Birth order modifies the effect of IL13 gene polymorphisms on serum IgE at age 10 and skin prick test at ages 4, 10 and 18: a prospective birth cohort study

Epigenetic Modifications in Placenta are Associated with the Child's Sensitization to Allergens

Prenatal environmental exposures are considered to contribute to the development of allergic sensitization by epigenetic mechanisms. The role of histone acetylation in the placenta has not been examined yet. We hypothesized that placental histone acetylation at the promoter regions of allergy-related immune regulatory genes is associated with the development of sensitization to allergens in the child. Histones H3 and H4 acetylation at the promoter regions of 6 selected allergy-related immune regulatory genes was assessed by a chromatin immunoprecipitation assay in 173 term placentas collected in the prospective birth-cohort ALADDIN. The development of IgE sensitization to allergens in the children was followed from 6 months up to 5 years of age. We discovered significant associations of histone acetylation levels with decreased risk of allergic sensitization in 3 genes. Decreased risk of sensitization to food allergens was associated with higher H3 acetylation levels in placentas at the IFNG and SH2B3 genes, and for H4 acetylation in HDAC4. Higher HDAC4 H4 acetylation levels were also associated with a decreased risk of sensitization to aeroallergens. In conclusion, our results suggest that acetylation of histones in placenta has a potential to predict the development of sensitization to allergens in children.

Prevalence and Associated Risk Factors of Bronchial Asthma in Children in Santo Domingo, Dominican Republic

Background

Bronchial asthma is an important health problem worldwide. There is insufficient data on the prevalence of bronchial asthma among school children in Santo Domingo, Dominican Republic.

Objective

The objective of this study is to assess the prevalence of asthma and its related risk factors among school children in Santo Domingo, Dominican Republic.

Materials and methods

A cross-sectional study using a modified questionnaire was conducted in Santo Domingo among 600 children aged three to 11 eleven years. The prevalence of asthma and its associated risk factors such as birth order, family history of asthma, family history of allergy, exposure to pets at home, exposure to tobacco smoke, and source of fuel used at home were collected. The relevant data collected was analyzed using the Statistical Package for the Social Sciences (SPSS) 24.0. (IBM Corp., Armonk, NY) software.

Results

The prevalence of asthma was found to be 22.0%. Age, family history of asthma, family history of allergy, exposure to tobacco smoke, and birth order showed statistical significance. The source of fuel used at home, gender, and exposure to pets were not statistically significant to be considered as risk factors associated with asthma in the population studied.

Conclusion

With an asthma prevalence of 22.0% in the pediatric population, the Dominican Republic has one of the highest national rates of asthma in the pediatric population in Latin America. Proper education, screening, and prevention can help lower the burden of this disease economically and socially.

Association of season of birth with DNA methylation and allergic disease

BACKGROUND

Season of birth influences allergy risk; however, the biological mechanisms underlying this observation are unclear. The environment affects DNA methylation, with potentially long-lasting effects on gene expression and disease. This study examined whether DNA methylation could underlie the association between season of birth and allergy.

METHODS

In a subset of 18-year-old participants from the Isle of Wight (IoW) birth cohort (n = 367), the risks of birth season on allergic outcomes were estimated. Whole blood epigenome-wide DNA methylation was measured, and season-associated CpGs detected using a training-and-testing-based technique. Validation method examined the 8-year-old Prevention and Incidence of Asthma and Mite Allergy (PIAMA) cohort. The relationships between DNA methylation, season of birth and allergy were examined. CpGs were analysed in IoW third-generation cohort newborns.

RESULTS

Autumn birth increased risk of eczema, relative to spring birth. Methylation at 92 CpGs showed association with season of birth in the epigenome-wide association study. In validation, significantly more CpGs had the same directionality than expected by chance, and four were statistically significant. Season-associated methylation was enriched among networks relating to development, the cell cycle and apoptosis. Twenty CpGs were nominally associated with allergic outcomes. Two CpGs were marginally on the causal pathway to allergy. Season-associated methylation was largely absent in newborns, suggesting it arises post-natally.

CONCLUSIONS

This study demonstrates that DNA methylation in adulthood is associated with season of birth, supporting the hypothesis that DNA methylation could mechanistically underlie the effect of season of birth on allergy, although other mechanisms are also likely to be involved.

Do firstborn children have an increased risk of ADHD?

OBJECTIVE

Although previous reports have found no birth-order influence on ADHD risk, the authors hypothesize that being the firstborn is a risk factor for developing ADHD.

METHOD

They selected all of the currently treated ADHD outpatients (n = 748) from our database. Families with adopted sons, nonnuclear families, and families with only one child and with sons (affected or unaffected) younger than 6 or older than 18 years were excluded. A total of 181 families with 213 ADHD sons met the inclusion criteria. We used all siblings without a clinical diagnosis of ADHD and who had no contact with our service as our unaffected controls (n = 173).

RESULTS

The bivariate analysis showed that ADHD was associated with birth order and that firstborn children had nearly twice the ADHD risk of children with other birth orders.

CONCLUSION

birth order can be an ADHD risk factor in clinical samples.

Interleukin-13 genetic variants, household carpet use and childhood asthma

Interleukin (IL)-13 genetic polymorphisms have shown adverse effects on respiratory health. However, few studies have explored the interactive effects between IL-13 haplotypes and environmental exposures on childhood asthma. The aims of our study are to evaluate the effects of IL-13 genetic variants on asthma phenotypes, and explore the potential interaction between IL-13 and household environmental exposures among Taiwanese children. We investigated 3,577 children in the Taiwan Children Health Study from 14 Taiwanese communities. Data regarding children's exposure and disease status were obtained from parents using a structured questionnaire. Four SNPs were tagged accounting for 100% of the variations in IL-13. Multiple logistic regression models with false-discovery rate (FDR) adjustments were fitted to estimate the effects of IL-13 variants on asthma phenotypes. SNP rs1800925, SNP rs20541 and SNP rs848 were significantly associated with increased risks on childhood wheeze with FDR of 0.03, 0.04 and 0.04, respectively. Children carrying two copies of h1011 haplotype showed increased susceptibility to wheeze. Compared to those without carpet use and h1011 haplotype, children carrying h1011 haplotype and using carpet at home had significantly synergistic risks of wheeze (OR, 2.5; 95% CI, 1.4–4.4; p for interaction, 0.01) and late-onset asthma (OR, 4.7; 95% CI, 2.0–10.9; p for interaction, 0.02). In conclusions, IL-13 genetic variants showed significant adverse effects on asthma phenotypes among children. The results also suggested that asthma pathogenesis might be mediated by household carpet use.

Brief report: Asperger's syndrome and sibling birth order

Prior investigations suggest that birth order position may be associated with the risk for developing a pervasive developmental disorder. This retrospective chart review examined the birth order status of 29 psychiatrically-referred patients with Asperger's Syndrome (AS). Eighty-six percent of the subjects were first born. The finding was statistically significant when compared to an expected random distribution of AS subjects χ(2) (1, N = 29) = 9.18, p < 0.01. The reasons for such an association are unclear though birth stoppage, obstetric complications, and immunological mechanisms may play a role.

Early life precursors, epigenetics, and the development of food allergy

Food allergy (FA), a major clinical and public health concern worldwide, is caused by a complex interplay of environmental exposures, genetic variants, gene-environment interactions, and epigenetic alterations. This review summarizes recent advances surrounding these key factors, with a particular focus on the potential role of epigenetics in the development of FA. Epidemiologic studies have reported a number of nongenetic factors that may influence the risk of FA, such as timing of food introduction and feeding pattern, diet/nutrition, exposure to environmental tobacco smoking, prematurity and low birth weight, microbial exposure, and race/ethnicity. Current studies on the genetics of FA are mainly conducted using candidate gene approaches, which have linked more than 10 genes to the genetic susceptibility of FA. Studies on gene-environment interactions of FA are very limited. Epigenetic alteration has been proposed as one of the mechanisms to mediate the influence of early life environmental exposures and gene-environment interactions on the development of diseases later in life. The role of epigenetics in the regulation of the immune system and the epigenetic effects of some FA-associated environmental exposures are discussed in this review. There is a particular lack of large-scale prospective birth cohort studies that simultaneously assess the interrelationships of early life exposures, genetic susceptibility, epigenomic alterations, and the development of FA. The identification of these key factors and their independent and joint contributions to FA will allow us to gain important insight into the biological mechanisms by which environmental exposures and genetic susceptibility affect the risk of FA and will provide essential information to develop more effective new paradigms in the diagnosis, prevention, and management of FA.

Quantifying and modeling birth order effects in autism

Autism is a complex genetic disorder with multiple etiologies whose molecular genetic basis is not fully understood. Although a number of rare mutations and dosage abnormalities are specific to autism, these explain no more than 10% of all cases. The high heritability of autism and low recurrence risk suggests multifactorial inheritance from numerous loci but other factors also intervene to modulate risk. In this study, we examine the effect of birth rank on disease risk which is not expected for purely hereditary genetic models. We analyzed the data from three publicly available autism family collections in the USA for potential birth order effects and studied the statistical properties of three tests to show that adequate power to detect these effects exist. We detect statistically significant, yet varying, patterns of birth order effects across these collections. In multiplex families, we identify V-shaped effects where middle births are at high risk; in simplex families, we demonstrate linear effects where risk increases with each additional birth. Moreover, the birth order effect is gender-dependent in the simplex collection. It is currently unknown whether these patterns arise from ascertainment biases or biological factors. Nevertheless, further investigation of parental age-dependent risks yields patterns similar to those observed and could potentially explain part of the increased risk. A search for genes considering these patterns is likely to increase statistical power and uncover novel molecular etiologies.

Sibling number and prevalence of allergic disorders in pregnant Japanese women: baseline data from the Kyushu Okinawa Maternal and Child Health Study

BACKGROUND

Although an inverse relationship between number of siblings and likelihood of allergic disorders has been shown in many epidemiological studies, the biological mechanism underlying this phenomenon has not yet been identified. There is no epidemiological research regarding the sibling effect on allergic disorders in Japanese adults. The current cross-sectional study examined the relationship between number of siblings and prevalence of allergic disorders among adult women in Japan.

METHODS

Subjects were 1745 pregnant women. This study was based on questionnaire data. The definitions of wheeze and asthma were based on criteria from the European Community Respiratory Health Survey whereas those of eczema and rhinoconjunctivitis were based on criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for age, region of residence, pack-years of smoking, secondhand smoke exposure at home and at work, family history of asthma, atopic eczema, and allergic rhinitis, household income, and education.

RESULTS

The prevalence values of wheeze, asthma, eczema, and rhinoconjunctivitis in the past 12 months were 10.4%, 5.5%, 13.0%, and 25.9%, respectively. A significant inverse exposure-response relationship was observed between the number of older siblings and rhinoconjunctivitis, but not wheeze, asthma, or eczema (P for trend=0.03); however, the adjusted odds ratio (OR) for having 2 or more older siblings was not significant although the adjusted OR for having 1 older sibling was statistically significant (adjusted OR=0.71 [95% CI: 0.56-0.91]). Number of total siblings and number of younger siblings were not related to wheeze, asthma, eczema, or rhinoconjunctivitis.

CONCLUSIONS

This study found a significant inverse relationship between the number of older siblings and the prevalence of rhinoconjunctivitis among pregnant Japanese women. Our findings are likely to support the intrauterine programming hypothesis; however, we could not rule out the hygiene hypothesis.

Genome-wide association studies on IgE regulation: are genetics of IgE also genetics of atopic disease?

PURPOSE OF REVIEW

Total IgE levels are considered a useful endophenotype for studying the genetics of atopic diseases. However, the role and significance of genetic factors influencing IgE regulation for atopic diseases as endpoints is unclear.

RECENT FINDINGS

Recently, genome-wide association studies (GWASs) have been applied to atopic traits with considerable success. A total of seven published GWASs on asthma, one GWAS on eczema, and one GWAS on total IgE have reported 11 new loci. Most of these loci appear to be trait-specific. A notable exception is the Th2 cytokine cluster, where genetic variation seems to be relevant across atopic phenotypes.

SUMMARY

GWASs have identified several novel asthma and eczema loci as well as novel loci for IgE levels. In this review, we evaluate the interrelation between these loci and summarize to which degree recent findings on IgE reflect genetic vulnerability for atopic disease.