Complex association patterns for inflammatory mediators in induced sputum from subjects with asthma.

BACKGROUND: The release of various inflammatory mediators into the bronchial lumen is thought to reflect both the type and degree of airway inflammation, eosinophilic Th2, and Th9, or neutrophilic Th1, and Th17, in patients with asthma. AIMS: We investigated whether cytokines and chemokines differed in sputum from subjects with more severe compared with milder asthma and whether unbiased factor analysis of cytokine and chemokine groupings indicates specific inflammatory pathways. METHODS: Cell-free supernatants from induced sputum were obtained from subjects with a broad range of asthma severity (n = 158) and assessed using Milliplex® Cytokines/Chemokine kits I, II and III, measuring 75 individual proteins. Each cytokine, chemokine or growth factor concentration was examined for differences between asthma severity groups, for association with leucocyte counts, and by factor analysis. RESULTS: Severe asthma subjects had 9 increased and 4 decreased proteins compared to mild asthma subjects and fewer differences compared to moderate asthma. Twenty-six mediators were significantly associated with an increasing single leucocyte type: 16 with neutrophils (3 interleukins [IL], 3 CC chemokines, 4 CXC chemokines, 4 growth factors, TNF-α and CX3CL1/Fractalkine); 5 with lymphocytes (IL-7, IL-16, IL-23, IFN-α2 and CCL4/MIP1ß); IL-15 and CCL15/MIP1δ with macrophages; IL-5 with eosinophils; and IL-4 and TNFSF10/TRAIL with airway epithelial cells. Factor analysis grouped 43 cytokines, chemokines and growth factors which had no missing data onto the first 10 factors, containing mixes of Th1, Th2, Th9 and Th17 inflammatory and anti-inflammatory proteins. CONCLUSIONS: Sputum cytokines, chemokines and growth factors were increased in severe asthma, primarily with increased neutrophils. Factor analysis identified complex inflammatory protein interactions, suggesting airway inflammation in asthma is characterized by overlapping immune pathways. Thus, focus on a single specific inflammatory mediator or pathway may limit understanding the complexity of inflammation underlying airway changes in asthma and selection of appropriate therapy.

Responsiveness to oral prednisolone in severe asthma is related to the degree of eosinophilic airway inflammation.

BACKGROUND: Patients with severe asthma appear relatively corticosteroid resistant. Corticosteroid responsiveness is closely related to the degree of eosinophilic airway inflammation. The extent to which eosinophilic airway inflammation in severe asthma responds to treatment with systemic corticosteroids is not clear. OBJECTIVE: To relate the physiological and inflammatory response to systemic corticosteroids in asthma to disease severity and the baseline extent of eosinophilic inflammation. METHODS: Patients with mild/moderate and severe asthma were investigated before and after 2 weeks of oral prednisolone (Clintrials.gov NCT00331058 and NCT00327197). We pooled the results from two studies with common protocols. The US study contained two independent centres and the UK one independent centre. The effect of oral corticosteroids on FEV1 , Pc20, airway inflammation and serum cytokines was investigated. Baseline measurements were compared with healthy subjects. RESULTS: Thirty-two mild/moderate asthmatics, 50 severe asthmatics and 35 healthy subjects took part. At baseline, both groups of asthmatics had a lower FEV1 and Pc20 and increased eosinophilic inflammation compared to healthy subjects. The severe group had a lower FEV1 and more eosinophilic inflammation compared to mild/moderate asthmatics. Oral prednisolone caused a similar degree of suppression of eosinophilic inflammation in all compartments in both groups of asthmatics. There were small improvements in FEV1 and Pc20 for both mild/ moderate and severe asthmatics with a correlation between the baseline eosinophilic inflammation and the change in FEV1 . There was a ~50% reduction in the serum concentration of CXCL10 (IP-10), CCL22 (MDC), CCL17 (TARC), CCL-2 (MCP-1) and CCL-13 (MCP-4) in both asthma groups after oral corticosteroids. CONCLUSIONS AND CLINICAL RELEVANCE: Disease severity does not influence the response to systemic corticosteroids. The study does not therefore support the concept that severe asthma is associated with corticosteroid resistance. Only baseline eosinophilic inflammation was associated with the physiological response to corticosteroids, confirming the importance of measuring eosinophilic inflammation to guide corticosteroid use.

eQTL of bronchial epithelial cells and bronchial alveolar lavage deciphers GWAS-identified asthma genes.

BACKGROUND: Genome-wide association studies (GWASs) have identified various genes associated with asthma, yet, causal genes or single nucleotide polymorphisms (SNPs) remain elusive. We sought to dissect functional genes/SNPs for asthma by combining expression quantitative trait loci (eQTLs) and GWASs. METHODS: Cis-eQTL analyses of 34 asthma genes were performed in cells from human bronchial epithelial biopsy (BEC, n = 107) and from bronchial alveolar lavage (BAL, n = 94). RESULTS: For TSLP-WDR36 region, rs3806932 (G allele protective against eosinophilic esophagitis) and rs2416257 (A allele associated with lower eosinophil counts and protective against asthma) were correlated with decreased expression of TSLP in BAL (P = 7.9 × 10(-11) and 5.4 × 10(-4) , respectively) and BEC, but not WDR36. Surprisingly, rs1837253 (consistently associated with asthma) showed no correlation with TSLP expression levels. For ORMDL3-GSDMB region, rs8067378 (G allele protective against asthma) was correlated with decreased expression of GSDMB in BEC and BAL (P = 1.3 × 10(-4) and 0.04) but not ORMDL3. rs992969 in the promoter region of IL33 (A allele associated with higher eosinophil counts and risk for asthma) was correlated with increased expression of IL33 in BEC (P = 1.3 × 10(-6) ) but not in BAL. CONCLUSIONS: Our study illustrates cell-type-specific regulation of the expression of asthma-related genes documenting SNPs in TSLP, GSDMB, IL33, HLA-DQB1, C11orf30, DEXI, CDHR3, and ZBTB10 affect asthma risk through cis-regulation of its gene expression. Whenever possible, disease-relevant tissues should be used for transcription analysis. SNPs in TSLP may affect asthma risk through up-regulating TSLP mRNA expression or protein secretion. Further functional studies are warranted.

An airway epithelial iNOS-DUOX2-thyroid peroxidase metabolome drives Th1/Th2 nitrative stress in human severe asthma.

Severe refractory asthma is associated with enhanced nitrative stress. To determine the mechanisms for high nitrative stress in human severe asthma (SA), 3-nitrotyrosine (3NT) was compared with Th1 and Th2 cytokine expression. In SA, high 3NT levels were associated with high interferon (IFN)-γ and low interleukin (IL)-13 expression, both of which have been reported to increase inducible nitric oxide synthase (iNOS) in human airway epithelial cells (HAECs). We found that IL-13 and IFN-γ synergistically enhanced iNOS, nitrite, and 3NT, corresponding with increased H(2)O(2). Catalase inhibited whereas superoxide dismutase enhanced 3NT formation, supporting a critical role for H(2)O(2), but not peroxynitrite, in 3NT generation. Dual oxidase-2 (DUOX2), central to H(2)O(2) formation, was also synergistically induced by IL-13 and IFN-γ. The catalysis of nitrite and H(2)O(2) to nitrogen dioxide radical (NO(2)(•)) requires an endogenous peroxidase in this epithelial cell system. Thyroid peroxidase (TPO) was identified by microarray analysis ex vivo as a gene distinguishing HAEC of SA from controls. IFN-γ induced TPO in HAEC and small interfering RNA knockdown decreased nitrated tyrosine residues. Ex vivo, DUOX2, TPO, and iNOS were higher in SA and correlated with 3NT. Thus, a novel iNOS-DUOX2-TPO-NO(2)(•) metabolome drives nitrative stress in HAEC and likely in SA.

Severe chronic allergic (and related) diseases: a uniform approach--a MeDALL--GA2LEN--ARIA position paper.

Concepts of disease severity, activity, control and responsiveness to treatment are linked but different. Severity refers to the loss of function of the organs induced by the disease process or to the occurrence of severe acute exacerbations. Severity may vary over time and needs regular follow-up. Control is the degree to which therapy goals are currently met. These concepts have evolved over time for asthma in guidelines, task forces or consensus meetings. The aim of this paper is to generalize the approach of the uniform definition of severe asthma presented to WHO for chronic allergic and associated diseases (rhinitis, chronic rhinosinusitis, chronic urticaria and atopic dermatitis) in order to have a uniform definition of severity, control and risk, usable in most situations. It is based on the appropriate diagnosis, availability and accessibility of treatments, treatment responsiveness and associated factors such as comorbidities and risk factors. This uniform definition will allow a better definition of the phenotypes of severe allergic (and related) diseases for clinical practice, research (including epidemiology), public health purposes, education and the discovery of novel therapies.

Predicting worsening asthma control following the common cold.

The asthmatic response to the common cold is highly variable, and early characteristics that predict worsening of asthma control following a cold have not been identified. In this prospective multicentric cohort study of 413 adult subjects with asthma, the mini-Asthma Control Questionnaire (mini-ACQ) was used to quantify changes in asthma control and the Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21) to measure cold severity. Univariate and multivariable models were used to examine demographic, physiological, serological and cold-related characteristics for their relationship to changes in asthma control following a cold. Clinically significant worsening of asthma control was observed following a cold (mean+/-SD increase in mini-ACQ score of 0.69+/-0.93). Univariate analysis demonstrated that season, centre location, cold duration and cold severity measurements were all associated with a change in asthma control. Multivariable analysis of the covariates available within the first 2 days of cold onset revealed that the day 2 and cumulative sum of day 1 and 2 WURSS-21 scores were significant predictors of the subsequent changes in asthma control. In asthmatic subjects, cold severity within the first 2 days can be used to predict subsequent changes in asthma control. This information may help clinicians prevent deterioration in asthma control following a cold.

Overview of the pharmacogenetics of asthma treatment.

Asthma affects approximately 300 million individuals worldwide. Medications comprise a substantial portion of asthma expenditures. Despite the availability of three primary therapeutic classes of medications, there are a significant number of nonresponders to therapy. Available data, as well as previous pharmacogenetic studies, suggest that genetics may contribute as much as 60-80% to the interindividual variability in treatment response. In this methodologic review, after providing a broad overview of the asthma pharmacogenetics literature to date, we describe the application of a novel family-based screening algorithm to the analysis of pharmacogenetic data and highlight our approach to identifying and verifying loci influencing asthma treatment response. This approach seeks to address issues related to multiple comparisons, statistical power, population stratification, and failure to replicate from which previous population-based or case-control pharmacogenetic association studies may suffer. Identification of such replicable loci is the next step towards the goal of 'individualized therapy' for asthma.

Polymorphisms of the ADAM33 gene are associated with accelerated lung function decline in asthma.

BACKGROUND: Asthma is a genetically complex disease characterized by respiratory symptoms, intermittent airway obstruction and airway hyper-responsiveness due to airway inflammation and remodelling. The ADAM33 gene is associated with asthma and airway hyper-responsiveness and is postulated as a gene for airway remodelling. OBJECTIVE: To investigate whether polymorphisms of the ADAM33 gene are associated with accelerated lung function decline in patients with asthma. METHODS: In a cohort of 200 asthma patients followed over 20 years, eight single nucleotide polymorphisms of the ADAM33 gene were analysed to estimate their effect on annual FEV(1) decline. RESULTS: The rare allele of the S_2 polymorphism was significantly associated with excess decline in FEV(1) (P<0.05). CONCLUSION: These findings suggest that a variant in ADAM33 is not only important in the development of asthma but also in disease progression, possibly related to enhanced airway remodelling.

Genome scan for loci linked to mite sensitivity: the Collaborative Study on the Genetics of Asthma (CSGA).

Mite sensitivity has been reported to be a major risk factor for asthma. As part of the Collaborative Study on the Genetics of Asthma (CSGA), a genome scan using mite reactivity (Dermatophagoides Pteronyssinus (Der p) and Dermatophagoides farinae (Der f)) as the phenotype was conducted. In 287 CSGA families, 122 were informative for linkage. Evidence supporting linkage was observed for regions on chromosome 19 (D19S591, lod=2.43, P=0.0008; D19S1037, lod=1.57, P=0.007) and chromosome 20 (D20S473/D20S604, lod=1.41, P=0.01). All three ethnic groups appeared to contribute to the evidence for linkage on chromosome 20. African-American families gave strongest support for linkage on chromosomes 3 (D3S2409, lod=1.33, P=0.01), 12 (D12S373, lod=1.51, P=0.008) and 18 (ATA82B02, lod=1.32, P=0.01). Caucasian families showed strong evidence for linkage on chromosome 19 (D19S591, lod=3.51, P=0.00006). Hispanic families supported linkage on chromosomes 11 (D11S1984, lod=1.56, P=0.007), 13 (D13S787, lod=1.30, P=0.01) and 20 (D20S470, lod=1.71, P=0.005). These results suggest that multiple genes may be involved in controlling skin reactivity to Dermatophoigoies.

Polymorphisms in the CYP1B1 gene are associated with increased risk of prostate cancer.

CYP1B1 has been evaluated as a candidate gene for various cancers because of its function in activating environmental procarcinogens and catalysing the conversion of oestrogens to genotoxic catechol oestrogens. To test the hypothesis that genetic polymorphisms in the CYP1B1 gene may associate with the risk for prostate cancer (CaP), we compared the allele, genotype, and haplotype frequencies of 13 single nucleotide polymorphisms (SNPs) of CYP1B1 among 159 hereditary prostate cancer (HPC) probands, 245 sporadic CaP cases, and 222 unaffected men. When each of the SNPs was analysed separately, marginally significant differences were observed for allele frequencies between sporadic cases and controls for three consecutive SNPs (-1001C/T, -263G/A, and -13C/T, P=0.04-0.07). Similarly, marginally significant differences between sporadic cases and controls in the frequency of variant allele carriers were observed for five consecutive SNPs (-1001C/T, -263G/A, -13C/T, +142C/G, and +355G/T, P=0.02-0.08). Interestingly, when the combination of these five SNPs was analysed using a haplotype approach, a larger difference was found (P=0.009). One frequent haplotype (C-G-C-C-G of -1001C/T, -263G/A, -13C/T, +142C/G, and +355G/T) was associated with an increased risk for CaP, while the other frequent haplotype (T-A-T-G-T) was associated with a decreased risk for CaP. These findings suggest that genetic polymorphisms in CYP1B1 may modify the risk for CaP.

Risk factors associated with the presence of irreversible airflow limitation and reduced transfer coefficient in patients with asthma after 26 years of follow up.

BACKGROUND: Childhood asthma is generally believed to be a disorder with a good prognosis. However, some asthmatics develop irreversible airway obstruction, probably as a result of airway remodelling. METHODS: After 21-33 years, 228 adults (aged 13-44 years at baseline) with a history of asthma were re-examined to assess risk factors for the development of irreversible airway obstruction (IAO, forced expiratory volume in 1 second (FEV(1)) <80% predicted and reversibility <9% predicted) and a reduced postbronchodilator transfer coefficient (carbon monoxide transfer factor/alveolar volume, <80% predicted), both characteristics of COPD. RESULTS: At follow up, 41% did not have airway obstruction (NAO), 43% had reversible airway obstruction (RAO), and 16% had IAO; 23% had a reduced transfer coefficient. Patients with RAO had asthma-like characteristics (wheezing, asthma attacks, bronchial hyperresponsiveness (BHR)) while patients with IAO had COPD-like symptoms (cough, phlegm, dyspnoea) at follow up. The development of IAO is determined by a lower FEV(1), less reversibility of airway obstruction and, surprisingly, less severe BHR at initial screening. Eighty percent of the patients with asthma who used anti-inflammatory medication still had airway obstruction, but IAO developed less frequently. Smoking was associated with a reduced transfer coefficient but not with the development of IAO. Female sex was associated with a reduced transfer coefficient, whereas corticosteroid use was not. CONCLUSIONS: Although IAO and a low transfer coefficient are both characteristics of COPD, they represent distinct entities in adult asthmatics in terms of symptomatology, aetiology, and probably in therapeutic approaches and disease prevention.

Sibling effect on atopy in children of patients with asthma.

BACKGROUND: Multiple population studies have shown the presence of a sibling effect on atopic disease. However, it is unclear if the sibling effect is also of importance in subjects who are genetically at high risk for the development of atopy. OBJECTIVE: To study the presence of a sibling effect on markers of atopy (serum total IgE, specific IgE, skin tests) and asthma (bronchial hyper-responsiveness to histamine) in families ascertained through a parent with asthma. METHODS: First-degree offspring in 200 asthma families were studied (n = 541). Mixed effects regression models were used to account for the dependence of the observations within a family, and to adjust for possible confounding variables. RESULTS: Multiple regression analysis showed that having older siblings was inversely related to atopy, defined as >/= 2, >/= 3, >/= 4, or >/= 5 skin tests (P = 0.07-0.009). In addition, family size (number of siblings) had a significant protective effect on the presence of specific IgE to common aeroallergens (P = 0.03). Exposure to cigarette smoke in the first 3 years of life significantly increased the risk of having specific IgE to common aeroallergens (P = 0.04). No sibling effect was detected for serum total IgE or bronchial hyper-responsiveness to histamine. CONCLUSIONS: This study shows a protective sibling effect on the presence and severity of atopy but not on bronchial hyper-responsiveness in children who are genetically at risk. The identification of the sibling effect in high-risk families stresses the need to understand the basis of this effect, in order to design future prevention programmes.

Subjects with mild and moderate asthma respond to segmental allergen challenge with similar, reproducible, allergen-specific inflammation.

BACKGROUND: The relationship between severity of asthma and bronchial inflammation is poorly understood. OBJECTIVE: We examined acute and subacute inflammatory responses to allergen in subjects with mild and moderate persistent asthma to evaluate whether different cellular and mediator responses to endobronchial allergen challenge are associated with differences in disease severity. METHODS: Segmental allergen challenge was performed in 8 subjects with mild and 10 subjects with moderate allergic asthma to compare baseline airways inflammation and allergen-induced inflammatory responses 24 hours later. This evaluation was repeated after 6 weeks in 9 subjects to investigate the reproducibility of these inflammatory responses. RESULTS: Subjects with mild and moderate asthma had similar decreases in FEV(1) in response to segmental allergen challenge (9.1% +/- 4.2% vs 15.1% +/- 4.6%, P = .35). There was no difference in inflammatory cell counts or cytokine concentrations in the groups with mild and moderate asthma at baseline or after saline or allergen challenge. Repeat segmental allergen challenge 6 weeks later showed that these cellular and cytokine responses were reproducible. CONCLUSION: Segmental allergen challenge in subjects with mild and moderate asthma produces similar allergen-specific physiologic and inflammatory responses that are reproducible 6 weeks later. In this model of allergic asthma, acute responses to allergen do not appear to be related to disease severity.

Identification and association of polymorphisms in the interleukin-13 gene with asthma and atopy in a Dutch population.

Asthma and atopy are related conditions that may share similar genetic susceptibility. Linkage studies have identified a region on chromosome 5q that contains biologic candidates for both asthma and atopy phenotypes, including several proinflammatory cytokines. Interleukin (IL)-13, one of the candidate genes in the region, is directly involved in the regulation of immunoglobulin E and has been associated with both asthma and atopy. We sought to identify new polymorphisms in the IL-13 gene, and evaluated the involvement of a subset of these variants in asthma and atopy in a case-control study using probands and spouses from a Dutch asthma family study. IL-13 was sequenced in 20 probands and 20 unaffected spouses, and 10 polymorphisms were identified, four novel and six previously reported. Three single nucleotide (nt) polymorphisms (SNPs) were detected in the 5'-promoter region, two in intron 1, and five in exon 4. Only one of the exon 4 SNPs resulted in an amino-acid change (Arg130Gln). We analyzed three SNPs in IL-13 in an extended group of 184 probands and their spouses: one in the promoter region (-1111), the Arg130Gln (nt position 4257), and a 3' untranslated region SNP (nt position 4738). The most significant associations were observed to asthma (P = 0.005), bronchial hyperresponsiveness (P = 0.003), and skin-test responsiveness (P = 0.03) with the -1111 promoter. These results provide evidence that variation in the IL-13 gene is involved in the pathogenesis of asthma and atopy. Further investigation is required to determine which specific alleles or combination of alleles contribute to these phenotypes, and the possible downstream effects of the resulting change in IL-13 levels or activity.

Linkage and association of CYP17 gene in hereditary and sporadic prostate cancer.

Androgens are essential for prostate development, growth and maintenance and the association between androgen levels and prostate cancer is well established. Since the CYP17 gene encodes the enzyme cytochrome P450c17alpha, which mediates 17alpha-hydroxylase and 17,20-lyase activities in the androgen biosynthesis pathway, sequence variations in the gene and association with increased risk to prostate cancer has been studied. In particular, several groups have studied the association between a polymorphism in the 5' promoter region and prostate cancer using a population-based association approach. However, the results from these studies were inconclusive. To further study this polymorphism and its possible role in hereditary prostate cancer (HPC), we performed a genetic linkage analysis and family-based association analysis in 159 families, each of which contains at least 3 first-degree relatives with prostate cancer. In addition, we performed a population-based association analysis to compare the risk of this polymorphism to hereditary and sporadic prostate cancer in 159 HPC probands, 249 sporadic prostate cancer patients and 211 unaffected control subjects. Evidence for linkage at the CYP17 gene region was found in the total 159 HPC families (LOD = 1.3, p = 0.01, at marker D10S222). However, family-based association tests did not provide evidence for overtransmission of either allele of the CYP17 polymorphism to affected individuals in the HPC families. The allele and genotype frequencies of the polymorphism were not statistically different among the HPC probands, sporadic cases and unaffected control subjects. In conclusion, our results suggest that the CYP17 gene or other genes in the region may increase the susceptibility to prostate cancer in men; however, the polymorphism in the 5' promoter region has a minor role if any in increasing prostate cancer susceptibility in our study sample.

A comparison of short-term treatment with inhaled fluticasone propionate and zafirlukast for patients with persistent asthma.

PURPOSE: To compare the short-term efficacy and safety of low-dose fluticasone propionate with that of oral zafirlukast therapy for patients previously treated with beta-2-agonists alone, and to evaluate the potential therapeutic benefit of switching from zafirlukast to a low-dose inhaled corticosteroid. SUBJECTS AND METHODS: This study consisted of a 4-week randomized, double-blind treatment period followed by a 4-week open-label period. Two hundred ninety-four patients > or =12 years old with asthma previously uncontrolled with beta-2-agonists alone were randomly assigned to treatment with low-dose inhaled fluticasone (88 microg twice daily) or oral zafirlukast (20 mg twice daily). After 4 weeks, all patients discontinued their double-blind therapy and received open-label fluticasone (88 microg twice daily). Outcomes included pulmonary function, asthma symptoms, albuterol use, asthma exacerbations, and adverse events. RESULTS: During the double-blind treatment period, fluticasone patients had significantly greater improvements in morning peak flow (29.3 L/min vs. 18.3 L/min), percentage of symptom-free days (19.8% vs. 11.6%), and daily albuterol use (-1.8 puffs per day vs. -1.1 puffs per day) compared with zafirlukast patients (P < or =0.025, each comparison). During the open-label treatment period, patients switched from zafirlukast to fluticasone experienced additional improvements in morning peak flow (17.2 L/min), evening peak flow (13.6 L/min), and FEV(1) (0.11 liter) and daily albuterol use (-0.9 puffs daily) compared with values obtained at the end of the double-blind treatment period (P < or =0.001, each comparison). CONCLUSION: Low-dose fluticasone was more effective than zafirlukast in improving pulmonary function and symptoms in patients with persistent asthma. In addition, switching patients from zafirlukast to fluticasone further improved clinical outcomes.

Ethnic differences in asthma and associated phenotypes: collaborative study on the genetics of asthma.

BACKGROUND: In the Collaborative Study on the Genetics of Asthma, 314 families with 2584 subjects were characterized for asthma and allergy. OBJECTIVE: The purpose of this investigation was to examine clinical heterogeneity observed in asthma and allergic characteristics among 3 ethnic groups (African American, white, and Hispanic family members). METHODS: Pulmonary function parameters and asthma associated phenotypes were compared among the ethnic groups. RESULTS: In comparison with the other groups, African American sibling pairs had a significantly lower baseline FEV(1) percent of predicted (P =.0001) and a higher rate of skin test reactivity to cockroach allergen (P =.0001); Hispanic sibling pairs had significantly more skin reactivity overall (P =.001); and white sibling pairs had significantly lower total serum IgE (P <.05). In addition, there were significantly more relatives with asthma among the African American families than among the white and the Hispanic families (P =.001). CONCLUSION: Although different environmental backgrounds should be considered, these clinical differences could be due to differences in genetic susceptibility among the ethnic groups, such as those suggested by our previous genome screen.

Linkage and association studies of prostate cancer susceptibility: evidence for linkage at 8p22-23.

Multiple lines of evidence have implicated the short arm of chromosome 8 as harboring genes important in prostate carcinogenesis. Although most of this evidence comes from the identification of frequent somatic alterations of 8p loci in prostate cancer cells (e.g., loss of heterozygosity), studies have also suggested a role for 8p genes in mediation of inherited susceptibility to prostate cancer. To further examine this latter possibility, we performed linkage analyses, in 159 pedigrees affected by hereditary prostate cancer (HPC), using 24 markers on the short arm of chromosome 8. In the complete set of families, evidence for prostate cancer linkage was found at 8p22-23, with a peak HLOD of 1.84 (P=.004), and an estimate of the proportion of families linked (alpha) of 0.14, at D8S1130. In the 79 families with average age at diagnosis >65 years, an allele-sharing LOD score of 2.64 (P=.0005) was observed, and six markers spanning a distance of 10 cM had LOD scores >2.0. Interestingly, the small number of Ashkenazi Jewish pedigrees (n=11) analyzed in this study contributed disproportionately to this linkage. Mutation screening in HPC probands and association analyses in case subjects (a group that includes HPC probands and unrelated case subjects) and unaffected control subjects were carried out for the putative prostate cancer-susceptibility gene, PG1, previously localized to the 8p22-23 region. No statistical differences in the allele, genotype, or haplotype frequencies of the SNPs or other sequence variants in the PG1 gene were observed between case and control subjects. However, case subjects demonstrated a trend toward higher homozygous rates of less-frequent alleles in all three PG1 SNPs, and overtransmission of a PG1 variant to case subjects was observed. In summary, these results provide evidence for the existence of a prostate cancer-susceptibility gene at 8p22-23. Evaluation of the PG1 gene and other candidate genes in this area appears warranted.

Evidence for a prostate cancer linkage to chromosome 20 in 159 hereditary prostate cancer families.

Prostate cancer is the most common malignancy diagnosed in men in the US. Genetic susceptibility to prostate cancer has been well documented. A region at chromosome 20q13 (HPC20) has been reported to be linked to a prostate cancer susceptibility gene. To confirm this finding, we genotyped 16 markers spanning approximately 95 cM on chromosome 20 in 159 hereditary prostate cancer (HPC) families. Positive (but not statistically significant) linkage scores were observed from 20pter to 20q11, with the highest non-parametric linkage (NPL) score for the complete dataset of 1.02 (P=0.15) being observed at D20S195 at 20q11. Evidence for linkage from parametric analyses with a dominant or a recessive model was weak. Interestingly, consistent with the original findings of linkage to 20 g higher linkage scores were observed in the subsets of families with a later age at diagnosis (> or =65 years; n=80, NPL=1.94, P=0.029 at D20S186), fewer than five affected family members (n=69, NPL=1.74, P=0.037 at D20S889), or without male-to-male disease transmission (n=60, NPL=1.01, P=0.15 at D20S117). The region with positive linkage scores spanned approximately 60 cM from 20pter to 20q11 in these subsets of families. Our results are consistent with a prostate cancer susceptibility locus on chromosome 20.

Genomewide screen and identification of gene-gene interactions for asthma-susceptibility loci in three U.S. populations: collaborative study on the genetics of asthma.

The genomewide screen to search for asthma-susceptibility loci, in the Collaborative Study on the Genetics of Asthma (CSGA), has been conducted in two stages and includes 266 families (199 nuclear and 67 extended pedigrees) from three U.S. populations: African American, European American, and Hispanic. Evidence for linkage with the asthma phenotype was observed for multiple chromosomal regions, through use of several analytical approaches that facilitated the identification of multiple disease loci. Ethnicity-specific analyses, which allowed for different frequencies of asthma-susceptibility genes in each ethnic population, provided the strongest evidence for linkage at 6p21 in the European American population, at 11q21 in the African American population, and at 1p32 in the Hispanic population. Both the conditional analysis and the affected-sib-pair two-locus analysis provided further evidence for linkage, at 5q31, 8p23, 12q22, and 15q13. Several of these regions have been observed in other genomewide screens and linkage or association studies, for asthma and related phenotypes. These results were used to develop a conceptual model to delineate asthma-susceptibility loci and their genetic interactions, which provides a promising basis for initiation of fine-mapping studies and, ultimately, for gene identification.