpha promoter (-308A) and CD14 promoter (-159C) polymorphisms in terms of BHR. CLINICAL IMPLICATIONS: The TNF-alpha polymorphism might be a disease-modifying gene in asthma and modulated by the CD14 gene.