Familial occurrence of atopic disease: genetic versus environmental factors

Genome-wide meta-analysis implicates variation affecting mast cell biology in urticaria

BACKGROUND

Urticaria is characterized by inappropriate mast cell degranulation leading to the development of wheals and/or angioedema. Twin and family studies indicate that there is a substantial heritable component to urticaria risk.

OBJECTIVE

Our aim was to identify genomic loci at which common genetic variation influences urticaria susceptibility.

METHODS

Genome-wide association studies of urticaria (including all subtypes) from 3 European cohorts (UK Biobank, FinnGen, and the Trøndelag Health Study [HUNT]) were combined through statistical meta-analysis (14,306 urticaria cases and 650,664 controls). Cases were identified via electronic health care records from primary and/or secondary care. To identify putative causal variants and genes, statistical fine-mapping, colocalization, and interrogation of publicly available single-cell transcriptome sequencing resources were performed.

RESULTS

Genome-wide significant associations (P < 5 × 10-8) were identified at 6 independent loci. These included 2 previously reported association signals at 1q44 and the human leucocyte antigen region on chromosome 6. Genes with expected or established roles in mast cell biology were associated with the 4 other genome-wide association signals (GCSAML, FCER1A, TPSAB1, and CBLB). Colocalization of association signals consistent with the presence of shared causal variants was observed between urticaria susceptibility and increased expression of GCSAML (posterior probability of colocalization [PPcoloc] = 0.89) and FCER1A (PPcoloc = 0.91) in skin.

CONCLUSION

Common genetic variation influencing the risk of developing urticaria was identified at 6 genomic loci. The relationship between genes with roles in mast cell biology and several association signals implicates genetic variability of specific components of mast cell function in the development of urticaria.

Risk of asthma in offspring of asthmatic fathers versus mothers: A population-based study of 21,000 individuals in Denmark

Parental asthma or allergy have been linked to higher risk of asthma in a child; this occurs to a variable extent in different study populations. Moreover, it is debated whether maternal more so than paternal asthma history is a stronger predisposing factor: while in some countries/populations the maternal effect was clearly seen over paternal, in others the parental effects were equivalent, and in a few studies paternal effect dominated. Here we aimed to determine parental asthma and allergy effect in the Danish GEneral SUburban population Study (GESUS). This cross-sectional study has involved 21,362 adults aged 20+ years in the suburbs of Copenhagen. We used a combination of questionnaire approach, history of prescribed asthma medications and pulmonary function testing to determine odds ratios for maternal and paternal (and combined) asthma and allergy linked to asthma in the test subjects. We found that the input of maternal vs. paternal asthma effect was approximately equal (age and sex-adjusted OR 2.46, 95% CI: 2.15-2.81 for asthmatic mothers vs. 2.97, 2.58-3.42 for asthmatic fathers), except for the "ever asthma" age and sex-adjusted odds ratios where paternal allergy seems to have conferred a marginally greater effect (age and sex-adj. OR 1.96 for maternal allergy vs. 2.44 for paternal allergy, p = 0.03). Stratifying for gestational tobacco smoking did not affect the maternal results. We conclude that in the GESUS study parental asthma or allergy were strongly linked to higher asthma risk in offspring, without a prominent maternal or paternal effect.

Fetal-Derived Immune Cells at the Roots of Lifelong Pathophysiology

Tissue-resident innate immune cells exert a wide range of functions in both adult homeostasis and pathology. Our understanding of when and how these cellular networks are established has dramatically changed with the recognition that many lineages originate at least in part from fetal sources and self-maintain independently from hematopoietic stem cells. Indeed, fetal-derived immune cells are found in most organs and serous cavities of our body, where they reside throughout the entire lifespan. At the same time, there is a growing appreciation that pathologies manifesting in adulthood may be caused by adverse early life events, a concept known as “developmental origins of health and disease” (DOHaD). Yet, whether fetal-derived immune cells are mechanistically involved in DOHaD remains elusive. In this review, we summarize our knowledge of fetal hematopoiesis and its contribution to adult immune compartments, which results in a “layered immune system.” Based on their ontogeny, we argue that fetal-derived immune cells are prime transmitters of long-term consequences of prenatal adversities. In addition to increasing disease susceptibility, these may also directly cause inflammatory, degenerative, and metabolic disorders. We explore this notion for cells generated from erythro-myeloid progenitors (EMP) produced in the extra-embryonic yolk sac. Focusing on macrophages and mast cells, we present emerging evidence implicating them in lifelong disease by either somatic mutations or developmental programming events resulting from maternal and early environmental perturbations.

Parent-specific effects on risk of developing allergic sensitization and asthma in childhood

BACKGROUND

Parent's history of atopic traits increases the risk of the same traits in their children, but mother's history may confer an increased risk compared to father's history.

OBJECTIVE

To investigate parent-specific effects on risk of developing allergic sensitization and asthma in childhood.

METHODS

We included 685 parent-child trios from the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC2010) cohort. Parent's asthma was assessed by structured interviews and child's asthma was diagnosed prospectively at regular visits to the COPSAC clinic until age 6. Specific IgE and total IgE levels were measured in parents and children by age 0.5, 1.5 and 6 years. Associations between parent and child disease traits were analyzed using general estimating equations model adjusted for breastfeeding and maternal smoking during 3rd trimester.

RESULTS

Maternal compared to paternal elevated specific IgE increased the child's risk of elevated specific IgE from 0-6 years: adjusted odds ratio (aOR)mother = 1.49 [1.09-2.03], P = .01 and aORfather = 1.32 [0.96-1.82], P = .08. Maternal elevated total IgE also increased the child's risk of elevated total IgE: adjusted relative risk (aOR)mother = 4.32 [1.51-10.8], P < .01, while a trend was observed for paternal total IgE: aORfather = 2.01 [0.76-4.82], P = .13. Individual time point analyses showed that the maternal effect was strongest in early life, whereas the parental effects were comparable by age 6. A similar parent-specific pattern was observed for the child's risk of asthma.

CONCLUSIONS AND CLINICAL RELEVANCE

The effect of mother's history of atopic traits on the child's risk of developing the same traits in early childhood was stronger than the effect from father's history, which was not evident before age 6. This suggests that maternal non-genetic factors seem to confer an added disease risk to the child, particularly in early life.

How does parental history of atopic disease predict the risk of atopic dermatitis in a child? A systematic review and meta-analysis

BACKGROUND

Parental history of atopic disease is a well-established risk factor for the development of atopic dermatitis (AD), but several aspects of this association remain unclear.

OBJECTIVE

We sought to determine the association of parental history of atopic disease with AD in offspring.

METHODS

We searched PubMed and EMBASE through June 2018 for relevant records and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled odds ratios (ORs) with 95% CI were calculated using random-effects models.

RESULTS

A total of 163 records covering 149 unique studies were included. Of these, 119 studies were included in the meta-analysis. Individuals with parental history of atopic disease had increased odds of AD (OR, 1.81; 95% CI, 1.65-1.99). Parental asthma (OR, 1.56; 95% CI, 1.18-2.05) and allergic rhinitis (OR, 1.68; 95% CI, 1.34-2.11) had a smaller effect than AD (OR, 3.30; 95% CI, 2.46-4.42). The effect of maternal and paternal history was comparable for all atopic diseases. An increase in odds was observed when comparing the effect of having 1 (OR, 1.30; 95% CI, 1.15-1.47) or 2 atopic parents (OR, 2.08; 95% CI, 1.83-2.36), as well as having a parent with 1 (OR, 1.49; 95% CI, 1.28-1.74) or more atopic diseases (OR, 2.32; 95% CI, 1.92-2.81).

CONCLUSIONS

This study provides evidence-based risk estimates that may guide physicians who counsel parents with a history of atopic disease about their children's risk of AD. This information is of particular importance for future efforts toward establishing prophylactic interventions for AD on a general population level.

Prevalence of rhinitis and associated factors in schoolchildren who live in the Amazon islands

BACKGROUND

The prevalence of rhinitis has been reported to be higher in urban areas.

OBJECTIVE

To determine the prevalence of rhinitis in schoolchildren who lived on two islands in the Brazilian Amazon, including a rural island and an urban island, and to identify the associated risk factors.

METHODS

Four hundred children (200 per island) were evaluated by using the International Study of Asthma and Allergy in Childhood standard written questionnaire (rhinitis module). A convenience sample for both islands was selected based on the age group of the study (5-8 years). The children were assessed for potential risk factors (complementary written questionnaire) identified by logistic regression.

RESULTS

The prevalence of active rhinitis was significantly higher in the children who lived on Outeiro Island compared with Combú Island (34.5% versus 18.0%, respectively). The associated risk factors for rhinitis symptoms on Combú Island included parental history of rhinitis (odds ratio [OR] 9.4 [95% confidence interval {CI}, 2.1-41.4]) and delivery by caesarean-section (OR 5.2 [95% CI, 1.2-21.9]), and for Outeiro Island included parental history of rhinitis (OR 4.5 [95% CI, 1.7-11.2]) and of asthma (OR 3.8 [95% CI, 1.5-9.8]), nocturnal cough in the previous year (OR 5.8 [95% CI, 2.1-16.0]), breast-feeding (≥6 months) (OR 9.6 [95% CI, 1.1-82.1]), moisture (OR 2.4 [95% CI, 0.9-6.4]), and consumption of fruit juice more than two times a week (OR 4.3 [95% CI, 1.2-15.0]).

CONCLUSION

The different risk factors identified for rhinitis on each island indicated the role of the urban environment in the development of the disease.

Introduction to genetics and genomics in asthma: genetics of asthma

While asthma is a heterogeneous disease, a strong genetic basis has been firmly established. Rather than being a single disease entity, asthma consists of related, overlapping syndromes [Barnes (Proc Am Thor Soc 8:143-148, 2011)] including three general domains: variable airway obstruction, airway hyper-responsiveness, and airway inflammation with a considerable proportion, but not all, of asthma being IgE-mediated further adding to its heterogeneity. This chapter reviews the approaches to the elucidation of genetics of asthma from the early evidence of familial clustering to the current state of knowledge with genome-wide approaches. The conclusion is that research efforts have led to a tremendous repository of genetic determinants of asthma, most of which fall into the above phenotypic domains of the syndrome. We now look to future integrative approaches of genetics, genomics (Chap. 10), and epigenetics (Chap. 11) to better understand the causal mechanism through which, these genetic loci act in manifesting asthma.

Different implications of paternal and maternal atopy for perinatal IgE production and asthma development

Asthma is a hereditary disease associated with IgE-mediated reaction. Whether maternal atopy and paternal atopy have different impacts on perinatal IgE production and asthma development remains unclear. This paper reviews and summarizes the effects of maternal and paternal atopy on the developmental aspects of IgE production and asthma. Maternal atopy affects both pre- and postnatal IgE production, whereas paternal atopy mainly affects the latter. Maternally transmitted genes GSTP1 and FceRI-beta are associated with lung function and allergic sensitization, respectively. In IgE production and asthma development, the maternal influence on gene-environment interaction is greater than paternal influence. Maternal, paternal, and/or postnatal environmental modulation of allergic responses have been linked to epigenetic mechanisms, which may be good targets for early prevention of asthma.

Food allergy: riding the second wave of the allergy epidemic

Food allergy is a substantial and evolving public health issue, recently emerging over the last 10-15 yr as a 'second wave' of the allergy epidemic. It remains unclear why this new phenomenon has lagged decades behind the 'first wave' of asthma, allergic rhinitis and inhalant sensitization. In regions like Australia, which lead the respiratory epidemic, challenge-proven IgE-mediated food allergy now affects up to 10% of infants. Although their parents were among the first generation to experience the large-scale rise in allergic diseases, disorders of oral tolerance were previously uncommon. Of further concern, this new generation appears less likely to outgrow food allergy than their predecessors with long-term implications for disease burden. Allergic disease has been linked to the modern lifestyle including changing dietary patterns, changing intestinal commensal bacteria and vehicular pollution. It is not yet known whether the rise in food allergy is a harbinger of earlier and more severe effects of these progressive environmental changes or whether additional or unrelated lifestyle factors are implicated. New studies suggest environmental factors can produce epigenetic changes in gene expression and disease risk that may be potentially heritable across generations. The rising rates of maternal allergy, a strong direct determinant of allergic risk, could also be amplifying the effect of environmental changes. Preliminary evidence that non-Caucasian populations may be even more susceptible to the adverse effects of 'westernisation' has substantial global implications with progressive urbanization of the more populous regions in the developing world. Unravelling the environmental drivers is critical to curtail a potential tsunami of allergic disease.

Prevalence and risk factors for allergic rhinitis in primary schoolchildren in Budapest

OBJECTIVE

There is growing evidence that the prevalence of allergic diseases is increasing, especially among children. The aim of this study was to evaluate the incidence and risk factors of allergic rhinitis in 6-12-year-old schoolchildren in Budapest.

METHODS

A total of 6335 children aged between 6 and 12 years attending 21 randomly selected primary schools in Budapest were surveyed in September 2007 by using a questionnaire consisting in part of questions compiled by the International Study of Asthma and Allergies in Childhood and in part of questions based on our own experience.

RESULTS

3933 of the questionnaires (1976 M/1957 F) were appropriately completed by the parents. The prevalence of current allergic rhinitis was 14.9% (n=530), that of physician-diagnosed allergic rhinitis was 11.6% (n=413), and that of cumulative allergic rhinitis was 26.5% (n=943). Male gender (p<0.001), family history of atopy (p<0.001), eczema (p<0.001), urticaria (p<0.001), itchy-watery eyes (p<0.001), coughing (p<0.001), wheezing (p<0.001), a hearing impairment (p<0.001), itching of the palate (p<0.001), frequent upper airway infection (p<0.001), frequent rhinosinusitis (p<0.001), a history of tonsillectomy (p<0.01), a history of adenoidectomy (p<0.001), antibiotics given in the first year of life (p<0.001), paracetamol given in the first year of life (p<0.001), living in a green area (p<0.001), the consumption of soft drinks containing preservatives or colourants (p<0.04), feather bedding (p<0.01), living in a house made of concrete (p<0.001), living not far from an air-polluting factory or mine (p<0.001), and long-lasting disease before the appearance of the allergy (p<0.001) were all significant factors involving an increased risk of allergic rhinitis symptoms. The frequent consumption of tomatoes, nuts, margarine and butter significantly affected the cumulative allergic rhinitis prevalence.

RESULTS

Overall, the 12-month prevalence of allergic rhinitis in these 6-12-year-old children in Budapest was 14.9%, which is higher than reported from other European countries. Our findings differ from those on other cohorts in that exposure to ragweed and to indoor environmental factors in concrete housing estates in Budapest may be of particular importance as concerns allergic sensitization.

Frequency of familial occurrence in 164 patients with allergic bronchopulmonary aspergillosis

BACKGROUND

Asthma is known to run in families. Allergic bronchopulmonary aspergillosis (ABPA) occurs predominantly in patients with asthma. However, there are only 6 reports of familial occurrence over a period of 35 years.

OBJECTIVE

To determine the frequency of familial occurrence in 164 patients with ABPA diagnosed over a period of 22 years in one unit.

METHODS

The 164 patients with ABPA were reviewed for the occurrence of familial ABPA. Symptomatic family members were evaluated for the presence of ABPA as well as allergic Aspergillus sinusitis (AAS). Allergic bronchopulmonary aspergillosis and AAS were diagnosed as per criteria established.

RESULTS

Of the 164 patients with ABPA, familial occurrence was detected in 4 pairs of first degree relatives, 2 of whom were parent-child while the other 2 were siblings. Familial ABPA was seen in 4.9% of the total patients. Of these 8 patients seven had symptoms of rhinitis while 4 had sinusitis confirmed on computed tomography of paranasal sinuses. Allergic Aspergillus sinusitis was detected in 3 of these 4 patients. The fourth patient with sinusitis did not consent to surgery required to confirm the diagnosis. Five of our 8 patients, prior to referral, had received antituberculous therapy. All patients responded favourably to oral prednisolone.

CONCLUSION

Familial occurrence was documented in 4.9% of the 164 patients with ABPA.

Incidence rates of asthma, rhinitis and eczema symptoms and influential factors in young children in Sweden

AIM

To estimate the incidence rates for asthma, rhinitis and eczema symptoms and to investigate the importance of different influential factors for the incidence of these symptoms.

METHODS

The Dampness in Building and Health study commenced in the year 2000 in Värmland, Sweden with a parental questionnaire based on an ISAAC protocol to all children in the age of 1-6 years. Five years later a follow-up questionnaire was sent to the children that were 1-3 years at baseline. In total, 4779 children (response rate = 73%) participated in both surveys and constitute the study population in this cohort study.

RESULTS

The 5-year incidence of doctor-diagnosed asthma was 4.9% (95% CI 4.3-5.3), rhinitis was 5.7% (5.0-6.4) and eczema was 13.4% (12.3-14.5). However, incidence rates strongly depend on the health status of the baseline population. Risk factors for incident asthma were male gender and short period of breast-feeding. Allergic symptoms in parents were also a strong risk factor for incident asthma, as well as for rhinitis and eczema.

CONCLUSION

When comparing incident rates of asthma between different studies it is important to realize that different definitions of the healthy baseline population will give rise to different incident rates.

A genetic variation in inositol polyphosphate 4 phosphatase a enhances susceptibility to asthma

RATIONALE

Microarray data from mouse studies have identified a number of genes to be differentially expressed in allergen-sensitized mice lungs.

OBJECTIVES

Taking leads from these datasets, we attempted to identify novel genes associated with atopic asthma in humans.

METHODS

We performed family-based genetic association analysis on selected markers within or in proximity of 21 human homologs of genes short-listed from ovalbumin-sensitized mouse studies in the Gene Expression Omnibus database of the National Center for Biotechnology Information. Family-based and case-control studies were undertaken for fine mapping and functional variation analysis of INPP4A (inositol polyphosphate 4 phosphatase type I). Western blot analysis was performed to analyze INPP4A protein stability from human platelets.

MEASUREMENTS AND MAIN RESULTS

Our genetic association studies of 21 human genes in 171 trios led to the identification of a biallelic repeat (rs3217304) in INPP4A, associated with atopic asthma (P = 0.009). Further studies using additional three single nucleotide polymorphisms (SNPs), +92031A/T, +92344C/T, and +131237C/T, and two microsatellite markers, D2S2311 and D2S2187, revealed significant genetic associations with loci +92031A/T (P = 0.0012) and +92344C/T (P = 0.004). A nonsynonymous SNP, +110832A/G (Thr/Ala), present within a sequence enriched with proline, glutamic acid, serine, and threonine (PEST), in proximity of these two loci, showed a significant association with atopic asthma (P = 0.0006). The association results were also replicated in an independent cohort of 288 patients and 293 control subjects (P = 0.004). PEST score and Western blot analyses indicated a functional role of this SNP in regulating INPP4A protein stability.

CONCLUSIONS

In our study, INPP4A was identified as a novel asthma candidate gene, whereby the +110832A/G (Thr/Ala) variant affected its stability and was significantly associated with asthma.

Maternal influence in the transmission of asthma susceptibility

Asthma is one of the most common chronic diseases in children, with increasing morbidity and mortality. A genetic predisposition and exposure to allergens have been implicated as major risk factors for the development of asthma. However, increasing evidence indicates that the mother plays a crucial role in mediating the development of fetal-infant immune responses to inhaled allergens. The exact nature and mechanism of this maternal influence and how it might be associated with the development of allergic sensitization and asthma are not clear. Under normal conditions, the maternal environment during pregnancy promotes an initial Th2 skewed immune response in the offspring which transitions to a nonallergic Th1 type response after birth. However, the allergic mother's influence may delay the normal transition to a nonallergic immune response to inhaled allergens in her children, thus increasing the risk for the development of allergic sensitization and/or asthma. Understanding the underlying mechanisms by which the maternal immune environment can influence the development of the fetal-infant immune response to inhaled allergens may lead to identifying new targets for the prevention of allergic sensitization and asthma.

A graphical assessment of p-values from sliding window haplotype tests of association to identify asthma susceptibility loci on chromosome 11q

Background

Past work on asthmatic African American families revealed a strong linkage peak with modest evidence of association on chromosome 11q. Here, we perform tests of association for asthma and a panel of 609 SNPs in African American subjects using a sliding window approach. While efficient in screening a region of dense genotyping, this approach does create some problems: high numbers of tests, assimilating thousands of results, and questions about setting priorities on regions with association signals.

Results

We present a newly developed tool, Graphical Assessment of Sliding P-values or GrASP, which uses color display to indicate the width of the sliding windows, significance of individual tests, density of SNP coverage and location of known genes that simplifies some of these issues, and use it to identify regions of interest in these data.

Conclusion

We demonstrate that GrASP makes it easier to visualize, summarize and prioritize regions of interest from sliding window haplotype analysis, based jointly on the p-value from all the tests from these windows and the building of haplotypes of significance in the region. Using this approach, five regions yielded strong evidence for linkage and association with asthma, including the prior peak linkage region.

Paternal history of asthma and airway responsiveness in children with asthma

RATIONALE

Little is known regarding the relationship between parental history of asthma and subsequent airway hyperresponsiveness (AHR) in children with asthma.

OBJECTIVES

We evaluated this relationship in 1,041 children with asthma participating in a randomized trial of antiinflammatory medications (the Childhood Asthma Management Program [CAMP]).

METHODS

Methacholine challenge testing was performed before treatment randomization and once per year over an average of 4.5 years postrandomization. Cross-sectional and longitudinal repeated measures analyses were performed to model the relationship between PC20 (the methacholine concentration causing a 20% fall in FEV1) with maternal, paternal, and joint parental histories of asthma. Models were adjusted for potential confounders.

MEASUREMENTS AND MAIN RESULTS

At baseline, AHR was strongly associated with a paternal history of asthma. Children with a paternal history of asthma demonstrated significantly greater AHR than those without such history (median log(e)PC20, 0.84 vs. 1.13; p = 0.006). Although maternal history of asthma was not associated with AHR, children with two parents with asthma had greater AHR than those with no parents with asthma (median log(e)PC20, 0.52 vs. 1.17; p = 0.0008). Longitudinal multivariate analysis of the relation between paternal history of asthma and AHR using repeated PC20 measurements over 44 months postrandomization confirmed a significant association between paternal history of asthma and AHR among children in CAMP.

CONCLUSIONS

Our findings suggest that the genetic contribution of the father is associated with AHR, an important determinant of disease severity among children with asthma.

Inflammatory sinonasal disease

Inflammation of the nose and sinuses is a clinical problem frequently encountered in the practice of otolaryngology. The most common of these inflammatory illnesses are allergic rhinitis and acute and chronic rhinosinusitis. The recognition of inflammatory sinonasal diseases and an understanding of their pathophysiology are essential to successful management of these common illnesses.

Association of parental eczema, hayfever, and asthma with atopic dermatitis in infancy: birth cohort study

OBJECTIVE

To evaluate the association of parental history of atopic disease with childhood atopic dermatitis, and to examine the relative strength of associations with maternal and paternal disease.

DESIGN

Mothers were recruited to the Avon longitudinal study of parents and children (ALSPAC) from the eighth week of pregnancy. Before parturition, both parents were asked, separately, to report their lifetime history of eczema, asthma, and hayfever. Parents reported symptoms of atopic dermatitis in their children at ages 6, 18, 30, and 42 months.

RESULTS

Of 8530 children with complete information on rash at ages 6, 18, 30, and 42 months, 7969 had complete information on maternal atopic disease and 5658 on maternal and paternal atopic disease. There was a strong association between parental eczema and childhood atopic dermatitis: odds ratio 1.69 (95% confidence interval, 1.47 to 1.95) for maternal eczema only, 1.74 (1.44 to 2.09) for paternal eczema only, and 2.72 (2.09 to 3.53) for eczema in both parents. Associations with parental asthma or hayfever were attenuated after controlling for parental eczema. There was no evidence that associations with maternal atopy were stronger than with paternal.

CONCLUSIONS

Associations between parents' atopic disease and the risk of atopic dermatitis in offspring vary according to the type of atopic disease in the parents, but not according to parental sex. These results are at variance with previous studies reporting stronger associations with maternal than paternal atopy, and suggest that there is no "parent-of-origin" effect in atopic dermatitis. Parental eczema may be a better marker than parental asthma/hayfever in predisposing to childhood eczema.

Parental allergic status influences the risk of developing allergic sensitization and an asthmatic-like phenotype in canine offspring

Increasing evidence suggests that parental allergic status, especially that of the mother, may play a unique and important role in influencing the development of fetal infant immune responses to inhaled allergens, independently of genetic predisposition. We have developed an experimental model in dogs where the offspring from allergic parents, when exposed to inhaled allergen, develop allergic sensitization and an asthmatic phenotype, whereas the offspring from non-allergic parents do not. Offspring from ragweed-sensitized (two litters, n = 10) or non-sensitized (two litters, n = 11) Beagle dogs were exposed repeatedly, by inhalation, to ragweed or filtered air (negative control) beginning within 1 week after birth. Serum levels of total immunoglobulin (Ig)E, and ragweed-specific IgE and IgG, were measured at specific time-points up to 40 weeks after birth. Cell differentials in the bronchoalveolar lavage were determined on days 1 and 4 following ragweed instillation into the offspring's lungs at 26 weeks of age. Changes in pulmonary resistance following challenge with histamine and ragweed (five breaths) were measured at 40 weeks after birth. Offspring from sensitized parents exposed to ragweed developed elevated serum total IgE and ragweed-specific IgE and IgG, and showed an increased pulmonary resistance to histamine and ragweed, and increased numbers of eosinophils in bronchoalveolar lavage. In contrast, offspring from non-sensitized parents did not exhibit this immune response. These results suggest that parental allergic sensitivity is important in the development of allergic sensitization and an asthmatic phenotype in the offspring.

Evidence for asthma susceptibility genes on chromosome 11 in an African-American population

Initial genome-wide scan data provided suggestive evidence for linkage of the asthma phenotype in African-American (AA), but not Caucasian, families to chromosome 11q markers (peak at D11S1985; LOD=2). To refine this region, mapping analysis of 91 AA families (51 multiplex families and 40 asthmatic case-parent trios) was performed with an additional 17 markers flanking the initial peak linkage marker. Multipoint analyses of the 51 multiplex families yielded significant evidence of linkage with a peak non-parametric linkage score of 4.38 at marker D11S1337 (map position 68.6 cM). Furthermore, family-based association and transmission disequilibrium tests conducted on all 91 families showed significant evidence of linkage in the presence of disequilibrium for several individual markers in this region. A putative susceptibility locus was estimated to be at map position 70.8 cM with a confidence interval spanning the linkage peak. Evidence from both linkage and association analyses suggest that this region of chromosome 11 contains one or more susceptibility genes for asthma in these AA families.

The epidemiology of atopic dermatitis in Italian schoolchildren

BACKGROUND

Atopic dermatitis (AD) is common in children in industrialized countries. Only one large population study on its prevalence has been conducted in Italy, based on self-report questionnaire. The present study was designed to estimate the prevalence of AD in schoolchildren in Italy by dermatologists' assessment and by UK Working Party criteria, and to investigate associated symptoms and factors.

METHODS

Cross-sectional survey on a random sample of 9-year-old schoolchildren from seven Italian cities. Children were examined by experienced dermatologists. Parents and teachers answered standardized questionnaires.

RESULTS

Of the 1369 children examined, 88 had a diagnosis of AD, with an estimated point prevalence of 5.8% (95% CI 4.5-7.1) in the reference population. The reported lifetime prevalence was 15.2 (95% CI 12.2-18.2) for AD, 11.9% (95% CI 9.0-14.8) for asthma, and 17.6% (95% CI 14.6-20.7) for rhino-conjunctivitis. The strongest associated factor was the presence of AD in at least one parent. No association of AD with maternal smoking during pregnancy, birth weight, maternal age at the time of the child birth and breast-feeding was observed. The environmental characteristics of the house and the school did not correlate with the prevalence of AD. Episodes of lower respiratory tract infections were associated with asthma, and to a lower extent also with AD and rhinitis.

CONCLUSIONS

The prevalence of doctor-diagnosed AD in Italian schoolchildren is comparable to those reported for other developed countries. Family history of atopy was the single most important associated factor, while the complex interplay of environmental factors remains to be elucidated.

Allergic rhinitis and asthma: the link further unraveled

Allergic asthma and rhinitis are manifestations of the atopic syndrome. Although the diseases commonly occur together, it is still unclear why some allergic patients develop only asthma and others only rhinitis. The reason for the variety in clinical expression of allergic airway disease is not known. Besides a genetic predisposition, environmental factors contribute to the development of the allergic phenotype. Local and systemic inflammatory processes also seem to be involved, however, their exact contribution to the clinical picture of airway allergy still remains to be elucidated. Although it is clear that the condition of the upper airways has an impact on lower airway physiology, the mechanisms underlying this relation are far from being resolved. To date, most data point towards a systemic link between upper and lower airways, involving bloodstream and bone marrow. In this article, the latest developments with regard to nasobronchial interaction in allergic airway disease will be reviewed. Epidemiologic, experimental and clinical data underline the importance of a global approach in allergic rhinitis and asthma.

Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis

Allergic rhinitis (AR) is a heterogeneous disorder that despite its high prevalence is often undiagnosed. It is characterized by one or more symptoms including sneezing, itching, nasal congestion, and rhinorrhea. Many causative agents have been linked to AR including pollens, molds, dust mites, and animal dander. Seasonal allergic rhinitis (SAR) is fairly easy to identify because of the rapid and reproducible onset and offset of symptoms in association with pollen exposure. Perennial AR is often more difficult to detect than SAR because of the overlap with sinusitis, respiratory infections, and vasomotor rhinitis. SAR can result in hyperresponsiveness to allergens such as cigarette smoke, once pollen season is over. Perennial AR is defined as occurring during approximately 9 months of the year. AR affects an estimated 20 to 40 million people in the United States alone, and the incidence is increasing; an estimated 20% of cases are SAR; 40% of cases are perennial rhinitis; and 40% of cases are mixed. The pathophysiology of SAR is complex. There is a strong genetic component to the allergic response, which is driven through mucosal infiltration and action on plasma cells, mast cells, and eosinophils. The allergic response occurs in two phases, which are considered the "early" and "late" phase responses. Early phase response occurs within minutes of exposure to the allergen and tends to produce sneezing, itching, and clear rhinorrhea; late phase response occurs 4 to 8 hours after allergen exposure and is characterized by congestion, fatigue, malaise, irritability, and possibly neurocognitive deficits. The key to diagnosis of AR is awareness of signs and symptoms. IgE antibody tests to detect specific allergens are the standard method used today; however, in addition, diagnosis must be confirmed with a positive history and demonstration that the symptoms are the result of IgE-mediated inflammation.

Paths to panic disorder/agoraphobia: an exploratory analysis from age 3 to 21 in an unselected birth cohort

OBJECTIVE

To evaluate childhood temperamental traits and early illness experiences in the etiology of adult panic disorder with agoraphobia.

METHOD

Evaluated temperamental and illness experience factors, at ages 3 through 18, as predictors of panic and agoraphobia at ages 18 or 21 in an unselected sample (N = 992). Analyses were conducted with classification trees.

RESULTS

Experience with respiratory ill health predicted panic/agoraphobia relative to other anxiety disorders and healthy controls. Also, temperamental emotional reactivity at age 3 predicted panic/agoraphobia in males but did not predict other anxiety disorders, compared with healthy controls. Furthermore, temperament and ill health interacted with gender.

CONCLUSIONS

Results are discussed in terms of cognitive theories of fear of physical symptoms and biological models of respiratory disturbance for panic/agoraphobia.

Assessing infant suck dysfunction: case management

Based on this more thorough assessment, the lactation consultant may be able to identify all of the factors contributing to this complex case. In some situations, her skilled interventions will suffice once the underlying problem is addressed. Occasionally, she will identify a factor that falls outside of her area of expertise; when this happens, she must make the appropriate referrals. For example, a referral to a physician for a frenotomy or suspected neurological or other medical problem is appropriate. It is clear that because Baby E's problems were not resolved after 6 weeks of concerned effort, something was missed. It would certainly be appropriate for the lactation consultant to refer the dyad to another lactation consultant who has more expertise in handling clinically challenging breastfeeding problems. If possible, the referring lactation consultant should accompany the dyad so that she can improve her clinical skills. Assuming Baby E does not have underlying medical problems, the most likely causes of Baby E's difficulties are anatomical variation and/or sucking dysfunction. Because the baby is so fussy, it also would be wise to consider the possibility of allergies or food tolerance. Our first rule is " Feed the baby." The second rule is " Correct or work on correcting the problem or problems." Our goal is to achieve exclusive breastfeeding or as close an approximation as possible. We almost never give up on this goal, but we do educate the mother and work professionally with her choices. Until the baby is breastfeeding well, the lactation consultant will probably need to instruct the mother to continue using a pump ( preferably a hospital-grade, electric, bilateral pump). The mother should use the pump physiologically, pumping as many times a day as the baby would breastfeed. As soon as the situation improves, the mother should be instructed to wean gradually from the pump and any other breastfeeding equipment she is using. The goal should always be to help the mother and baby acheive a breastfeeding relationship, preferably without the use of any devices. We usually suggest that the mother avoid all rubber nipples and pacifiers during this learning period. Babies have a strong need to suck. Correct sucking helps the baby organize and be soothed. Whenever possible, we prefer infants to use their mother's breasts for pacification, warmth, love, smell, and food rather than artificial nipples and devices. Mothers almost always want to know how much work and time is involved before committing to following suggested treatment plans. As a general rule, we have found that it will take approximately the same number of weeks as the baby's age to solve the problems completely. In this case, it will probably take about 6 weeks until mother and baby graduate from "breastfeeding school." The first 2 weeks would most likely be very intense for the whole family, with the mother getting very little sleep. VJ is likely to cry when talking to the lactation consultant during this period of intense change. It is helpful during these times to listen to the mother, reinforce that you know how hard she is working and that what she is feeling is normal. Giving the mother a hug and complimenting her mothering efforts go a long way toward encouraging her to continue. It is not a time to give up. The second 2 weeks typically are easier, as everybody is used to the workload and required skills. The focus becomes refining skills. The last 2 weeks is usually a time to reduce and then wean off the equipment and exercises. This timing is just a guideline and must always be individualized. Although it is a tremendous amount of work for the mother, baby, family, and lactation consultant to correct well-established but incorrect breastfeeding behaviors, we have never met a mother who was sorry that she chose to tackle the problem. Even if she tries and then gives up or achieves only a partial milk supply or partial breastfeeding relationship, she can take pleasure in knowing that she left no stone unturned. Unfortunately, mothers and babies with presentations similar to that of VJ and Baby E all too often fail to establish an exclusive breastfeeding relationship. Not only are patience, dedication, time, and skills needed, but there are often multiple underlying problems that need to be solved. With a thorough assessment and appropriate use of skills and equipment by the lactation consultant, success is much more likely. This particular dyad should be able to acheive an exclusive breastfeeding relationship.

Family patterns of asthma, atopy and airway hyperresponsiveness: an epidemiological study

BACKGROUND

The patterns of inheritance of asthma have largely been explored using data of symptom history collected by questionnaires which are subject to bias and which may therefore distort the measured relationship.

OBJECTIVE

The purpose of this study was to examine family patterns of allergic disease using objective measurements of atopy and of airway hyperresponsiveness (AHR).

METHODS

A large random sample of children aged 8-11 years was studied and 3 months later, their parents were also invited for study. Of the sample of 1655 children, both parents of 661 children were studied. In all subjects, respiratory illness history was measured by questionnaire, atopy by skin tests and AHR by responsiveness to histamine.

RESULTS

The odds ratio for a child to have AHR if either parent had the same condition was approximately 2. 0, which was the same as the odds ratio for wheeze or diagnosed asthma in the presence of the same condition in either parent. The odds ratio for atopy was smaller (approximately 1.4, NS) but the risk of a nonatopic child having AHR if the parent had AHR was 3.0 (P = 0.01). The correlation between weal size in the child and parent was poor and the severity of AHR in the child was only modestly correlated with the severity of AHR in the parent (R = 0.51, P = 0.04).

CONCLUSION

The use of objective measurements did not strengthen the association between atopic or asthmatic conditions in the parent and child, but did suggest that atopy and AHR are inherited independently.

Does allergy in parents depend on allergy in their children? Recall bias in parental questioning of atopic diseases. Multicenter Allergy Study Group

BACKGROUND

A positive atopic family history has proved to be one important risk factor for the development of atopic diseases in offspring. However, many epidemiologists are concerned about the accuracy and reliability of data because responses to questionnaires can be biased for many reasons.

OBJECTIVE

The study investigated whether responses of parents questioned about their atopic diseases change depending on the development of atopic symptoms in their children.

METHODS

During a prospective birth cohort study on atopy in children (the Multicenter Allergy Study) parents filled out questionnaires twice within 2 years about their atopic diseases. Differences between the 2 responses were examined by log-linear and logistic regression models depending on the diagnosed atopy status of the study children.

RESULTS

Mothers tended to report more atopic diseases in the second questioning than in the first, indicating a nondifferential misclassification. Fathers were influenced by the development of atopic diseases in their children: they reported significantly more atopic diseases if the child developed atopic illness with atopic dermatitis.

CONCLUSION

In parental questioning about atopic diseases, a recall bias must be considered for the association of atopic family history and atopy in children. Especially in case-control and cross-sectional studies, such misclassifications can result in biased estimates of prognosis and risk factors.

Association of 3 gene polymorphisms with atopic diseases

BACKGROUND

Various peptidases, including angiotensin-converting enzyme (ACE), inactivate some inflammatory peptides that are considered to influence the pathogenesis of atopic diseases. This enzyme is also involved in the conversion or activation of 2 bronchoconstriction mediators: angiotensin II from angiotensinogen and endothelin (ET), respectively.

OBJECTIVE

We tested a hypothesis that asthma or other atopic diseases are associated with insertion/deletion ACE, M235T angiotensinogen, and TaqI ET-1 gene polymorphisms.

METHODS

A case-control approach was used in the study. Healthy subjects (141 persons) were used as control subjects, and 231 patients with histories of atopic asthma, allergic rhinitis, atopic dermatitis, or a combination thereof were studied. ACE genotype was determined by PCR, angiotensinogen M235T and ET-1 by PCR, and restriction analysis by AspI and TaqI, respectively.

RESULTS

We found the significant association of the insertion/deletion polymorphism of the ACE, as well as that of M235T polymorphism of the angiotensinogen genes, with the group of patients with atopic diseases ( P =.0025 and P =.0204, respectively). No difference was proved for the intron 4 (position 8000) polymorphism in the ET-1 gene when comparing the atopic patients with the control group (P =.1774). A significant difference was found between groups of patients with both asthma and rhinitis and patients without both respiratory atopic diseases (P =.0033).

CONCLUSION

It follows that the examined polymorphisms in the genes for ACE, angiotensinogen, and ET-1 could participate in the etiopathogenesis of atopic diseases.

Linkage and allelic association of atopy and markers flanking the IL4-receptor gene

BACKGROUND

Atopy, a clinical syndrome characterized by heightened IgE responsiveness, is largely determined by genetic factors. The disease may well be heterogeneous but the mode of inheritance is unknown. Several genes have been named which affected IgE responsiveness. However, results are conflicting reflecting heterogeneity and a complicated inheritance pattern of the atopic syndrome. In 1994 linkage of the 5q32 gene region and elevated total IgE levels were reported, leaving the IL4 gene as a prominent candidate.

OBJECTIVES

We were interested in a possible involvement of the IL4-receptor gene in the development of atopy.

METHODS

We employed sib-pair linkage analysis using highly polymorphic microsatellite markers within and flanking the IL4 receptor gene in atopic families, characterized for specific sensitization to inhalant allergens and elevated total serum IgE. Allele sizes were determined for all microsatellite probes to allow transmission disequilibrium analysis.

RESULTS

We found significant sharing of maternal but not paternal alleles in affected sibs from two independent populations, both of which presented enhanced IgE responsiveness. Linkage and maternal inheritance could be confirmed by transmission disequilibrium analysis.

CONCLUSIONS

We conclude from our findings that maternal inheritance of a gene in the chromosome 16p12 region increases the risk for enhanced IgE responsiveness. The most prominent candidate in this region is represented by the IL4 receptor gene.

Parental and neonatal risk factors for atopy, airway hyper-responsiveness, and asthma

BACKGROUND

Previous studies have not resolved the importance of several potential risk factors for the development of childhood atopy, airway hyperresponsiveness, and wheezing, which would allow the rational selection of interventions to reduce morbidity from asthma. Risk factors for these disorders were examined in a birth cohort of 1037 New Zealand children.

METHODS

Responses to questions on respiratory symptoms and measurements of lung function and airway responsiveness were obtained every two to three years throughout childhood and adolescence, with over 85% cohort retention at age 18 years. Atopy was determined by skin prick tests at age 13 years. Relations between parental and neonatal factors, the development of atopy, and features of asthma were determined by comparison of proportions and logistic regression.

RESULTS

Male sex was a significant independent predictor for atopy, airway hyper-responsiveness, hay fever, and asthma. A positive family history, especially maternal, of asthma strongly predicted childhood atopy, airway hyperresponsiveness, asthma, and hay fever. Maternal smoking in the last trimester was correlated with the onset of childhood asthma by the age of 1 year. Birth in the winter season increased the risk of sensitisation to cats. Among those with a parental history of asthma or hay fever, birth in autumn and winter also increased the risk of sensitisation to house dust mites. The number of siblings, position in the family, socioeconomic status, and birth weight were not consistently predictive of any characteristic of asthma.

CONCLUSIONS

Male sex, parental atopy, and maternal smoking during pregnancy are risk factors for asthma in young children. Children born in winter exhibit a greater prevalence of sensitisation to cats and house dust mites. These data suggest possible areas for intervention in children at risk because of parental atopy.

A genome-wide search for quantitative trait loci underlying asthma

Asthma now affects one child in seven in the United Kingdom. Most cases (95%) of childhood asthma are associated with atopy, the immunoglobulin E (IgE)-mediated familial syndrome of allergic asthma, eczema and rhinitis. Segregation analysis has consistently suggested the presence of major genes influencing atopy and IgE levels, with the expectation that these genes may be identified by positional cloning or the examination of candidate genes. Here we report the results of a genome-wide search for linkage to one qualitative and four quantitative traits associated with allergic (atopic) asthma. We have identified six potential linkages (P<0.001), five of which are to quantitative traits. Monte Carlo simulations show that 1.6 false-positive linkages at this level of significance would be expected from the data. One linkage, to chromosome 11q13, has been established previously. Three of the new loci show evidence of linkage to a second panel of families, in which maternal effects and pleiotropy of linked phenotypes are seen. The results demonstrate the extent and the complexity of the genetic predisposition to asthma.

Prevalence of allergic diseases in schoolchildren in relation to family history, upper respiratory infections, and residential characteristics

The prevalences of asthma, allergic rhinitis (AR), and eczema were analyzed in relation to retrospective risk factors from birth in a questionnaire study of schoolchildren in two areas covering the whole climatic span of Sweden: the Göteborg area on the southwestern coast (7-year-olds, n = 1649) and Kiruna, a mining town in the northernmost inland mountains (7-9-year-olds, n = 832). The strongest background factor, a family history of the diseases, was more common in children with another strong risk factor, particularly for asthma: high frequency of upper respiratory tract infection (URTI). Other significant risk factors related to high indoor humidity caused an increased prevalence of both allergic diseases and URTI. Active mechanical ventilation of the homes caused a slight reduction of the prevalence of allergic diseases, and repainting or new wallpaper in the bedroom of the child after birth caused a moderately increased risk of allergic disease. This study illustrates the interaction between genetic and environmental risk factors with special emphasis on factors related to an unventilated indoor climate, which may have substantially contributed to the current increase of the diseases in the country.

Neonatal IgA and IgE levels among infants with paternal heredity for atopic disease

Serum IgA and IgE levels were studied in the postnatal period in 21 infants having a paternal heredity of atopic disease. Three different sampling techniques were used, aspirated cord blood (CB), gravity-collected cord blood, and capillary collected blood at 4-5 days of age. Significant differences among the three sampling techniques were recorded for IgA (P < 0.01), but not for IgE. The IgA levels decreased from birth to 4-5 days of age in 90% (19/21 of infants (P < 0.01). The corresponding decrease in IgE levels was 20%. This postnatal difference in the frequency of decreasing/increasing IgA and IgE levels was significant (P < 0.05). An analysis of CB IgA to detect maternal contamination of CB was found to be of questionable value, since only 50% (2/4) of the cases with an elevated CB-IgA level could be considered contaminated. The results of this study further emphasize that aspiration of CB and capillary collection of blood at 4-5 days of age are the best sampling techniques to avoid contamination. The general finding that paternal heredity had no significant influence on infant IgE contrasts with the strong influence of maternal heredity. Further studies will show whether the explanation lies in genetic or transplacental factors, or in both kinds of factors.