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

RATIONALE: The genomic response to allergen challenge in asthma has not been characterized.We identified genes that are upregulated by allergen challenge in murine asthma using microarray and quantitative PCR (Q-PCR) analyses.METHODS: Ragweed (RW) sensitized BALB/c mice were challenged with either RW or vehicle (n=5-6 per group), and sacrificed kinetically at 1, 2, 4, 24, 72 and 168 hrs.Whole lung mRNA from mice sacrificed at 4 hrs were analyzed for 13,000 genes using Affymetrix gene array, and all time point samples were examined by Q-PCR.RESULTS: Gene array analyses identified 51 genes upregulated by RW challenge >2.5 fold.RW challenge induced the signaling molecules PIM3 and C-FOS within I hr, and both peaked (2-5 fold) by 2-4 hrs.Pro-inflammatory gene IL:4 was upregulated 30-fold at 1 hr, 80-90 fold at 2-4 hrs, and 10-fold at 24 hrs.RW challenge also upregulated the pro-inflaminatory genes MCP-3 and MCP-I 45-fold and 5-fold respectively at 4 hrs, and both persisted at these levels at 24 hrs.By four hours, RW challenge upregulated the anti-inflammatory genes CISH 5-fold, SOCS-I 8-fold, Serine protease inhibitor 2.1 10-fold and FcR'/IIB 5-fold.These genes, except FcR~tlIB, were minimally upregulated at 24 hrs.CONCLUSIONS: The results suggest that the upregulation of antiinflammatory genes CISH, SOCS-I, SP12-1 and FcRTIIB in response to RW challenge is not sufficient to prevent the massive and sustained increase in pro-inflammatory genes like IL-4, MCP-l and MCP-3, which are known to drive a vigorousTh2 allergic inflammation.

OBJECTIVES: Expression of the gene encoding the seven transmembrane receptor complement anaphylotoxin C5a (C5aR) on bronchial, epithelial, vascular endothelial and smooth muscle cells in the lung implicates its importance in pulmonary inflammation.Previously, C5 was identified as a susceptibility locus for allergen-induced airway hyperresponsiveness in a murine model of asthma, and linkage to the C5aR locus ( 19q 13.3-q 13.4) has been reported in several populations.METHODS: To identify allelic variants associated with asthma and atopy in the C5aR gene, we screened the promoter region by direct sequence in a Caucasian pool of asthmatics (N=I0) and a pool of healthy controls (N=10).We identified a T to C substitution at position -245 which was not reported in the original published sequence (GeneBank Acc.No.: $56556).Genomic DNA was subsequently screened for C5aR(T-245C) by restriction fragment length polymorphism (RFLP) in an Afro-Caribbean population (N=783) of asthmatic children and their parents (trios) from Barbados.RESULTS: Frequency of T and C alleles were 49.7% and 50.3%, respectively.Transmission disequilibrium test (TDT) analysis of 164 informative trios in the Barbados data set revealed no association of C5aR(C-245T) with asthma (P=0.2752) or tlgE (P=0.3571).CONCLUSIONS: These results suggest that C5aR(C-245T) may not be involved in the development of asthma in this population of African descent.

Variance components models were used to analyze total IgE levels in families ascertained though the Collaborative Study of the Genetics of Asthma (CSGA) using a genome-wide array of polymorphic markers. While IgE levels are known to be associated with clinical asthma and recognized to be under strong genetic control (here the heritability was estimated at 44-60% in the three racial groups), specific genes influencing this trait are still largely unknown. Multipoint analysis of 323 markers yielded little indication of specific regions containing a trait locus controlling total serum IgE levels (adjusted for age and gender). Although a number of regions showed LOD statistics above 1.5 in Caucasian families (chromosome 4) and in African-American families (chromosomes 2 and 4), none yielded consistent evidence in all three racial groups. Analysis of total IgE adjusted for gender, age and Allergy Index (a quantitative score of skin test sensitivity to 14 common aeroallergens) was conducted on these data. In this analysis, a much stronger signal for a trait locus controlling adjusted log[total IgE] was seen on the telomeric end of chromosome 18, but only in Caucasian families. This region accounted for most of the genetic variation in log[total IgE], and may represent a quantitative trait locus for IgE levels independent of atopic response. Oligogenic analysis accounting simultaneously for the contribution of this locus on chromosome 18 and other chromosomal regions showing some evidence of linkage in these Caucasian families (on chromosomes 2, 4 and 20) failed to yield significant evidence for interaction.

Background: Allergic diseases are one of the major causes of morbidity in the developed countries today, and the prevalence of these diseases is increasing steadily. Study of total serum gE level is important in understanding the genetics of allergic iseases because IgE levels are considered to be a crucial pathogenic component. IL-13 plays an important role in the induction of IgE synthesis and in the pathogenesis of allergic diseases. Objective: We sought to examine potential variation at the IL13 gene and estimate its effect on elevated IgE level and atopic dermatitis (AD). Methods: We conducted mutational analyses of the IL13 gene by using single-stranded conformation polymorphism and DNA sequencing. Case control studies for high-IgE phenotype and AD were performed by using subjects from the German MAS-90 cohort. Results: A novel IL13 coding region variant at 4257 bp (G to A, fourth exon) was identified. Case control studies of a German sample from the MAS-90 cohort showed significant associations between the presence of the A allele and two atopic phenotypes: high IgE (odds ratio, 2.38; 95% confidence interval, 1.35-4.21; P = .0026) and AD (odds ratio, 1.77; 95% confidence interval, 1.06-2.96; P = .03). Conclusion: This IL13 coding region variant may be involved in the pathogenesis of AD and high total serum IgE level in a study population of white subjects. (J Allergy Clin Immunol 2000;106:167-70.)

Background: Asthma is a complex disease characterized by a high prevalence of allergic diathesis and the almost ubiquitous presence of upper airway disease (eg, rhinitis). Previously, we observed linkage of asthma among Afro-Caribbean families to markers in chromosome 12q, which contains a number of genes encoding for products closely related to allergic airway inflammation and disease. Objective: To identify susceptibility loci in chromosome 12q contributing to the genetics of upper and lower airway diseases and to expand the region to include genes encoding IFN-γ (IFNG ) and one of the signal transducers and activators of transcription (STAT6 ), we conducted further linkage studies among 33 multiplex families. Methods: We characterized 528 subjects from Barbados for asthma; 82% were characterized for allergic rhinitis. Two-point and multipoint linkage analysis of 22 microsatellite markers (spanning ~79 centimorgan) was performed. Results: Affected sib-pair analysis revealed significant evidence for linkage to asthma over approximately 30 cM (P < .05 to .002), with the best evidence for linkage at a CA repeat polymorphism in the first intron of IFNG in 12q21.1 (P = .002). Evidence of linkage to allergic rhinitis was observed in the same region (D12S313 , P = 0.006, and IFNGCA , P = .01, respectively). Multipoint linkage analysis also provided evidence for linkage to asthma, with the best nonparametric linkage analysis score at D12S326 (nonparametric linkage score = 3.8, P = .0008). Modest evidence for linkage to allergic rhinitis was observed next to D12S326 at D12S1052 (P = .036). Conclusions: Our findings suggest that (1) one or more loci in the chromosome 12q13.12–q23.3 region are contributing to the expression of the clinical phenotype asthma and the strongest evidence for linkage is in a region near the gene encoding IFNG and (2) a susceptibility locus for both asthma and allergic rhinitis maps to this region. (J Allergy Clin Immunol 1999;104:485-91.)

As part of our effort in searching for genetic factors contributing to the susceptibility to atopy and asthma, we have focused on a 'positional candidate' approach in identifying CC chemokine gene polymorphisms and their functional correlates. To date, a single-nucleotide polymorphism was found in the RANTES proximal promoter region, and a high degree of sequence variation was identified in the 3'-untranslated region -of the eotaxin gene. Also, we are pursuing a series of functional genomics' studies designed to identify differentially expressed genes in a panel of allergen-specific human Th2 cells and in antigen-induced hyperreactive murine airways. This is performed using a combination of protocols including suppression-subtractive hybridization and cDNA array hybridizations with 18.363 nonredundant sequences. A data base is being generated from a list of subtracted cDNA sequences and array-positive clones to categorize differentially expressed genes. Sequences are being placed in biologically relevant categories on the basis of function (i.e., receptor, signal transduction pathways, transcription, and translation). With the increasing amount of sequence information compiled by the Human Genome Project, it will be particularly challenging to integrate functional gene-mapping efforts to define and compare aberrant genotypes/phenotypes in atopic diseases.

Background: Dermatophagoides pteronyssinus (Der p) is one of the most frequently implicated allergens in atopic diseases. Although HLA could play an important role in the development of the IgE response to the Der p allergens, genetic regulation by non-HLA genes influences certain HLA-associated IgE responses to complex allergens.Objective: To clarify genetic control for the expression of Der p-specific IgE, responsiveness, we conducted a genome-wide search for genes influencing Der p-specific IgE antibody levels by using 45 Caucasian and 53 African American families ascertained as part of the Collaborative Study on tho Genetics of Asthma (CSGA).Methods: Specific IgE antibody levels to the Der p crude allergen and to the purified allergens Der p 1 and Der p 2 were measured. Multipoint, nonparametric linkage analysis of 370 polymorphic markers was performed with the GENE-HUNTER program.Results: The best evidence of genes controlling specific IgE response to Der p was obtained in 2 novel regions: chromosomes 2q21-q23 (P =.0033 for Caucasian subjects) and 8p23-p21 (P =.0011 for African American subjects). Three regions previously proposed as candidate regions for atopy, total IgE, or asthma also showed evidence for linkage to Der p-specific IgE responsiveness: 6p21 (P =.0064) and 13q32-q34 (P = 0.0064) in Caucasian subjects and 5q23-q33 (P = 0.0071) in African American subjects.Conclusions: No single locus generated overwhelming evidence for linkage in terms of established criteria and guidelines for a genome-wide screening, which supports previous assertions of a heterogeneous etiology for Der p-specific IgE responsiveness. Two novel regions, 2q21-q23 and 8p23-p21, that were identified in this study merit additional study.

Asthma is an inflammatory airways disease associated with intermittent respiratory symptoms, bronchial hyperresponsiveness (BHR) and reversible airflow obstruction and is phenotypically heterogeneous(1,2). Patterns of clustering and segregation analyses in asthma families have suggested a genetic component to asthma(3-6). Previous studies reported linkage of BHR and atopy to chromosomes 5q (refs 7-9), 6p (refs 10-12), 11q (refs 13-15), 14q (ref. 16), and 12q (ref. 17) using candidate gene approaches. However, the relative roles of these genes in the pathogenesis of asthma or atopy are difficult to assess outside of the context of a genome-wide search. One genome-wide search in atopic sib pairs has been reported(18), however, only 12% of their subjects had asthma. We conducted a genome-wide search in 140 families with greater than or equal to 2 asthmatic sibs, from three racial groups and report evidence for linkage to six novel regions: 5p15 (P = 0.0008) and 17p11.1-q11.2 (P = 0.0015) in African Americans; 11p15 (P = 0.0089) and 19q13 (P = 0.0013) in Caucasians; 2q33 (P = 0.0005) and 21q21 (P = 0.0040) in Hispanics. Evidence for linkage was also detected in five regions previously reported to be linked to asthma-associated phenotypes: 5q23-31 (P = 0.0187), 6p21.3-23 (P = 0.0129), 12q14-24.2 (P = 0.0042), 13q21.3-qter (P = 0.0014), and 14q11.2-13 (P = 0.0062) in Caucasians and 12q14-24.2 (P = 0.0260) in Hispanics.

To identify genes potentially relevant in atopic asthma, we analyzed markers in chromosome 12q15–q24.1 for linkage to asthma and total serum IgE concentration. Sib-pair analyses of 10 markers in 345 full- and 219 half-sib pairs from 29 multiplex Afro-Caribbean families provided evidence for linkage to this region for both asthma and total serum IgE. Certain alleles at these loci showed significant evidence of transmission disequilibrium with both asthma and high IgE. Using 6 of these markers and 11 additional markers, evidence for linkage of total IgE to 12q was also found in 12 Caucasian Amish kindreds (24 nuclear families) by both sib-pair and transmission disequilibrium analyses. These findings suggest that the 12q15–q24.1 region may contain a gene(s) controlling asthma and the associated “high total IgE” trait.