Genetics of asthma and allergic disease

CD14 promoter polymorphisms have no functional significance and are not associated with atopic phenotypes

OBJECTIVES

A polymorphism at CD14/-159 has been reported to be associated with atopic phenotypes in several studies. However, conflicting results from association studies in different populations have been reported. This study aimed to investigate the relationship between CD14 promoter polymorphisms and atopic phenotypes in Singaporean Chinese and the biological characterization of these polymorphisms.

METHODS

A total of 171 atopic and 160 non-atopic adult subjects were included and their serum soluble CD14 (sCD14) and total immunoglobulin E (tIgE) levels were measured. Screening of single nucleotide polymorphisms (SNPs) in the CD14 promoter was performed using direct PCR-sequencing and restriction fragment length polymorphism methods. The functional significance of SNPs was investigated using reporter assay system.

RESULTS

Three previous reported SNPs (CD14/-159, -1145 and -1359) and a novel SNP (CD14/-550) were detected. Significant linkage disequilibrium was found among these four loci of CD14 gene. However, no significant difference was found in the genotype frequencies of these SNPs between non-atopy and atopy groups. Furthermore, no transcriptional activities of these SNPs were detected using reporter gene assay in three cell-lines (HepG-2, THP-1 and U937).

CONCLUSIONS

This study confirms three reported SNPs and one novel SNP in the CD14 promoter in our local population. However, these SNPs do not play a decisive role in the development of atopic phenotypes.

A genome-wide search for linkage to asthma phenotypes in the genetics of asthma international network families: evidence for a major susceptibility locus on chromosome 2p

Asthma is a complex disease and the intricate interplay between genetic and environmental factors underlies the overall phenotype of the disease. Families with at least two siblings with asthma were collected from Europe, Australia and the US. A genome scan using a set of 364 families with a panel of 396 microsatellite markers was conducted. Nonparametric linkage analyses were conducted for asthma and three asthma-related phenotypes: bronchial hyper-reactivity (BHR), strict definition of asthma and atopic asthma. Nine chromosomal regions with LOD scores greater than 1.5 were identified (chromosomes 1q, 2p, 3q, 4p, 4q, 6q, 12q, 20p and 21). Linkage refinement analysis was performed for three BHR loci by genotyping single nucleotide polymorphisms at an average marker density of 1 cM. The LOD scores increased to 3.07 at chromosome 4p and 4.58 at chromosome 2p, while the chromosome 6p locus did not refine. The LOD score at the chromosome 2p locus is highly significant on a genome-wide basis. The refined locus covers a region with a physical size of 12.2 Mb. Taken together, these results provide evidence for a major asthma susceptibility locus on chromosome 2p.

Families discovering asthma in their high-risk infants and toddlers with severe persistent disease

Interpretive phenomenology was used to discover the earliest experiences of families of children younger than 4 years hospitalized for severe persistent asthma. The children who were African American or Latino and living in poverty were at highest risk of morbidity and mortality. Three families with distinctly varied responses to early symptoms were chosen from an investigation of 11 families for this study. Each gave three home interviews and participated in home observations. All families experienced life-changing responses to their children's distressed breathing. All had experienced asthma in themselves or others that shaped their beliefs and management patterns. Family experiences prior to and following diagnosis are discussed. Findings suggest that understanding these experiences and respecting families' earliest responses will help clarify established family management patterns for severe asthma in infants and toddlers and will enhance the ability of providers to guide the care of these families and children.

Immunoglobulin G4-antibodies to rBet v 1 and risk of sensitization and atopic disease in the child

BACKGROUND

In 1993 extremely high levels of birch-pollen were recorded in Stockholm, Sweden. This provided an opportunity to evaluate the effects of aeroallergen exposure (exp.) on the early immune response.

OBJECTIVE

To assess the influence of exp. to birch-pollen during pregnancy and infancy on the allergen-specific IgE- and IgG4-antibody (ab) response and the development of atopic disease in children.

METHODS

A total of 970 children with atopic heredity and born in Stockholm 1992, 1993 or 1994 were investigated at age 4.5-5 years. They were divided into five groups; high-dose exp. at 1 year of age, high-dose exp. at 0-3 months, low-dose exp. at 0-3 months, high-dose exp. during pregnancy and low-dose exp. during pregnancy. The children were examined and skin prick tested with inhalant and food allergens. IgE abs (against birch-pollen and recombinant Bet v 1(rBet v1)) and IgG4 abs (against rBet v 1) were analysed in serum. All children were assembled in one group to assess the effects of different ab responses (IgE/IgG4) on the development of atopic disease.

RESULTS

Children exposed to high doses of birch-pollen during the first 3 months of life more often had detectable levels of IgG4 abs to rBet v 1 than the children in the other groups (P < 0.001), independent of sensitization to birch. Overall, the risk of allergic rhinoconjunctivitis was increased among children sensitized to birch-pollen and appeared more pronounced in children without detectable levels of IgG4 ab to rBet v 1 (Odds ratio 9.4; 95% Confidence interval: 5.5-16.1). IgE sensitization to birch-pollen seemed to have a stronger influence on the development of atopic disease than the IgG4-ab response.

CONCLUSION

Exposure to high doses of inhalant allergens during the early postnatal period is associated with detectable levels of allergen-specific IgG4 ab even at 5 years of age. An immune modulating effect by IgG4 on symptoms of allergic rhinoconjunctivitis is suggested in children sensitized to birch.

The G protein-coupled receptors: pharmacogenetics and disease

Genetic variation in G-protein coupled receptors (GPCRs) is associated with a wide spectrum of disease phenotypes and predispositions that are of special significance because they are the targets of therapeutic agents. Each variant provides an opportunity to understand receptor function that complements a plethora of available in vitro data elucidating the pharmacology of the GPCRs. For example, discrete portions of the proximal tail of the dopamine D1 receptor have been discovered, in vitro, that may be involved in desensitization, recycling and trafficking. Similar in vitro strategies have been used to elucidate naturally occurring GPCR mutations. Inactive, over-active or constitutively active receptors have been identified by changes in ligand binding, G-protein coupling, receptor desensitization and receptor recycling. Selected examples reviewed include those disorders resulting from mutations in rhodopsin, thyrotropin, luteinizing hormone, vasopressin and angiotensin receptors. By comparison, the recurrent pharmacogenetic variants are more likely to result in an altered predisposition to complex disease in the population. These common variants may affect receptor sequence without intrinsic phenotype change or spontaneous induction of disease and yet result in significant alteration in drug efficacy. These pharmacogenetic phenomena will be reviewed with respect to a limited sampling of GPCR systems including the orexin/hypocretin system, the beta2 adrenergic receptors, the cysteinyl leukotriene receptors and the calcium-sensing receptor. These developments will be discussed with respect to strategies for drug discovery that take into account the potential for the development of drugs targeted at mutated and wild-type proteins.

Population stratification confounds genetic association studies among Latinos

In the United States, asthma prevalence and mortality are the highest among Puerto Ricans and the lowest among Mexicans. Case-control association studies are a powerful strategy for identifying genes of modest effect in complex diseases. However, studies of complex disorders in admixed populations such as Latinos may be confounded by population stratification. We used ancestry informative markers (AIMs) to identify and correct for population stratification among Mexican and Puerto Rican subjects participating in case-control studies of asthma. Three hundred and sixty-two subjects with asthma (Mexican: 181, Puerto Rican: 181) and 359 ethnically matched controls (Mexican: 181, Puerto Rican: 178) were genotyped for 44 AIMs. We observed a greater than expected degree of association between pairs of AIMs on different chromosomes in Mexicans (P < 0.00001) and Puerto Ricans (P < 0.00002) providing evidence for population substructure and/or recent admixture. To assess the effect of population stratification on association studies of asthma, we measured differences in genetic background of cases and controls by comparing allele frequencies of the 44 AIMs. Among Puerto Ricans but not in Mexicans, we observed a significant overall difference in allele frequencies between cases and controls (P = 0.0002); of 44 AIMs tested, 8 (18%) were significantly associated with asthma. However, after adjustment for individual ancestry, only two of these markers remained significantly associated with the disease. Our findings suggest that empirical assessment of the effects of stratification is critical to appropriately interpret the results of case-control studies in admixed populations.

Asthma management issues in infancy and childhood

The prevalence of asthma has been increasing worldwide over the past 2 decades, especially the prevalence of childhood asthma. Currently, the prevalence of childhood asthma is around 3-20% in different countries based on the report from the International Study of Asthma and Allergies in Children (ISAAC). Asthma in childhood is predominantly an extrinsic asthma. In general, countries in the coastal, temperate, and subtropical zones have the highest prevalence of mite- and cockroach-sensitive asthma. Countries in the sub-arctic or semi-arid areas have a lower prevalence of childhood asthma, mostly associated with sensitization to pet dander, moulds, and pollens. Many genes have been linked to asthma in different ethnic populations. A global consensus for the management of asthma in adults and children >5 years of age has been made possible in the Global Initiative for Asthma (GINA) guidelines, where a step-wise management program using inhaled medication with and without oral anti-inflammatory drugs is recommended. The management of asthma in children <5 years of age remains inconclusive. Recent studies suggest that inherited susceptibility associated with risk factors from the prenatal and postnatal environment is likely to promote allergic sensitization and development of asthma. Consequently, early prevention of prenatal sensitization in utero and environmental control of early life exposure to various allergens may decrease the incidence of childhood asthma. In the management of moderate persistent asthma in infants and young children <5 years of age, airway resistance tests (FEV(1) or PEF) are not of significance, but assessment of respiratory rate and skin pulse oximeter measurements of arterial oxygen saturation are helpful. Moreover, recent advances in pharmacogenetics and pharmacogenomics may provide better individualized care for early pharmacological prevention of childhood asthma via selective modulation of airway remodeling.

Interleukin-5 reduces the expression of uteroglobin-related protein (UGRP) 1 gene in allergic airway inflammation

Airway inflammation is thought to play a major role in the pathogenesis of bronchial asthma. The precise role of individual inflammatory cells, mediator and asthma related genes in allergic lung diseases is not completely understood. The uteroglobin-related protein (UGRP) 1 was proposed to be an asthma candidate gene and play a role in regulating lung inflammation, however its precise function in the airways remains obscure. In this investigation, we used a mouse model of allergic airway inflammation to establish a relationship between UGRP 1 and IL-5 in airway inflammation. Ovalbumin (OVA) challenged mice demonstrate eosinophilia in airway tissues and high levels of IL-5 in bronchoalveolar lavage (BAL) fluid analogous to that found in bronchial asthma. Interestingly, these "OVA-challenged" mice show down-regulation of Ugrp1 expression as compared with the control group. Regression analysis further demonstrates a significant negative correlation between Ugrp1 mRNA expression in the lung and IL-5 levels in BAL fluid with r = 0.948 and P < 0.0001 when IL-5 levels were normalized by log transformation. Intranasal instillation of IL-5 to mice revealed an inhibitory effect of IL-5 on the expression of Ugrp1 mRNA. Together, these results indicate an involvement of IL-5 in the down-regulation of Ugrp1 expression in airway inflammation such as allergic asthma disease.

Genetic susceptibility and single-nucleotide polymorphisms

The completion of the Human Genome Project has provided insight into human genetic variation, most commonly represented by single-nucleotide polymorphisms. There is presently a great deal of interest in linking genetic and phenotypic variation in the form of severity of, and susceptibility to, common multifactorial diseases. This article provides a background to recent advances in genetics, focusing on the application to common neonatal disorders and the practical difficulties of genetic association studies, as well as highlighting the potential impact on clinical practice.

IL-13 R130Q, a common variant associated with allergy and asthma, enhances effector mechanisms essential for human allergic inflammation

Genetic factors are known to strongly influence susceptibility to allergic inflammation. The Th2 cytokine IL-13 is a central mediator of allergy and asthma, and common single-nucleotide polymorphisms in IL13 are associated with allergic phenotypes in several ethnically diverse populations. In particular, IL13+2044GA is expected to result in the nonconservative replacement of arginine 130 (R130) with glutamine (Q). We examined the impact of IL13+2044GA on the functional properties of IL-13 by directly comparing the activity of WT IL-13 and IL-13 R130Q on primary human cells involved in the effector mechanisms of allergic inflammation. Our results show that IL-13 R130Q was significantly more active than WT IL-13 in inducing STAT6 phosphorylation and CD23 expression in monocytes and hydrocortisone-dependent IgE switching in B cells. Notably, IL-13 R130Q was neutralized less effectively than WT IL-13 by an IL-13R2 decoy. Decreased neutralization of the minor variant could contribute to its enhanced in vivo activity. Neither IL-13 variant was able to engage T cells, which suggests that increased allergic inflammation in carriers of IL13+2044A depends on enhanced IL-13-mediated Th2 effector functions rather than increased Th2 differentiation. Collectively, our data indicate that natural variation in the coding region of IL13 may be an important genetic determinant of susceptibility to allergy.

Association of the hCLCA1 gene with childhood and adult asthma

Asthma is caused by bronchial inflammation. This inflammation involves mucus overproduction and hypersecretion. Recently, a mouse model of asthma showed that gob-5 is involved in the pathogenesis of asthma. The gob-5 gene is involved in mucus secretion and its expression is upregulated upon antigen attack in sensitized mice. The observation suggests that human homologue of gob-5, hCLCA1 (human calcium-dependent chloride channel-1), may be involved in human disease. We screened for single-nucleotide polymorphisms (SNPs) in hCLCA1 in the Japanese population. We identified eight SNPs, and performed association studies using 384 child patients with asthma, 480 adult patients with asthma, and 672 controls. In haplotype analysis, we found a different haplotype distribution pattern between controls and childhood asthma (P<0.0001) and between controls and adult asthma (P=0.0031). We identified a high-risk haplotype (CATCAAGT haplotype; P=0.0014) and a low-risk haplotype (TGCCAAGT haplotype; P=0.00010) in cases of childhood asthma. In diplotype analysis, patients who had the CATCAAGT haplotype showed a higher risk for childhood asthma than those who did not (P=0.0011). Individuals who had the TGCCAAGT haplotype showed a lower risk for childhood asthma than those who did not (P<0.0001). Our data suggested that variation of the hCLCA1 gene affects patients' susceptibility for asthma.

A coding polymorphism in the CYSLT2 receptor with reduced affinity to LTD4 is associated with asthma

BACKGROUND

Cysteinyl leukotrienes (CYSLTR) are potent biological mediators in the pathophysiology of asthma for which two receptors have been characterized, CYSLTR1 and CYSLTR2. The leukotriene modifying agents currently used to control bronchoconstriction and inflammation in asthmatic patients are CYSLTR1-specific leukotriene receptor antagonists. In this report, we investigated a possible role for therapeutic modulation of CYSLTR2 in asthma by investigating genetic association with asthma and further characterization of the pharmacology of a coding polymorphism.

METHODS

The association of CYSLTR2 polymorphisms with asthma was assessed by transmission disequilibrium test in two family-based collections (359 families from Denmark and Minnesota, USA and 384 families from the Genetics of Asthma International Network).

RESULTS

A significant association of the coding polymorphism, 601A>G, with asthma was observed (P = 0.003). We replicated these findings in a collection of 384 families from the Genetics of Asthma International Network (P = 0.04). The G allele is significantly under-transmitted to asthmatics, indicating a possible role for this receptor in resistance to asthma. The potency of cysteinyl leukotrienes at the wild-type CYSLTR2 and the coding polymorphism 601A>G were assessed using a calcium mobilization assay. The potency of LTC4 and LTE4 was similar for both forms of the receptor and LTB4 was inactive, however, LTD4 was approximately five-fold less potent on 601A>G compared to wild-type CYSLTR2.

CONCLUSIONS

Since 601A>G alters the potency of LTD4 and this variant allele may be associated with resistance to asthma, it is possible that modulation of the CYSLTR2 may be useful in asthma pharmacotherapy.

A second-generation genomic screen for multiple sclerosis

Multiple sclerosis (MS) is a debilitating neuroimmunological and neurodegenerative disorder. Despite substantial evidence for polygenic inheritance of the disease, the major histocompatibility complex is the only region that clearly and consistently demonstrates linkage and association in MS studies. The goal of this study was to identify additional chromosomal regions that harbor susceptibility genes for MS. With a panel of 390 microsatellite markers genotyped in 245 U.S. and French multiplex families (456 affected relative pairs), this is the largest genomic screen for MS conducted to date. Four regions met both of our primary criteria for further interest (heterogeneity LOD [HLOD] and Z scores >2.0): 1q (HLOD=2.17; Z=3.38), 6p (HLOD=4.21; Z=2.26), 9q (HLOD; Z=2.71), and 16p (HLOD=2.64; Z=2.05). Two additional regions met only the Z score criterion: 3q (Z=2.39) and 5q (Z=2.17). Further examination of the data by country (United States vs. France) identified one additional region demonstrating suggestive linkage in the U.S. subset (18p [HLOD=2.39]) and two additional regions generating suggestive linkage in the French subset (1p [HLOD=2.08] and 22q [HLOD=2.06]). Examination of the data by human leukocyte antigen (HLA)-DR2 stratification identified four additional regions demonstrating suggestive linkage: 2q (HLOD=3.09 in the U.S. DR2- families), 6q (HLOD=3.10 in the French DR2- families), 13q (HLOD=2.32 in all DR2+ families and HLOD=2.17 in the U.S. DR2+ families), and 16q (HLOD=2.32 in all DR2+ families and HLOD=2.13 in the U.S. DR2+ families). These data suggest several regions that warrant further investigation in the search for MS susceptibility genes.

Maternal pollen allergy may be more important than birch pollen exposure during pregnancy for atopic airway disease in the child

In 1993 extremely high levels of birch pollen were recorded in Stockholm, Sweden. We investigated the effects of this exposure on sensitization and development of atopic airway disease in children. The aim of this study was to assess the influence of maternal birch sensitization and symptoms of pollen allergy, as well as exposure to birch pollen during pregnancy, on sensitization and development of atopic airway disease in children. A total of 387 children with atopic heredity (70% had atopic mothers) and born in Stockholm 1993 or 1994 were investigated at age 4.5-5 yr. The children were examined and skin prick tested with inhalant and food allergens. IgE-antibodies against birch pollen and recombinant birch pollen allergen were analyzed in serum. The same tests were performed on the mothers. Children of mothers with symptoms of pollen allergy more often showed symptoms of rhinoconjunctivitis at age 4.5-5, after both high dose [Odds ratio (OR) 5.3; 95% confidence interval (CI): 2.0-13.7] and low dose (OR 4.0; 95% CI: 1.5-10.9) exposure to birch pollen during pregnancy. Similar tendencies were noted for children of mothers sensitized to birch, where stronger effects were suggested in boys (OR 3.8; 95% CI: 1.3-11.5) than in girls (OR 1.2; 95% CI: 0.2-5.5) in the high-dose exposed group. For asthma symptoms and sensitization to birch in the children the results were less consistent. It may be concluded that, maternal pollen allergy seems to have a stronger influence on the development of rhinoconjunctivitis in children with a family history of atopy than the degree of allergen exposure during pregnancy.

Gender-limited association of cytotoxic T-lymphocyte antigen-4 (CTLA-4) polymorphism with cord blood IgE levels

Allergic mechanism has long been attributed to IgE-mediated reaction. The relationship between gene polymorphism and cord blood IgE (CB IgE) is unclear. We investigated whether elevation of CB IgE levels was associated with polymorphisms of cytotoxic T-lymphocyte antigen 4 (CTLA-4) at (-318) CT and (+49) AG positions in a gender-limited fashion. CB IgE levels were determined by Pharmacia CAP system and the CTLA-4 polymorphisms at (-318) and (+49) were determined by restriction fragment length polymorphism (RFLP). A total of 644 consecutive umbilical cord bloods were collected for this study. 32.9% of newborn infants had detectable IgE levels (> or =0.35 kU/l). 25.6% of the male newborns had elevated CB IgE levels (> or =0.5 kU/l) similar to those of the female newborns (22.7%). The CTLA-4 polymorphism at (+49) but not (-318) was significantly associated with elevated CB IgE levels (p = 0.004). The association of CTLA-4 (+49) A allele with elevated CB IgE levels was found only in females. Both male and female infants with different CTLA-4 (-318) genotypes had no difference in the rates of elevated CB IgE levels. A linkage disequilibrium between CTLA-4 (+49) G and (-318) C allele was found in this Chinese population. Subjects with the (+49, GG and -318, CC) genotype had a significantly lower rate of elevated CB IgE levels. Association of the CTLA-4 (+49) polymorphism with elevated CB IgE levels was found only in female infants. Newborn infants with the (+49, GG and -318, CC) genotype tended to have a low rate of elevated CB IgE.

Association study of 15 novel single-nucleotide polymorphisms of the T-bet locus among Finnish asthma families

OBJECTIVE

T-box expressed in T cells (T-bet) is a transcription factor regulating the commitment of T helper (Th) cells by driving the cells into the Th1 direction. Abnormal Th1/Th2 balance may lead to complex disorders like asthma or autoimmune diseases. Recent studies have suggested that T-bet might be a candidate gene for asthma. This led us to screen 23 Finnish individuals for single-nucleotide polymorphisms (SNPs) in the T-bet locus and study the association between the SNPs and high serum IgE level and asthma.

METHODS

We screened all six exons, adjacent intronic areas and 2 kb of the 5'-flanking region from 23 individuals utilizing WAVE trade mark technology. To explore whether T-bet is associated in serum IgE regulation or asthma we genotyped the SNPs in a Finnish asthmatic founder population. The association analyses were made using haplotype pattern mining.

RESULTS

Fifteen novel SNPs were found in the T-bet gene. Within the Finnish asthmatic founder population, there was no association between T-bet SNPs and high serum IgE level or asthma.

CONCLUSIONS

The genetic variability in the T-bet gene does not play a role in the pathogenesis of human asthma. Our results provide a novel panel of SNPs in T-bet and will help determine whether the SNPs have a functional role in other T cell-mediated diseases.

Hyper IgE in New Zealand black mice due to a dominant-negative CD23 mutation

Immunoglobulin E (IgE) plays a critical role in both resistance to parasitic infection and allergy to environmental antigens. The IgE response is in turn regulated by the B-cell co-receptor CD23, and CD23-deficient mice show exaggerated IgE responses and airway hyper-responsiveness. In this report, we show that New Zealand black (NZB) mice express a variant CD23 allele, with mutations in both the C-lectin-binding domain and stalk region, which fails to bind IgE at high affinity and has reduced expression on the cell surface. Expression of the variant CD23 chain interferes with trimerisation of the receptor and has a dominant-negative effect leading to reduced IgE binding in crosses between NZB and other strains. Genetic mapping shows that the variant CD23 leads to an exaggerated primary IgE response, which is independent of other strain-specific effects. These results suggest that NZB mice or mice carrying the variant allele will be useful models for studying both allergy and quantitative traits associated with atopy. The exaggerated IgE response provides an explanation for the natural resistance of NZB mice to parasitic infection by Leishmania.

The IL12B gene is associated with asthma

The IL12B gene on chromosome 5q31-33 encodes the p40 subunit of interleukin 12, an immunomodulatory cytokine. To test the hypothesis that the IL12B gene contains polymorphisms associated with asthma, we genotyped six haplotype-tagging polymorphisms in the IL12B gene, both in 708 children enrolled in the Childhood Asthma Management Program (CAMP) and in their parents. Using the family-based association test (FBAT) program and its haplotype (HBAT) and phenotype (PBAT) options, we tested each polymorphism and haplotype for association with asthma and asthma-related phenotypes. We tested positive associations for replication in a case-control study comparing 177 adult moderate-to-severe asthmatics with 177 nonasthmatic controls. In whites in the CAMP cohort, the A allele of the IL12B G4237A polymorphism was undertransmitted to asthmatic children (P=.0008, recessive model), the global test for haplotypes for affection status was positive (P=.009, multiallelic chi (2)), and two polymorphisms were associated with different atopy phenotypes. In addition, we found a strong association between the IL12B_4237 and IL12B_6402 polymorphisms and an asthma-severity phenotype in whites, which we also found in the independent population of white adult asthmatics. IL12B may be an important asthma gene.

DNA microarray analysis of chromosomal susceptibility regions to identify candidate genes for allergic disease: a pilot study

OBJECTIVE

To examine whether DNA microarray analysis of chromosomal susceptibility regions for allergy can help to identify candidate genes.

MATERIAL AND METHODS

Nasal biopsies were obtained from 23 patients with allergic rhinitis and 12 healthy controls. RNA was extracted from the biopsies and pooled into three patient and three control pools. These were then analysed in duplicate with DNA microarrays containing 12626 genes. Candidate genes were further examined in nasal biopsies (real-time polymerase chain reaction) and blood samples (single nucleotide polymorphisms) from other patients with allergic rhinitis and from controls.

RESULTS

A total of 37 differentially expressed genes were identified according to criteria involving both the size and consistency of the gene expression levels. The chromosomal location of these genes was compared with the chromosomal susceptibility regions for allergic disease. Using a statistical method, five genes were identified in these regions, including serine protease inhibitor, Kazal type, 5 (SPINK5) and HLA-DRB2. The relevance of these genes was examined in other patients with allergic rhinitis and in controls; none of the genes were differentially expressed in nasal biopsies. Moreover, no association between allergic rhinitis and SPINK5 polymorphisms was found, at either the genotype or haplotype level.

CONCLUSIONS

DNA microarray analysis of chromosomal susceptibility regions did not lead to identification of candidate genes that could be validated in a new material. However, because gene polymorphisms may cause differential gene expression, further studies, including validation data, are needed to examine this approach.

A cysteinyl leukotriene 2 receptor variant is associated with atopy in the population of Tristan da Cunha

The clinical heterogeneity of asthma suggests that the contribution of genetic variability in candidate gene loci to well-defined phenotypes, such as atopy, may be examined to identify appropriate genetic risk factors for asthma. The gene encoding the cysteinyl leukotriene 2 (CysLT2) receptor has been implicated in atopy since it is localized to a region of chromosome 13q14 that has been linked to atopy in several populations and the cysteinyl leukotrienes are known to activate eosinophils and mast cells in atopy. Accordingly, we analysed the contribution of CysLT2 receptor gene variation to atopy in the inhabitants of Tristan da Cunha, a population characterized by both a founder effect and a 47% prevalence of atopy. Single-stranded conformational polymorphism analysis revealed four variants. Among these, the M201V [corrected] variant was activated with four-fold less potency by leukotriene D4 (LTD4) in a calcium flux assay. The CysLT2 receptor partial agonist, BAY u9773, also showed four-fold lower potency on the M201V [corrected] variant. The M201V [corrected] mutation is located within the extracellular region of the fifth transmembrane spanning domain of CysLT2 receptor, a position that may alter ligand binding and effector signalling. The novel M201V [corrected] CysLT2 receptor variant was associated with atopy (21%) on Tristan da Cunha compared with those who were non-atopic (7%) (Fisher's exact test, P=0.0016) in a manner that was independent of asthma (two-way ANOVA, P=0.0015). This represents the first association of a coding mutation in the CysLT2 receptor gene, located on chromosome 13q14, with the atopic phenotype found in the Tristan da Cunha population.

Meta and pooled analysis of European coeliac disease data

Four full genome scans have been carried out by the partners of the European cluster on coeliac disease as well as follow-up studies of candidate regions. No region outside HLA showed significant linkage to the disease in any single study. We first applied a meta-analysis based on a modification of Genome Screen Meta-Analysis to take into account the different linkage statistics, the arbitrariness of bin cutoff points, as well as the sample size of each study. We then performed a pooled linkage analysis of all families and raw genotypes. Besides the HLA region, already known to harbour a risk factor for coeliac disease, both approaches leave very little doubt on the presence of a genetic risk factor in the 5q31-33 region. This region was suggested by several individual studies, but did not reach statistical values high enough to be conclusive when data sets were analysed separately.

Polymorphism of the immune-braking gene CTLA-4 (+49) involved in gender discrepancy of serum total IgE levels and allergic diseases

BACKGROUND

A variety of genes are related to allergic disorders in different ethnic populations. The genetic basis for the gender discrepancy of allergic diseases remains to be determined.

OBJECTIVE

This study was conducted to investigate whether IL-4 promoter (-590 C/T) and cytotoxic T lymphocyte antigen 4 (CTLA-4) (+49 A/G) polymorphisms were correlated with a gender discrepancy of total IgE levels and allergic diseases in a Chinese population.

METHODS

A total of 1333 participants aged 19-49 years were enrolled in this study. Allergic diseases were recognized by the presence of asthma, rhinitis or atopic dermatitis in conjunction with detectable specific IgE in the blood. Polymorphisms of IL-4 promoter (-590) and CTLA-4 (+49) were determined by restriction fragment length polymorphism.

RESULTS

Males or females with allergic diseases had higher total IgE levels than those without (P=0.000). Females with the A/A genotype in the CTLA-4 (+49) position had significantly higher total IgE levels than those with A/G, and those with the G/G genotype had the lowest IgE levels (154.9 vs. 107.1 vs. 79.8 KU/L; mean log values: 1.79 vs. 1.65 vs. 1.54, P< 0.001). However, males with different genotypes in the CTLA-4 (+49) position exhibited no difference in the total IgE levels. Females with allergic rhinitis had a significantly higher frequency of the A/A genotype in the CTLA-4 (+49) polymorphism than those without atopic diseases (P=0.016). In contrast, males with and without allergic disorders exhibited no significant difference in the CTLA-4 (+49) polymorphisms (P>0.05). The IL-4 promoter (-590) polymorphisms, however, had no correlation with the total IgE levels or allergic diseases in either females or males.

CONCLUSION

In females only, the CTLA-4 (+49), but not the IL-4 promoter (-590), polymorphism was significantly associated with elevation of total IgE levels and allergic rhinitis. Here, we have, for the first time, demonstrated a gender-linked genetic relationship with allergic disease.

Multipoint linkage disequilibrium mapping for complex diseases

Linkage disequilibrium (LD) or association studies using case-parent trios have become a common approach to locate unobserved susceptibility genes underlying complex diseases. With the availability of ever more dense marker maps, how to utilize the information carried by multiple markers simultaneously remains challenging. Recently, Liang et al. ([2001a] Am. J. Hum. Genet. 68: 937-950) proposed a multipoint LD method to estimate the location of a susceptibility gene within a framework map along with its sampling uncertainty. Two important features of this method are that 1) it uses all trios whether parents are heterozygous for a given marker or not, and 2) it provides a single test statistic for the null hypothesis of no linkage or no LD to the region, avoiding the multiple testing problem encountered when performing individual transmission disequilibrium tests (TDT) for each marker individually. In this paper, we discuss how this method can be expanded to address important issues pertaining to complex diseases in a unified fashion. These issues include, among others, gene-gene and gene-environment interactions, genetic heterogeneity, phenotypic refinement, and paternal vs. maternal transmission. We applied this method to asthmatic case-parent trios from the Collaborative Study on the Genetics of Asthma (CSGA), and found that the previous evidence for linkage and LD in a 13.6 cM region of chromosome 11 can be attributed to maternal transmission, while there was no evidence of excess paternal transmission. Furthermore, such discrepancy in preferential transmission was most evident among probands with early onset age (6 years old or younger).

TIM-1, a novel allergy and asthma susceptibility gene

Atopic diseases, including asthma, allergic rhinitis, and atopic dermatitis, are caused by environmental factors in genetically predisposed individuals. Although the prevalence of these diseases has risen dramatically over the past two decades, it has been difficult to identify the underlying causes of these diseases due to the complex interplay between the genetic and environmental factors involved. Using a congenic mouse model of asthma, we simplified this complex trait and identified the novel T cell immunoglobulin domain, mucin-like domain (TIM) gene family, that encodes transmembrane proteins expressed by CD4 T cells. Recent studies demonstrate that the TIM family, particularly TIM-1, plays a critical role in immune responses that regulate the development of atopic diseases. In humans, certain polymorphic variants of TIM-1 are strongly associated with protection against atopy, and this association occurs only in individuals who have had past infection with hepatitis A virus (HAV). Since TIM-1 functions as the cellular receptor for HAV, activation of T cells through TIM-1 by HAV or by its natural ligand may affect T cell differentiation and the development of Th2-driven allergic inflammatory responses. Epidemiologically, HAV infection is associated with a reduced risk of developing atopy, and because the incidence of HAV infection has been significantly reduced in industrialized countries over the past 30 years, the discovery of a genetic interaction between HAV and TIM-1 provides the first molecular genetic evidence for the hygiene hypothesis.

[An increase in allergic diseases in childhood--current hypotheses and possible prevention]

During the last few decades there has ben a significant rise in the prevalence of allergic diseases such as asthma, hay fever and atopic dermatitis. Epidemiological studies strongly suggest that this increase is real and not due to changes in diagnostic labelling. It has become increasingly clear that a complex interplay between genetic and environmental factors account for this phenomenon. Genetically predisposed individuals are at an increased susceptibility to develop asthma or other allergic diseases when exposed to certain environmental or lifestyle factors. Particularly passive smoking has been shown to increase the risk for asthma in many studies and for atopy at least in some studies. This association is less clear for the exposure to sulfur dioxide, particulate matter, diesel exhaust and ozone. Lifestyle factors like socioeconomic status, sib-ship size, early childhood infections, dietary habits, growing up in antroposophic families or on a farm are more and more realised to be of great relevance for the development of allergic conditions. At the moment, there is a lot of uncertainty about which recommendations should be given for primary prevention. Recent studies have challenged the old paradigma that avoidance of early allergen contact could prevent the development of allergic disease. However, there is consensus that avoidance of smoking during pregnancy and avoidance of passive smoking during childhood should be recommended for primary prevention of asthma.

Genetic variants of the IL13 and IL4 genes and atopic diseases in at-risk children

We studied a cohort containing 368 children at high risk of developing atopy and atopic disorders and 540 parents of those children to investigate whether the IL13 Arg130Gln and C-1112 T polymorphisms were associated with these outcomes. We also investigated whether haplotypes consisting of any two polymorphisms of IL13 Arg130Gln, IL13 C-1112 T and IL4 C-589 T were associated with these phenotypes. In 288 white children, the IL13 130Gln allele was associated with atopy (RR=1.9, P=0.047), and with atopic dermatitis (RR=2.5, P=0.014). The associations were confirmed using a family-based test of association (P=0.027 and 0.030, respectively) in all subjects. In white subjects there were associations of haplotypes consisting of IL13 Arg130Gln and IL4 C-589 T with atopic dermatitis (P=0.006) and with atopy (P=0.009). Our data suggest that the IL13 Arg130Gln polymorphism and haplotypes consisting of IL13 Arg130Gln and IL4 C-589 T were associated with the development of atopy and atopic dermatitis at 24 months of age.

A functional polymorphism in the promoter/enhancer region of the FOXP3/Scurfin gene associated with type 1 diabetes

FOXP3/Scurfin, a member of forkhead/winged-helix proteins, is involved in the regulation of T-cell activation, and essential for normal immune homeostasis. The FOXP3/Scurfin gene is located on chromosome Xp11.23, which includes one of the type 1 diabetes susceptible loci. Therefore, we investigated whether the human FOXP3/Scurfin gene might be a new candidate gene for type 1 diabetes. We first screened the human FOXP3/Scurfin gene for microsatellite and single nucleotide polymorphisms. Next, we performed an association study between the FOXP3/Scurfin gene and type 1 diabetes. Then, the evaluation of promoter/enhancer activity of the intron with (GT)(n) polymorphism was performed by dual luciferase reporter assay. We demonstrated two regions contained microsatellite polymorphisms; one was (GT)(n), located on intron zero and the other (TC)(n) on intron 5, which were under linkage-disequilibrium. The (GT)(15) allele showed a significantly higher frequency in patients with type 1 diabetes than in controls (43.1% vs 32.6%, P=0.0027). The genotype frequencies of (GT)(15)/(GT)(15) in female patients and of (GT)(15) in male patients tended to be higher than those in female ( P=0.064) and male ( P=0.061) controls, respectively. A significant difference in the enhancer activity between (GT)(15) and (GT)(16) dinucleotide repeats was detected. In conclusion, the FOXP3/Scurfin gene appears to confer a significant susceptibility to type 1 diabetes in the Japanese population.

Saturation of the 5q31-q33 candidate region for coeliac disease

The first genome wide screening performed on Italian affected sib-pair families (Greco et al. 1998) gave evidence for linkage with coeliac disease in the 5q region. This finding was replicated in a second independent dataset (Greco et al. 2001). Overall, pooling both samples, the highest MLS value (2.92) was found for the most centromeric marker tested, D5S640. In the present study, the 5q31-q33 region was saturated with 12 new markers around D5S640, in order to verify whether there would be a shift of the MLS position. This study allowed us to support our previous finding of linkage for the region 5q31-q33, with the most significant MLS value at D5S2014, very close to the marker D5S640. No evidence for interaction between this risk factor and the one in the HLA region was found. Furthermore, many different groups have independently obtained analogous results for this region, confirming the presence of a susceptibility locus in the region 5q31-q33. This region contains several interesting candidate genes for coeliac disease.

Genetic analyses in asthma: current concepts and future directions

Asthma is a complex genetic disorder with a heterogeneous phenotype, largely attributed to the interactions among many genes and between these genes and the environment. Numerous loci and candidate genes have been reported to show linkage and association of asthma and the asthma-associated phenotypes, atopy, elevated immunoglobulin E (IgE) levels, and bronchial hyper-responsiveness to alleles of microsatellite markers and single nucleotide polymorphisms (SNPs) within specific cytokine/chemokine, and IgE regulating genes. While many studies reporting these observations are compelling, only one asthma gene conferring high risk has been mapped. In this review, we present studies that support linkage and/or associations to the various genetic loci and genes in asthma. The first genome-wide scan for linkage to quantitative traits underlying asthma identified linkage on chromosome 4q, 6, 7, 11q, 13q and 16. A genome scan in American families from three racial groups revealed linkage to chromosome 2q, 5q, 6p, 12q, 13q and 14q. A two-stage scan in Hutterite families from the US found linkage on chromosome 5q, 12q, 19q and 21q. A screen in German families identified linkage to asthma on chromosome 2q, 6p, 9 and 12q and a two-stage genome scan in French families found replicated linkage on chromosomes 1p, 12q and 17q. A study of asthma in Finland showed linkage to high IgE on 7q14. Apart from a European linkage study of 199 families with atopic dermatitis, which demonstrated significant linkage to chromosome 3q21, three other studies have reported linkage results of genome-wide significance, including a linkage study in 175 Icelandic asthma families (14q24), a study in 533 Chinese families with bronchial hyper-responsiveness (chromosome 2) and a study in 47 Japanese families with mite-sensitive atopic asthma (5q31), suggesting that these regions may harbor genes contributing to the development of asthma and allergies. While significant progress has been made in the field of asthma genetics in the past decade, the clinical implications of the genes and genetic variations within the numerous candidate asthma genes that have been found to associate with the expression of the asthmatic phenotype, remain undetermined.

Molecular aspects of allergy

Atopic diseases such as asthma, rhinitis, eczema and food allergies have increased in most industrialised countries of the world during the last 20 years. The reasons for this increase are not known and different hypotheses have been assessed including increased exposure to sensitising allergens or decreased stimulation of the immune system during critical periods of development. In allergic diseases there is a polarisation of the Th2 response and an increase in the production of type 2 cytokines which are involved in the production of immunoglobulin E and the development of mast cells, basophils and eosinophils leading to inflammation and disease. The effector phase of atopy is initiated by interaction with Fc epsilon RI expressed on effector cells such as mast cells and basophils but also found on an ever increasing list of cells. Binding of a polyvalent allergen to the variable part of IgE leads to a cross-link of the receptor that triggers the cell to release histamine and pharmacological mediators of the symptomatic allergic response. Cross-linking of Fc epsilon RI by autoantibodies against the alpha-chain of the Fc epsilon RI, causing subsequent histamine release is thought to be involved in the pathogenesis of other diseases such as chronic idiopathic urticaria (CIU). To date, most therapeutic strategies are aimed at inhibiting and controlling components of the inflammatory response. Recently, new treatment strategies have emerged that focus on the development of preventive and even curative treatments. The most promising therapeutic approaches are aimed at inhibiting the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic anti-IgE or anti-Fc epsilon RIalpha autoantibodies. Clinical trials in humans using an humanised anti-IgE antibody showed that this antibody was well tolerated and reduced both symptoms and use of medication in asthma and allergic rhinitis. Thus interruption of the atopic cascade at the level of the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic antibodies is effective and represents an attractive therapy for the treatment of atopic disease.

Genetics of asthma

As is becoming increasingly apparent, both atopy and asthma (however they are clinically defined) are a diverse group of related conditions, which are similarly disparate in their origins. Despite this, genetic factors are clearly operational. Speaking to their relatedness, linkages have been found between similar chromosomal sites for both atopy and asthma. Speaking to their divergence, there are also reports of the same phenotypes displaying linkage to different chromosomal areas. The likely explanation for this is that both the atopy and asthma phenotypes are polygenetic, requiring that multiple genes (some of them common to both) be expressed. For example, it may be that three genes, such as "a," "b," and "c," are involved in the development of skin test reactivity. Having only two of these genes, such as "a" and "b" or "b" and "c," alone does not result in the development of the defined phenotype of skin test reactivity. At the same time, it may be that to develop asthma one also needs three genes, such as "c", "d," and "e." One gene "c" involved in atopy inflammation is needed for both asthma and skin test reactivity. Genes "a" and "b" are also needed to be present for skin test reactivity, and a different set of genes, "d" and "e," are needed for asthma to develop. These genes "a" and "b" may be needed to localize the process in the skin and "d" and "e" to localize the process in the lung (Fig. 1). In addition to having the genetic predisposition for atopy and its associated conditions, environmental interactions are involved. Environmental conditions may be the initiating trigger and cause a shift in the balance between the protection and susceptibility of getting the clinical picture. In summary, atopy and asthma seem to be related conditions, involving both environmental and genetic factors, most likely consisting of multiple genes, which may interact with each other and the environment. A deeper [figure: see text] understanding of these genetic bases and the roles that environmental factors play in the development and manifestations of these conditions will provide better methods of diagnosis and treatment.

A major susceptibility gene for asthma maps to chromosome 14q24

Asthma is a complex genetic disorder with a heterogeneous phenotype, largely attributed to the interactions among many genes and between these genes and the environment. Numerous loci and candidate genes have been reported to show linkage and association to asthma and atopy. Although some studies reporting these observations are compelling, no gene has been mapped that confers a sufficiently high risk of asthma to meet the stringent criteria for genomewide significance. Using 175 extended Icelandic families that included 596 patients with asthma, we performed a genomewide scan with 976 microsatellite markers. The families were identified by cross-matching a list of patients with asthma from the Department of Allergy/Pulmonary Medicine of the National University Hospital of Iceland with a genealogy database of the entire Icelandic nation. We detected linkage of asthma to chromosome 14q24, with an allele-sharing LOD score of 2.66. After we increased the marker density within the locus to an average of one microsatellite every 0.2 cM, the LOD score rose to 4.00. We designate this locus "asthma locus one" (AS1). Taken together, these results provide evidence of a novel susceptibility gene for asthma on chromosome 14q24.

Food allergy

Food allergy encompasses a range of disorders that result from adverse immune responses to dietary antigens. This group of conditions includes acute, potentially fatal reactions, and a host of chronic diseases that mainly affect the skin and gastrointestinal tract. Tools for diagnosis and management have not changed much in the past two decades, and include the clinical history, physical examination, tests for specific IgE antibody to suspected foods, elimination diets, oral food challenges, and provision of medications such as epinephrine for emergency treatment. However, much research in the past few years has enhanced our understanding of the clinical, epidemiological, and immunological aspects of these disorders. In this review I will discuss these advances and incorporate them into an improved diagnostic and management scheme. Additionally, emergent diagnostic, treatment, and prevention strategies are reviewed.

Effects of glutathione S-transferase M1, maternal smoking during pregnancy, and environmental tobacco smoke on asthma and wheezing in children

The rise in childhood asthma prevalence suggests a role for environmental factors in the etiology of this evolving epidemic; however, genetics also influence the occurrence of asthma. Glutathione S-transferase (GST) M1 may play a role in asthma and wheezing occurrence among those exposed to tobacco smoke, as it functions in pathways involved in asthma pathogenesis such as xenobiotic metabolism and antioxidant defenses. Effects of GSTM1 genotype, maternal smoking during pregnancy, and childhood environmental tobacco smoke (ETS) exposure on asthma and wheezing were investigated in 2,950 children enrolled in 4th, 7th, and 10th grade classrooms in 12 Southern California communities. The effects of in utero exposure to maternal smoking on asthma and wheezing occurrence were largely restricted to children with GSTM1 null genotype. Among GSTM1 null children, in utero exposure was associated with increased prevalence of early onset asthma (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.0-2.5), asthma with current symptoms (OR 1.7, 95% CI 1.1-2.8), persistent asthma (OR 1.6, 95% CI 1.1-2.4), lifetime history of wheezing (OR 1.8, 95% CI 1.3-2.5), wheezing with exercise (OR 2.1, 95% CI 1.3-3.3), wheezing requiring medication (OR 2.2, 95% CI 1.4-3.4), and emergency room visits in the past year (OR 3.7, 95% CI 1.9-7.3). Among children with GSTM1 (+) genotype, in utero exposure was not associated with asthma or wheezing. Our findings indicate that there are important long-term effects of in utero exposure in a genetically susceptible group of children.

Biochemical features, molecular biology and clinical relevance of the human 15-domain serine proteinase inhibitor LEKTI

Based on the isolation of a 55 amino acid peptide from human hemofiltrate, we cloned the cDNA for a novel human 15-domain serine proteinase inhibitor termed LEKTI. A trypsin-inhibiting activity was demonstrated for three different domains. High levels of expression of the corresponding gene were detected in oral mucosa, followed by the tonsils, parathyroid glands, thymus, and trachea. Hovnanian and coworkers recently found that certain mutations within the LEKTI gene are linked to the severe congenital disease Netherton syndrome and atopic manifestations (including asthma). Thus, a future therapeutic use of LEKTI is conceivable.

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.

LEKTI: a multidomain serine proteinase inhibitor with pathophysiological relevance

Proteinase inhibitors are important negative regulators of proteinase action in vivo and are thus involved in several pathophysiological processes. Starting with the isolation of two new peptides from human blood filtrate, we succeeded in cloning a cDNA encoding the precursor protein for a novel 15-domain Kazal-type-related serine proteinase inhibitor. Two of the 15 domains almost exactly match the Kazal-type pattern, whereas the other 13 domains exhibit only four instead of six cysteine residues. Since the corresponding gene is expressed in several lympho-epithelial tissues, we termed this inhibitor lympho-epithelial Kazal-type-related inhibitor (LEKTI). For three of the 15 LEKTI domains, we demonstrated a significant trypsin-inhibiting activity. Recent results of another group show a relation between mutations within the LEKTI gene and the severe congenital disorder Netherton syndrome. In this review article, we give an overview of the already known data on the structure, processing, gene expression, and pathophysiological role of LEKTI.

Positive association to IgE levels and a physical map of the 13q14 atopy locus

Linkage of atopy and associated traits to a locus on chromosome 13q14 has been identified by several studies in diverse populations. We have previously shown the putative atopy gene to be contained within an interval of approximately 5 Mb flanked by D13S328 and D13S1269 and centred on D13S273. We have now extended this work using a top-down approach to physical mapping. A YAC contig was constructed covering the D13S328 and D13S1269 interval. Thirty-one ESTs were mapped to the contig. We constructed a BAC and PAC contig flanking D13S273 by approximately 750 kb in either direction. The interval contained 27 of the 31 ESTS from the YAC contig. Seven previously unknown microsatellites were recovered and then typed in two subject panels. A positive association between the total serum Immunoglobulin E concentration and the novel USAT24G1 microsatellite was discovered (P(corrected)<0.005) and replicated in a second panel of families. The discovery of a region of positive association within the BAC/PAC contig will permit identification of the atopy gene from this locus.

A polymorphism in the human UGRP1 gene promoter that regulates transcription is associated with an increased risk of asthma

Several traits associated with asthma phenotypes, such as high total serum immunoglobulin E and bronchial hyperresponsiveness, have been linked by numerous genome-screen studies and linkage analyses to markers on human chromosome 5q31-q34. In the present article, we describe UGRP1 (encoding uteroglobin-related protein 1) as one of asthma-susceptibility genes that is located on chromosome 5q31-q32. UGRP1 is a homodimeric secretory protein of 17 kDa and is expressed only in lung and trachea. The G --> A polymorphism was identified at -112 bp in the human UGRP1 gene promoter. The -112A allele is responsible for a 24% reduction in the promoter activity in relation to the -112G allele, as examined by transfection analysis. Electrophoretic mobility-shift analysis revealed that an unknown nuclear factor binds to the region around -112 bp. The binding affinity with the -112A oligonucleotide was reduced by approximately one half, as compared with the -112G oligonucleotide. In a case-control study using 169 Japanese individuals (84 patients with asthma and 85 healthy control individuals), those with a -112A allele (G/A or A/A) were 4.1 times more likely to have asthma than were those with the wild-type allele (G/G).

Genome scans and microarrays: converging on genes for schizophrenia?

Systematic genome-wide scans to date have shown that genes of major effect are not common causes of schizophrenia, but independent linkage studies looking for schizophrenia susceptibility genes are converging on a number of key chromosomal locations. Microarray expression analysis may identify new candidate genes and pathways, and a number of intriguing preliminary findings have already been reported.

Genotype predictors of response to asthma medications

The search for the genetic basis of asthma and other allergic diseases has identified many candidate genes. Some of these genes have been investigated to determine whether they influence a person's response to asthma medication. Several studies have shown that polymorphisms in the beta 2 -adrenergic receptor gene influence responsiveness to beta-agonists. Polymorphisms in the 5-lipoxygenase gene and the leukotriene C 4 synthase gene have been associated with response to medications that target leukotriene metabolism. Results such as these suggest the potential for pharmacogenetic tailoring of therapy for individual asthmatic patients. To date, no polymorphisms have been identified that influence response to anticholinergics or are involved in steroid resistance.

A genomewide search for quantitative-trait loci underlying asthma

A genomewide screen for quantitative-trait loci (QTLs) that underlie asthma was performed on 533 Chinese families with asthma, by the unified Haseman-Elston method. Nine asthma-related phenotypes were studied, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), airway responsiveness as indicated by methacholine (MTCH)-challenge test, serum total immunoglobulin E (TIgE), serum-specific immunoglobulin E, eosinophil count in peripheral blood, and skin-prick tests with three different allergens (cockroach, Dermatophagoides pteronyssinus, and D. farinae). Our study showed significant linkage between airway responsiveness to MTCH and D2S1780 on chromosome 2 (P<.00002) and provided suggestive evidence (P<.002) for six additional possible QTLs: D10S1435 and D22S685, for FEV1; D16S412, for FVC; D19S433, for airway responsiveness to MTCH; D1S518, for TIgE; and D4S1647, for skin reactivity to cockroach. No significant or suggestive evidence of linkage for the other four traits was found.

Association of cytokine polymorphic inheritance and in vitro cytokine production in anti-CD3/CD28-stimulated peripheral blood lymphocytes

BACKGROUND

Genetic variations in cytokine genes are thought to regulate cytokine protein production. However, studies using T cell mitogens have not always demonstrated a significant relationship between cytokine polymorphisms and in vitro protein production. Furthermore, the functional consequence of a polymorphism at position -330 in the IL-2 gene has not been described. We associated in vitro protein production with cytokine gene polymorphic genotypes after costimulation of cultured peripheral blood lymphocytes.

METHODS

PBL were isolated from forty healthy volunteers. Cytokine protein production was assessed by enzyme-linked immunosorbent assay. Polymorphisms in interleukin- (IL) 2, IL-6, IL-10, tumor necrosis factor (TNF-alpha), tumor growth factor (TGF-beta), and interferon (IFN-gamma) were determined by polymerase chain reaction (PCR).

RESULTS

Statistical difference between protein production and cytokine polymorphic variants in the IL-10, IFN-gamma, and TNF-alpha genes was not evident after 48-hour stimulation with concanavalin-A. In contrast, after anti-CD3/CD28 stimulation significant differences (P<0.05) were found among high and low producers for IL-2, IL-6, and among high, intermediate, and low producers for IFN-gamma, and IL-10. Augmented levels of IL-2 in individuals that were homozygous for the polymorphic IL-2 allele were due to an early and sustained enhancement of IL-2 production. No association was found among TNF-alpha and TGF-beta genotypes and protein production.

CONCLUSION

Polymorphisms in IL-2, IL-6, IL-10, and IFN-gamma genes are associated with their protein production after anti-CD3/CD28 stimulation. The profound effect of the IL-2 gene polymorphism in homozygous individuals may serve as a marker for those that could mount the most vigorous allo- or autoimmune responses, or perhaps become tolerant more easily.

Recombinant allergens/allergen standardization

Recombinant allergens are genetically engineered isoforms representing allergen molecules from allergen extracts. Immunologic responses of allergic patients toward allergen extracts define the major allergens. For the average allergic patient, the diagnostic sensitivity and treatment efficacy correlate with the concentration of major allergen. Standardization of allergen products (extracts or genetically engineered allergens) can therefore advantageously be performed using a selected recombinant major allergen as a standard. The standardization will furthermore require reagents for which both monospecific, monoclonal, or preferably, recombinant antibodies can be used. Due to differences in the allergenic activity of individual isoallergens and the naturally occurring mixture of isoallergens found in an allergen extract, and due to additional contribution to the allergenic activity from other molecules in the extract, a biologic potency assessment must always be performed as a supplement. This is also the case for a genetically engineered allergen product.