Eotaxin gene single nucleotide polymorphisms in the promoter and exon regions are not associated with susceptibility to atopic dermatitis, but two of them in the promoter region are associated with serum IgE levels in patients with atopic dermatitis

Association between CCL5, CCL11, and CCL17 polymorphisms and atopic dermatitis risk: A systematic review and meta-analysis

BACKGROUND

Atopic dermatitis (AD) is a common and recurrent inflammatory disease with strong genetic susceptibility. The abnormal production of chemokines plays an important role in the occurrence and development of AD.

METHODS

A comprehensive online literature search was performed in databases of China National Knowledge Infrastructure, Wanfang, VIP China Science and Technology Journal Database, China Biomedical Literature Database, PubMed, Embase and Cochrane Library to retrieve relevant articles published from January 2000 to October 2022. The odds ratio (OR) with its 95% confidence interval (CI) was employed to calculate this relationship.

RESULTS

A total of 7 studies were finally screened out, including 1316 AD patients and 1099 controls. There were 3 studies for CC chemokine ligand 5 (CCL5) polymorphisms, 2 for CCL11 polymorphisms, and 2 for CCL17 polymorphisms, respectively. The meta-analysis revealed a significant association between the CCL5 - 403G/A polymorphism and AD under the allelic model (A vs G: OR = 1.25, 95% CI = 1.02-1.52, P = .03), heterozygous model (AG vs GG: OR = 1.40, 95% CI = 1.08-1.80, P = .01) and dominant model (AA + AG vs GG: OR = 1.38, 95% CI = 1.08-1.76, P = .01) in a fixed-effect model. The allelic model (G vs C: OR = 1.46, 95% CI = 1.07-1.98, P < .01) and dominant model (GG + GC vs CC: OR = 1.74, 95% CI = 1.23-2.47, P < .001) of the CCL5 - 28C/G polymorphism were also associated with an increased risk of AD. However, this significant association was not found in other alleles and genotypes (P > .05).

CONCLUSION

Our results show that the A allele, AG and AA + AG genotypes of the CCL5 - 403G/A polymorphism, the G allele and GG + GC genotype of the CCL5 - 28C/G polymorphism are risk factors for AD. Future studies with large population are still needed to further explore those correlations.

Childhood atopic dermatitis: current developments, treatment approaches, and future expectations

Atopic dermatitis (AD) is the most common chronic inflammatory skin disorder of childhood. Underlying factors that contribute to AD are impaired epithelial barrier, alterations in the lipid composition of the skin, immunological imbalance including increased Th2/Th1 ratio, proinflammatory cytokines, decreased T regulatory cells, genetic mutations, and epigenetic alterations. Atopic dermatitis is a multifactorial disease with a particularly complicated pathophysiology. Discoveries to date may be considered the tip of the iceberg, and the increasing number of studies in this field indicate that there are many points to be elucidated in AD pathophysiology. In this review, we aimed to illustrate the current understanding of the underlying pathogenic mechanisms in AD, to evaluate available treatment options with a focus on recently discovered therapeutic agents, and to determine the personal, familial, and economic burdens of the disease, which are frequently neglected issues in AD. Currently available therapies only provide transient solutions and cannot fully cure the disease. However, advances in the understanding of the pathogenic mechanisms of the disease have led to the production of new treatment options, while ongoing drug trials also have had promising results.

Molecular biology of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific genetic and immunological mechanisms. The rapid development of new techniques in molecular biology had ushered in new discoveries on the role of cytokines, chemokines, and immune cells in the pathogenesis of AD. New polymorphisms of AD are continually being reported in different populations. The physical and immunological barrier of normal intact skin is an important part of the innate immune system that protects the host against microbials and allergens that are associated with AD. Defects in the filaggrin gene FLG may play a role in facilitating exposure to allergens and microbial pathogens, which may induce Th2 polarization. Meanwhile, Th22 cells also play roles in skin barrier impairment through IL-22, and AD is often considered to be a Th2/Th22-dominant allergic disease. Mast cells and eosinophils are also involved in the inflammation via Th2 cytokines. Release of pruritogenic substances by mast cells induces scratching that further disrupts the skin barrier. Th1 and Th17 cells are mainly involved in chronic phase of AD. Keratinocytes also produce proinflammatory cytokines such as thymic stromal lymphopoietin (TSLP), which can further affect Th cells balance. The immunological characteristics of AD may differ for various endotypes and phenotypes. Due to the heterogeneity of the disease, and the redundancies of these mechanisms, our knowledge of the pathophysiology of the disease is still incomplete, which is reflected by the absence of a cure for the disease.

Lack of association between eotaxin-1 gene polymorphisms and nasal polyposis

OBJECTIVE

To examine whether there is an association of eotaxin-1 gene polymorphisms with nasal polyposis (NP).

STUDY DESIGN

Cross-sectional study.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

The study group included 85 patients with NP and 93 controls without sinonasal disease. Genotypes of eotaxin-1 (-384 A>G and +67 G>A) were identified by restriction fragment length polymorphism analyses after polymerase chain reaction.

RESULTS

The -384 A>G and +67 G>A single nucleotide polymorphisms were higher in patients with NP than in controls (P = .044 and P = .019, respectively). However, their relation was statistically poor (association coefficient = 0.18). Consistent with this result, comparisons of allele frequencies for both single nucleotide polymorphisms were not significantly different (-384 A>G, P = .164; +67 G>A, P = .144).

CONCLUSION

In this study, eotaxin-1 -384 A>G or 67 G>A genotypes were not associated with susceptibility to NP.

An update on the genetics of atopic dermatitis: scratching the surface in 2009

A genetic basis for atopic dermatitis (AD) has long been recognized. Historic documents allude to family history of disease as a risk factor. Before characterization of the human genome, heritability studies combined with family-based linkage studies supported the definition of AD as a complex trait in that interactions between genes and environmental factors and the interplay between multiple genes contribute to disease manifestation. A summary of more than 100 published reports on genetic association studies through mid-2009 implicates 81 genes, in 46 of which at least 1 positive association with AD has been demonstrated. Of these, the gene encoding filaggrin (FLG) has been most consistently replicated. Most candidate gene studies to date have focused on adaptive and innate immune response genes, but there is increasing interest in skin barrier dysfunction genes. This review examines the methods that have been used to identify susceptibility genes for AD and how the underlying pathology of this disease has been used to select candidate genes. Current challenges and the potential effect of new technologies are discussed.

The genetics of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a complex genetic disorder influenced by environmental factors. The mode of inheritance and genes involved are not clear.

RESULTS

This report here is focusing on the current progress in searching the disease-susceptibility genes of AD via both the linkage studies and candidate gene approaches. Genome-wide linkage studies have identified multiple susceptibility loci on 3q and 17q. Candidate region linkage studies identify other susceptibility loci on 5q23-33, 11q13, and 13q12-14. At least 28 candidate genes have to date been verified in association studies, but only association with genes of interleukin (IL)-4, IL-13, IL-4RA, mast cell chymase, and serine protease inhibitor, kazal-type 5 have been replicated in more than two different studies. More halpotype tests and family-based association studies may help to shed more light for the candidate gene approach.

CONCLUSION

Determining the candidate susceptibility genes for AD is not only helping understanding the pathophysiology but also affecting the response to therapy, which is important in pharmacogenetics. The effect of environmental trigger may also have to be considered to elucidate the real face of the disease.

Genetic susceptibility to atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disorder with an increasing prevalence in industrialized countries. AD belongs to the group of allergic disorders that includes food allergy, allergic rhinitis, and asthma. A multifactorial background for AD has been suggested, with genetic as well as environmental factors influencing disease development. Recent breakthroughs in genetic methodology have greatly augmented our understanding of the contribution of genetics to susceptibility to AD. A candidate gene association study is a general approach to identify susceptibility genes. Fifty three candidate gene studies (50 genes) have identified 19 genes associated with AD risk in at least one study. Significant associations between single nucleotide polymorphisms (SNPs) in chemokines (chymase 1-1903A > G), cytokines (interleukin13 Arg144Gln), cytokine receptors (interleukin 4 receptor 1727G > A) and SPINK 1258G > A have been replicated in more than one studies. These SNPs may be promising for identifying at-risk individuals. SNPs, even those not strongly associated with AD, should be considered potentially important because AD is a common disease. Even a small increase in risk can translate to a large number of AD cases. Consortia and international collaborative studies, which may maximize study efficacy and overcome the limitations of individual studies, are needed to help further illuminate the complex landscape of AD risk and genetic variations.

Clinical correlations of recent developments in the pathogenesis of atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease with a steadily increasing prevalence affecting 10-20 of infants and 1-3 of adults globally. It is often the first clinical manifestation of atopic disease preceding asthma and allergic rhinitis. Probably half of the children with atopic dermatitis develop some other form of atopic disease later in life. The pathogenesis involves a complex interplay of factors including genetic predisposition due to altered immune or skin barrier function, interactions with the environment such as food and allergen exposures, and infectious triggers of inflammation. In this review, we summarize the recent advances in understanding the contribution of different factors in the pathophysiology of atopic dermatitis and how insights provide new therapeutic potential for its treatment.

The chemokine network. II. On how polymorphisms and alternative splicing increase the number of molecular species and configure intricate patterns of disease susceptibility

In this second review on chemokines, we focus on the polymorphisms and alternative splicings and on their consequences in disease. Because chemokines are key mediators in the pathogenesis of inflammatory, autoimmune, vascular and neoplastic disorders, a large number of studies attempting to relate particular polymorphisms of chemokines to given diseases have already been conducted, sometimes with contradictory results. Reviewing the published data, it becomes evident that some chemokine genes that are polymorphic have alleles that are found repeatedly, associated with disease of different aetiologies but sharing some aspects of pathogenesis. Among CXC chemokines, single nucleotide polymorphisms (SNPs) in the CXCL8 and CXCL12 genes stand out, as they have alleles associated with many diseases such as asthma and human immunodeficiency virus (HIV), respectively. Of CC chemokines, the stronger associations occur among alleles from SNPs in CCL2 and CCL5 genes and a number of inflammatory conditions. To understand how chemokines contribute to disease it is also necessary to take into account all the isoforms resulting from differential splicing. The first part of this review deals with polymorphisms and the second with the diversity of molecular species derived from each chemokine gene due to alternative splicing phenomena. The number of molecular species and the level of expression of each of them for every chemokine and for each functionally related group of chemokines reaches a complexity that requires new modelling algorithms akin to those proposed in systems biology approaches.

A hexanucleotide repeat upstream of eotaxin gene promoter is associated with asthma, serum total IgE and plasma eotaxin levels

BACKGROUND

Eotaxin (CCL11) is a small protein produced in the lungs of patients with asthma, and is a potent chemoattractant for eosinophils.

AIM

To elucidate the role of eotaxin in asthma by an association study of functional and novel eotaxin polymorphisms in case-control and family-based study designs.

METHODS

Eotaxin +67G/A, -384A/G and -426C/T single-nucleotide polymorphisms and a hexanucleotide (GAAGGA)(n) repeat 10.9 kb upstream of the gene were genotyped in a cohort of age, sex and ethnically matched patients with asthma (n = 235) and healthy controls (n = 239), and also in a study population of 230 families with asthma recruited from north/northwest India. Total serum IgE (TsIgE) and plasma eotaxin levels were measured using ELISA.

RESULTS

+67G/A polymorphism was found to be significantly associated with asthma in case-control (p = 0.009) and family-based studies (p = 0.006). Its functional role, as it was correlated with plasma eotaxin levels (p = 0.006), was also demonstrated. Further, -384C/T single-nucleotide polymorphism was found to be significantly associated with log(10) TsIgE (p = 0.016 in case-control and p = 0.018 in families) and eotaxin levels (p = 0.007). Most interestingly, for the first time, a highly significant association of the newly studied (GAAGGA)(n) hexanucleotide repeat with asthma (p = 3x10(-6)), log(10)TsIgE (p = 0.006) and eotaxin levels (p = 0.004) was observed. G_A_C_8 was also identified as an important risk haplotype associated with high TsIgE and plasma eotaxin levels.

CONCLUSIONS

This study provides further evidence that eotaxin polymorphisms are associated with the development of asthma by regulating eotaxin levels and reinforces towards the scanning of other chemokine genes present at 17q21 locus for their association with asthma and related phenotypes.

Association of beta-defensin 1 single nucleotide polymorphisms with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic multifactorial allergic disease with unclear etiology. The antimicrobial human beta-defensin 1 is chemotactic for dendritic cells, which are important regulators of allergic immune responses. In an attempt to identify useful markers that could predict susceptibility to AD, we investigated single nucleotide polymorphisms (SNPs) of the beta-defensin 1 gene (DEFB1) with potential functional consequences.

METHODS

Four SNPs of the DEFB1 gene were genotyped either by real-time polymerase chain reaction or polymerase chain reaction-restriction fragment length polymorphisms in 59 patients with AD and 151 controls from the Mexican population. Correlation analyses were carried out between genetic, environmental and clinical variables in AD patients.

RESULTS

The genotypes associated with susceptibility to AD and no other allergy were 692 GG (OR = 3.21, 95% CI 1.37-7.34) and 1654 AA (OR = 17.37, 95% CI 1.62-860.83). The allele 668 C is a risk factor for AD (OR = 2.23, 95% CI 1.22-4.01) and the allele A in site 1836 correlates with earlier age at onset (Spearman's rho = 0.232; p = 0.03). The prolonged duration of breastfeeding correlates with earlier age at onset as well as with the severity of AD.

CONCLUSIONS

The DEFB1 gene is probably involved in the incidence and development of AD, but additional functional studies will be necessary to understand the biological role of these SNPs.

Eotaxin polymorphisms and serum total IgE levels in children with asthma

BACKGROUND

Eotaxin (chemokine, CC motif, ligand; CCL11) is a potent eosinophil chemoattractant strongly implicated in the pathobiology of asthma. Genetic variation at the CCL11 locus has been correlated with serum total IgE, blood eosinophil counts, and circulating eotaxin protein levels in several case-control asthma studies. Family-based association studies of CCL11 genetic variants have not been reported to date.

OBJECTIVE

To evaluate 9 common CCL11 single nucleotide polymorphisms (SNPs) in nuclear families ascertained through patients with asthma participating in the Childhood Asthma Management Program study.

METHODS

Single nucleotide polymorphism genotyping was performed by using minisequencing and probe hybridization platforms. Family-based association analysis for asthma and 4 asthma-related intermediate quantitative phenotypes was performed by using FBAT.

RESULTS

One SNP, -384A>G, was associated with asthma among African American families (P = .01). CCL11 SNPs and haplotypes were not associated with asthma among white or Hispanic families. Two low-frequency alleles in strong pairwise linkage disequilibrium, -426C and IVS2+199A, were associated with lower serum total IgE levels (P = .0006 and P = .009, respectively) in white families, whereas 2 more common variants, -576C and g.4438C, were associated with higher IgE levels in African American families (P = .01-.04). Haplotype analysis in the white cohort provided additional evidence of association with serum total IgE, implicating 2 haplotypes. No single SNP or haplotype associations were observed with blood eosinophil levels, FEV(1), or airway responsiveness.

CONCLUSION

These findings provide further evidence that genetic variation at the CCL11 locus is an important determinant of serum total IgE levels among patients with asthma.

The genetics of atopic dermatitis: recent findings and future options

Atopic dermatitis (AD) is a chronic pruritic skin disease affecting up to 15% of children in industrialized countries. AD belongs to the group of allergic disorders that include food allergy, allergic rhinitis, and asthma. A multifactorial background for AD has been suggested, with genetic as well as environmental factors influencing disease development. Genome-wide screens for AD have been completed in four different populations to date. Interestingly, the susceptibility regions identified for AD show little overlap with asthma susceptibility regions, suggesting that, at least in part, separate genes might be involved in the pathogenesis of the different atopic disorders. Instead, some of the identified regions overlap with susceptibility regions for psoriasis, another chronic skin disease. Thus, genes expressed in the skin might play an important role in AD pathogenesis, in addition to genes influencing atopic diatheses. Although no veritable "AD gene" has been identified by positional cloning to date, examples from other complex genetic disorders such as asthma show that this goal is likely to be reached in the near future. Candidate gene studies, on the other hand, have identified 19 genes that were shown to be associated with AD in at least one study. The results of genome-wide screens as well as candidate gene studies are evaluated here in detail.

A single nucleotide polymorphism on the promoter of eotaxin1 associates with its mRNA expression and asthma phenotypes

Eotaxin1 plays a pivotal role in eosinophil-associated inflammation. Previously, we demonstrated 14 single-nucleotide polymorphisms (SNPs) in the human eotaxin1 gene and the association between the EOT+67G>A allele and the level of IgE. In this study, we investigated the association between the SNPs and plasma eotaxin1 levels, peripheral blood eosinophil counts, and PC20 methacholine values in normal and asthmatic subjects, and the effects of SNPs on the process of eotaxin1 production. The EOT-576C>T and EOT-384A>G polymorphisms and haplotypes (ht1 and ht4) were significantly associated with plasma eotaxin1 levels in the asthmatics (p < 0.001-0.040). The log [plasma eotaxin1] values correlated with the log [serum total IgE] values in the asthmatics and the normal controls (p = 0.012 and p = 0.004, respectively), and with the log [PC20 methacholine] values in the asthmatics (p = 0.014). A DNA-protein complex was formed with EOT-384A>G, but not with the other SNPs of the promoter. The interaction was stronger with the minor allele than with the common allele, and was reduced upon TNF-alpha exposure. TNF-alpha-stimulated PBMCs from the asthmatics with the minor allele homozygote expressed significantly lower levels of eotaxin1 mRNA than those from individuals with the common allele. The EOT+67G>A polymorphism, which substitutes alanine with threonine, did not affect eotaxin1 production or activity. Our data suggest that the EOT-384A>G SNP participates in the regulation of eotaxin1 expression by providing a potential binding site for a repressor, and that the ANOVA of EOT-384A>G may predict asthma phenotypes.

The suggestive association of eotaxin-2 and eotaxin-3 gene polymorphisms in Korean population with allergic rhinitis

The eotaxin gene family (eotaxin, eotaxin-2 and eotaxin-3) has been implicated in the recruitment of eosinophils, basophiles and Th2 lymphocytes that are central aspects of allergic diseases. To determine whether single-nucleotide polymorphisms (SNPs) of the eotaxin-2 and eotaxin-3 genes are associated with susceptibility to allergic rhinitis, we scanned 178 allergic rhinitis patients and 281 controls without allergic rhinitis using the direct sequencing and single-base extension (SBE) methods. We also calculated the haplotype frequencies between +179T>C and +275C>T of eotaxin-2 and +2497T>G of eotaxin-3 in both controls and allergic rhinitis patients. The haplotype frequency between controls and allergic rhinitis patients was suggestively associated (P=0.0001). The genotype frequencies of eotaxin-3 +2497T>G in allergic rhinitis patients were suggestively different from those in non-allergic rhinitis controls (P=<0.0007). Our results strongly suggest that the SNP of eotaxin-3 might be associated with susceptibility to allergic rhinitis.

Analysis of the polymorphisms in eotaxin gene family and their association with asthma, IgE, and eosinophil

The eotaxin gene family (eotaxin, eotaxin-2, and eotaxin-3) has been implicated in the recruitment of eosinophils, basophiles, and Th2 lymphocytes that is a central aspect of allergic diseases such as asthma. To determine whether the single nucleotide polymorphisms (SNPs) of eotaxin gene family are associated with susceptibility to asthma, we scanned 225 asthma patients and 294 non-asthmatic controls using the direct sequencing method. We further investigated the relationships among each SNP, eosinophils, and serum total IgE levels in asthma patients. Eleven SNPs were identified in the eotaxin gene family. We found that EoB179T > C (P = 0.0001), EoB275C > T (P = 0.018) of the eotaxin-2 and EoA2497T > G (P = 0.003) of the eotaxin-3 were significantly associated with the susceptibility of asthma. Furthermore, our data demonstrated for the first time that EoA2497T > G (P = 0.005) is related to serum total IgE level while EoA77C > T (P = 0.035) and EoA2497T > G (P = 0.033) are related to the peripheral blood eosinophil counts in asthma. Our results suggest that the polymorphisms of the eotaxin gene family are associated with the susceptibility of asthma and Eotaxin-3 might play the critical role for the recruitment of eosinophils and the maintenance of IgE levels.

Threonine for alanine substitution in the eotaxin (CCL11) gene and the risk of incident myocardial infarction

Recent studies suggest that the chemokine eotaxin may participate in atherosclerosis. Threonine (T) for alanine (A) substitution at amino acid 23 in the eotaxin gene (CCL11) has been associated with risk of developing allergic-inflammatory disorders. However, no genetic-epidemiological data are available on the risk of cardiovascular disease associated with this polymorphism. Using DNA samples collected at baseline in a prospective cohort of 14,916 initially healthy American men, we evaluated the A23T polymorphism among 523 individuals who subsequently developed myocardial infarction (MI) and among 2092 individuals who remained free of reported cardiovascular disease over a mean follow-up period of 13.2 years. The T23 allele was significantly associated with risk of myocardial infarction (odds ratio (OR) in an age and smoking adjusted recessive model of inheritance, 1.86; 95% confidence interval (CI), 1.15-3.01; P = 0.012). This risk effect remained statistically significant in analyses further controlling for body mass index, history of hypertension, the presence of diabetes, and randomized treatment assignment (OR, 1.95; 95% CI, 1.19-3.18; P = 0.008). In this cohort, a T for A substitution at amino acid 23 in the eotaxin gene is associated with increased risk for incident myocardial infarction. If confirmed in other cohorts, these data support the emerging hypothesis that eotaxin participates in atherosclerosis.

Recent development in genomic and proteomic research for asthma

PURPOSE OF REVIEW

Asthma is a complex genetic disorder with a heterogeneous phenotype attributed to the interactions among many genes and the environment. This review highlights recent developments in asthma genomic and proteomic research.

RECENT FINDINGS

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 hyperresponsiveness to alleles of microsatellite markers and single nucleotide polymorphisms within specific cytokine/chemokine, and IgE regulating genes. Although many studies reporting these observations are compelling, only a few genes conferring significant risk have been mapped. Although significant progress has been made in the field of asthma genetics in the past decade, the clinical implications of the genetic variations within the numerous candidate asthma genes, which have been found to associate with the expression of the asthmatic phenotype, remain largely undetermined. However, in the past year the scientific community has benefited from postgenomic discoveries, with the recent cloning of two asthma genes, ADAM 33 and PHF11, and this has generated new information that is benefiting others.

SUMMARY

The asthma genetics field has advanced considerably in recent years, with new information being generated that has led to improved understanding of the pathobiology underlying this complex disorder. This has also generated interest in the study of gene-gene interaction and how linkage disequilibrium blocks and haplotypes can be used as functional units to pinpoint mutations and capture relative risk of mutated genes in complex disorders.

Association studies for asthma and atopic diseases: a comprehensive review of the literature

Hundreds of genetic association studies on asthma-related phenotypes have been conducted in different populations. To date, variants in 64 genes have been reported to be associated with asthma or related traits in at least one study. Of these, 33 associations were replicated in a second study, 9 associations were not replicated either in a second study or a second sample in the same study, and 22 associations were reported in just a single published study. These results suggest the potential for a great amount of heterogeneity underlying asthma. However, many of these studies are methodologically limited and their interpretation hampered by small sample sizes.

Novel case-control test in a founder population identifies P-selectin as an atopy-susceptibility locus

To avoid problems related to unknown population substructure, association studies may be conducted in founder populations. In such populations, however, the relatedness among individuals may be considerable. Neglecting such correlations among individuals can lead to seriously spurious associations. Here, we propose a method for case-control association studies of binary traits that is suitable for any set of related individuals, provided that their genealogy is known. Although we focus here on large inbred pedigrees, this method may also be used in outbred populations for case-control studies in which some individuals are relatives. We base inference on a quasi-likelihood score (QLS) function and construct a QLS test for allelic association. This approach can be used even when the pedigree structure is far too complex to use an exact-likelihood calculation. We also present an alternative approach to this test, in which we use the known genealogy to derive a correction factor for the case-control association chi2 test. We perform analytical power calculations for each of the two tests by deriving their respective noncentrality parameters. The QLS test is more powerful than the corrected chi2 test in every situation considered. Indeed, under certain regularity conditions, the QLS test is asymptotically the locally most powerful test in a general class of linear tests that includes the corrected chi2 test. The two methods are used to test for associations between three asthma-associated phenotypes and 48 SNPs in 35 candidate genes in the Hutterites. We report a highly significant novel association (P=2.10-6) between atopy and an amino acid polymorphism in the P-selectin gene, detected with the QLS test and also, but less significantly (P=.0014), with the transmission/disequilibrium test.