5' flanking region polymorphism of the gene encoding leukotriene C4 synthase does not correlate with the aspirin-intolerant asthma phenotype in the United States

Main Polymorphisms in Aspirin-Exacerbated Respiratory Disease

Aspirin exacerbated respiratory disease (AERD) is a condition caused by increased bronchoconstriction in people with asthma after taking aspirin or another NSAID. Molecular analysis of the human genome has opened up new perspectives on human polymorphisms and disease. This study was conducted to identify the genetic factors that influence this disease due to its unknown genetic factors. We evaluated research studies, letters, comments, editorials, eBooks, and reviews. PubMed/MEDLINE, Web of Sciences, Cochrane Library, and Scopus were searched for information. We used the keywords polymorphisms, aspirin-exacerbated respiratory disease, asthma, allergy as search terms. This study included 38 studies. AERD complications were associated with polymorphisms in ALOX15, EP2, ADRB2, SLC6A12, CCR3, CRTH2, CysLTs, DPCR1, DPP10, FPR2, HSP70, IL8, IL1B, IL5RA, IL-13, IL17RA, ILVBL, TBXA2R, TLR3, HLA-DRB and HLA-DQ, HLA-DR7, HLA-DP. AERD was associated with heterogeneity in gene polymorphisms, making it difficult to pinpoint specific gene changes. Therefore, diagnosing and treating AERD may be facilitated by examining common variants involving the disease.

Aspirin-Induced Delayed Urticaria in Children with Kawasaki Disease: A Retrospective Case-Control Study

Background

Aspirin remains a key component of the standard therapy for Kawasaki disease (KD) in children. Although it is well known that aspirin can cause hypersensitivity such as aspirin-induced urticaria (AIU), AIU in children with KD has not been described.

Methods

A retrospective case-control study was conducted to investigate AIU clinical features, biochemical parameters, treatment and outcomes in children with KD. Furthermore, biomarkers for predicting AIU were explored using the receiver operating characteristic (ROC) curve analysis.

Results

We identified 46 AIU cases with 22 boys and 24 girls during April 2015–May 2019. Eighty-nine age-matched KD patients without AIU were randomly chosen as controls. The proportions of children with allergy history and aspirin doses administered in the 2 groups were found not to be significantly different. AIU group had substantially higher baseline C-reactive protein and NT-proBNP levels, and increased neutrophil percent. AIU appeared 6.0 (4.0, 8.0) days after aspirin treatment. Aspirin withdrawal and anti-allergic treatment were applied for AIU, and AIU disappeared in 1–3 days. Baseline NT-proBNP predicted AIU with an AUC of 0.70 (95% CI [0.60 to 0.79]) for sensitivity and specificity of 72.1% and 62.5%, respectively, for a cut-off value of 612.9 mg/L. The length of hospital stay for AIU patients was significantly greater compared with controls.

Conclusion

AIU in KD children is not related to gender or aspirin dose, and those with AIU have more severe inflammation at admission. Aspirin should be withdrawn for AIU management. Baseline NT-proBNP may serve as a valuable biomarker to predict AIU.

Association of CYP2C19 and HSP70 Genes Polymorphism with Aspirin- Exacerbated Respiratory Disease in a Kurd Population

BACKGROUND

CYP2C19 a metabolizing enzyme and Heat Shock Proteins (HSP) are induced in stress conditions, such as hypoxia and ischemia. Recently, polymorphism in the CYP2C19 and HSP genes has been established in Aspirin-Exacerbated Respiratory Disease (AERD).

OBJECTIVE

We investigated the polymorphism of these two genes in Kurdish patients with AERD.

METHODS

This study involved 306 subjects, referred to the Be'sat hospital in Kurdistan Province, which were divided into three groups, (i) Aspirin Induced Asthma (AIA), (ii) Aspirin Tolerant Asthma (ATA), and (iii) healthy subjects as control. The subjects as control and ATA\AIA groups were verified by the physician. The demographic data of each subject with respect to age, sex, parental education, and residence was collected. Spirometry was performed on subjects and blood samples were collected for serum Immunoglobulin E (IgE) estimation and molecular tests. Genotyping was done for CYP2C19 681G>A، CYP2C19 636G>A, and HSPA1B1267A>G by using PCR- Restriction Fragment Length Polymorphism (RFLP) and for HSPA1B-179C>T by High Resolution Melting (HRM).

RESULTS

Demographic statistics were not significantly different between the three groups (p>0.05). Further, genotypes were also not observed to be significantly different in the genes of CYP2C19 681G>A, CYP2C19 636G>A and HSPA1B1267A>G (p>0.05). However, the heterozygote genotype in HSPA1B-179 C>T in AIA group was higher than the control group (p<0.05). Notably, 92.8 % of the subjects showed heterozygote genotype in HSPA1B1267 A>G. In clinical tests, FEV-1, FVC, and asthma severity in the AIA group were higher than control and additionally IgE levels were lower in this group (p<0.05).

CONCLUSION

The results confirm the association of polymorphism in the HSPA1B-179C>T and HSPA1B1267A>G with AERD in the Kurdish population.

NSAID-Exacerbated Respiratory Disease (NERD): From Pathogenesis to Improved Care

Nonsteroidal antiinflammatory drug (NSAID)-exacerbated respiratory disease (NERD) is characterized by moderate-to-severe asthma and a higher prevalence of chronic rhinosinusitis/nasal polyps, but is a highly heterogeneous disorder with various clinical manifestations. Two major pathogenic mechanisms are: (1) overproduction of cysteinyl leukotrienes with dysregulation of arachidonic acid metabolism and (2) increased type 2 eosinophilic inflammation affected by genetic mechanisms. Aspirin challenge is the gold standard to diagnose NERD, whereas reliable in vitro biomarkers have yet not been identified. Therapeutic approaches have been done on the basis of disease severity with the avoidance of culprit and cross-reacting NSAIDs, and when indicated, aspirin desensitization is an effective treatment option. Biologic approaches targeting Type 2 cytokines are emerging as potential therapeutic options. Here, we summarize the up-to-date evidence of pathophysiologic mechanisms and diagnosis/management approaches to the patients with NERD with its phenotypic classification.

A new treatment for severe pulmonary arterial hypertension based on an old idea: inhibition of 5-lipoxygenase

It has been generally accepted that severe forms of pulmonary arterial hypertension are associated with inflammation. Plasma levels in patients with severe pulmonary arterial hypertension show elevated levels of interleukins and mediators of inflammation and histologically the diseased small pulmonary arterioles show infiltrates of inflammatory and immune cells. Here, we review the literature that connects pulmonary hypertension with the arachidonic acid/5-lipoxygenase-derived leukotriens. This mostly preclinical background data together with the availability of 5-lipoxygenase inhibitors and leukotriene receptor blockers provide the rationale for testing the hypothesis that 5-lipoxygenase products contribute to the pathobiology of severe pulmonary arterial hypertension in a subgroup of patients.

Complementary Participation of Genetics and Epigenetics in Development of NSAID-exacerbated Respiratory Disease

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD) has attracted a great deal of attention because of its association with severe asthma. However, it remains widely underdiagnosed in asthmatics as well as the general population. Upon pharmacological inhibition of cyclooxygenase 1 by NSAIDs, production of anti-inflammatory prostaglandin E2 and lipoxins ceases, while release of proinflammatory cysteinyl leukotrienes increases. To determine the underlying mechanisms, many studies have attempted to elucidate the genetic variants, such as single nucleotide polymorphisms, responsible for alterations of prostaglandins and leukotrienes, but the results of these genetic studies could not explain the whole genetic pathogenesis of NERD. Accordingly, the field of epigenetics has been introduced as an additional contributor to genomic alteration underlying the development of NERD. Recently, changes in CpG methylation, as one of the epigenetic components, have been identified in target tissues of NERD. This review discusses in silico analyses of both genetic and epigenetic components to gain a better understanding of their complementary roles in the development of NERD. Although the molecular mechanisms underlying NERD pathogenesis remain poorly understood, genetic and epigenetic variations play significant roles. Our results enhance the understanding of the genetic and epigenetic mechanisms involved in the development of NERD and suggest new approaches toward better diagnosis and management.

Hypersensitivity reactions to nonsteroidal anti-inflammatory drugs: an update on pharmacogenetics studies

Nonsteroidal anti-inflammatory drugs are the medications most frequently involved in hypersensitivity reactions to drugs. These can be induced by specific immunological and nonimmunological mechanisms, being the latter the most frequent. The nonimmunological mechanism is related to an imbalance of inflammatory mediators, which is aggravated by the cyclooxygenase inhibition. Genetic studies suggest that multiples genes and additional mechanisms might be involved. The proposals of this review is summarize the contribution of variations in genes involved in the arachidonic acid, inflammatory and immune pathways as well as the recent genome-wide association studies findings related to cross-intolerant nonsteroidal anti-inflammatory drugs hypersensitivity reactions. In addition, using integration of different genetic studies, we propose new target genes. This will help to understand the underlying mechanism of these reactions.

Physiopathology and genetics in aspirin-exacerbated respiratory disease

INTRODUCTION

Aspirin-exacerbated respiratory disease (AERD) is a clinical entity characterized by hypersensitivity to aspirin leading to asthma and chronic rhinosinusitis with nasosinusal polyposis. The pathophysiology of the disease involves disruption at the level of arachidonic acid metabolism. Therefore, genetic association studies have been focused on the genes coding this pathway. As other mechanisms involved in the genesis of the disease were elucidated, the corresponding genes were also explored.

AIM

To describe the association reported in the literature between gene polymorphisms involved in the pathophysiology or therapeutic processes of AERD.

RESULTS

There is a genetic association between polymorphisms of genes involved in the synthesis of proteins related to arachidonic acid metabolism (LTC4S, ALOX5), antigen presentation (HLA), inflammation (IL5, IL17), and aspirin metabolism (CYP2C19).

CONCLUSIONS

Genetic association research in AERD has evaluated studies of SNPs in metabolic pathways related to arachidonic acid. Recently, whole genome analysis strategies have allowed the detection of new genetic variants that were previously not considered. Furthermore, these studies have identified SNPs that are associated with inflammatory processes, which could serve as diagnostic markers or predictors of the therapeutic response.

What we know about nonsteroidal anti-inflammatory drug hypersensitivity

Nonsteroidal anti-inf lammatory drugs (NSAIDs) are widely prescribed for the treatment of inflammatory diseases, but their use is frequently related to hypersensitivity reactions. This review outlines our current knowledge of NSAID hypersensitivity (NHS) with regard to its pathogenic, molecular, and genetic mechanisms, as well as diagnosis and treatment. The presentation of NHS varies from a local (skin and/or airways) reaction to systemic reactions, including anaphylaxis. At the molecular level, NHS reactions can be classified as cross-reactive (mediated by cyclooxygenase inhibition) or selective (specific activation of immunoglobulin E antibodies or T cells). Genetic polymorphisms and epigenetic factors have been shown to be closely associated with NHS, and may be useful as predictive markers. To diagnose NHS, inhalation or oral challenge tests are applied, with the exclusion of any cross-reactive NSAIDs. For patients diagnosed with NHS, absolute avoidance of NSAIDs/aspirin is essential, and pharmacological treatment, including biologics, is often used to control their respiratory and cutaneous symptoms. Finally, desensitization is recommended only for selected patients with NHS. However, further research is required to develop new diagnostic methods and more effective treatments against NHS.

Genetic variants in arachidonic acid pathway genes associated with NSAID-exacerbated respiratory disease

AIM

NSAIDs are the most frequent cause of hypersensitivity drug reactions. We have examined the association between NSAID-exacerbated respiratory disease (NERD) and genetic variants in arachidonic acid metabolism genes.

PATIENTS & METHODS

We included 250 NERD patients, 260 NSAID-tolerant asthmatic (NTA) subjects and 315 healthy controls.

RESULTS

Significant associations with NERD were identified for: ALOX15 rs3892408 C/C homozygous genotype (NERD vs NTA; p = 0.0001, pc = 0.0011; NERD vs controls; p = 0.0001, pc = 0.0011), PTGS-1 rs5789 A/A homozygous genotype (NERD vs NTA; p = 0.0001, pc = 0.0011; NERD vs controls; p = 0.0001, pc = 0.0011), PTGS-1 rs10306135 A/A homozygous genotype (NERD vs NTA; p = 0.0009, pc = 0.0091; NERD vs controls; p = 0.0064, pc = 0.045). Differences in ALOX5 copy number variations were also found (NERD vs NTA; p = 0.010; NERD vs controls; p = 0.0001).

CONCLUSION

These results improve our understanding of the underlying mechanisms of NERD and may help develop a predictive test for this pathology. Original submitted 3 November 2014; Revision submitted 2 April 2015.

Recent advance in investigation of gene polymorphisms in Japanese patients with aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is a complex clinical syndrome characterised by severe asthmatic attack upon treatment with aspirin and/or non-steroidal anti-inflammatory drugs (NSAIDs). Genetic predisposition has been considered as a crucial determinant and candidate genes have concentrated especially on cysteinyl leukotrienes (LTs)-related genes as the inhibitory action of aspirin and NSAIDs on cyclooxygenase activity may cause overproduction of cysteinyl LTs. However, conflicting results have been reported, in parallel with replication studies in different ethnic groups. Thus, future areas of investigations need to focus on comprehensive approaches towards the discovery of other genetic biomarkers. Unfortunately, few papers have been reported about gene polymorphisms in Japanese patients with AERD. Here, we described on our recent genetic investigations on B2ADR, IL-13, IL-17A, CYP2C19, TBXA2R, CRTH2 and HSP70. This review indicates potential genetic biomarkers contributing to the early diagnosis of AERD, which may include CYP2C19 and HSP70 gene polymorphisms, and future validation studies in independent population are required to provide reassurance about our findings.

Unraveling the genetic basis of aspirin hypersensitivity in asthma beyond arachidonate pathways

Although aspirin-exacerbated respiratory disease (AERD) has attracted a great deal of attention because of its association with severe asthma, it remains widely under-diagnosed in the asthmatic population. Oral aspirin challenge is the best method of diagnosing AERD, but this is a time-consuming procedure with serious complications in some cases. Thus, development of non-invasive methods for easy diagnosis is necessary to prevent unexpected complications of aspirin use in susceptible patients. For the past decade, many studies have attempted to elucidate the genetic variants responsible for risk of AERD. Several approaches have been applied in these genetic studies. To date, a limited number of biologically plausible candidate genes in the arachidonate and immune and inflammatory pathways have been studied. Recently, a genome-wide association study was performed. In this review, the results of these studies are summarized, and their limitations discussed. In addition to the genetic variants, changes in methylation patterns on CpG sites have recently been identified in a target tissue of aspirin hypersensitivity. Finally, perspectives on application of new genomic technologies are introduced; these will aid our understanding of the genetic pathogenesis of aspirin hypersensitivity in asthma.

Pathogenesis of aspirin-exacerbated respiratory disease and reactions

Physiologic and pharmacologic studies support the hypothesis that aspirin-exacerbated respiratory disease (AERD) involves fundamental dysregulation in the production of and end-organ responsiveness to both antiinflammatory eicosanoids (prostaglandin E2) and proinflammatory effectors (cysteinyl leukotrienes). The acquired nature of AERD implies a disturbance in a potential epigenetic control mechanism of the relevant mediator systems, which may be a result of incompletely clarified environmental factors (eg, viral or bacterial infections, inhaled pollutants).

Biochemical pathogenesis of aspirin exacerbated respiratory disease (AERD)

Aspirin exacerbated respiratory disease (AERD) is a distinct clinical entity characterized by eosinophilic rhinosinusitis, asthma and often nasal polyposis. Exposure to aspirin or other nonsteroid anti-inflammatory drugs (NSAIDs) exacerbates bronchospasms with asthma and rhinitis. Disease progression suggests a skewing towards TH2 type cellular response along with moderate to severe eosinophil and mast cell infiltration. Alterations in upper and lower airway cellular milieu with abnormalities in eicosanoid metabolism and altered eicosanoid receptor expression are the key features underlying AERD pathogenesis. Dysregulation of arachidonic acid (AA) metabolism, notably reduced prostaglandin E2 (PGE2) synthesis compared to their aspirin tolerant counterpart and relatively increased PGD2 production, a TH2/eosinophil chemoattractant are reported in AERD. Underproduced PGE2 is metabolized by overexpression of 15 prostaglandin dehydrogenase (15-PGDH) to inactive products further reducing PGE2 at real time. This relives the inhibitory effect of PGE2 on 5-lipoxygenase (5-LOX) resulting in overproduction of cysteinyl leukotrienes (CysLTs). Diminished formation of CysLT antagonists called lipoxins (LXs) also augments CysLTs responsiveness. Occasional intake of NSAIDs favors even more 5-LOX product formation, further narrowing the bronchoconstrictive bottle neck, resulting in acute asthmatic exacerbations along with increased mucus production. This review focuses on abnormalities in biochemical and molecular mechanisms in eicosanoid biosynthesis, eicosanoid receptor dysregulation and associated polymorphisms with special reference to arachidonic acid metabolism in AERD.

The -444A/C polymorphism in the LTC4S gene and the risk of asthma: a meta-analysis

BACKGROUND AND AIMS

The -444A/C polymorphism in the leukotriene C4 synthase (LTC4S) gene has been implicated in susceptibility to asthma, but a large number of studies have reported inconclusive results. The aim of this study was to investigate the association between the -444A/C polymorphism in the LTC4S gene and asthma risk using meta-analysis.

METHODS

We searched Pubmed, Embase, CNKI and Wanfang databases. Statistical analysis was performed using the software Revman4.2 and STATA10.0.

RESULTS

A total of 3042 cases and 1902 controls in 13 case-control studies were included in the meta-analysis. The results indicated that the variant C allele carriers (CC + AC) did not have increased/decreased risk of asthma when compared with the homozygote AA (CC + AC vs. AA: OR = 1.13, 95% CI = 1.00-1.28, p = 0.06). In the subgroup analysis by age, ethnicity and aspirin sensitivity, significantly elevated risks were found only in Caucasians (OR = 1.21, 95% CI = 1.02-1.44, p = 0.03) and aspirin-tolerant populations (OR = 1.36, 95% CI = 1.12-1.65, p = 0.002) but not in other subgroups.

CONCLUSIONS

This meta-analysis suggested that the -444A/C polymorphism in the LTC4S gene would be a risk factor for asthma in Caucasians and aspirin-tolerant populations. Future studies are needed to validate our results.

Current view on nasal polyps management in Samter's triad patients

The nasal polyps associated with Samter's triad are often very extensive, difficult to treat, with great tendency to recurrence. In this paper the current opinion on nasal polyps management in aspirin triad patients was presented.

PATHOGENESIS

Opinions on pathogenesis of these disease was remembered as well as its epidemiology.

DIAGNOSTIC METHODS

The available diagnostic methods were presented. Treatment options: The available preservative treatment options was analyzed including aspirin desensitization. The role of surgical treatment, functional endoscopic sinus surgery was analyzed.

Expression of arachidonate metabolism enzymes and receptors in nasal polyps of aspirin-hypersensitive asthmatics

BACKGROUND

The pathogenesis of rhinosinusitis in aspirin-exacerbated airway disease is closely linked to the disequilibrium in arachidonic acid metabolism. Although considerable amounts of data concerning impaired eicosanoid production are available, the precise mechanism and pathogenesis of the disease are still unknown. The aim of the present study was to assess the expression of enzymes belonging to the arachidonic acid cascade and receptors for arachidonate derivative metabolites in nasal polyps from aspirin- hypersensitive (AH) and aspirin-tolerant (AT) patients with rhinosinusitis.

METHODS

Cells expressing cysteinyl leukotriene (CysLT) receptors (CysLT(1) and CysLT(2)), arachidonate 5-lipoxygenase, leukotriene B(4) receptor type 1, E-prostanoid receptors (EP(2) and EP(4)), cyclooxygenase (COX)-1 and COX-2 were detected by immunocytochemistry in nasal polyps obtained from 10 AH patients and 18 AT patients.

RESULTS

There was a significantly higher density of cells expressing CysLT(1) and CysLT(2) receptors in nasal polyps from AH patients than from AT patients (p < 0.001). In contrast, the density of cells expressing EP(2) receptor and COX-2 was significantly lower in AH patients than in AT patients (p < 0.02). The number of COX-2-positive epithelial cells was significantly reduced in AH polyps (p < 0.04).

CONCLUSIONS

The elevated number of nasal polyp cells expressing CysLT receptors and lack of cells expressing EP(2) receptor and COX-2 may be related to a more severe course of hyperplastic rhinosinusitis in aspirin hypersensitivity.

IL-13 and IL-17A gene polymorphisms in Japanese patients with aspirin-exacerbated respiratory disease

BACKGROUND

The role of interleukin (IL) 13 and IL-17A in aspirin-exacerbated respiratory disease (AERD) remains unknown.

OBJECTIVE

To analyze the IL-13 and IL-17A gene polymorphisms in Japanese patients with AERD.

METHODS

The single-nucleotide polymorphisms in each gene were examined in patients with AERD, patients with aspirin-tolerant asthma (ATA), and healthy controls.

RESULTS

Frequencies of the TT/CT genotype of the IL-13 -1111C>T gene were higher than frequencies of the CC genotype in AERD patients compared with ATA patients (P < .001). In female patients with AERD, frequencies of the TT/CT genotype were higher than those of the CC genotype compared with female patients with ATA (P < .001). However, genotype frequencies of IL-13 Arg110Gln did not differ between AERD and ATA patients. Frequencies of the CC genotype of the IL-17A -737C>T gene were higher than those of the TT/CT genotype in AERD patients compared with ATA patients (P = .02). In female patients with AERD, frequencies of the CC genotype were higher than those of the TT/CT genotype compared with female patients with ATA (P = .03). Forced expiratory volume in 1 second (percentage predicted) in AERD patients with the CC genotype of the IL-13 -1111C>T gene was lower than that in the patients with the TT/CT genotype. AERD patients with the TT/CT genotype of the IL-17A -737C>T gene had a higher peripheral total eosinophil count compared with the patients with the CC genotype. The comparison of the clinical characteristics according to the IL-13 Arg110Gln gene polymorphism showed no difference.

CONCLUSIONS

These findings suggest that the IL-13 -1111C>T and IL-17A -737C>T gene sequence variations might have a role in the development of AERD.

Arg16Gly β2-adrenergic receptor gene polymorphism in Japanese patients with aspirin-exacerbated respiratory disease

BACKGROUND

There has been no report that investigated β(2)-adrenergic receptor (ADRB2) gene polymorphism in patients with aspirin-exacerbated respiratory disease (AERD).

METHODS

DNA in the specimens in three groups of study subjects classified patients with AERD, patients with aspirin-tolerant asthma (ATA) and normal controls was extracted, and the target DNA sequence of the ADRB2 was amplified using a set of primers to generate an amplicon of 219 bp in length. Allelic discrimination assay for single nucleotide polymorphisms relating to the ADRB2 gene expression was carried out by using a previously described single nucleotide polymorphism detective system, sequence-specific thermal-elution chromatography.

RESULTS

The frequency of the Gly variant allele in patients with AERD was significantly lower than that in patients with ATA (p = 0.007), and the odds ratio (OR) of AERD to ATA associated with wild-type ArgArg homozygote was 3.300. Frequencies of wild-type ArgArg homozygote are significantly higher than those of variant-type ArgGly/GlyGly genotype in patients with AERD compared with those with ATA (p < 0.001, OR = 3.153). In patients with AERD, frequencies of wild-type ArgArg homozygote in both female and male patients are significantly higher than those of variant-type ArgGly/GlyGly genotype in male patients compared with those with ATA (p < 0.001, OR = 5.128 and p = 0.007, OR = 4.367, respectively). Also, in patients with AERD, frequencies of wild-type ArgArg homozygote in female patients are significantly higher than those of variant-type ArgGly/GlyGly genotype in female patients compared with those with ATA (p = 0.002, OR = 2.825).

CONCLUSIONS

We were the first to analyze Arg16Gly ADRB2 gene polymorphism in Japanese patients with AERD, and showed that Arg16Gly ADRB2 gene polymorphism in Japanese patients with AERD is different from that in the patients with ATA.

Genetic mechanisms in aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) refers to the development of bronchoconstriction in asthmatics following the exposure to aspirin or other nonsteroidal anti-inflammatory drugs. The key pathogenic mechanisms associated with AERD are the overproduction of cysteinyl leukotrienes (CysLTs) and increased CysLTR1 expression in the airway mucosa and decreased lipoxin and PGE2 synthesis. Genetic studies have suggested a role for variability of genes in disease susceptibility and the response to medication. Potential genetic biomarkers contributing to the AERD phenotype include HLA-DPB1, LTC4S, ALOX5, CYSLT, PGE2, TBXA2R, TBX21, MS4A2, IL10, ACE, IL13, KIF3A, SLC22A2, CEP68, PTGER, and CRTH2 and a four-locus SNP set composed of B2ADR, CCR3, CysLTR1, and FCER1B. Future areas of investigation need to focus on comprehensive approaches to identifying biomarkers for early diagnosis.

Genetic association analysis of TAP1 and TAP2 polymorphisms with aspirin exacerbated respiratory disease and its FEV1 decline

Aspirin exacerbated respiratory disease (AERD) induces bronchoconstriction in asthmatic patients characterized with a clinical condition of severe decline in forced expiratory volume in one second (FEV1) after ingestion of aspirin. Two genes consisting a heterodimer, transporter 1 and 2, ATP-binding cassette, sub-family B (MDR/TAP) (TAP1 and TAP2) within the major histocompatibility complex (MHC) region, have been implicated in immunodeficiency and bronchiectasis development. To investigate the associations of TAP1 and TAP2 genetic polymorphisms with AERD and phenotypic FEV1 decline, a total of 43 common single-nucleotide polymorphisms (SNPs) including 12 SNPs of TAP1 and 31 SNPs of TAP2 were genotyped in 93 AERD patients and 96 aspirin-tolerant asthma controls. Interestingly, regression analysis revealed that polymorphisms and haplotypes of TAP2 were associated with FEV1 decline by aspirin provocation (P=0.002-0.04), with about twofold decline rate of FEV1 in most of minor homozygotes compared with major homozygotes. In addition, nominal evidences of association between TAP2 and AERD development were observed (P=0.02-0.04). However, TAP1 polymorphisms showed no relations to both AERD and FEV1 decline after aspirin challenge (P>0.05). Although further functional evaluations and replications are required, our preliminary findings provide supporting information that variants of TAP2 might be predisposing factors for FEV1 decline-related symptoms.

Genetics and phenotyping in chronic sinusitis

Chronic sinusitis with nasal polyposis historically has been treated as a single monolithic clinical disorder. Just as asthma is now accepted as numerous heterogeneous diseases, chronic sinusitis should also be viewed as comprising several diseases with varying causes, with each one characterized by distinct histologic and gene and protein expression patterns. This includes recognition of the need to define these diseases based on the presence or absence of an eosinophilic infiltrate but also on additional distinctions based on unique agents that drive their development and perpetuation. As a collection of heterogeneous diseases, proper differential diagnosis is required to delineate appropriate therapeutic intervention. This review will focus on recognized distinct presentations of chronic sinus disease, including distinguishing the clinical presentations, cellular and molecular characteristics, genetic differences, and current treatment options for each.

Genome-wide and follow-up studies identify CEP68 gene variants associated with risk of aspirin-intolerant asthma

Aspirin-intolerant asthma (AIA) is a rare condition that is characterized by the development of bronchoconstriction in asthmatic patients after ingestion of non-steroidal anti-inflammatory drugs including aspirin. However, the underlying mechanisms of AIA occurrence are still not fully understood. To identify the genetic variations associated with aspirin intolerance in asthmatics, the first stage of genome-wide association study with 109,365 single nucleotide polymorphisms (SNPs) was undertaken in a Korean AIA (n = 80) cohort and aspirin-tolerant asthma (ATA, n = 100) subjects as controls. For the second stage of follow-up study, 150 common SNPs from 11 candidate genes were genotyped in 163 AIA patients including intermediate AIA (AIA-I) subjects and 429 ATA controls. Among 11 candidate genes, multivariate logistic analyses showed that SNPs of CEP68 gene showed the most significant association with aspirin intolerance (P values of co-dominant for CEP68, 6.0×10⁻⁵ to 4.0×10⁻⁵). All seven SNPs of the CEP68 gene showed linkage disequilibrium (LD), and the haplotype of CEP68_ht4 (T-G-A-A-A-C-G) showed a highly significant association with aspirin intolerance (OR  = 2.63; 95% CI  = 1.64–4.21; P = 6.0×10⁻⁵). Moreover, the nonsynonymous CEP68 rs7572857G>A variant that replaces glycine with serine showed a higher decline of forced expiratory volume in 1s (FEV₁) by aspirin provocation than other variants (P = 3.0×10⁻⁵). Our findings imply that CEP68 could be a susceptible gene for aspirin intolerance in asthmatics, suggesting that the nonsynonymous Gly74Ser could affect the polarity of the protein structure.

Update on recent advances in the management of aspirin exacerbated respiratory disease

Aspirin intolerant asthma (AIA) is frequently characterized as an aspirin (ASA)-exacerbated respiratory disease (AERD). It is a clinical syndrome associated with chronic severe inflammation in the upper and lower airways resulting in chronic rhinitis, sinusitis, recurrent polyposis, and asthma. AERD generally develops secondary to abnormalities in inflammatory mediators and arachidonic acid biosynthesis expression. Upper and lower airway eosinophil infiltration is a key feature of AERD; however, the exact mechanisms of such chronic eosinophilic inflammation are not fully understood. Cysteinyl leukotriene over-production may be a key factor in the induction of eosinophilic activation. Genetic studies have suggested a role for variability of genes in disease susceptibility and response to medication. Potential genetic biomarkers contributing to the AERD phenotype include HLA-DPB1*301, LTC4S, ALOX5, CYSLT, PGE2, TBXA2R, TBX21, MS4A2, IL10 -1082A > G, ACE -262A > T, and CRTH2 -466T > C; the four-locus SNP set was composed of B2ADR 46A > G, CCR3 -520T > G, CysLTR1 -634C > T, and FCER1B -109T > C. Management of AERD is an important issue. Aspirin ingestion may result in significant morbidity and mortality, and patients must be advised regarding aspirin risk. Leukotriene receptor antagonists (LTRA) that inhibit leukotriene pathways have an established role in long-term AERD management and rhinosinusitis. Aspirin desensitization may be required for the relief of upper and lower airway symptoms in AERD patients. Future research should focus on identification of biomarkers for a comprehensive diagnostic approach.

Pharmacogenetics of asthma in children

Allergic diseases such as bronchial asthma and atopic dermatitis develop by a combination of genetic and environmental factors. Several candidate causative genes of asthma and atopy have been reported as the genetic factors. The clinical features of patients and causes of diseases vary. Therefore, personalized medicine (tailor-made medicine) is necessary for the improvement of quality of life (QOL) and for asthma cure. Pharmacogenetics is very important for personalized medicine. Here, we present the genetics and pharmacogenetics of asthma in children. Finally, we show the guideline for personalized medicine for asthma, particularly in childhood, including the pharmacogenetics of anti-asthmatic drugs, preliminarily produced by the authors.

Leukotriene pathway polymorphisms are associated with altered cysteinyl leukotriene production in children with acute asthma

Cysteinyl leukotrienes (cysLTs) are pro-inflammatory mediators with increasing evidence for a role in childhood acute asthma. This study examined the influence of polymorphisms in cysLT pathway genes on urinary leukotriene E(4) (uLTE(4)) levels and clinical status in acute asthmatic children. Children aged 2-16 years were recruited during an asthma attack (n=205). Where possible, asthma severity scores were assigned, ALOX5AP G-336A, ALOX5 G-1708A, LTC4S A-444C and G-1072A, GPX4 C718T, and CYSTLTR1 T927C genotypes were determined and uLTE(4) was measured in acute and convalescent samples. uLTE(4) levels were higher acutely compared with convalescence (acute GM: 115.7pg/mg creatinine; 95% CI 88.6-151.1, convalescence GM: 66.4pg/mg creatinine; 95% CI 51.5-85.6; n=50 paired samples, p=0.003) and paired sample analysis showed genotype-specific effects with significantly increased uLTE(4) for LTC(4)S-444AA (acute GM: 127.9pg/mg creatinine; 95% CI 91.8-178.3, convalescence GM: 68.2pg/mg creatinine; 95% CI 50.5-92.0; n=32, p=0.002), LTC(4)S-1072 GG (acute GM: 126.7pg/mg creatinine; 95% CI 95.4-168.3, convalescence GM: 78.9pg/mg creatinine; 95% CI 59.7-104.1; n=39, p=0.019) and CYSLTR1 927 TT/T_ (acute GM: 96.8pg/mg creatinine; 95% CI 73.8-126.9, convalescence GM: 62.4pg/mg creatinine; 95% CI 46.8-83.3; n=28, p=0.036) but not AC/CC, GA/AA, or TC/CC/C_, respectively. When we compared the allele frequencies of the CYSLTR1 SNP between asthmatics and non-asthmatics, the 927C allele was found to be a risk allele for asthma (OR=2.13, 95% CI: 1.06-4.26, p=0.033). Genotypes were not associated with acute or convalescent uLTE(4) levels alone and neither the SNPs nor uLTE(4) correlated with acute asthma severity. Leukotriene pathway gene polymorphisms may influence the magnitude of cysLT production during an attack, yet their influence alone may not be substantial enough to alter the severity of exacerbations.

Leukotriene pathway genetics and pharmacogenetics in allergy

Leukotrienes (LT) are biologically active lipid mediators known to be involved in allergic inflammation. Leukotrienes have been shown to mediate diverse features of allergic conditions including inflammatory cell chemotaxis/activation and smooth muscle contraction. Cysteinyl leukotrienes (LTC(4), LTD(4) and, LTE(4)) and the dihydroxy leukotriene LTB(4) are generated by a series of enzymes/proteins constituting the LT synthetic pathway or 5-lipoxygenase (5-LO) pathway. Their function is mediated by interacting with multiple receptors. Leukotriene receptor antagonists (LTRA) and LT synthesis inhibitors (LTSI) have shown clinical efficacy in asthma and more recently in allergic rhinitis. Despite growing knowledge of leukotriene biology, the molecular regulation of these inflammatory mediators remains to be fully understood. Genes encoding enzymes of the 5-LO pathway (i.e. ALOX5, LTC4S and LTA4H) and encoding for LT receptors (CYSLTR1/2 and LTB4R1/2) provide excellent candidates for disease susceptibility and severity; however, their role remains unclear. Preliminary data also suggest that 5-LO pathway/receptor gene polymorphism can predict patient responses to LTSI and LTRA; however, the exact mechanisms require elucidation. The aim of this review was to summarize the recent advances in the knowledge of these important mediators, focusing on genetic and pharmacogenetic aspects in the context of allergic phenotypes.

What do we know about the genetics of aspirin intolerance?

Although acetylsalicylic acid is prescribed for a broad range of diseases, it can induce a wide array of clinically recognized hypersensitivity reactions, including aspirin-intolerant asthma (AIA) with rhinitis and aspirin-intolerant urticaria (AIU) with anaphylaxis. Altered eicosanoid metabolism is the generally accepted mechanism of aspirin intolerance; the overproduction of cysteinyl leucotrienes has been suggested to play a causative role in both AIA and AIU. Genetic markers suggested for AIA include HLA-DPBI*0301, leucotriene C4 synthase (LTC4S), ALOX5, CYSLT, PGE2, TBXA2R and TBX21. Similarly, HLA-DB1*0609, ALOX5, FCER1A and HNMT have been identified as possible genetic markers for AIU. An additional low-risk genetic marker for AIA is MS4A2, which encodes the beta-chain of FCER1. Other single and sets of two or more interacting genetic markers are currently being investigated. Analyses of the genetic backgrounds of patients with AIA and AIU will promote the development of early diagnostic and therapeutic interventions, which may reduce the incidence of AIA and AIU.

Aspirin-sensitive respiratory disease

Aspirin-sensitive respiratory disease (ASRD) is a condition characterized by persistent and often severe inflammation of the upper and lower respiratory tracts. Patients develop chronic eosinophilic rhinosinusitis, nasal polyposis, and asthma. The ingestion of aspirin and other cyclooxygenase-1 (COX-1) inhibitors induces exacerbations of airway disease that may be life-threatening. Thus, aspirin sensitivity is a phenotypic marker for the syndrome, yet nearly all affected individuals can be desensitized by the administration of graded doses of aspirin, leading to long-term clinical benefits. Patients with aspirin sensitivity are often able to tolerate selective COX-2 inhibitors. The pathogenesis of ASRD is underpinned by abnormalities in eicosanoid biosynthesis and eicosanoid receptor expression coupled with intense mast cell and eosinophilic infiltration of the entire respiratory tract. This review focuses on the molecular, cellular, and biochemical abnormalities characterizing ASRD and highlights unanswered questions in the literature and potential future areas of investigation.

Association of IL-13 polymorphisms with leukotriene receptor antagonist drug responsiveness in Korean children with exercise-induced bronchoconstriction

BACKGROUND

IL-13 is a pivotal cytokine in allergic inflammation and bronchial hyperresponsiveness, and is known to influence leukotriene levels.

OBJECTIVE

We investigated whether IL-13 polymorphisms may be associated with clinical phenotypes and drug responsiveness to the leukotriene receptor antagonist (LTRA) in Korean asthmatic children with exercise-induced bronchoconstriction (EIB).

METHODS

We enrolled 242 normal controls and 374 patients with asthma. Of the asthmatic patients, 100 performed exercise challenge tests before and after receiving montelukast (5 mg/day) for 8 weeks and included 80 subjects in drug responsiveness analysis. We assessed IL-13 polymorphisms (-1512A/C, -1112C/T, +2044G/A) through PCR-restriction fragment length polymorphism analysis.

RESULTS

Significantly higher total IgE levels and maximum percent fall in forced expiratory volume in 1 s (FEV1) (%) after exercise challenge test were found in asthmatic patients carrying one or two copies of the IL-13 +2044A versus those homozygous for +2044G (P=0.011 and 0.040, respectively). We further noted a correlation of total IgE with maximum percent fall in FEV1 (%) in asthmatic patients, as well as a reverse correlation with improvement of maximum percent fall in FEV1 (%) after exercise challenge tests. Finally, we observed a significant association between responsiveness to montelukast and IL-13 -1112C/T polymorphism and the haplotype of IL-13 polymorphisms.

CONCLUSION

The IL-13 +2044G/A polymorphism may be associated with atopy and EIB severity in Korean children with EIB, and thus could potentially be considered as a disease-modifying gene. Moreover, the IL-13 -1112C/T polymorphism and the haplotype of IL-13 polymorphisms seem to be associated with LTRA drug responsiveness, and thus might prove useful as a target for modulation of LTRA drug responsiveness.

Pharmacogenetics of aspirin-intolerant asthma

Leukotriene overproduction is the major characteristic of aspirin-intolerant asthma (AIA). Most studies examining the molecular genetic mechanisms of AIA have focused on leukotriene-related genes, including ALOX5, LTC4S, TXA2R and prostanoid-receptor genes. One study suggested that the human leukocyte antigen (HLA) allele DPB1*0301 may be a genetic marker for the AIA phenotype in European and Asian populations, and HLA-DPB1*0301 has been suggested as a useful genetic marker for predicting more favorable responders to leukotriene-receptor antagonists for long-term management of AIA. Although several reports have indicated possible associations between genetic polymorphisms and variable responses to leukotriene modifiers in nonaspirin sensitive asthmatic patients, few have suggested relationships between such genetic polymorphisms and variable responses to asthma drugs in AIA patients.

Functional polymorphism and differential regulation of CYSLTR1 transcription in human airway smooth muscle and monocytes

Cysteinyl leukotrienes play an important role in the pathophysiology of many inflammatory disorders, including asthma. The aim of this study was to characterize the mechanisms underlying transcriptional regulation of the human cysteinyl leukotriene receptor 1 (hCYSLTR1) gene. 5'RACE was performed on human airway smooth muscle (HASM) and peripheral blood mononuclear cells. A1128-bp region of the hCYSLTR1 main putative promoter was screened for polymorphisms by sequencing of 48 individuals. Luciferase reporter gene assays were performed using fragments of the core promoter (232 bp to 1128 bp) in HASM and THP1 cells. Three hCYSLTR1 transcripts were found, one representing 90% of all messenger RNA identified. The genomic location of the transcription start sites suggested there are two putative hCYSLTR1 promoters. The majority of the transcriptional activity of the main putative promoter was detected between -232 and -679 bp. Four singlenucleotide polymorphisms in strong linkage disequilibrium were found in the region studied: -561 (rs7066737), -642 (rs2806489), -781 (rs2637204), and -940 (rs321029), with three haplotypes observed. In THP1 cells, the G allele (-642) caused a twofold decrease in luciferase expression compared to the Aallele. These data suggest that the majority of hCYSLTR1 transcripts in HASM and monocytes arise from a single promoter located immediately upstream of the 5\' untranslated region, although rarer transcripts can also occur. This study also raises the possibility that cell-type-dependent differences in transcriptional activity caused by the presence of specific haplotypes within the main CYSLTR1 promoter may be a predictor of disease risk or treatment response.

Nonsteroidal anti-inflammatory drug hypersensitivity in preschool children

: Although extensively studied in adults, nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity in children, especially in young children, remains poorly defined. Pediatricians, prescribing antipyretics for children, rarely encounter significant problems, but the few epidemiologic studies performed show conflicting results. Although it is clear that some patients with acetylsalicylic acid (ASA)-sensitive asthma have their clinical onset of disease in childhood and bronchoconstriction after ASA challenge is seen in 0 to 22% of asthmatic children so challenged, ibuprofen at antipyretic doses may cause acute respiratory problems only in a very small number of mild to moderate asthmatics. The recently elucidated mechanism of action of acetaminophen may explain some occurrences of adverse reactions in patients with cross-reactive NSAID hypersensitivity on the basis of its inhibitory activity on the newly described enzyme, cyclooxygenase (COX)-3. This nonspecific sensitivity to inhibition of COX is most likely genetically determined and shows a remarkable association with atopic disease even in the very young age group and possibly an increased predilection in specific ethnic groups. This review summarizes state-of-the-art published data on NSAID hypersensitivity in preschool children.

Responsiveness to montelukast is associated with bronchial hyperresponsiveness and total immunoglobulin E but not polymorphisms in the leukotriene C4 synthase and cysteinyl leukotriene receptor 1 genes in Korean children with exercise-induced asthma (EIA)

BACKGROUND

As previous studies have shown that cysteinyl leukotrienes are important mediators in exercise-induced bronchoconstriction (EIB), and leukotriene receptor antagonists (LTRAs) such as montelukast have been shown to improve post-exercise bronchoconstrictor responses, we herein investigated whether clinical responsiveness to montelukast was associated with polymorphisms in the genes encoding leukotriene C4 synthase (LTC4S) and cysteinyl leukotriene receptor 1 (CysLTR1) and/or clinical parameters in Korean asthmatic children with EIB.

METHODS

The study population consisted of 100 asthmatic children with EIB. The individuals studied were given exercise challenge tests before and after receiving montelukast (5 mg/day) for 8 weeks. Responders were defined as children showing>10% post-treatment improvement in forced expiratory volume in 1 s (FEV1). The LTC4S A(-444)C and CysLTR1 T(+927)C polymorphisms were genotyped by PCR-restriction fragment length polymorphism analysis.

RESULTS

Of 100 enrolled children, 68 were classified as responders and 32 were classified as non-responders. No significant association was observed between montelukast responsiveness and LTC4S or CysLTR1 genotype, either alone or in combination. In contrast, montelukast-induced improvement in FEV(1) after exercise was correlated with higher pre-treatment PC20 (methacholine) values (r=0.210, P=0.036) and lower total IgE levels (r=-0.216, P=0.031).

CONCLUSIONS

The LTC4S A(-444)C and CysLTR1 T(+927)C genotypes do not appear to be useful for predicting clinical responsiveness to montelukast, whereas bronchial hyperresponsiveness and total IgE appear to predict the degree of montelukast responsiveness in Korean asthmatic children with EIB.

Pathogenesis, diagnosis, and treatment of aspirin intolerance

OBJECTIVES

To provide an overview of aspirin intolerance (AI), to summarize the latest genetic and pathophysiologic findings, and to discuss the current therapeutic recommendations, including aspirin desensitization.

DATA SOURCES

Using the PubMed database, a systematic search of articles published between 1968 and 2006 was performed to evaluate the current literature on AI. The bibliographies of selected articles served as a source of additional literature.

STUDY SELECTION

Included articles were selected for their relevance to the pathogenesis, diagnosis, and management of AI.

RESULTS

The prevalence of AI is approximately 0.3% to 0.9%, but AI is often overlooked. It can display a wide range of clinical pictures, such as acute asthma attacks, urticaria, angioedema, chronic rhinitis, myocardial ischemia, and anaphylactic shock. Regarding the pathogenesis of AI, modifications of eicosanoid metabolism are supposed to underlie AI, including aspirin-induced asthma and aspirin-induced urticaria. However, the pathogenesis of AI has not yet been clearly elucidated. Associations of several HLA alleles with subtypes of AI, such as aspirin-induced urticaria and aspirin-induced asthma, and single nucleotide polymorphisms in genes encoding enzymes involved in arachidonic acid metabolism have been shown.

CONCLUSIONS

Because aspirin therapy should be avoided in AI patients, the use of alternative drugs is recommended. Patients intolerant of alternative drugs and those with therapy-resistant asthma or sinusitis benefit from aspirin desensitization.

Differential contribution of the CysLTR1 gene in patients with aspirin hypersensitivity

In this study, we compared the roles of CysLT receptor type 1 (CysLTR1) and leukotriene C4 synthase (LTC4S) gene polymorphisms in two major aspirin-related allergic diseases, aspirin-intolerant asthma (AIA) and aspirin-induced chronic urticaria/angioedema (AICU). CysLTR1-634C>T and LTC4S-444A>C polymorphisms were genotyped and its functional effect on the promoter activity was compared. As in vivo functional study, changes of peripheral mRNA level of CysLTR1 were measured by real-time PCR before and after aspirin challenge. A significant association was found for the CysLTR1 promoter polymorphism and the AIA phenotype compared to AICU (P = 0.015). In U937 cells, the variant genotype reporter construct showed significantly higher promoter activity than the common genotype (P < 0.05). The CysLTR1 mRNA levels increased significantly after aspirin challenge in AIA patients (P = 0.013). In conclusion, the CysLTR1 polymorphism may contribute to develop to the AIA phenotype and be used as a genetic marker for differentiating two major aspirin hypersensitivity phenotypes.

Association between polymorphisms in prostanoid receptor genes and aspirin-intolerant asthma

BACKGROUND

Genetic predisposition is linked to the pathogenesis of aspirin-intolerant asthma. Most candidate gene approaches have focused on leukotriene-related pathways, whereas there have been relatively few studies evaluating the effects of polymorphisms in prostanoid receptor genes on the development of aspirin-intolerant asthma. Therefore, we investigated the potential association between prostanoid receptor gene polymorphisms and the aspirin-intolerant asthma phenotype.

METHODS

We screened for genetic variations in the prostanoid receptor genes PTGER1, PTGER2, PTGER3, PTGER4, PTGDR, PTGIR, PTGFR, and TBXA2R using direct sequencing, and selected 32 tagging single nucleotide polymorphisms among the 77 polymorphisms with frequencies >0.02 based on linkage disequilibrium for genotyping. We compared the genotype distributions and allele frequencies of three participant groups (108 patients with aspirin-intolerant asthma, 93 patients with aspirin-tolerant asthma, and 140 normal controls).

RESULTS

Through association analyses studies of the 32 single nucleotide polymorphisms, the following single nucleotide polymorphisms were found to have significant associations with the aspirin-intolerant asthma phenotype: -616C>G (P=0.038) and -166G>A (P=0.023) in PTGER2; -1709T>A (P=0.043) in PTGER3; -1254A>G (P=0.018) in PTGER4; 1915T>C (P=0.015) in PTGIR; and -4684C>T (P=0.027), and 795T>C (P=0.032) in TBXA2R. In the haplotype analysis of each gene, the frequency of PTGIR ht3[G-G-C-C], which includes 1915T>C, differed significantly between the aspirin-intolerant asthma patients and aspirin-tolerant asthma patients (P=0.015).

CONCLUSION

These findings suggest that genetic polymorphisms in PTGER2, PTGER3, PTGER4, PTGIR, and TBXA2R play important roles in the pathogenesis of aspirin-intolerant asthma.

Hypersensitivity to paracetamol in Asian children with early onset of nonsteroidal anti-inflammatory drug allergy

BACKGROUND

The published incidence of paracetamol cross-reactivity in adults and adolescents with nonsteroidal anti-inflammatory drug (NSAID) reactions is low and all data on such reactions in young children is sparse. The study aim was to characterize the clinical presentation and cross-reactivity with paracetamol in patients with a reported onset of NSAID hypersensitivity before 6 years of age.

METHODS

A retrospective case review was done of patients with cross-reactive hypersensitivity reactions to antipyretic/analgesic medications from the pediatric allergy clinic of the Kendang Kerbau Hospital, Singapore. Included patients reported the onset of such reactions before 6 years of age. Hypersensitivity was established through a detailed history of recurrent reactions to NSAIDs or an oral provocation test.

RESULTS

Eighteen patients fulfilled the diagnostic criteria within the study period. Eighty-three percent had cross-reactive reactions with paracetamol. When compared to the group of children with later onset of NSAID hypersensitivity, children with onset before 6 years of age had a significantly increased likelihood of reacting to paracetamol (odds ratio 9.6, 95% confidence interval 1.6-58.0, p < 0.05).

CONCLUSION

Paracetamol seems to be a major eliciting drug in this group of children.

G-protein-coupled receptors and asthma endophenotypes: the cysteinyl leukotriene system in perspective

Genetic variation in specific G-protein coupled receptors (GPCRs) is associated with a spectrum of respiratory disease predispositions and drug response phenotypes. Although certain GPCR gene variants can be disease-causing through the expression of inactive, overactive, or constitutively active receptor proteins, many more GPCR gene variants confer risk for potentially deleterious endophenotypes. Endophenotypes are traits, such as bronchiole hyperactivity, atopy, and aspirin intolerant asthma, which have a strong genetic component and are risk factors for a variety of more complex outcomes that may include disease states. GPCR genes implicated in asthma endophenotypes include variants of the cysteinyl leukotriene receptors (CYSLTR1 and CYSLTR2), and prostaglandin D2 receptors (PTGDR and CRTH2), thromboxane A2 receptor (TBXA2R), beta2-adrenergic receptor (ADRB2), chemokine receptor 5 (CCR5), and the G protein-coupled receptor associated with asthma (GPRA). This review of the contribution of variability in these genes places the contribution of the cysteinyl leukotriene system to respiratory endophenotypes in perspective. The genetic variant(s) of receptors that are associated with endophenotypes are discussed in the context of the extent to which they contribute to a disease phenotype or altered drug efficacy.