Association between ADAM33 polymorphisms and adult asthma in the Japanese population

ADAM33's Role in Asthma Pathogenesis: An Overview

Asthma is a complex chronic respiratory disease characterized by airway hyperresponsiveness, inflammation, and obstruction. Many genes have been identified as associated with asthma but none with such substantial significance as the ADAM33 gene due to its role in airway remodeling and bronchial hyperresponsiveness. This review summarizes the current knowledge on the genetic and functional aspects of ADAM33 in asthma pathogenesis. We highlight its genetic variants associated with asthma susceptibility and severity, as well as the functional effects of ADAM33 on airway remodeling, smooth muscle cell proliferation, and its interplay with environmental factors. Additionally, we discuss the potential clinical implications of ADAM33 as a therapeutic target for asthma management.

Polymorphism in ADAM33 gene associated with asthmatics in West Bengal, India - An investigation by in-silico analysis

Introduction

Asthma is one of the common chronic polygenic inflammatory diseases. Genome wide association studies have identified ADAM33 as an asthma candidate gene. The present study investigated possible association of rs2280090 (T1), rs2280091 (T2) and rs3918396 (S1) single nucleotide polymorphisms (SNPs) of ADAM33 with aeroallergen induced asthma in West Bengal population, India. In addition, in-silico analysis was performed to find out changes in protein function.

Methods

Forced expiratory volume in 1 second (FEV1)/Forced vital capacity (FVC), peak expiratory flow rate (PEFR) were assessed using spirometry in 1039 participants. Allergic sensitivity of 619 spirometry positive asthma patients was assessed by skin prick test (SPT) against 22 aeroallergens. For genotyping of T1, T2, and S1 SNPs in 540 allergic asthma patient and 420 control subjects, polymerase chain reaction-based restriction fragment length polymorphism was performed. Total Immunoglobulin-E (IgE) level was measured in both patients and controls. ADAM333 haplotype blocks were constructed using Haploview software v.4.2. Structural model of transmembrane and cytoplasmic domains of ADAM33 was generated using RaptorX. Protein-protein interaction was analysed using the STRING server.

Results

Highest number of patient sensitivity was observed towards Cocos nusifera (n = 215) and Dermatophagoides farinae (n = 229). Significant difference in sensitivity was observed between child and late adult (P = 0.03), child and early adult (P = 0.02), adolescent and late adult (P = 0.02) and adolescent and early adult (P = 0.01). Genotypic frequencies differed significantly between patients and controls (P < 0.05). rs2280090 GG, rs2280091GG and AG genotype, and rs3918396 AA carried significant risk for asthma (P = 0.02, P = 0.008, P = 0.04, P = 0.01 respectively). ADAM33 T1, T2, and S1 polymorphisms were in high Linkage Disequilibrium (D = 0.98). Haplotype consisting of rs2280090G, rs2280091G and rs3918396A alleles were found significantly higher in patient population in comparison with controls (OR = 2.03). IgE level differed significantly among different genotypes for T1, T2, and S1 SNPs analysed in pair (P < 0.0001). FEV1/FVC ratio differed significantly among different genotypes for T1, T2 and S1 SNPs analysed in pair (P < 0.0001). Significant difference of FEV1/FVC was also found between GGA and AAG haplotype (P < 0.0001). In-silico analysis revealed T1 and T2 polymorphisms are located in cytoplasmic domain of ADAM33 may cause bronchial smooth muscle cell mobility and cellular hyperplasia as well as cytoskeletal remodelling by altered interaction with different cytoplasmic proteins found by string analysis.

Conclusion

Present study showed significant association of T1, T2, and S1 polymorphisms of ADAM33 with aeroallergen-induced asthma in West Bengal, India. These polymorphisms may be used as prognostic markers and possible targets for therapeutics in future.

Association between ADAM33 polymorphisms and asthma risk: a systematic review and meta-analysis

Background

Asthma is a common complex chronic, inflammatory polygenic disease with heterogeneous manifestations, affecting individuals of all age groups and posing an immense burden on healthcare resources. A number of studies have identified the association between a disintegrin and metalloprotease 33 (ADAM33) polymorphisms and asthma risk, however, the results still remain inconclusive. The objective of the present study was to identify the effect of ADAM33 variants in asthma susceptibility.

Methods

Eligible case-control studies published between January 2000 and June 2018 was searched and retrieved from online electronic databases. The odds ratio (OR) with its 95% confidence interval (CI) was employed to calculate the effect.

Results

A total of 63 case-control studies were finally screened out, including 13,280 asthma patients and 13,340 controls. Eleven SNPs of ADAM33 gene were identified. Our results detected a significant association between ADAM33 T2, Q1, F + 1 and AA genotype of T + 1 polymorphisms and asthma risk in total population. Subgroup analysis by ethnicities showed that the alleles and genotypes of T2, Q1 and F + 1 polymorphisms were associated with asthma susceptibility among Asian populations, while V4 polymorphism was associated with asthma among Caucasian populations. Subgroup analysis by ages showed that T2, F + 1 and ST + 4 polymorphisms were associated with childhood asthma, while Q1 and V4 polymorphisms were associated with asthma risk in adults. Subgroup analysis by asthma severity showed that only the G allele of ADAM33 T1 polymorphism was associated with the severity of asthma when compared with the controls. In addition, T2, Q1 and F + 1 polymorphisms of ADAM33 were significantly associated with increased the asthma risk in Chinese asthma patients.

Conclusions

Our results found that T2, Q1 and F + 1 polymorphisms of ADAM33 gene might contribute to asthma risk. Future well-designed case-control studies with large population and more ethnicities are still needed to estimate the association.

Association of ADAM33 gene polymorphisms with asthma in Mongolian and Han groups in Inner Mongolia

Polymorphisms in the gene encoding for A disintegrin and metalloprotease 33 (ADAM33) are closely associated with the risk of bronchial asthma attacks in different populations. We collected blood samples from 248 asthma patients - 130 of the Han ethnic group and 118 of the Mongolian ethnic group - living in the Inner Mongolia region of China, and analyzed the single nuclear polymorphisms (SNPs) of the T1, T2 and V4 loci of the ADAM33 gene using PCR-RFLP (restriction fragment length polymorphism). In addition, we also tested 256 healthy controls (134 and 122 from the Han and Mongolian ethnic groups respectively) for the same SNPs. Three genotypes of the T1, T2 and V4 loci were predominantly detected: while polymorphisms in the T1 locus were significantly associated with asthma risk in both Mongolian and Han ethnicities (P < 0.05, ∗P < 0.05), that in the V4 locus were relevant only in the Mongolian patients (P < 0.05, ∗P > 0.05). In contrast, polymorphisms in the T2 locus showed no significant association with asthma risk in either ethnic group (P > 0.05, ∗P > 0.05).

IL4Rα and ADAM33 as genetic markers in asthma exacerbations and type-2 inflammatory endotype

BACKGROUND

Genetic markers of susceptibility to asthma exacerbations in adults remain unclear.

OBJECTIVE

To identify genetic markers of asthma exacerbations, particularly in patients with type-2 inflammatory endotype.

METHODS

In this observational study of patients enrolled in the Kinki Hokuriku Airway disease Conference multicenter study, frequency of exacerbations requiring systemic corticosteroids during 2 years after enrolment and associated risk factors was determined. For genetic marker analysis, interleukin-4 receptor α (IL4RA) rs8832 and a disintegrin and metalloprotease 33 (ADAM33) S_2 (rs528557), T_1 (rs2280091), T_2 (rs2280090), and V_4 (rs2787094) variants were included. Elevated serum periostin levels at enrolment (≥95 ng/mL, defined as type-2 inflammatory endotype) were considered in the analysis.

RESULTS

Among 217 patients who were successfully followed up for 2 years after enrolment, 60 patients showed at least one asthma exacerbation during the 2 years. Airflow limitation (%FEV₁ <80%) and recent exacerbations but not genetic variants were identified as risk markers of exacerbations. A total of 27 patients showed type-2 inflammatory endotype (serum periostin ≥95 ng/mL at enrolment) and subsequent exacerbations; risk factors in these patients were airflow limitation (odds ratio, 6.51; 95% confidence interval (CI): 2.37-18.6; P=.0003), GG genotype of IL4RA rs8832 (odds ratio, 4.01; 95% CI: 1.47-11.0; P=.007), and A allele of ADAM33 T_2 (odds ratio, 2.81; 95% CI: 1.05-7.67; P=.04) by multivariate analysis. In addition, GG genotype of IL4RA rs8832 was associated with type-2 endotype, whereas A allele of ADAM33 T_2 was associated with mixed type of eosinophilic/type-2 and neutrophilic inflammations.

CONCLUSIONS AND CLINICAL RELEVANCE

IL4RA and ADAM33 variants may be risk markers of asthma exacerbations in type-2 inflammatory endotype. Precise endotyping may facilitate the identification of genetic risk markers of asthma exacerbations.

Genetic variants of ADAM33 are associated with asthma susceptibility in the Punjabi population of Pakistan

OBJECTIVE

A disintegrin and metalloproteinase 33 (ADAM33) gene has been considered as an asthma susceptibility gene due to its possible role in airway remodeling, abnormal cell proliferation, and differentiation. Association of this gene with asthma has been reported in several genetic studies on various populations. The current study aims to evaluate the association of ADAM33 gene polymorphisms with the risk of asthma in the Punjabi population of Pakistan.

METHOD

A total of 101 asthma patients and 102 age-matched healthy controls from Lahore, a city in Punjab, were recruited. ADAM33 single nucleotide polymorphisms (SNPs) T + 1[rs2280089], T2[rs2280090], T1[rs2280091], ST + 5[rs597980], ST + 4[rs44707], S2[rs528557], Q - 1[rs612709], and F + 1[rs511898] were genotyped in both patients and controls using single base extension and capillary electrophoresis-based genetic analyzer. The basic allelic and genotypic model was analyzed for association of the SNPs with asthma using SHEsis software. Haploview software was used to calculate pairwise linkage disequilibrium (LD) among six of the genotyped SNPs.

RESULTS

Of the 8 SNPs genotyped, only S2[rs528557] showed significant association with asthma (Allele p = 0.0189, Genotype p = 0.021). SNPs T + 1[rs2280089], T2[rs2280090], T1[rs2280091], ST + 4[rs44707], S2[rs528557], and Q - 1[rs612709] were found to be in moderate to strong LD. The significantly higher frequency of haplotype "AAGTCG" in healthy controls suggests a protective effect against asthma risk in the studied population (p = 0.0059).

CONCLUSION

These findings suggest that genetic variants of ADAM33 gene may play important roles in asthma susceptibility in the Punjabi population of Pakistan.

ADAM33 and ADAM12 genetic polymorphisms and their expression in Egyptian children with asthma

BACKGROUND

The ADAM family is involved in some pathologic processes, such as inflammation and asthma.

OBJECTIVES

To assess the association between ADAM33 and ADAM12 single-nucleotide polymorphisms (SNPs) with asthma risk and severity and to investigate the effect of ADAM33 and ADAM12 polymorphisms on expression of these proteases in sputum.

METHODS

Two SNPs of the ADAM33 gene, F+1 (rs511898) G/A and ST+4 (rs44707) A/C, and 2 SNPs of the ADAM12 gene, rs3740199 and rs1871054, were analyzed in 400 asthma cases and 200 controls aged 3 to 14 years using the polymerase chain reaction-restriction fragment length polymorphism method. Messenger RNA expression profile of ADAM33 and ADAM12 proteases in sputum from studied groups was determined by reverse transcription polymerase chain reaction.

RESULTS

ADAM33 F+1 homozygous mutant genotype (AA) and ST+4 heterozygous and homozygous mutant genotype (AC and CC) and mutant alleles of both polymorphisms were significantly associated with asthma risk and severity in moderate and severe subgroups. Patients with the ADAM12 (rs3740199) CC genotype were at increased risk for moderate and severe asthma. Messenger RNA levels of ADAM12 were significantly increased in asthmatic children compared with controls, whereas we were not able to detect the expression of ADAM33 in the sputum of the groups studied. The ADAM12 expression was significantly higher in homozygous CC (variant type) compared with homozygous GG (wild type) of both ADAM12 rs3740199 and rs1871054 in the asthmatic group.

CONCLUSION

Our analysis suggests a likely role for ADAM33 and ADAM12 in the development of asthma in Egyptian children. Furthermore, ADAM12 polymorphisms may affect ADAM12 expression in asthma.

The ADAM33 S2 polymorphism is associated with susceptibility to pediatric asthma in the Chinese Han population

BACKGROUND

The disintegrin and metalloprotease domain containing protein 33 (ADAM33) is a novel susceptibility gene for asthma and airway hyperresponsiveness, particularly in the Asian population. We investigated the influence of ADAM33 polymorphisms on the serum levels of ADAM33 and the susceptibility to pediatric asthma in the Chinese Han population.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism analysis was employed to study the genotypic distribution of F+1, T1, and S2 in ADAM33 in a cohort of 120 pediatric asthma patients and 105 healthy controls. The serum levels of secreted ADAM33 protein were measured in all the study subjects using the enzyme-linked immunosorbent assay (ELISA).

RESULTS

This case-control study showed that the distribution of F+1 and T1 genotypes of ADAM33 was not significantly different between pediatric asthma patients and healthy controls (p > 0.05); however, the genotype and allele frequencies of the S2 polymorphism were significantly different between asthmatic patients and healthy controls (both p < 0.05). In addition, the frequency of CGC and CGG haplotypes exhibited statistically significant differences, with lower CGC and higher CGG frequencies found in the case group compared to the control group. Finally, in comparison to healthy controls, the serum levels of ADAM33 protein were significantly lower in patients carrying the S2 polymorphism.

CONCLUSION

Our results provide evidence that the ADAM33 S2 polymorphism is associated with increased susceptibility to pediatric asthma and that the CGG haplotype for the F+1, T1, and S2 polymorphisms is associated with an elevated risk of pediatric asthma in the Han population, whereas the CGC haplotype appears to confer a protective effect. Our results may prove useful for population-based screening to affect early intervention.

A disintegrin and metalloprotease 33 polymorphism association with COPD in long-term tobacco smokers of the ethnic Kashmiri population of India

Background:

Chronic obstructive pulmonary disease (COPD) is characterized by an interaction of various environmental influences especially cigarette smoking and genetic determinants. The prevalence of this disease is ever increasing and characterization of the genetic determinants of the disease has been undertaken globally. The ‘A disintegrin and metalloprotease 33’ (ADAM 33) gene is one candidate gene that has been studied.

Objective:

Our objective was to investigate whether single nucleotide polymorphisms in ADAM33 gene are associated with COPD in long-term tobacco smokers in the ethnic Kashmiri population of northern India.

Materials and Methods:

This was a randomized case-control study, which included 78 stable COPD (GOLD stage11-IV) patients, who were compared with 77 age- and sex-matched long-term tobacco smokers (>20 pack years) without any evidence of COPD. Polymorphic analysis for three single nucleotide polymorphisms (SNPs), (T1, T2, and Q1) of the ADAM33 gene was done by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) followed by sequencing. The data were analyzed by descriptive statistics and comparative evaluation was done by parametric/non-parametric tests.

Results:

The analysis of the T1, T2, and Q1 SNPs, revealed that the frequencies of the T2GG, T1GG, and the Q1AG genotypes were significantly higher in patients with COPD in comparison with the controls (P < 0.001). Similarly, the T1G and T2G allele frequency was higher in the patients than in the controls (p = 0.177 and 0.43, respectively).

Conclusion:

Three SNPs of the ADAM33 gene were significantly associated with COPD in the Kashmiri population of India. This study establishes the possible role of ADAM33 SNPS in the causation of COPD. Further studies across different geographical areas in the country will unravel the contribution of this gene in the causation of COPD in India.

Association between genetic polymorphisms in the ADAM33 gene and asthma risk: a meta-analysis

The aim of this study was to evaluate the associations between the rs3918396 G>A and rs528557 C>G polymorphisms in the disinterring and metalloproteinase domain 33 (ADAM33) gene and asthma risk. We searched CISCOM, CINAHL, Web of Science, PubMed, Google Scholar, EBSCO, Cochrane Library, and CBM databases from inception through August 1st, 2013 without language restrictions. Meta-analysis was performed using the STATA 12.0 software. Crude odds ratios (ORs) with their 95% confidence intervals (95% CI) were calculated. Thirteen case-control studies were included with a total of 7104 asthma patients and 8172 healthy controls. Our meta-analysis results revealed that ADAM33 rs528557 C>G polymorphism was associated with an increased risk of asthma (all p<0.05). However, we found no correlation between the ADAM33 rs3918396 G>A polymorphism and asthma risk (all p>0.05). Subgroup analysis by ethnicity indicated that the ADAM33 rs528557 C>G polymorphism might be strongly associated with an increased risk of asthma among both Caucasian and Asian populations (All p<0.05). No significant association was found between the ADAM33 rs3918396 G>A polymorphism and the risk of asthma among the studied ethnicities (All p>0.05). The present meta-analysis suggests that the ADAM33 rs528557 C>G polymorphism may contribute to susceptibility to asthma. Thus, the ADAM33 rs528557 C>G polymorphism may be utilized as a biomarker for early diagnosis of asthma.

Association study on ADAM33 polymorphisms in mite-sensitized persistent allergic rhinitis in a Chinese population

Background

The ADAM33 gene has been identified as a potentially important asthma candidate gene and polymorphisms in this gene have been shown to be associated with asthma and seasonal allergic rhinitis.

Objective

To assess whether the ADAM33 polymorphisms are associated with persistent allergic rhinitis (PER) due to house dust mites in a Chinese population.

Methods

In a hospital-based case-control study of 515 patients with mite-sensitized PER and 495 healthy controls, we genotyped seven single nucleotide polymorphisms (SNPs) in ADAM33. Serum levels of eosinophil cationic protein, total IgE and allergen-specific IgE against Dermatophagoides pteronyssinus and Dermatophagoides farinae were measured by the ImmunoCAP assays.

Results

In the single-locus analysis, three polymorphisms, rs3918392 (F1), rs528557 (S2) and rs2787093, were significantly associated with mite-sensitized PER. SNP S2 was associated with significantly increased risk both of asthmatic and nonasthmatic mite-sensitized PER. In the combined genotypes analysis, individuals with 2–4 risk alleles had a significantly higher risk of mite-sensitized PER (adjusted OR = 1.99, 95% CI = 1.50–2.62) than those with 0–1 risk alleles. Haplotype-based association analysis revealed that the ACAGCCT haplotype might have potential to protect against mite-sensitized PER (adjusted OR = 0.67; 95% CI = 0.49–0.90).

Conclusions

Polymorphisms in the ADAM33 gene may contribute to susceptibility of mite-sensitized PER in this Chinese population.

Association between ADAM33 S2 and ST+4 polymorphisms and susceptibility to asthma: a meta-analysis

OBJECTIVE

The aim of this study was to determine whether ADAM33 (a disintegrin and metalloproteinase domain 33) polymorphisms confer susceptibility to asthma in different populations.

METHODS

We performed a meta-analysis on the association between the ADAM33 S2, ST+4, F+1, S1, and V4 polymorphisms and asthma.

RESULTS

Thirteen studies in ten reports, which included 4942 patients and 7933 controls, were available for the meta-analysis. Meta-analysis stratified by ethnicity indicated an association between the ADAM33 S2 2 allele and asthma in Europeans (OR=0.912, 95% CI=0.851-0.977, p=0.009). Meta-analysis revealed an association between asthma and the ADAM33 ST+4 2 allele (OR=0.783, 95% CI=0.762-0.999, p=0.048). Stratification by ethnicity indicated an association between the ADAM33 ST+4 polymorphism and asthma in Asians. Stratification by age indicated an association between the ADAM33 ST+4 2 allele and asthma in adults (OR=0.863, 95% CI=0.782-0.964, p=0.008). However, no association was found between asthma and the ADAM33 F+1, S1, and V4 polymorphisms.

CONCLUSIONS

This meta-analysis demonstrates that the ADAM33 S2 polymorphism confers susceptibility to asthma in Europeans and the ADAM33 ST+4 polymorphism is associated with asthma in Asians and adults.

A disintegrin and metalloprotease 33 (ADAM33) gene polymorphisms and the risk of asthma: a meta-analysis

Polymorphisms in the ADAM33 gene have been associated with asthma, but the data are controversial. Therefore, we reviewed the related studies and quantitatively summarized the associations between ADAM33 polymorphisms and asthma risk using meta-analysis. A dominant model (AA+Aa vs. aa), recessive model (AA vs. Aa+aa), additive model (AA vs. aa) and allelic model (A vs. a) were used to estimate the association between ADAM33 polymorphism and asthma risk. A total of 29 case-control studies referring to 14 SNPs were identified: rs2280091(T1), rs2787094(V4), rs528557(S2), rs2280090(T2), rs511898(F+1), rs44707(ST+4), rs3918396(S1), rs543749(V-1), rs574174(ST+7), rs597980(ST+5), rs2853209(S+1), rs2280089(T+1), rs612709(Q-1), and rs3746631(V5). The results indicated that S1, V-1, V5, S+1, S2, ST+4, ST+7, ST+5, and Q-1 were not associated with asthma. Significant associations were found with the T1, V4, F+1 and T+1 polymorphisms in the overall population. In the subgroup analysis by ethnicity, a positive result was only found for the T1, V4, F+1 and T2 polymorphisms in Asia but not in Europe or Latin America. This meta-analysis provides evidence that the T1, V4, F+1, T2, and T+1 polymorphisms in the ADAM33 gene are risk factors for asthma, especially in the Asian population.

Haplotypic association of ADAM33 (T+1, S+1 and V - 3) gene variants in genetic susceptibility to asthma in Indian population

AIM

The aim of this study was to find out if the ADAM33 gene polymorphisms T+1(A>G), S+1(T>A) and V - 3(C>T) and their haplotypes play any role in genetic susceptibility to asthma.

SUBJECTS AND METHODS

Three hundred and ninety healthy controls and 386 asthmatic patients from Lucknow, India, were recruited for the study. Subjects were aged between 1-50 years. Among total recruited asthma cases, 95 (24.6%) had mild intermittent asthma, 235 (60.9%) had mild persistent asthma and 56 (14.5%) had moderate persistent asthma. Genotyping was carried out using the Polymerase Chain Reaction and Restriction Fragment Length polymorphism (PCRRFLP) method.

RESULTS

No significant differences in the genotype or allele frequencies of ADAM33 gene polymorphisms between asthmatic patients and healthy controls were found [p-value>0.05 (All the p-values were Bonferroni corrected)]. Also, no association of studied SNPs with the severity of the disease asthma was observed. However, the TTA haplotype was observed to be associated with asthma (OR = 3.4; 95%CI = 1.4-8.7; p = 0.002).

CONCLUSIONS

SNPs, T+1, S+1 and V - 3 do not individually confer any significant risk of asthma or its severity, but haplotype analysis suggests all three polymorphisms together play an important role in the disease of asthma.

Control of allergen-induced inflammation and hyperresponsiveness by the metalloproteinase ADAMTS-12

A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) constitute a family of endopeptidases related to matrix metalloproteinases. These proteinases have been largely implicated in tissue remodeling associated with pathological processes. Among them, ADAMTS12 was identified as an asthma-associated gene in a human genome screening program. However, its functional implication in asthma is not yet documented. The present study aims at investigating potential ADAMTS-12 functions in experimental models of allergic airways disease. Two different in vivo protocols of allergen-induced airways disease were applied to the recently generated Adamts12-deficient mice and corresponding wild-type mice. In this study, we provide evidence for a protective effect of ADAMTS-12 against bronchial inflammation and hyperresponsiveness. In the absence of Adamts12, challenge with different allergens (OVA and house dust mite) led to exacerbated eosinophilic inflammation in the bronchoalveolar lavage fluid and in lung tissue, along with airway dysfunction assessed by increased airway responsiveness following methacholine exposure. Furthermore, mast cell counts and ST2 receptor and IL-33 levels were higher in the lungs of allergen-challenged Adamts12-deficient mice. The present study provides, to our knowledge, the first experimental evidence for a contribution of ADAMTS-12 as a key mediator in airways disease, interfering with immunological processes leading to inflammation and airway hyperresponsiveness.

T1 and T2 ADAM33 single nucleotide polymorphisms and the risk of childhood asthma in a Saudi Arabian population: a pilot study

BACKGROUND AND OBJECTIVES

Genetic association studies have demonstrated that over 100 variants in target genes (including ADAM33) are associated with airway remodeling and hyper-responsiveness in different ethnic groups; however, this has never been evaluated in Arabic populations. The objective of this study was to determine whether ADAM33 polymorphisms that are associated with asthma in a population of asthmatic children from Saudi Arabia.

DESIGN AND SETTING

A cross-sectional pilot study comparing the polymorphisms of normal subjects and asthmatic patients from Saudi Arabia over a period of 1 year.

PATIENTS AND METHODS

One hundred and seven Saudi asthmatic children and 87 healthy Saudi children of 3-12 years old were assessed for allelic association of ADAM33 T1 (rs2280091), T2 (rs2280090), ST+4 (rs44707) and S1 (rs3918396) SNPs to asthma. Genotyping was done by real-time PCR, multiplex ARMS and PCR-RFLP.

RESULTS

T1 and T2 SNP genotype frequencies in asthmatic children were significantly different compared to controls (P < .05), indicating allelic association with asthma. The T1 A/G and G/G and the T2 A/G and A/A genotypes (P=.0013 and P=.008, respectively) but not S1 and ST+4, increased the risk of asthma when using the best fit dominant model. Strong linkage disequilibrium between T1 (rs2280091) and T2 (rs2280090) was observed (r2=0.83; D'=0.95; P < .001). The haplotype G-A-A-C was significantly more frequent in asthmatics, thus supporting the association of T1 G-allele and T2 A-allele with increased predisposition to asthma (P=.007).

CONCLUSIONS

T1 A/G and T2 G/A ADAM33 polymorphisms, but not S1 or ST+4, were significantly associated with asthma development in Saudi children, like those reported for white and Hispanic populations in the United States.

Association between ADAM33 T1 polymorphism and susceptibility to asthma in Asians

OBJECTIVE

The aim of this study was to determine whether the ADAM33 (a disintegrin and metalloproteinase domain 33) T1 (rs2280091), T2 (rs2280090), and ST+7 (rs574174) polymorphisms confer susceptibility to asthma.

METHODS

A meta-analysis stratified by ethnicity and age was conducted on associations between the ADAM33 T1, T2, and ST+7 polymorphisms and asthma.

RESULTS

Eleven studies, which included 4,124 patients and 7,094 controls, were available for the meta-analysis. Meta-analysis revealed an association between asthma and the ADAM33 T1 GG genotype [odds ratio (OR) = 2.257, 95 % confidence interval (CI) = 1.577-3.228, p = 8.42 × 10(-7)]. Stratification by ethnicity indicated an association between this genotype and asthma in Asians (OR = 2.683, 95 % CI = 1.799-4.001, p = 1.31 × 10(-7)), and stratification by age indicated an association between it and asthma in adults (OR = 1.895, 95 % CI = 1.005-3.573, p = 0.048). However, no association was found between asthma and the ADAM33 T2 and ST+7 polymorphisms.

CONCLUSIONS

This meta-analysis demonstrates that the ADAM33 T1 polymorphism confers susceptibility to asthma in Asians, but no association was found between the ADAM33 T2 and ST+7 polymorphisms and asthma susceptibility.

ADAM33 genetic polymorphisms, smoking, and rhinoconjunctivitis in Japanese women: the Kyushu Okinawa Maternal and Child Health Study

Two previous studies have demonstrated a significant relationship between ADAM33 single nucleotide polymorphisms (SNPs) and allergic rhinitis. Here, we investigated this issue in young adult Japanese women. The study included 393 women who met the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC) for rhinoconjunctivitis. Controls included 767 women without rhinoconjunctivitis according to the ISAAC criteria who had not been diagnosed with allergic rhinitis by a doctor. The GC genotype of rs2787094, the CT genotype of rs628977, and the haplotype containing the rs2787094 C allele, the rs628977 T allele, the rs2853209 T allele, and the rs612709 G allele were significantly inversely associated with rhinoconjunctivitis. The AA genotype of rs2853209, the GA genotype of rs612709, and the haplotype carrying the rs2787094 G allele, the rs628977 C allele, the rs2853209 A allele, and the rs612709 G allele were significantly positively associated with rhinoconjunctivitis. A significant inverse relationship between rs628977 and rhinoconjunctivitis was demonstrated only in women who had never smoked, indicating a significant interaction between rs628977 and smoking. Our results suggest that SNPs and haplotypes in the ADAM33 gene are associated with rhinoconjunctivitis. This study is the first to demonstrate an interaction between rs628977 and smoking that affects rhinoconjunctivitis.

Association of ADAM33 gene polymorphisms with adult-onset asthma and its severity in an Indian adult population

ADAM33, a member of the ADAM (a disintegrin and metalloprotease) gene family, is an asthma susceptibility gene originally identified by positional cloning. In the present study, we investigated the possible association of five single-nucleotide polymorphisms (SNPs) in the ADAM33 (rs511898, rs528557, rs44707, rs597980 and rs2787094) with adult-onset asthma in an Indian population. The study included 175 patients with mild intermittent (n = 44), mild persistent (n = 108) or moderate persistent (n = 23) subgroups of asthma, and 253 nonasthmatic control individuals. SNPs were genotyped with the help of restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) method, and data were analysed using chi-square test and logistic regression model. Bonferroni's correction for multiple comparisons was applied for each hypothesis. Genotypes and allele frequencies of SNPs rs511898 and rs528557 were significantly associated with adult-onset asthma (P = 0.010-<0.001). A significant association of the homozygous mutant genotype and mutant alleles of SNPs rs2787094, rs44707 and rs597980 with the asthma was also observed (P = 0.020-<0.001). A positive association between asthma and haplotypes AGCCT, GGCCT, AGACT, GCAGT, GGACT, ACCCC and AGACC were also found (P = 0.036-<0.001, OR = 2.07-8.49). Haplotypes AGCGT, GCAGC, ACAGC, ACAGT, GGAGC and GGCGT appear to protect against asthma (P = 0.013-<0.0001, OR = 0.34-0.10). Our data suggest that ADAM33 gene polymorphisms serve as genetic risk factors for asthma in Indian adult population.

ADAM33 gene polymorphisms associate with asthma susceptibility and severity in East China han population

OBJECTIVE

Multiple genetic and environmental factors impact the pathogenesis of asthma. ADAM33 (a disintegrin and metalloproteinase domain 33) represents a novel susceptibility gene for asthma in several diverse populations. The aim of this study was to determine whether single nucleotide polymorphisms (SNPs) of the ADAM33 gene associate with asthma susceptibility and severity in the Chinese Han population.

METHODS

A total of 224 subjects were enrolled, including 74 normal controls and 150 asthmatic patients. The asthmatic enrollees were further categorized into high- or low-severity groups according to the percentage of forced expiratory volume in 1 second of predicted value, symptoms, nighttime awakening, requirement for short-acting β2-agonist, and interference with normal activities. Six SNPs (F + 1, ST + 4, S1, S2, T1, and T2) in ADAM33 were genotyped using the polymerase chain restriction fragment length polymorphism method.

RESULTS

Three SNPs (F + 1, T1, and T2) of ADAM33 were found to have significant associations with asthma in the study population (p = .0058-.0067). The allele frequencies of two SNPs (F + 1, T1) in both the low- and high-severity groups were significantly different from the allele frequency in the control group. The allelic frequency of the T2 SNP was significantly different from that of the control group only in the high-severity group (p = .0081). Haplotype analysis demonstrated that the frequency of 7575G, 12433T, and 12462C (GTC haplotype) is higher in healthy controls than amongst asthma patients (78.4% vs. 61.8%, p = .0004).

CONCLUSIONS

Polymorphisms of the ADAM33 gene associate with asthma susceptibility in the east China Han population, and the genetic association is stronger in high-severity asthmatics.

Association of ADAM33 gene polymorphisms with asthma in a Chinese population

BACKGROUND AND AIM

Asthma is a very common disease involving genetic and environmental factors. A disintegrin and metalloproteinase 33 (ADAM33) has been one of the most exciting candidate genes for asthma since its first association with the disease in the white population. Recently, studies on the association of ADAM33 gene polymorphisms with the risk of asthma have been controversial. We therefore focused on testing the hypothesis that either single-nucleotide polymorphisms (SNPs) of the ADAM33 gene may be associated with asthma risk. The aim of this study was to evaluate the potential relationship between polymorphisms of ADAM33 and asthma in a Han population in China.

METHODS

A case control study was conducted in a Han population of eastern Chinese population. A total of 329 asthma patients and a control group of 316 healthy volunteers were recruited for this study. Four polymorphic sites (F+1, S2, T2 and V4) were selected for genotyping. Genotypes were determined by the allele-specific polymerase chain reaction with fluorescence melting curves and DNA sequencing method. Data were analysed using the chi-squared test software.

RESULTS

Statistically significant differences in the distributions of the S2 site between patients and controls were observed (χ2=7.140, P<0.05).

CONCLUSION

These preliminary results suggest an association between ADAM33 polymorphisms S2 C/G and asthma in a Chinese Han population. The SNPs (F+1 C/T, T2 G/A and V4 C/G) of the ADAM33 gene may be the causal variants in asthma disease, but the strength of this evidence is limited by our small sample size.

Association of ADAM33 gene polymorphisms with asthma in Indian children

Asthma is the most common chronic disorder in childhood, and asthma exacerbation is an important cause of childhood morbidity and hospitalization. In the present study, the relationship between single-nucleotide polymorphisms (SNPs) of the ADAM33 gene and asthma in Indian children has been examined using a case-control study. Five SNPs of the ADAM33 gene, F+1(rs511898) G/A, S2 (rs528557) G/C, ST+4 (rs44707) A/C, ST+5 (rs597980) C/T and V4 (rs2787094) C/G, were analyzed in 211 asthma cases and 137 controls aged 1-15 years using the PCR-restriction fragment length polymorphism method. Data were statistically analyzed using the χ(2)-test and logistic regression model. Haplotype estimation and linkage disequilibrium were conducted using the expectation-maximization algorithm. The genotypes and allele frequencies of SNPs S2 and ST+5 of the ADAM33 gene were significantly associated with asthma risk (P = 0.020 - < 0.001), whereas F+1, ST+4, V4 homozygous mutant genotypes and mutant alleles were significantly associated with increased asthma risk (P = 0.031 - < 0.001). A positive association was also found with haplotypes AGCCT, GGACT and AGCCC (P = < 0.001, odds ratio (OR) = 6.10-6.50), whereas ACAGT, AGCGC, AGCGT, GCAGC and GCCGT showed protective association with asthma (P = 0.019-0.000, OR = 0.50-0.20). Taken together, out results suggest that ADAM33 gene polymorphisms may modify individual susceptibility to develop childhood asthma in the Indian population.

Unifying candidate gene and GWAS Approaches in Asthma

The first genome wide association study (GWAS) for childhood asthma identified a novel major susceptibility locus on chromosome 17q21 harboring the ORMDL3 gene, but the role of previous asthma candidate genes was not specifically analyzed in this GWAS. We systematically identified 89 SNPs in 14 candidate genes previously associated with asthma in >3 independent study populations. We re-genotyped 39 SNPs in these genes not covered by GWAS performed in 703 asthmatics and 658 reference children. Genotyping data were compared to imputation data derived from Illumina HumanHap300 chip genotyping. Results were combined to analyze 566 SNPs covering all 14 candidate gene loci. Genotyped polymorphisms in ADAM33, GSTP1 and VDR showed effects with p-values <0.0035 (corrected for multiple testing). Combining genotyping and imputation, polymorphisms in DPP10, EDN1, IL12B, IL13, IL4, IL4R and TNF showed associations at a significance level between p = 0.05 and p = 0.0035. These data indicate that (a) GWAS coverage is insufficient for many asthma candidate genes, (b) imputation based on these data is reliable but incomplete, and (c) SNPs in three previously identified asthma candidate genes replicate in our GWAS population with significance after correction for multiple testing in 14 genes.

Association of IL-4 and ADAM33 gene polymorphisms with asthma in an Indian population

There are more than 100 candidate genes of asthma located on 23 human chromosomes. Interleukin-4 (IL-4), located on chromosome 5q31, and ADAM33, located on chromosome 20p13, and some single nucleotide polymorphisms (SNPs) of these genes have been shown to be associated with asthma and its manifestations in different populations. The most prominent SNPs of IL-4 and ADAM33 are 589C>T and 400A>G, respectively. There are also controversial reports on the association of these SNPs with asthma. In the present study, we analyzed these two SNPs in 100 patients with asthma and 50 controls through PCR amplification and restriction digestion to evaluate association of these two SNPs with asthma. The nonsignificant differences were observed for the IL-4 promoter polymorphism C589T and the ADAM33 T1 polymorphism between asthmatic patients and controls (P = 0.638 and 0.943, respectively). Our data revealed that there is no association of these SNPs with asthma indicating that other SNPs of these genes or other genes might be involved in the manifestation of asthma.

Replication of genetic association studies in asthma and related phenotypes

In asthma genetics, the association of highly replicated susceptibility genes lacks consistency across populations. To identify genuine associations, we investigated the reproducibility of the 23 most promising asthma and asthma-related candidate genes in a moderately sized sample from the Japanese population. We compared the frequency of 33 polymorphisms in unrelated cases and controls and tested for their association with asthma, atopy and serum total IgE levels using allele frequency, codominant, dominant and recessive genotype models. On the basis of the consistency of our findings with previous meta-analyses and large replication studies, IL13, TNF, ADAM33, IL4RA and TBXA2R might represent common major asthma and asthma-related trait genes. Individual gene assessment was extended to the interactions between two polymorphisms using our original method. Interactions between TBXA2R and ADAM33, and IL4RA and C3 were suggested to increase the risk for childhood and all asthma (adult and childhood asthma combined). The confirmation of previously reported associations between gene polymorphisms and phenotypes was problematic when as few as several hundred samples per group were used. Stratification of the subjects by environmental factors or other confounding factors may be necessary to improve the sensitivity and reliability of association results.

Evolutionary divergence and functions of the ADAM and ADAMTS gene families

The 'A-disintegrin and metalloproteinase' (ADAM) and 'A-disintegrin and metalloproteinase with thrombospondin motifs' (ADAMTS) genes make up two similar, yet distinct, gene families. The human and mouse genomes contain 21 and 24 putatively functional protein-coding ADAM genes, respectively, and 24 versus 32 putatively functional protein-coding ADAMTS genes, respectively. Analysis of evolutionary divergence shows that both families are unique. Each of the two families can be separated, if need be, into groups of more closely related members: six subfamilies for ADAM, four subfamilies for ADAMTS. The presence of both disintegrin and peptidase domains within the ADAM and ADAMTS proteins implies multiple biological roles within the cell. Membrane-anchored ADAM proteins are best known for their role in activating zymogens -- including tumour necrosis factor-α, epidermal growth factor (EGF) and amyloid precursor protein (APP). ADAM proteins can also participate in cell adhesion via their interaction with integrins in neighbouring cells. ADAMTS are secreted proteins that participate in extracellular matrix maintenance by way of their cleavage of procollagen and proteoglycans. ADAMTS proteins also are involved in coagulation by cleaving von Willibrand factor precursor protein. ADAM and ADAMTS proteins participate in a wide range of cellular processes, including cell adhesion and migration, ectodomain shedding, proteolysis, development, ovulation and angiogenesis. Because these enzymes are believed to play an important role in a number of pathologies, including Alzheimer's disease, rheumatoid arthritis, atherosclerosis, asthma and cancer progression, the products of the ADAM and ADAMTS genes represent promising drug targets for the prevention and management of a number of human diseases.

Role of ADAM and ADAMTS metalloproteinases in airway diseases

Lungs are exposed to the outside environment and therefore to toxic and infectious agents or allergens. This may lead to permanent activation of innate immune response elements. A Disintegrin And Metalloproteinases (ADAMs) and ADAMs with Thrombospondin motifs (ADAMTS) are proteinases closely related to Matrix Metalloproteinases (MMPs). These multifaceted molecules bear metalloproteinase and disintegrin domains endowing them with features of both proteinases and adhesion molecules. Proteinases of the ADAM family are associated to various physiological and pathological processes and display a wide spectrum of biological effects encompassing cell fusion, cell adhesion, "shedding process", cleavage of various substrates from the extracellular matrix, growth factors or cytokines... This review will focus on the putative roles of ADAM/ADAMTS proteinases in airway diseases such as asthma and COPD.

A Six-SNP haplotype of ADAM33 is associated with asthma in a population of Cartagena, Colombia

BACKGROUND

A disintegrin and metalloprotein-33 (ADAM33) participates in the bronchial remodeling process in asthma, and genetic analyses pointed it out as a candidate gene in asthma.

METHODS

To analyze the association between ADAM33 and asthma and total and mite-specific IgE levels in a population of the Caribbean Coast of Colombia, we genotyped 6 single-nucleotide polymorphisms of ADAM33 in 429 asthmatics, 401 controls and 116 family trios using fluorogenic probes. Total and specific IgE against Blomia tropicalis and Dermatophagoides pteronyssinus were determined by ELISA. Case-control and family-based analyses were performed. Case-control association analyses were corrected by population stratification using a set of 52 ancestry-informative markers.

RESULTS

Eight common haplotypes were identified; among them, H4 (GCAGGG) was associated with asthma in the family group (Z score: -2.049, p = 0.04). We also found an association between the TT genotype of ST+7 and asthma in the case-control study (p = 0.05) that disappeared after correcting for multiple testing. In the family-based analysis, this genotype was a risk factor for asthma (p = 0.01), high total IgE (Z score: 2.546, p = 0.01) and high specific IgE against B. tropicalis (p = 0.02) and D. pteronyssinus (Z score: 2.414, p = 0.01). V4 was associated with specific IgE against B. tropicalis (p = 0.03); T2 with asthma (p = 0.03), high total IgE (p = 0.02) and IgE against D. pteronyssinus (p = 0.03) and T1 with high total IgE (p = 0.04). None of these associations was maintained after correction for multiple testing.

CONCLUSIONS

Our findings suggest a relevant role of ADAM33 in thepathogenesis of asthma in this population.

The effects of Th2 cytokines on the expression of ADAM33 in allergen-induced chronic airway inflammation

A disintegrin and metalloprotease domain 33 (ADAM33) has been identified as an asthma susceptibility gene, which is associated with small-airway remodeling. However, the role of ADAM33 in the development of allergic airway inflammation is unclear. The present study used an established murine model of allergen-induced chronic airway inflammation, which was sensitized and then challenged by nebulized 2.5% ovalbumin (OVA) for 8 weeks (30 min/day, three times a week). The expression of ADAM33 mRNA detected by real time RT-PCR was significantly enhanced in the lung tissue of mice with OVA challenge, as compared with the group challenged with saline. This OVA-challenged model showed significant Th2-biased airway inflammation as well as airway remodeling with features of sub-epithelial fibrosis and mucus hyper-secretion. Furthermore, in vitro studies showed that IL-4 and IL-13 could significantly up-regulate the expression of ADAM33 mRNA in human fibroblasts in a concentration- and time-dependent manner as compared to normal controls. These results support the note that Th2 cytokines can up-regulate the expression of ADAM33 mRNA and ADAM33 may play an important role in the development of airway remodeling in allergen-induced chronic airway inflammation.

ADAM33 genetic polymorphisms and risk of atopic dermatitis among Japanese children

OBJECTIVES

ADAM33, a disintegrin and metalloproteinase 33, gene has been identified as an asthma susceptibility gene. The relationship between single nucleotide polymorphisms (SNPs) in ADAM33 and atopic dermatitis (AD) in Japanese children was examined using case-control design.

METHODS

Seven SNPs of ADAM33 (rs2853209, rs2787094, rs2280091, rs2280090, rs628977, rs597980, and rs528557) were analyzed in 140 AD cases and 258 controls aged 3 years.

RESULTS

Only rs2853209 (T>A) was significantly associated with AD risk. Sex-adjusted odds ratio (OR) for the AA versus the TT genotype was 0.55 (95% confidence interval (CI), 0.30-0.997). Consistent with the results of genotyping analysis, a haplotype carrying rs2853209 A allele was significantly associated with decreased risk of AD compared to all the other haplotypes combined (OR=0.26, 95% CI=0.08-0.69).

CONCLUSION

This is the first study to provide evidence for an association of the ADAM33 polymorphism with AD risk but the strength of this evidence is limited by our small sample size.

Association of ADAM33 gene polymorphisms with adult allergic asthma and rhinitis in a Chinese Han population

Background

Rhinitis and asthma are very common diseases involving genetic and environmental factors. Most patients with asthma also have rhinitis, which suggests the concept of 'one airway, one disease.' A disintegrin and metalloproteinase 33 (ADAM33) is the first asthma-susceptible gene to be discovered by positional cloning. To evaluate the potential influence of ADAM33 gene polymorphisms on allergic rhinitis (AR) and allergic asthma (AS), a case-control study was conducted on the Han population of northeast China.

Methods

Six polymorphic sites (V4, T+1, T2, T1, S1, and Q-1) were genotyped in 128 patients with AR, 181 patients with AS, and 151 healthy controls (CTR). Genotypes were determined by the polymerase chain restriction fragment length polymorphism (PCR-RFLP) method. Data were analyzed using the chi-square test with Haploview software.

Results

The single nucleotide polymorphisms (SNPs), V4 G/C, T+1 A/G, and T1 G/A, of the ADAM33 gene may be the causal variants in AR, whereas ADAM33 V4 G/C, T2 A/G, T1 G/A, and Q-1A/G may participate in the susceptibility of AS.

Conclusion

These results suggest that polymorphisms of the ADAM33 gene may modify individual susceptibility to AR and AS in a Chinese Han population.

Association of ADAM33 gene polymorphisms with adult concomitant allergic rhinitis and asthma in Chinese Han population

Allergic Rhinitis (AR) and allergic asthma (AS) are very common diseases involving genetic and environmental factors. Most patients with asthma also have rhinitis, which suggests the concept of 'one airway, one disease'. A disintegrin and metalloproteinase 33 (ADAM33) was discovered as the first asthma-susceptible gene by positional cloning. To evaluate the potential influences of ADAM33 gene polymorphisms on concomitant allergic rhinitis and asthma (ARA), a case-control study was conducted in Han population of Northeast China. Six polymorphic sites (V4, T + 1, T2, T1, S1 and Q - 1) were genotyped in 135 ARA patients and 151 controls (CTR). Genotypes were determined by the polymerase chain restriction fragment length polymorphism (PCR-RFLP) method. Data was analyzed using the Chisquaretest and Haploview software. The SNPs (V4 G/C, T2 A/G, T1 G/A, and Q - 1A/G) of the ADAM33 gene may be the causal variants in ARA disease.

Asthma genetics: personalizing medicine

Asthma is a chronic inflammatory lung disease that leads to significant morbidity, mortality, and economic burden. The clinical symptoms, which are a result of airway inflammation and reversible airway obstruction, have led to the mainstay of therapies for asthma: anti-inflammatory medications and bronchodilators. However, the efficacies of the various classes of medications are not equal among all patients and may be affected by asthma phenotypes, environmental exposures, and genetic differences. Similarly, the risk for developing asthma and the natural history of the disease show great inter-individual variability due to these same factors. Over the past few decades, much effort has been focused on the genetics of asthma, and investigators have identified more than one hundred potential asthma susceptibility genes, of which at least ten have been replicated in numerous independent studies. In parallel, researchers have also identified genetic factors that impact the pharmacotherapeutic responses to the major classes of asthma medications. While the results of previous studies have been promising, future investigations need to combine genetics, pharmacogenetics, accurate disease phenotyping, and environmental exposures to build the foundation for personalized and predictive medicine for the 21st century. The ultimate goal is to enable physicians to identify those at risk for asthma, intervene to prevent or attenuate the disease, and select the optimal medical regimen for each individual patient. If successful, the resulting paradigm shift in medical practice will lead to improved clinical outcomes and decreased health care expenditures.

Modeling the impact of genetic screening technologies on healthcare: theoretical model for asthma in children

BACKGROUND AND OBJECTIVE

This study focuses on the potential impact of genetic screening technologies on healthcare. Genetic screening for asthma in children was chosen as a case study to explore the cost effectiveness of applying early genetic screening to infants, and preventive treatment to the population at risk. Early intervention could prevent progression and facilitate clinical management of the disease. From the elite group of genetic markers that have been associated with asthma-related phenotypes, ADAM33 was the first published candidate gene detected by a positional cloning approach, marking the entry of asthma research into the genomic era. The model was, therefore, initially set for an ex ante analysis of the cost effectiveness of applying the preventive program to an infant population at risk, i.e. infants presenting wheezing episodes during the first year of life, and the ADAM33 ST+7 genetic marker, with the idea of expanding to further markers and their combinations lat a later date.

METHODS

In accordance with the US National Heart, Lung, and Blood Institute, four categories of asthma were considered. A Markov model was constructed, consisting of six mutually exclusive disease states (including healthy and dead states) with a simulation horizon of 100 years and a cycle length of 1 year. We define a scenario where early genetic screening was applied to infants presenting wheezing episodes during the first year of life and a preventive treatment to those children within this group who tested positive for selected ADAM33 polymorphism (ST+7). The cost-effectiveness analysis was performed from the third-party payer and patient perspective after year 6. We applied our model to a hypothetical cohort of 100 European infants.

RESULTS

The number of quality-adjusted life-years (QALYs) gained during the 6 years was 1.483, and the incremental cost-effectiveness ratio per QALY gained was euro 10,100/QALY. A sensitivity analysis was carried out that varied the discount rate and cost of genetic testing, and considered two different transition matrices for the preventive program. Three main conclusions were drawn from the sensitivity analysis. Firstly, if the discount rate for both cost and health outcomes is increased by 2%, the cost effectiveness of the preventive program does not vary significantly. Discounting costs and benefits at 5%, the preventive program appears cost effective (euro 11,100/QALY). Secondly, if the cost of genetic testing is increased to euro 100, the cost effectiveness of the preventive program remains within the limits of cost effectiveness. Thirdly, the cost of genetic screening, together with transition probabilities between health states, will determine the cost effectiveness of applying a preventive program based on genetic information.

CONCLUSIONS

Preventive treatment based on an early genetic screening of those children who present wheezing episodes during the first year of life, with treatment applied to those who test positive for the asthma-associated genetic marker ADAM33 ST+7, is theoretically cost effective. The model is a valuable tool for the ex ante assessment of the cost effectiveness of preventive schemes based on genetic screening. The value of modeling prior to clinical trials lies in informing study design and setting priorities for future research.

Comprehensive testing of positionally cloned asthma genes in two populations

RATIONALE

Replication of gene-disease associations has become a requirement in complex trait genetics.

OBJECTIVES

In studies of childhood asthma from two different ethnic groups, we attempted to replicate associations with five potential asthma susceptibility genes previously identified by positional cloning.

METHODS

We analyzed two family-based samples ascertained through an asthmatic proband: 497 European-American children from the Childhood Asthma Management Program and 439 Hispanic children from the Central Valley of Costa Rica. We genotyped 98 linkage disequilibrium-tagging single-nucleotide polymorphisms (SNPs) in five genes: ADAM33, DPP10, GPR154 (HUGO name: NPSR1), HLA-G, and the PHF11 locus (includes genes SETDB2 and RCBTB1). SNPs were tested for association with asthma and two intermediate phenotypes: airway hyperresponsiveness and total serum immunoglobulin E levels.

MEASUREMENTS AND MAIN RESULTS

Despite differing ancestries, linkage disequilibrium patterns were similar in both cohorts. Of the five evaluated genes, SNP-level replication was found only for GPR154 (NPSR1). In this gene, three SNPs were associated with asthma in both cohorts, although the opposite alleles were associated in either study. Weak evidence for locus-level replication with asthma was found in the PHF11 locus, although there was no overlap in the associated SNP across the two cohorts. No consistent associations were observed for the three other genes.

CONCLUSIONS

These results provide some further support for the role of genetic variation in GPR154 (NPSR1) and PHF11 in asthma susceptibility and also highlight the challenges of replicating genetic associations in complex traits such as asthma, even for genes identified by linkage analysis.

Mechanistic role of a disease-associated genetic variant within the ADAM33 asthma susceptibility gene

BACKGROUND

ADAM33 has been identified as an asthma-associated gene in an out-bred population. Genetic studies suggested that the functional role of this metalloprotease was in airway remodeling. However, the mechanistic roles of the disease-associated SNPs have yet to be elucidated especially in the context of the pathophysiology of asthma. One disease-associated SNP, BC+1, which resides in intron BC toward the 5' end of ADAM33, is highly associated with the disease.

METHODS

The region surrounding this genetic variant was cloned into a model system to determine if there is a regulatory element within this intron that influences transcription.

RESULTS

The BC+1 protective allele did not impose any affect on the transcription of the reporter gene. However, the at-risk allele enforced such a repressive affect on the promoter that no protein product from the reporter gene was detected. These results indicated that there exists within intron BC a regulatory element that acts as a repressor for gene expression. Moreover, since SNP BC+1 is a common genetic variant, this region may interact with other undefined regulatory elements within ADAM33 to provide a rheostat effect, which modulates pre-mRNA processing. Thus, SNP BC+1 may have an important role in the modulation of ADAM33 gene expression.

CONCLUSION

These data provide for the first time a functional role for a disease-associated SNP in ADAM33 and begin to shed light on the deregulation of this gene in the pathophysiology of asthma.

Public data mining shows extended linkage disequilibrium around ADAM33

BACKGROUND

ADAM33 has been described to be the first positional cloned asthma gene. Consecutive association studies have found inconsistent results. At present no functional relevant variation is being known.

OBJECTIVE

Aim of the study was to test if genes in close physical distance could also be responsible for the observed linkage signal.

METHOD

We downloaded three public single-nucleotide polymorphism (SNP) data sets and tested if linkage disequilibrium extends beyond ADAM33.

RESULTS

Linkage disequilibrium extends upstream to a region including GDNF family receptor alpha (GFRA4), attractin (ATRN) and downstream to sialoadhesin (SN) with a peak recombinatory rate at ADAM33 exon S to V.

CONCLUSION

Resequencing of the ADAM33 region including GFRA4, ATRN and SN is expedient.

ADAM33 polymorphisms are associated with aspirin-intolerant asthma in the Japanese population

Multiple single nucleotide polymorphisms (SNPs) within ADAM33 have been reported to be associated with asthma and bronchial hyper-responsiveness in Caucasian populations. We examined whether these SNPs contribute to a predisposition to asthma, especially aspirin-intolerant asthma (AIA), in the Japanese population. Ten polymorphic sites (ST+4, ST+7, T1, T2, T+1, V-3, V-2, V-1, V4, V5) were genotyped in 102 AIA patients, 282 aspirin-tolerant asthma (ATA) patients and 120 control (CTR) subjects by direct sequencing. Haplotype frequencies were estimated by the expectation-maximization method. Differences in allele and haplotype frequencies among phenotypes were analyzed by the chi-square and permutation tests. ST+7, V-1 and V5 sites in the AIA group were significantly different from those in the ATA group (P=0.034-0.004) and from those in the CTR group (P=0.019-0.002). Haplotypes at three sites (ST+7, V-1, and V5) were significantly different in frequency between the AIA and ATA (P=0.008) or CTR (P=0.001) groups. Sequence variations in ADAM33 are likely to correlate with susceptibility to AIA in the Japanese population.