Genetic and T2 biomarkers linked to the efficacy of HDM sublingual immunotherapy in asthma

BACKGROUND

Hypersensitivity to house dust mite (HDM) allergens is a common cause of allergic asthma symptoms and can be effectively treated with allergy immunotherapy (AIT).

OBJECTIVE

To investigate whether genetic and type 2 (T2) inflammatory biomarkers correlate with disease severity in subjects with allergic asthma, and whether this can be modified by AIT.

METHODS

MITRA (NCT01433523) was a phase III, randomised, double-blind, placebo-controlled trial of HDM sublingual immunotherapy (SLIT)-tablets in adults with HDM allergic asthma. Post hoc analyses of the study population (N=742) evaluated associations between T2 inflammatory (blood eosinophils, eosinophil cationic protein (ECP), total IgE and tryptase) and genetic (single-nucleotide polymorphisms, SNP) biomarkers (n=582) for the primary study endpoint (time to first moderate/severe asthma exacerbation). SNP associations were verified in HDM-positive subgroup from an independent 3-year Severe Asthma Research Programme (SARP3) subject cohort.

RESULTS

An increased asthma exacerbation risk in subjects homozygous for SNP rs7216389 (chromosomal locus 17q12-21) was reduced (p=0.037) by treatment with HDM SLIT (HR=0.37 (95% CI 0.22 to 0.64), p<0.001). The associations between exacerbation risk and 17q12-21 SNPs were replicated in the SARP3 HDM-positive subgroup. High levels of T2 biomarkers were associated with increased risk of asthma exacerbations in the placebo group. HDM SLIT-tablet treatment reduced this risk (blood eosinophils: HR=0.50 (95% CI 0.30 to 0.85); ECP: HR=0.45 (95% CI 0.29 to 0.87); tryptase: HR=0.45 (95% CI 0.25 to 0.80)). The treatment effect was higher (p=0.006) for subjects with a higher number of elevated T2 biomarkers.

CONCLUSIONS

HDM SLIT-tablet AIT is efficacious in HDM-sensitised asthma subjects with a genetic asthma predisposition and/or an underlying T2 endotype.

TRIAL REGISTRATION NUMBER

NCT01433523.

Novel genetic variants associated with inhaled corticosteroid treatment response in older adults with asthma

INTRODUCTION

Older adults have the greatest burden of asthma and poorest outcomes. The pharmacogenetics of inhaled corticosteroid (ICS) treatment response is not well studied in older adults.

METHODS

A genome-wide association study of ICS response was performed in asthmatics of European ancestry in Genetic Epidemiology Research on Adult Health and Aging (GERA) by fitting Cox proportional hazards regression models, followed by validation in the Mass General Brigham (MGB) Biobank and Rotterdam Study. ICS response was measured using two definitions in asthmatics on ICS treatment: (1) absence of oral corticosteroid (OCS) bursts using prescription records and (2) absence of asthma-related exacerbations using diagnosis codes. A fixed-effect meta-analysis was performed for each outcome. The validated single-nucleotide polymorphisms (SNPs) were functionally annotated to standard databases.

RESULTS

In 5710 subjects in GERA, 676 subjects in MGB Biobank, and 465 subjects in the Rotterdam Study, four novel SNPs on chromosome six near PTCHD4 validated across all cohorts and met genome-wide significance on meta-analysis for the OCS burst outcome. In 4541 subjects in GERA and 505 subjects in MGB Biobank, 152 SNPs with p<5 × 10-5 were validated across these two cohorts for the asthma-related exacerbation outcome. The validated SNPs included methylation and expression quantitative trait loci for CPED1, CRADD and DST for the OCS burst outcome and GM2A, SNW1, CACNA1C, DPH1, and RPS10 for the asthma-related exacerbation outcome.

CONCLUSIONS

Multiple novel SNPs associated with ICS response were identified in older adult asthmatics. Several SNPs annotated to genes previously associated with asthma and other airway or allergic diseases, including PTCHD4.

Highlighting the importance of healthy sleep patterns in the risk of adult asthma under the combined effects of genetic susceptibility: a large-scale prospective cohort study of 455 405 participants

BACKGROUND

Individuals with asthma usually have comorbid sleep disturbances; however, whether sleep quality affects asthma risk is still unclear. We aimed to determine whether poor sleep patterns could increase the risk of asthma and whether healthy sleep patterns could mitigate the adverse effect of genetic susceptibility.

METHODS

A large-scale prospective study was performed in the UK Biobank cohort involving 455 405 participants aged 38-73 years. Polygenic risk scores (PRSs) and comprehensive sleep scores, including five sleep traits, were constructed. A multivariable Cox proportional hazards regression model was used to investigate the independent and combined effects of sleep pattern and genetic susceptibility (PRS) on asthma incidence. Subgroup analysis across sex and sensitivity analysis, including a 5-year lag, different covariate adjustments and repeat measurements were performed.

RESULTS

A total of 17 836 individuals were diagnosed with asthma during over 10 years of follow-up. Compared with the low-risk group, the HRs and 95% CIs for the highest PRS group and the poor sleep pattern group were 1.47 (95% CI: 1.41 to 1.52) and 1.55 (95% CI: 1.45 to 1.65), respectively. A combination of poor sleep and high genetic susceptibility led to a twofold higher risk compared with the low-risk combination (HR (95% CI): 2.22 (1.97 to 2.49), p<0.001). Further analysis showed that a healthy sleep pattern was associated with a lower risk of asthma in the low, intermediate and high genetic susceptibility groups (HR (95% CI): 0.56 (0.50 to 0.64), 0.59 (0.53 to 0.67) and 0.63 (0.57 to 0.70), respectively). Population-attributable risk analysis indicated that 19% of asthma cases could be prevented when these sleep traits were improved.

CONCLUSIONS

Individuals with poor sleep patterns and higher genetic susceptibility have an additive higher asthma risk. A healthy sleep pattern reflected a lower risk of asthma in adult populations and could be beneficial to asthma prevention regardless of genetic conditions. Early detection and management of sleep disorders could be beneficial to reduce asthma incidence.

Unlocking the secrets of long non-coding RNAs in asthma

Asthma is a very heterozygous disease, divided in subtypes, such as eosinophilic and neutrophilic asthma. Phenotyping and endotyping of patients, especially patients with severe asthma who are refractory to standard treatment, are crucial in asthma management and are based on a combination of clinical and biological features. Nevertheless, the quest remains to find better biomarkers that distinguish asthma subtypes in a more clear and objective manner and to find new therapeutic targets to treat people with therapy-resistant asthma. In the past, research to identify asthma subtypes mainly focused on expression profiles of protein-coding genes. However, advances in RNA-sequencing technologies and the discovery of non-coding RNAs as important post-transcriptional regulators have provided an entire new field of research opportunities in asthma. This review focusses on long non-coding RNAs (lncRNAs) in asthma; these are non-coding RNAs with a length of more than 200 nucleotides. Many lncRNAs are differentially expressed in asthma, and several have been associated with asthma severity or inflammatory phenotype. Moreover, in vivo and in vitro functional studies have identified the mechanisms of action of specific lncRNAs. Although lncRNAs remain not widely studied in asthma, the current studies show the potential of lncRNAs as biomarkers and therapeutic targets as well as the need for further research.

Plasma adiponectin and risk of asthma: observational analysis, genetic Mendelian randomisation and meta-analysis

BACKGROUND

Adiponectin, an adipocyte-secreted protein-hormone with inflammatory properties, has a potentially important role in the development and progression of asthma. Unravelling whether adiponectin is a causal risk factor for asthma is an important issue to clarify as adiponectin could be a potential novel drug target for the treatment of asthma.

OBJECTIVE

We tested the hypothesis that plasma adiponectin is associated observationally and causally (using genetic variants as instrumental variables) with risk of asthma.

METHODS

In the Copenhagen General Population Study, we did an observational analysis in 28 845 individuals (2278 asthma cases) with plasma adiponectin measurements, and a genetic one-sample Mendelian randomisation analysis in 94 868 individuals (7128 asthma cases) with 4 genetic variants. Furthermore, in the UK Biobank, we did a genetic two-sample Mendelian randomisation analysis in 462 933 individuals (53 598 asthma cases) with 12 genetic variants. Lastly, we meta-analysed the genetic findings.

RESULTS

While a 1 unit log-transformed higher plasma adiponectin in the Copenhagen General Population Study was associated with an observational OR of 1.65 (95% CI 1.29 to 2.08) for asthma, the corresponding genetic causal OR was 1.03 (95% CI 0.75 to 1.42). The genetic causal OR for asthma in the UK Biobank was 1.00 (95% CI 0.99 to 1.00). Lastly, genetic meta-analysis confirmed lack of association between genetically high plasma adiponectin and causal OR for asthma.

CONCLUSION

Observationally, high plasma adiponectin is associated with increased risk of asthma; however, genetic evidence could not support a causal association between plasma adiponectin and asthma.

Novel recessive locus for body mass index in childhood asthma

Most genome-wide association studies of obesity and body mass index (BMI) have so far assumed an additive mode of inheritance in their analysis, although association testing supports a recessive effect for some of the established loci, for example, rs1421085 in FTO In two whole-genome sequencing (WGS) studies of children with asthma and their parents (892 Costa Rican trios and 286 North American trios), we discovered an association between a locus (rs9292139) in LOC102724122 and BMI that reaches genome-wide significance under a recessive model in the combined analysis. As the association does not achieve significance under an additive model, our finding illustrates the benefits of the recessive model in WGS analyses.

Asthma and COVID-19: lessons learned and questions that remain

INTRODUCTION

Asthma is one of the most common chronic diseases worldwide. As a disease of the respiratory tract, the site of entry for the SARS-CoV-2 virus, there may be an important interplay between asthma and COVID-19 disease.

AREAS COVERED

We report asthma prevalence among hospitalized cohorts with COVID-19. Those with non-allergic and severe asthma may be at increased risk of a worsened clinical outcome from COVID-19 infection. We explore the epidemiology of asthma as a risk factor for the severity of COVID-19 infection. We then consider the role COVID-19 may play in leading to exacerbations of asthma. The impact of asthma endotype on outcome is discussed. Lastly, we address the safety of common asthma therapeutics. A literature search was performed with relevant terms for each of the sections of the review using PubMed, Google Scholar, and Medline.

EXPERT OPINION

Asthma diagnosis may be a risk factor for severe COVID-19 especially for those with severe disease or nonallergic phenotypes. COVID-19 does not appear to provoke asthma exacerbations and asthma therapeutics should be continued for patients with exposure to COVID-19. Clearly much regarding this topic remains unknown and we identify some key questions that may be of interest for future researchers.[Figure: see text].

CEACAM3 decreases asthma exacerbations and modulates respiratory syncytial virus latent infection in children

BACKGROUND

Respiratory syncytial virus (RSV) is associated with childhood asthma. Nevertheless, not all children exposed to RSV develop asthma symptoms, possibly because genes modulate the effects of RSV on asthma exacerbations.

OBJECTIVE

The purpose of this study was to identify genes that modulate the effect of RSV latent infection on asthma exacerbations.

METHODS

We performed a meta-analysis to investigate differentially expressed genes (DEGs) of RSV infection from Gene Expression Omnibus datasets. Expression quantitative trait loci (eQTL) methods were applied to select single nucleotide polymorphisms (SNPs) that were associated with DEGs. Gene-based analysis was used to identify SNPs that were significantly associated with asthma exacerbations in the Taiwanese Consortium of Childhood Asthma Study (TCCAS), and validation was attempted in an independent cohort, the Childhood Asthma Management Program (CAMP). Gene-RSV interaction analyses were performed to investigate the association between the interaction of SNPs and RSV latent infection on asthma exacerbations.

RESULTS

A total of 352 significant DEGs were found by meta-analysis of RSV-related genes. We used 38 123 SNPs related to DEGs to investigate the genetic main effects on asthma exacerbations. We found that eight RSV-related genes (GADD45A, GYPB, MS4A3, NFE2, RNASE3, EPB41L3, CEACAM6 and CEACAM3) were significantly associated with asthma exacerbations in TCCAS and also validated in CAMP. In TCCAS, rs7251960 (CEACAM3) significantly modulated the effect of RSV latent infection on asthma exacerbations (false-discovery rate <0.05). The rs7251960 variant was associated with CEACAM3 mRNA expression in lung tissue (p for trend=1.2×10^-7). CEACAM3 mRNA was reduced in nasal mucosa from subjects with asthma exacerbations in two independent datasets.

CONCLUSIONS

rs7251960 is an eQTL for CEACAM3, and CEACAM3 mRNA expression is reduced in subjects experiencing asthma exacerbations. CEACAM3 may be a modulator of RSV latent infection on asthma exacerbations.

Expression network analysis reveals cord blood vitamin D-associated genes affecting risk of early life wheeze

Cord blood 25-hydroxyvitamin D (25OHD) has been reported in association with risk of early life recurrent wheeze. In a subset of infants who participated in the Vitamin D Antenatal Asthma Reduction Trial, we demonstrated that higher cord blood 25OHD at birth (>31 ng/mL) was associated with a reduced risk of recurrent wheeze in the first year of life. We then identified a module of co-expressed genes associated with cord blood 25OHD levels >31 ng/mL. Genes in this module are involved in biological and immune pathways related to development and progression of asthma pathogenesis including the Notch1 and transforming growth factor-beta signalling pathways.

Rapid Evolution of Primate Type 2 Immune Response Factors Linked to Asthma Susceptibility

Host immunity pathways evolve rapidly in response to antagonism by pathogens. Microbial infections can also trigger excessive inflammation that contributes to diverse autoimmune disorders including asthma, lupus, diabetes, and arthritis. Definitive links between immune system evolution and human autoimmune disease remain unclear. Here we provide evidence that several components of the type 2 immune response pathway have been subject to recurrent positive selection in the primate lineage. Notably, substitutions in the central immune regulator IL13 correspond to a polymorphism linked to asthma susceptibility in humans. We also find evidence of accelerated amino acid substitutions as well as gene gain and loss events among eosinophil granule proteins, which act as toxic antimicrobial effectors that promote asthma pathology by damaging airway tissues. These results support the hypothesis that evolutionary conflicts with pathogens promote tradeoffs for increasingly robust immune responses during animal evolution. Our findings are also consistent with the view that natural selection has contributed to the spread of autoimmune disease alleles in humans.

Managing Asthma in Pregnancy (MAP) trial: FENO levels and childhood asthma

BACKGROUND

The single-center double-blind, randomized controlled Managing Asthma in Pregnancy (MAP) trial in Newcastle, Australia, compared a treatment algorithm using the fraction of exhaled nitric oxide (FENO) in combination with asthma symptoms (FENO group) against a treatment algorithm using clinical symptoms only (clinical group) in pregnant asthmatic women (Australian New Zealand Clinical Trials Registry, no. 12607000561482). The primary outcome was a 50% reduction in asthma exacerbations during pregnancy in the FENO group. However, the effect of FENO-guided management on the development of asthma in the offspring is unknown.

OBJECTIVE

We sought to investigate the effect of FENO-guided asthma management during pregnancy on asthma incidence in childhood.

METHODS

A total of 179 mothers consented to participate in the Growing into Asthma (GIA) double-blind follow-up study with the primary aim to determine the effect of FENO-guided asthma management on childhood asthma incidence.

RESULTS

A total of 140 children (78%) were followed up at 4 to 6 years of age. FENO-guided as compared to symptoms-only approach significantly reduced doctor-diagnosed asthma (25.9% vs 43.2%; odds ratio [OR], 0.46, 95% CI, 0.22-0.96; P = .04). Furthermore, frequent wheeze (OR, 0.27; 95% CI, 0.09-0.87; P = .03), use of short-acting β-agonists (OR, 0.49; 95% CI, 0.25-0.97; P = .04), and emergency department visits for asthma (OR, 0.17; 95% CI, 0.04-0.76; P = .02) in the past 12 months were less common in children born to mothers from the FENO group. Doctor-diagnosed asthma was associated with common risk alleles for early onset asthma at gene locus 17q21 (P = .01 for rs8069176; P = .03 for rs8076131), and higher airways resistance (P = .02) and FENO levels (P = .03). A causal mediation analysis suggested natural indirect effects of FENO-guided asthma management on childhood asthma through "any use" and "time to first change in dose" of inhaled corticosteroids during the MAP trial (OR: 0.83; 95% CI: 0.59-0.99, and OR: 0.90; 95% CI: 0.70-1.03, respectively).

CONCLUSIONS

FENO-guided asthma management during pregnancy prevented doctor-diagnosed asthma in the offspring at preschool age, in part mediated through changes in use and dosing of inhaled corticosteroids during the MAP trial.

Allergic Asthma: A Summary from Genetic Basis, Mouse Studies, to Diagnosis and Treatment

Asthma is an allergic disease that affects approximately 300 million people worldwide. Two of its phenotypes routinely assessed at the clinic include airway hyperresponsiveness and IgE production. They can be measured in a non-invasive manner and have been used for genetic studies. The genetic complexity of asthma and its phenotypes makes it difficult to map their genetic contributors. Human studies require large sample sizes and proper segregation of the population to control for potential confounding factors. As an alternative, asthma genetics can be studied in mice due to the high degree of homology in the genome and immune response between mice and humans. The variety of mouse strains and allergic asthma protocols allow to study different aspects of the disease while controlling for the genetic background. Studying the genetic basis of asthma phenotypes has helped gain a better understanding of the disease mechanism. Candidate genes identified from genetic studies have served as targets for the development of new and specialized treatments. New treatments are high in demand as the symptoms of a large number of asthmatics are not properly controlled with the existing treatment guidelines involving corticosteroids, β2-adrenoreceptor agonists, and anti-leukotrienes or leukotriene modifiers. Promising findings have been obtained from studies exploring new treatments targeting specific immune cell mediators, which were identified as candidates in genetic studies, and cell adhesion molecules. In addition to targeting members of the Th1/Th2 inflammatory profile, mediators of the omega-3 fatty acid pathway are also emerging as novel targets of drug intervention for allergic asthma.

A Multiomics Approach to Identify Genes Associated with Childhood Asthma Risk and Morbidity

Childhood asthma is a complex disease. In this study, we aim to identify genes associated with childhood asthma through a multiomics "vertical" approach that integrates multiple analytical steps using linear and logistic regression models. In a case-control study of childhood asthma in Puerto Ricans (n = 1,127), we used adjusted linear or logistic regression models to evaluate associations between several analytical steps of omics data, including genome-wide (GW) genotype data, GW methylation, GW expression profiling, cytokine levels, asthma-intermediate phenotypes, and asthma status. At each point, only the top genes/single-nucleotide polymorphisms/probes/cytokines were carried forward for subsequent analysis. In step 1, asthma modified the gene expression-protein level association for 1,645 genes; pathway analysis showed an enrichment of these genes in the cytokine signaling system (n = 269 genes). In steps 2-3, expression levels of 40 genes were associated with intermediate phenotypes (asthma onset age, forced expiratory volume in 1 second, exacerbations, eosinophil counts, and skin test reactivity); of those, methylation of seven genes was also associated with asthma. Of these seven candidate genes, IL5RA was also significant in analytical steps 4-8. We then measured plasma IL-5 receptor α levels, which were associated with asthma age of onset and moderate-severe exacerbations. In addition, in silico database analysis showed that several of our identified IL5RA single-nucleotide polymorphisms are associated with transcription factors related to asthma and atopy. This approach integrates several analytical steps and is able to identify biologically relevant asthma-related genes, such as IL5RA. It differs from other methods that rely on complex statistical models with various assumptions.

Genome-wide association study of the age of onset of childhood asthma

BACKGROUND

Childhood asthma is a complex disease with known heritability and phenotypic diversity. Although an earlier onset has been associated with more severe disease, there has been no genome-wide association study of the age of onset of asthma in children.

OBJECTIVE

We sought to identify genetic variants associated with earlier onset of childhood asthma.

METHODS

We conducted the first genome-wide association study of the age of onset of childhood asthma among participants in the Childhood Asthma Management Program (CAMP) and used 3 independent cohorts from North America, Costa Rica, and Sweden for replication.

RESULTS

Two single nucleotide polymorphisms (SNPs) were associated with earlier onset of asthma in the combined analysis of CAMP and the replication cohorts: rs9815663 (Fisher P= 2.31 × 10(-8)) and rs7927044 (P= 6.54 × 10(-9)). Of these 2 SNPs, rs9815663 was also significantly associated with earlier asthma onset in an analysis including only the replication cohorts. Ten SNPs in linkage disequilibrium with rs9815663 were also associated with earlier asthma onset (2.24 × 10(-7)

CONCLUSIONS

We have identified 2 SNPs associated with earlier onset of childhood asthma in 4 independent cohorts.

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Key Words

• asthma
• pediatrics
• age of onset
• asthma genetics
• c1orf100
• genome-wide association study
• pediatric asthma

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MESH Headings

• Adolescent
• Age of Onset
• Asthma/epidemiology
• Asthma/genetics
• Child
• Cohort Studies
• Costa Rica/epidemiology
• Female
• Genetic Predisposition to Disease
• Genome-Wide Association Study/methods
• Genotype
• Humans
• Linkage Disequilibrium
• Male
• North America/epidemiology
• Polymorphism, Single Nucleotide/genetics
• Sweden/epidemiology

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Grants

• R00 HL096840 NHLBI NIH HHS
• N01-HR-16051 NHLBI NIH HHS
• M01 RR002719 NCRR NIH HHS
• N01-HR-16044 NHLBI NIH HHS
• N01-HR-16048 NHLBI NIH HHS
• M01 RR000036 NCRR NIH HHS
• N01-HR-16045 NHLBI NIH HHS
• M01RR02719-14 NCRR NIH HHS
• M01 RR000051 NCRR NIH HHS
• HL66289 NHLBI NIH HHS
• R01 HL066289 NHLBI NIH HHS
• N01-HR-16047 NHLBI NIH HHS
• N01-HR-16046 NHLBI NIH HHS
• N02-HL-6-4278 NHLBI NIH HHS
• K01 HL004370 NHLBI NIH HHS
• N01-HR-16049 NHLBI NIH HHS
• RR00036 NCRR NIH HHS
• N01-HR-16052 NHLBI NIH HHS
• R37 HL066289 NHLBI NIH HHS
• N01-HR-16050 NHLBI NIH HHS
• Wellcome Trust
• WT084703MA Wellcome Trust
• N01HR16044 NHLBI NIH HHS
• M01RR00051 NCRR NIH HHS
• M01RR0099718-24 NCRR NIH HHS

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Affiliation(s)

Erick Forno Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Division of Pediatric Pulmonology, Dept. of Pediatrics, University of Miami, Miami, FL Harvard Medical School, Boston, MA
Jessica Lasky-Su Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Harvard Medical School, Boston, MA
Blanca Himes Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Harvard Medical School, Boston, MA
Judie Howrylak Channing Laboratory, Brigham and Women’s Hospital, Boston, MA
Clare Ramsey Dept. of Medicine, University of Manitoba, Winnipeg, Canada
John Brehm Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Division of Pulmonary/Critical Care Medicine, Dept. of Medicine, Brigham and Women’s Hospital, Boston, MA Harvard Medical School, Boston, MA
Barbara Klanderman Channing Laboratory, Brigham and Women’s Hospital, Boston, MA
John Ziniti Channing Laboratory, Brigham and Women’s Hospital, Boston, MA
Erik Melén Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Stockholm, Sweden
Goran Pershagen Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
Magnus Wickman Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden Sachs Children’s Hospital, Stockholm, Sweden
Fernando Martinez Department of Pediatrics, University of Arizona, Tucson, AZ
Dave Mauger Penn State Hershey College of Medicine, Hershey, PA
Christine Sorkness University of Wisconsin, Madison, WI
Kelan Tantisira Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Division of Pulmonary/Critical Care Medicine, Dept. of Medicine, Brigham and Women’s Hospital, Boston, MA Harvard Medical School, Boston, MA
Benjamin A. Raby Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Division of Pulmonary/Critical Care Medicine, Dept. of Medicine, Brigham and Women’s Hospital, Boston, MA Harvard Medical School, Boston, MA
Scott T. Weiss Channing Laboratory, Brigham and Women’s Hospital, Boston, MA Harvard Medical School, Boston, MA
Juan C. Celedón Division of Pediatric Pulmonary Medicine, Allergy and Immunology, Dept. of Pediatrics, Children’s Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA

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Genetics of asthma and allergy: what have we learned?

The overall purpose of this review is to present an update on genetic approaches to understanding the susceptibility and expression (severity) of common diseases, such as asthma and allergy. Five key questions are addressed in this review: (1) What phenotypes are being studied? Multiple disease phenotypes in carefully characterized patients are required. (2) Are the same genes that are important in disease susceptibility important in disease severity? (3) Are there racial differences in disease expression and genetic susceptibility? (4) Are the genes important in normal variation in lung function important in asthma severity? (5) Are the genes important in other common diseases, such as chronic inflammatory diseases or chronic obstructive pulmonary disease, important in asthma or allergy? In addition, a discussion of some of current areas of research is presented, including the issue that current genome-wide association study results do not account for a significant portion of trait variability, the potential role of rare variants and large genome-sequencing studies, and pharmacogenetics: is there a role for basing treatment decisions on the results of genetic testing? Finally, the potential usefulness of DNA, personalized medicine, is discussed.