Adult onset asthma and interaction between genes and active tobacco smoking: The GABRIEL consortium.

BACKGROUND: Genome-wide association studies have identified novel genetic associations for asthma, but without taking into account the role of active tobacco smoking. This study aimed to identify novel genes that interact with ever active tobacco smoking in adult onset asthma. METHODS: We performed a genome-wide interaction analysis in six studies participating in the GABRIEL consortium following two meta-analyses approaches based on 1) the overall interaction effect and 2) the genetic effect in subjects with and without smoking exposure. We performed a discovery meta-analysis including 4,057 subjects of European descent and replicated our findings in an independent cohort (LifeLines Cohort Study), including 12,475 subjects. RESULTS: First approach: 50 SNPs were selected based on an overall interaction effect at p<10-4. The most pronounced interaction effect was observed for rs9969775 on chromosome 9 (discovery meta-analysis: ORint = 0.50, p = 7.63*10-5, replication: ORint = 0.65, p = 0.02). Second approach: 35 SNPs were selected based on the overall genetic effect in exposed subjects (p <10-4). The most pronounced genetic effect was observed for rs5011804 on chromosome 12 (discovery meta-analysis ORint = 1.50, p = 1.21*10-4; replication: ORint = 1.40, p = 0.03). CONCLUSIONS: Using two genome-wide interaction approaches, we identified novel polymorphisms in non-annotated intergenic regions on chromosomes 9 and 12, that showed suggestive evidence for interaction with active tobacco smoking in the onset of adult asthma.

A multi-centre study of candidate genes for wheeze and allergy: the International Study of Asthma and Allergies in Childhood Phase 2.

BACKGROUND: Common polymorphisms have been identified in genes suspected to play a role in asthma. We investigated their associations with wheeze and allergy in a case-control sample from Phase 2 of the International Study of Asthma and Allergies in Childhood. METHODS: We compared 1105 wheezing and 3137 non-wheezing children aged 8-12 years from 17 study centres in 13 countries. Genotyping of 55 candidate single nucleotide polymorphisms (SNPs) in 14 genes was performed using the Sequenom System. Logistic regression models were fitted separately for each centre and each SNP. A combined per allele odds ratio and measures of heterogeneity between centres were derived by random effects meta-analysis. RESULTS: Significant associations with wheeze in the past year were detected in only four genes (IL4R, TLR4, MS4A2, TLR9, P<0.05), with per allele odds ratios generally <1.3. Variants in IL4R and TLR4 were also related to allergen-specific IgE, while polymorphisms in FCER1B (MS4A2) and TLR9 were not. There were also highly significant associations (P<0.001) between SPINK5 variants and visible eczema (but not IgE levels) and between IL13 variants and total IgE. Heterogeneity of effects across centres was rare, despite differences in allele frequencies. CONCLUSIONS: Despite the biological plausibility of IgE-related mechanisms in asthma, very few of the tested candidates showed evidence of association with both wheeze and increased IgE levels. We were unable to confirm associations of the positional candidates DPP10 and PHF11 with wheeze, although our study had ample power to detect the expected associations of IL13 variants with IgE and SPINK5 variants with eczema.

Associations of Fc epsilon R1-beta polymorphisms with immunoglobin E antibody responses to common inhalant allergens in a rural population.

BACKGROUND: Polymorphisms within the beta subunit of the high-affinity receptor for IgE (Fc epsilon R1-beta ) on chromosome 11q13 have been related to atopy and asthma and the lymphotoxin alpha (LT alpha) gene on chromosome 6 is implicated in asthma. OBJECTIVE: To elucidate the association of polymorphisms in the Fc epsilon R1-beta and LT alpha genes to IgE responses and asthma in a family-orientated rural population. METHODS: A total of 461 adult farmers, who participated in an epidemiological follow-up study on respiratory symptoms among farmers on the Swedish island of Gotland, were examined. The traits assessed included serum total IgE, IgE antibody responses to 21 common inhalant allergens and asthma. RESULTS: The 237G mutation was only detected in seven persons. Atopy was found to be associated with the RsaI-ex7 AB-genotype (OR = 1.9; P = 0.04). The RsaI-ex7 B allele had a significant influence on IgE responses to pollens and dust mites (OR = 5.5; P = 0.03 and OR = 5.2; P = 0.049, respectively). The influence of this allele was stronger when the association towards single dust mite species (Lepidoglyphus destructor) was estimated (OR = 7.1, P = 0.03) and the association increased even more when the major allergen of L. destructor (rLep d 2) was analysed (OR = 11.2, P = 0.02). These associations were independent of sex, age and smoking, and the estimates of RsaI-in2 independent of RsaI-ex7. RsaI-in2, RsaI-ex7 and LT alpha genotypes were unassociated with total serum IgE. No significant difference in the distribution of RsaI-in2, RsaI-ex7 and LT alpha genotypes was found among subjects with atopy or asthma compared to healthy controls. CONCLUSION: This study supports the notion that polymorphisms in the Fc epsilon R1-beta gene have significant effects on IgE responsiveness. Secondly, dust mites in rural populations influence the expression of genes on chromosome 11q13.

Gibbs sampling-based segregation analysis of asthma-associated quantitative traits in a population-based sample of nuclear families.

Asthma is a common, complex human disease. Elevated serum immunoglobulin E (IgE) levels, elevated blood eosinophil counts, and increased airway responsiveness are physiological traits that are characteristic of asthma. Few studies have investigated major gene effects for these traits in a population-based sample. Further, it is not known if any putative major genes may be common to two or more of these traits. We investigated the existence and nature of major genes modulating asthma-associated quantitative traits in an Australian population-based sample of 210 Caucasian nuclear families. The sharing of these major genes was also investigated. Segregation analysis was based upon a Markov Chain Monte Carlo (Gibbs sampling) approach as implemented in the program BUGS v0.6. All models included adjustment for age, height, tobacco smoke exposure, and gender. The segregation of total IgE levels, blood eosinophil counts, and dose-response slope (DRS) of methacholine challenge were all consistent with major loci at which a recessive allele acted to increase or decrease the phenotype. The respective estimated frequencies of the recessive alleles were 68% (total IgE), 10% (blood eosinophil count), and 27% (DRS). Extensive modelling suggested that the major loci controlling total serum IgE levels, blood eosinophil counts, and airway responsiveness represent different genes. These data provide evidence, for the first time, of the existence of at least 3 distinct genetic pathways involving major gene effects on physiological traits closely associated with asthma. These results have implications for gene discovery programs.

Familial aggregation and heritability of asthma-associated quantitative traits in a population-based sample of nuclear families.

Asthma is a common, genetically complex human disease. Elevated serum immunoglobulin E (IgE) levels, elevated blood eosinophil counts, variably reduced spirometric measures and increased airway responsiveness (AR) are physiological traits which are characteristic of asthma. We investigated the genetic and environmental components of variance of serum total and specific IgE levels, blood eosinophil counts, the forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), and AR in an Australian population-based sample of 232 Caucasian nuclear families. With the exception of FVC levels, all traits were closely associated with clinical asthma in this population. Loge total serum IgE levels had a narrow-sense heritability (h2N) of 47.3% (SE = 10. 0%). Specific serum IgE levels against house dust mite and Timothy grass, measured as a RAST Index, had a h2N of 33.8% (SE = 7.3%). FEV1 levels had a h2N of 6.1% (SE = 11.6%), whilst FVC levels had a h2N of 30.6% (SE = 26.8%). AR, quantified by the loge dose-response slope to methacholine (DRS), had a h2N of 30.3% (SE = 12.3%). These data are consistent with the existence of important genetic determinants of the pathophysiological traits associated with asthma. Our study suggests that total and specific serum IgE levels, blood eosinophil counts and airways responsiveness to inhaled agonist are appropriate phenotypes for molecular investigations of the genetic susceptibility to asthma.

Adult familial cryptogenic fibrosing alveolitis in the United Kingdom.

BACKGROUND: Familial cases of cryptogenic fibrosing alveolitis (CFA) have previously been reported; however, the prevalence and genetic background of this disorder are not known. The clinical and epidemiological findings of 25 families identified within the UK are reported. METHODS: Adult pulmonary physicians in the UK were asked to identify all families under their care in which two or more individuals had been diagnosed with fibrosing alveolitis of unknown cause. A detailed structured questionnaire was sent to each proband to delineate possible environmental/occupational exposures and to obtain complete pedigree data. Physicians were also asked to provide clinical and diagnostic information. RESULTS: Twenty five families were identified comprising 67 cases. Suitable data for analysis were available for 21 families (57 cases). The male:female ratio was 1. 75:1 (p<0.05). A high resolution computed tomographic (HRCT) scan was performed in 93% and a diagnosis of CFA confirmed on biopsy specimens in 32%. The mean age at diagnosis was 55.5 (2.5) years. Fifty percent of cases were ever smokers and 18% had been diagnosed as asthmatic. Exposure to known fibrogenic agents was recorded by 36% of patients. Clinical signs/symptoms and histological findings were indistinguishable from non-familial cases. CONCLUSIONS: This study represents the largest cohort of familial CFA cases reported to date and confirms a prevalence of 1.34 cases per 10(6) in the UK population. Although rare, such cases represent an important subgroup in which a genetic susceptibility to pulmonary fibrosis is particularly evident. Familial patients are younger at diagnosis but otherwise indistinguishable from non-familial cases. The mode of inheritance is as yet unclear but a number of genetic loci are likely to be involved and are the subject of ongoing studies.

Extended tumour necrosis factor/HLA-DR haplotypes and asthma in an Australian population sample.

BACKGROUND: Tumour necrosis factor (TNF) is a potent pro-inflammatory cytokine which is prominent in asthmatic airways. TNF shows genetic variations in secretion which are linked to polymorphisms in the TNF gene complex and the surrounding major histocompatibility (MHC) locus. These polymorphisms do not seem to be themselves functionally important. In these circumstances, the identification of disease associated haplotypes (combination of alleles on individual chromosomes) may narrow the search for polymorphisms which alter gene function. METHODS: TNF-308, LTalpha NcoI, and HLA-DRB1 polymorphisms were investigated for association with asthma, bronchial responsiveness, and medication use in 1004 subjects in 230 families from a general population sample. RESULTS: The common LTalpha NcoI*1/TNF-308*2/HLA-DRB1*03 haplotype, which was present in 11% of unrelated individuals, was weakly associated with asthma (OR = 1.38, p = 0.016, corrected for familial correlation). The rarer LTalpha NcoI*1/TNF-308*2/HLA-DRB1*02 haplotype, which was found in 0.6% of unrelated subjects, was more strongly associated with asthma (OR = 6.68, p = 0.002). This haplotype also showed association with bronchial hyperresponsiveness (OR = 21.9, p = 0. 0000) and the use of inhaled or oral steroids (OR 8.0, p = 0.04). CONCLUSIONS: The results of this study show only two extended TNF/HLA-DR haplotypes to be associated with asthma. The search for functional alleles responsible for an increased risk of asthma should concentrate on the LTalpha NcoI*1/TNF-308*2/HLA-DRB1*02 haplotype.

A genome-wide screen for asthma-associated quantitative trait loci in a mouse model of allergic asthma.

Asthma is the most common illness of childhood, affecting one child in seven in the UK. Asthma has a genetic basis, but genetic studies of asthma in humans are confounded by uncontrolled environmental factors, varying penetrance and phenotypic pleiotropy. An animal model of asthma would offer controlled exposure, limited and consistent genetic variation, and unlimited size of sibships. Following immunization and subsequent challenge with ovalbumin, the Biozzi BP2 mouse shows features of asthma, including airway inflammation, eosinophil infiltration and non-specific bronchial responsiveness. In order to identify genetic loci influencing these traits, a cross was made between BP2 and BALB/c mice, and a genome-wide screen carried out in the F2progeny of the F1intercross. Five potentially linked loci were identified, four of which corresponded to human regions of syntenic homology that previously have shown linkage to asthma-associated traits.

Fc epsilon R1-beta polymorphism and total serum IgE levels in endemically parasitized Australian aborigines.

Endemic helminthic infection is a major public-health problem and affects a large proportion of the world's population. In Australia, helminthic infection is endemic in Aboriginal communities living in tropical northern regions of the continent. Such infection is associated with nonspecific (polyclonal) stimulation of IgE synthesis and highly elevated total serum IgE levels. There is evidence that worm-infection variance (i.e., human capacity of resistance) and total serum IgE levels may be related to the presence of a major codominant gene. The beta chain of the high-affinity IgE receptor, Fc epsilon R1-beta, has been previously identified as a candidate for the close genetic linkage of the 11q13 region to IgE responses in several populations. We show a biallelic RsaI polymorphism in Fc epsilon R1-beta to be associated with total serum IgE levels (P = .0001) in a tropical population of endemically parasitized Australian Aborigines (n = 234 subjects). The polymorphism explained 12.4% of the total residual variation in serum total IgE and showed a significant (P = .0000) additive relationship with total serum IgE levels, across the three genotypes. These associations were independent of familial correlations, age, gender, racial admixture, or smoking status. Alleles of a microsatellite repeat in intron 5 of the same gene showed similar associations. The results suggest that variation in Fc epsilon R1-beta may regulate IgE-mediated immune responses in this population.

Tumour necrosis factor haplotypes and asthma.

Airway inflammation is a prominent feature of asthma. The pro-inflammatory cytokine Tumour Necrosis Factor shows constitutional variation in its level of secretion, which is linked to polymorphisms within the TNF gene complex and the surrounding MHC. In this study, 413 subjects in 88 nuclear families from a general population sample were examined for association with asthma and TNF polymorphisms. Ninety-two subjects were asthmatic, as defined by questionnaire. Asthma was significantly more common in subjects with allele 1 of the LT alpha NcoI polymorphism (LT alpha NcoI*1) (p = 0.005), and allele 2 of the TNF-308 polymorphism (TNF-308*2) (p = 0.004). The association was confined to the LT alpha NcoI*1/TNF-308*2 haplotype, so that it was not possible to differentiate between the effects of LT alpha NcoI and TNF-308 alleles. The HLA-DR locus was excluded as a cause of this association. The results suggest that genetic influences on inflammation may be important in the pathogenesis of asthma.

The association of HLA-DR3 with specific IgE to inhaled acid anhydrides.

We have undertaken a case referent study of the association between HLA allele frequency and specific IgE antibody to acid anhydride-human serum albumin (AA-HSA) conjugates among acid anhydride workers. Thirty cases with radio-allergosorbent test score versus AA-HSA conjugates > 2 were compared with 30 referents without specific IgE selected from the same factory sites as the cases and matched for age, sex, duration of exposure, atopic status, and smoking habit. We found a significant excess of HLA-DR3 in the cases with specific IgE to acid anhydrides when compared with the referents (50% versus 14%, Fisher's statistic = 8.4; odds ratio = 6, p = 0.05 corrected). The excess of HLA-DR3 was particularly associated with IgE versus trimellitic anhydride, with HLA-DR3 present in eight of 11 workers with and in two of 14 referents without IgE (Fisher's statistic = 8.5, odds ratio = 16, p = 0.004). The proportion of HLA-DR3 among the phthalic anhydride workers was not different in those with IgE (two of 12) from their referents (two of 14). These findings suggest MHC II proteins are an important determinant of the specificity of the IgE response to an inhaled hapten.

Radiographic abnormalities and mortality in subjects with exposure to crocidolite.

Plain chest radiographs from a one in six random sample of the workforce of the asbestos industry at Wittenoom, Western Australia between 1943 and 1966 have been classified for degree of profusion and pleural thickening by two independent observers according to the 1980 UICC-ILO Classification of Radiographs for the pneumoconioses to clarify the effect of degree of radiological abnormality on survival. A total of 1106 subjects were selected. Each subject's age, cumulative exposure to crocidolite, and time since first exposure were determined from employment records, the results of a survey of airborne concentrations of fibres > 5 mu in length conducted in 1966, and an exposure rating by an industrial hygienist and an ex-manager of the mine and mill at Wittenoom. By the end of 1986 193 subjects had died. Conditional logistic regression was used to model the relative risk of death in five separate case-control analyses in which the outcomes were deaths from: (1) all causes, (2) malignant mesothelioma, (3) lung cancer, (4) asbestosis, and (5) other causes excluding cancer and asbestosis. Up to 20 controls per case were randomly chosen from all men of the same age who were not known to have died before the date of death of the index case. After adjustment for exposure and time since first exposure, there were significant and independent effects of radiographic profusion and pleural thickening on all cause mortality. The effect of profusion was largely a result of the effect on mortality from malignant mesothelioma and asbestosis but not lung cancer. The effect of pleural thickening was greatest on mortality from other causes, mainly ischaemic heart disease. This study has shown that degree of radiographic abnormality has an independent effect on mortality from malignant mesothelioma, asbestosis, and all causes even after allowing for the effects of age, degree of exposure, and time since first exposure.

Natural history of pleural thickening after exposure to crocidolite.

Serial plain chest radiographs of 384 men who worked at the Wittenoom crocidolite mine and mill between 1943 and 1966 and who applied for pneumoconiosis compensation between 1948 and 1982 have been examined independently by two trained observers for pleural disease using the 1980 ILO-UICC classification of radiographs to record width and extent of pleural disease. Radiographs covering follow up periods of from two to 38 years were examined (median number of films per subject was nine). The degree of crocidolite exposure was estimated from employment records and a survey of airborne fibre concentrations performed in 1966. Agreement between the observers on the presence and degree of pleural disease in the final film for each subject was moderately close (Kendall's tau B = 0.62) and was least for subjects with thickening less than 5 mm in width. Diffuse pleural thickening extending for greater than 50% of the lateral chest wall was the most common type recorded by both observers. Minor pleural thickening frequently progressed in extent along the lateral chest wall but progression beyond 5 mm in thickness was less common. Pleural plaques were not seen to progress beyond their initial thickness or extent. The rate of onset of thickening in this population increased continually from the time of first exposure and also increased slightly with age. There was evidence that the level of total cumulative exposure to crocidolite increased the rate of onset of pleural thickening in the period between five and 15 years after first exposure. Rate of progression of established thickening was greatest in subjects who first developed thickening early after first exposure. The relative rate of progression decreased slowly with time from first signs of thickening and there was no evidence of any progression more than 15 years after onset.

Radiographic abnormalities and duration of employment in Western Australian iron-ore miners.

Plain chest radiographs of 788 Pilbara iron-ore miners from Western Australia have been examined by two independent observers for evidence of pneumoconiosis. The prevalence of any radiographic abnormality (a profusion grade of 0/1 or greater on the International Labour Office [ILO] scale) was 6.7% for Reader 1 and 9.9% for Reader 2. The prevalence of a definite radiographic abnormality (a profusion grade of 1/0 or greater on the ILO scale) was 1.9% for Reader 1 and 2.8% for Reader 2. The prevalence of any abnormality, as identified by either or by both observers, was significantly related to age. The relationship between a radiographic abnormality and the duration of employment was less clear. The results indicate a need for more detailed and comprehensive studies of the effects of iron-ore dust in this industry.

Changes in blood gas levels after nebuhaler and nebulizer administration of terbutaline in severe chronic airway obstruction.

It has been suggested that patients with severe chronic airway obstruction might suffer dangerous hypoxia after administration of a beta-agonist through an air driven nebulizer. Twenty patients with severe chronic airway obstruction (12 male, mean age 71.1 (SEM 1.5) yr) were monitored with a Biox oximeter and Hewlett-Packard capnometer before and after 4 mg terbutaline was delivered through an air driven nebulizer or Nebuhaler. The eight patients with chronic hypoxia (mean PaO2 6.76 kPa, PaCO2 7.47 kPa. FEV1 0.53 l) experienced a 4.7% increase in oxygen saturation (SaO2) and 2.9% fall in transcutaneous carbon dioxide tension (PtcCO2) (p less than 0.05) during all treatments, followed by a return to initial levels. These changes were attributable to increased ventilation whilst breathing through a mouthpiece. A similar trend was seen in the SaO2 of the twelve normoxic patients (mean PaO2 9.32 kPa, PaCO2 5.34 kPa, FEV1 0.8 l), but there was a sustained fall in PtcCO2 of 3.7% (p less than 0.001) after administration of terbutaline. Inhaled terbutaline in the dosage given did not cause hypoxia in patients with severe chronic airflow obstruction, but nebulizer and Nebuhaler use was associated with a rise in SaO2 related to increased ventilation whilst breathing through a mouthpiece.

Dysgerminoma, gonadoblastoma, and testicular germ cell neoplasia in phenotypically female and male siblings with 46 XY genotype.

46 XY gonadal dysgenesis is a syndrome characterized by a female phenotype with streak gonads and complicated by the frequent occurrence of germ cell tumors. The syndrome and the risk of malignant disease occur in female siblings sharing the XY genotype, and screening of female siblings and prophylactic gonadectomy in those affected is generally recommended. A family of four siblings is described in which two phenotypically female XY children and one male each have developed germ cell tumors, demonstrating that brothers of affected sisters may also be at risk.

Benign and malignant pleural effusions in former Wittenoom crocidolite millers and miners.

Serial plain chest radiographs taken between 1943 and 1982 for 280 claimants for compensation for asbestosis and 32 claimants for malignant pleural mesothelioma from the Wittenoom asbestos industry were reviewed by two observers to identify diffuse pleural thickening and pleural effusion. A pleural effusion which appeared and resolved within two years without radiographic or clinical evidence of underlying malignancy, infection or cardiac failure was seen in 15 cases by reader 1 and 24 cases by reader 2. Eighteen cases of effusion, determined from clinical records to be caused by malignant pleural mesothelioma, were seen by reader 1 and 20 by reader 2. The latent periods between commencing work and the first radiograph showing effusion were much shorter for subjects with benign asbestos pleural effusion than for subjects with effusion due to malignant pleural mesothelioma, although there was considerable overlap in the range. The longest latent period for benign asbestos pleural effusion was 22 years and the shortest period for effusion due to malignant pleural mesothelioma was 12 years. The latent period for benign asbestos pleural effusion was inversely related to total cumulative exposure, whereas that for effusion due to malignant pleural mesothelioma was significantly shorter for subjects who had worked in the mill than for those who had worked in the mine. A long latent period and a history of working in the mill were significant discriminators for a malignant as opposed to a benign basis for an effusion. The appearance of a benign asbestos pleural effusion appeared to be a risk factor for the severity of subsequent diffuse pleural thickening.(ABSTRACT TRUNCATED AT 250 WORDS)

Compensation, radiographic changes, and survival in applicants for asbestosis compensation.

The survival of 354 claimants for compensation for pulmonary asbestosis among former workers of the Wittenoom crocidolite mine and mill in Western Australia has been examined. There were 118 deaths up to December 1982. The median time between start of work and claim for compensation was 17 years. The standardised mortality ratio (SMR) for deaths from all causes was 2.65 (p less than 0.0001). The SMR for pneumoconiosis was 177.2 (p less than 0.0001), bronchitis and emphysema 2.6 (p = 0.04), tuberculosis 44.6 (p less than 0.0001), respiratory cancer (including five deaths from malignant pleural mesothelioma) 6.4 (p less than 0.0001), gastrointestinal cancer 1.6 (p = 0.22), all other cancers 1.6 (p = 0.17), heart disease 1.4 (p = 0.07), and all other causes 2.18 (p = 0.004). Plain chest radiographs taken within two years of claiming compensation were found for 238 subjects and were categorised independently by two observers according to the International Labour Organisation criteria without knowledge of exposure or compensation details. Profusion of radiographic opacities, age at claiming compensation, work in the Wittenoom mill, and degree of disability awarded by the pneumoconiosis medical board were significant predictors of survival, but total estimated exposure to asbestos was not. Radiographic profusion and degree of disability were, however, predictable by total exposure. The median survival from claim for compensation was 17 years in subjects with ILO category 1 pneumoconiosis, 12 years in category 2, and three years in category 3.