A genome-wide association study of asthma symptoms in Latin American children

New variants of the DAD1 and OXA1L genes are associated with asthma and atopy in an adult population

Asthma is a complex disease characterized by reversible and intermittent airway obstruction that has shown a high prevalence and unacceptable mortality in adults. In recent years, several genome-wide association studies (GWAS) have identified variants linked to asthma susceptibility. The DAD1 gene is known for regulating programmed cell death, and OXA1L is described for its involvement in mitochondrial biogenesis and oxidative phosphorylation. The present study aimed to identify variants in the DAD1 and OXA1L genes and to evaluate the association with asthma and atopy markers in adults. 1,084 individuals were divided into mild to moderate asthma, severe asthma, and participants with no asthma (controls). Association analyses were performed using a multivariate logistic regression model adjusted for sex, age, body mass index (BMI), smoking, forced expiratory volume in 1 s (FEV1), and component ancestry master (PC1) using PLINK 1.9 software. This study identified new variants in the DAD1 and OXA1L genes that had never been described before. The C allele of rs200470407 in OXA1L was negatively associated with poor asthma control (OR: 0.32; p-value 0.049) and increased IL-13 (p-value < 0.0001). The alternative allele of rs1681577 was associated with severe asthma (OR: 2.23; p-value 0.01), pulmonary obstruction (OR: 4.12; p-value 0.046), and eosinophilia (OR: 2.42; p-value < 0.001). Our findings demonstrate that variants in the DAD1 and OXA1L genes are linked to asthma and atopy in Brazilian adults.

Molecular networks in atopic mothers impact the risk of infant atopy

BACKGROUND

The prevalence of atopic diseases has increased with atopic dermatitis (AD) as the earliest manifestation. We assessed if molecular risk factors in atopic mothers influence their infants' susceptibility to an atopic disease.

METHODS

Pregnant women and their infants with (n = 174, high-risk) or without (n = 126, low-risk) parental atopy were enrolled in a prospective birth cohort. Global differentially methylated regions (DMRs) were determined in atopic (n = 92) and non-atopic (n = 82) mothers. Principal component analysis was used to predict atopy risk in children dependent on maternal atopy. Genome-wide transcriptomic analyses were performed in paired atopic (n = 20) and non-atopic (n = 15) mothers and cord blood. Integrative genomic analyses were conducted to define methylation-gene expression relationships.

RESULTS

Atopic dermatitis was more prevalent in high-risk compared to low-risk children by age 2. Differential methylation analyses identified 165 DMRs distinguishing atopic from non-atopic mothers. Inclusion of DMRs in addition to maternal atopy significantly increased the odds ratio to develop AD in children from 2.56 to 4.26. In atopic compared to non-atopic mothers, 139 differentially expressed genes (DEGs) were identified significantly enriched of genes within the interferon signaling pathway. Expression quantitative trait methylation analyses dependent on maternal atopy identified 29 DEGs controlled by 136 trans-acting methylation marks, some located near transcription factors. Differential expression for the same nine genes, including MX1 and IFI6 within the interferon pathway, was identified in atopic and non-atopic mothers and high-risk and low-risk children.

CONCLUSION

These data suggest that in utero epigenetic and transcriptomic mechanisms predominantly involving the interferon pathway may impact and predict the development of infant atopy.

Assessing the prevalence and severity of asthma, rhinitis, and eczema among schoolchildren (6-7 and 13-14 years old) in Khuzestan, Iran: a cross-sectional survey

Background

Asthma and allergic complications are the most common chronic disorders in children and adolescents. This study aimed to determine the prevalence and severity of asthma, allergic rhinitis, eczema among schoolchildren, and some related risk factors.

Methods

The cross-sectional study was performed in 2019 and involved 4000 students aged 6–7 years and 4000 students aged 13–14 years (both girls and boys) from urban schools in Khuzestan Province, southwestern Iran. We used the multi-stage sampling method. Data were collected using the Persian version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire.

Results

The prevalence of current wheeze, wheeze ever and asthma ever in the age group of 6–7 years was 3.8, 4.5, and 1.8%, respectively; in the age group of 13–14 years, it was 4.4, 5.9, and 3.4, respectively. In terms of gender, males (4.9, 6.0, and 2.7 percent, respectively) had substantially higher rates of current wheeze, wheeze ever, and asthma ever compared to the girls (2.8, 3.6, and 2.0 percent, respectively) (p < 0.001). The prevalence of rhinitis, Hay fever, and eczema among young people was 5.3%, 3.5%, and 1.0%, respectively. Current wheeze was more common in children with allergic rhinitis in the last 12 months (30.3% vs. 2.7%, p < 0.001), Hay fever (32.8% vs. 0.3%, p < 0.001) and eczema (27.8% vs 3.8%, p < 0.001), compared to children who did not.

Conclusions

The prevalence and severity of asthma symptoms were significantly associated with allergic rhinitis, eczema, and gender.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03520-x.

Transcriptome-Wide m6A Methylome and m6A-Modified Gene Analysis in Asthma

N6-methyladenosine (m6A) modification is one of the most prevalent RNA modification forms and is an important posttranscriptional mechanism for regulating genes. In previous research, we found that m6A regulator–mediated RNA methylation modification was involved in asthma; however, the specific modified genes are not clear. In this study, we systematically evaluated the transcriptome-wide m6A methylome and m6A-modified genes in asthma. Here, we performed two high-throughput sequencing methods, methylated RNA immunoprecipitation sequencing (MeRIP-seq), and RNA sequencing (RNA-seq) to identify key genes with m6A modification in asthma. Through difference analysis, we found that 416 methylation peaks were significantly upregulated and 152 methylation peaks were significantly downregulated, and it was mainly distributed in 3′ UTR. Furthermore, compared with the control group, there were 2,505 significantly upregulated genes and 4,715 significantly downregulated genes in the asthma group. Next, through a combined analysis of transcriptome and differential peaks, 14 differentially expressed genes related to RNA methylation modification were screened. Finally, through 87 health controls and 411 asthma cases from the U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes) program, we verified three m6A-modified key genes (BCL11A, MATK, and CD300A) and found that they were mainly distributed in exons and enriched in 3' UTR. Our findings suggested that intervening in m6A-modified genes may provide a new idea for the treatment of asthma.

ADIPOQ and LEP variants on asthma and atopy: Genetic association modified by overweight

BACKGROUND

Asthma and atopy are considered condition associated with obesity, being affected by genetic and environmental factors. The LEP and ADIPOQ genes, responsible for the expression and secretion of leptin and adiponectin, respectively, and polymorphisms in such genes have been linked to both diseases, independently, and also with the obesity-associated asthma phenotype in populations with high European ancestry and high-income countries. However, in mixed populations, there are few studies evaluating the impact of these variants in genes associated with the phenotype of asthma and obesity. Thus, the aim of this study was to investigate variants in LEP and ADIPOQ associated with asthma and atopy, and whether overweight modifies that effect.

METHODS

The study involved 203 asthmatics children and 813 control subjects (between 5 and 11 years old), with or without overweight, from the SCAALA (Asthma and Allergy Social Changes in Latin America) program. Among them, 831 had data for allergy markers, being 258 atopic and 573 non-atopic. Genotyping was performed using a commercial panel Omnium Illumina 2.5. Logistic regression was performed to identify associations expected by using PLINK 1.09 and three genetic models: additive, dominant and recessive adjusted for sex, age, helminth infection, BMI and Principal Components (PC) 1 and 2, for ancestry, in order to control the confounding factor by population structure.

RESULTS

For asthma, G allele of rs822396, in ADIPOQ, was positively associated in additive model (OR 1.4, 95% CI 1.08-1.83) and T allele of rs1063537 in dominant model (OR 1.52, 95% CI 1.01-2.30). In LEP, rs11763517 (C allele) and rs11760956 (A allele) were both negatively associated with asthma in the additive model (OR 0.70, 95% CI 0.54-0.91; OR 0.66, 95% CI 0.50-0.89) respectively, and the A allele of rs2167270 in dominant model (OR 0.71, 95% CI 0.51-0.98). The G allele of rs12706832 showed a positive association with asthma in the recessive model (OR 1.66, 95% CI 1.06-2.61). When the population was stratified by the BMI / Age Z-Score, the protection observed for asthma between the variants rs11760956, rs11763517 and rs2167270 was lost overweight individuals; The protection observed for atopy was lost in all variants (rs16861205, rs2167270 and rs17151919) in the overweight group.

CONCLUSION

These results suggest that SNPs on the LEP and ADIPOQ genes may have an impact on atopy and asthma. Furthermore, we also show that the asthma and atopy protection attributed to variants on LEP and ADIPOQ genes is lost in individuals exposed to overweight.

WSB1 and IL21R Genetic Variants Are Involved in Th2 Immune Responses to Ascaris lumbricoides

Genetic and epigenetic factors are considered to be critical for host-parasite interactions. There are limited data on the role of such factors during human infections with Ascaris lumbricoides. Here, we describe the potential role of genetic factors as determinants of the Th2 immune response to A. lumbricoides in Brazilian children. Stool samples were collected from the children to detect A. lumbricoides by microscopy and peripheral blood leukocytes (PBLs) were cultured in whole blood cultures for detection of cytokines (IL-5, IL-10, and IL-13) in vitro. Levels of anti-A. lumbricoides IgE and IgG4 were measured in plasma. DNA was extracted from PBLs and genotyped using Illumina 2.5 Human Omni Beadchip. Candidate genes associated with A. lumbricoides responses were identified and SNVs in these selected genes associated with the Th2 immune response to A. lumbricoides. Haplotype, gene expression, and epigenetic analyses were done to identify potential associations with Th2 immune responses. GWAS on samples from 1,189 children identified WSB1 as a candidate gene, and IL-21R was selected as a biologically relevant linked gene for further analysis. Variants in WSB1 and IL21R were associated with markers of Th2 immune responses: increased A. lumbricoides-specific IgE and IL-5/IL-13 by PBLs from infected compared to uninfected individuals. In infected children, WSB1 but not IL21R gene expression was suppressed and increased methylation was observed in the WSB1 promoter region. This is the first study to show an association between genetic variants in WSB1 and IL21R and Th2 immune responses during A. lumbricoides infections in children. WSB1/IL21R pathways could provide a potential target for the treatment of Th2-mediated diseases.

Co-methylation analysis in lung tissue identifies pathways for fetal origins of COPD

COPD likely has developmental origins; however, the underlying molecular mechanisms are not fully identified. Investigation of lung tissue-specific epigenetic modifications such as DNA methylation using network approaches might facilitate insights linking in utero smoke (IUS) exposure and risk for COPD in adulthood.We performed genome-wide methylation profiling for adult lung DNA from 160 surgical samples and 78 fetal lung DNA samples isolated from discarded tissue at 8-18 weeks of gestation. Co-methylation networks were constructed to identify preserved modules that shared methylation patterns in fetal and adult lung tissues and associations with fetal IUS exposure, gestational age and COPD.Weighted correlation networks highlighted preserved and co-methylated modules for both fetal and adult lung data associated with fetal IUS exposure, COPD and lower adult lung function. These modules were significantly enriched for genes involved in embryonic organ development and specific inflammation-related pathways, including Hippo, phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT), Wnt, mitogen-activated protein kinase and transforming growth factor-β signalling. Gestational age-associated modules were remarkably preserved for COPD and lung function, and were also annotated to genes enriched for the Wnt and PI3K/AKT pathways.Epigenetic network perturbations in fetal lung tissue exposed to IUS and of early lung development recapitulated in adult lung tissue from ex-smokers with COPD. Overlapping fetal and adult lung tissue network modules highlighted putative disease pathways supportive of exposure-related and age-associated developmental origins of COPD.

Genetic polymorphisms in vitamin D pathway influence 25(OH)D levels and are associated with atopy and asthma

Background

Vitamin D deficiency or insufficiency, has been associated with atopy and lack of asthma control. Our objective was to investigate associations between variants in genes of vitamin D pathway with serum levels of 25-hydroxyvitamin D (25(OH)D), atopy, asthma and asthma severity in teenagers from Northeast Brazil.

Methods

This is a cross sectional study nested in a cohort population of asthma. 25(OH)D was quantified from 968 of 11–17 years old individuals by ELISA. Asthma diagnosis was obtained by using the ISAAC Phase III questionnaire. Specific IgE was determined by ImmunoCAP; genotyping was performed using the 2.5 HumanOmni Biochip from Illumina. Statistical analyses were performed in PLINK 1.07 and SPSS 22.1.

Results

After quality control, 104 Single Nucleotides Variants (SNVs) in vitamin D pathway genes, typed in 792 individuals, were included in the analysis. The allele A of rs10875694 on VDR was positively associated with atopy (OR = 1.35; 95% CI 1.01–1.81). The allele C of rs9279 on VDR, was negatively associated with asthma risk (OR = 0.66; 95% CI 0.45–0.97), vitamin D insufficiency (OR = 0.78; 95% CI 0.70–0.96) and higher VDR expression. Two variants in VDR were associated with asthma severity, the allele A of rs2189480 (OR = 0.34; 95% CI 0.13–0.89) and the allele G of rs4328262 (OR = 3.18; 95% CI 1.09–9.28). The combination of variants in CYP2R1 and CYP24A1 (GAC, to rs10500804, rs12794714 and rs3886163, respectively) was negatively associated with vitamin D production (β = − 1.24; 95% CI − 2.42 to − 0.06).

Conclusions

Genetic variants in the vitamin D pathway affect vitamin D serum levels and, thus, atopy and asthma.

Reconstructing recent population history while mapping rare variants using haplotypes

Haplotype-based methods are a cost-effective alternative to characterize unobserved rare variants and map disease-associated alleles. Moreover, they can be used to reconstruct recent population history, which shaped distribution of rare variants and thus can be used to guide gene mapping studies. In this study, we analysed Illumina 650 k genotyped dataset on three underrepresented populations from Eastern Europe, where ancestors of Russians came into contact with two indigenous ethnic groups, Bashkirs and Tatars. Using the IBD mapping approach, we identified two rare IBD haplotypes strongly enriched in asthma patients of distinct ethnic background. We reconstructed recent population history using haplotype-based methods to reconcile this contradictory finding. Our ChromoPainter analysis showed that these haplotypes each descend from a single ancestor coming from one of the ethnic groups studied. Next, we used DoRIS approach and showed that source populations for patients exchanged recent (<60 generations) asymmetric gene flow, which supported the ChromoPainter-based scenario that patients share haplotypes through inter-ethnic admixture. Finally, we show that these IBD haplotypes overlap with asthma-associated genomic regions ascertained in European population. This finding is consistent with the fact that the two donor populations for the rare IBD haplotypes: Russians and Tatars have European ancestry.

Quality of Life of asthmatic children and their caregivers

Objectives:

To assess Quality of Life (QOL), and its associated factors between asthmatic children and their caregivers, and determine the correlation between QOL of patients and caregivers, at King Abdulaziz University Hospital (KAUH), Jeddah.

Methods:

A cross-sectional study was conducted among eligible participants who attended Pediatric Pulmonology Outpatient Clinic of KAUH, during 2016/2017. A data collection sheet was used. The standardized Arabic version of Pediatric Asthma Quality of Life Questionnaire (PAQLQ) for children aged 7 - 17 years was completed. The caregiver who accompanied the child fulfilled the Pediatric Asthma Caregiver’s Quality of Life Questionnaire (PACQLQ). Descriptive and inferential analyses were performed.

Results:

QOL scores were reduced among asthmatic children who had other type of allergy, or a family history of allergies. Uncontrolled management of asthma presented by frequent waking-up at night, frequent wheezes, visiting Emergency Rooms (ER), or hospital admission was associated with poor QOL of both asthmatic children and their caregivers. There is a positive correlation between child symptoms domain of PAQLQ and emotional domain of PACQLQ of their caregivers.

Conclusion:

Uncontrolled asthma was associated with poor QOL of asthmatic child and caregivers. Better management of asthma is recommended to improve their QOL.

Genome-wide burden and association analyses implicate copy number variations in asthma risk among children and young adults from Latin America

The genetic architecture of asthma was relatively well explored. However, some work remains in the field to improve our understanding on asthma genetics, especially in non-Caucasian populations and with regards to commonly neglected genetic variants, such as Copy Number Variations (CNVs). In the present study, we investigated the contribution of CNVs on asthma risk among Latin Americans. CNVs were inferred from SNP genotyping data. Genome wide burden and association analyses were conducted to evaluate the impact of CNVs on asthma outcome. We found no significant difference in the numbers of CNVs between asthmatics and non-asthmatics. Nevertheless, we found that CNVs are larger in patients then in healthy controls and that CNVs from cases intersect significantly more genes and regulatory elements. We also found that a deletion at 6p22.1 is associated with asthma symptoms in children from Salvador (Brazil) and in young adults from Pelotas (Brazil). To support our results, we conducted an in silico functional analysis and found that this deletion spans several regulatory elements, including two promoter elements active in lung cells. In conclusion, we found robust evidence that CNVs could contribute for asthma susceptibility. These results uncover a new perspective on the influence of genetic factors modulating asthma risk.

Food Consumption as a Modifier of the Association between LEPR Gene Variants and Excess Body Weight in Children and Adolescents: A Study of the SCAALA Cohort

No studies showing that food consumption is a modifier of the association of variants of the leptin receptor gene (LEPR) with body weight have involved a Brazilian population. The aim of this study was to evaluate the modifying effect of dietary intake on the association between the LEPR gene and excess weight. In this study, 1211 children and adolescents aged 4⁻11 years were assessed. Participants were genotyped for 112 single-nucleotide variants of the LEPR gene. Anthropometric measurements were performed, and dietary data were obtained. Logistic regressions were used to study the associations of interest. Of the participants, 13.4% were overweight/obese. The risk allele (G) of the rs1137100 variant was associated with excess weight in individuals with fat consumption below the median (odds ratio OR = 1.92; 95% confidence interval CI = 1.18⁻3.14), with daily frequency of consumption of drink/artificial juice (OR = 2.15; 95% CI = 1.26⁻3.68) and refined cereals (OR = 2.17; 95% CI = 1.31⁻3.62) above the median. The risk allele (G) of variant rs1177681 was also associated with excess weight (OR = 2.74; 95% CI = 1.65⁻4.57) in subjects with a daily frequency of refined cereal consumption above the median. The association between LEPR and excess weight can be modulated by the type and distribution of dietary fatty acids, sugary drinks, and refined cereals.

Polymorphisms in the DAD1 and OXA1L genes are associated with asthma and atopy in a South American population

Atopic asthma, which is characterized by the chronic inflammation and morbidity of airways, is a disease of great complexity, and multiple genetic and environmental factors are involved in its etiology. In the first genome-wide association study (GWAS) conducted in Brazil for asthma, a positive association was found between atopic asthma and a variant (rs1999071), which is located between the DAD1 and OXA1L genes, although neither gene has previously been reported to be associated with asthma or allergies. The DAD1 gene is involved in the regulation of programmed cell death, and OXA1L is involved in biogenesis and mitochondrial oxidative phosphorylation. This study aimed to evaluate how polymorphisms in DAD1 and OXA1L are associated with asthma and markers of atopy in individuals from the Salvador cohort of the SCAALA (Social Change Asthma and Allergy in Latin America) program. The DNA of 1220 individuals was genotyped using the Illumina 2.5 Human Omni Bead chip. Logistic regression analyses were performed with PLINK 1.9 software to verify the association between DAD1 and OXA1L polymorphisms and asthma and atopic markers, adjusted for sex, age, helminth infections and ancestry markers, using an additive model. The DAD1 and OXA1L genes were associated with some of the evaluated phenotypes, such as asthma, skin prick test (SPT), specific IgE for aeroallergens, and Th1/Th2-type cytokine production. Using qPCR, as well as in silico gene expression analysis, we have demonstrated that some of the polymorphisms in both genes are able to affect their respective gene expression levels. In addition, DAD1 was over-expressed in asthmatic patients when compared with controls. Thus, our findings demonstrate that variants in both the DAD1 and OXA1L genes may affect atopy and asthma in a Latin American population with a high prevalence of asthma.

Genetic variants in RORA are associated with asthma and allergy markers in an admixed population

Asthma and allergy affect hundreds of millions of people from childhood to old age. In most of them, the inflammatory process of respiratory allergies involves the participation of type 2 cytokines, derived from T helper-2 (Th2)-cell, and Group 2 Innate Lymphoid (ILC2) Cells. An efficient memory Th2 cell response is dependent on IL-13 produced by ILC2s, causing allergic lung inflammation and elevated serum levels of immunoglobulin E. ILC2 cells are derived from common lymphoid progenitors and their growing depends on the transcription factor RORA. The aim of this work was to identify genetic variants in RORA associated with asthma phenotypes and allergy markers. Genomic DNA samples of 1246 individuals participating from Social Changes Asthma and Allergy in Latin America Program (SCAALA) have been genotyped using Illumina Human 2.5 Omni Beadchip. Logistics regressions have been performed to analyze the association among RORA variants and asthma, skin prick tests (SPT), specific IgE and type 2 cytokine production. Twelve single nucleotide variants (SNVs) were significantly associated with atopy (P < 0.01), in which four of them, rs10162630, rs17191519, rs17270243, and rs55796775 and their haplotypes were strongly and positively associated (P < 0.001). Furthermore, these variants increased the RORA gene expression in silico analysis. Other SNVs in RORA were associated with allergy markers, atopic and non-atopic asthma. Therefore, it is believed that variants in RORA gene may influence immunologic features of asthma and allergies and could be possible targets for future treatment of allergic diseases.

Multiobjective grammar-based genetic programming applied to the study of asthma and allergy epidemiology

Background

Asthma and allergies prevalence increased in recent decades, being a serious global health problem. They are complex diseases with strong contextual influence, so that the use of advanced machine learning tools such as genetic programming could be important for the understanding the causal mechanisms explaining those conditions. Here, we applied a multiobjective grammar-based genetic programming (MGGP) to a dataset composed by 1047 subjects. The dataset contains information on the environmental, psychosocial, socioeconomics, nutritional and infectious factors collected from participating children. The objective of this work is to generate models that explain the occurrence of asthma, and two markers of allergy: presence of IgE antibody against common allergens, and skin prick test positivity for common allergens (SPT).

Results

The average of the accuracies of the models for asthma higher in MGGP than C4.5. IgE were higher in MGGP than in both, logistic regression and C4.5. MGGP had levels of accuracy similar to RF, but unlike RF, MGGP was able to generate models that were easy to interpret.

Conclusions

MGGP has shown that infections, psychosocial, nutritional, hygiene, and socioeconomic factors may be related in such an intricate way, that could be hardly detected using traditional regression based epidemiological techniques. The algorithm MGGP was implemented in c ++ and is available on repository: http://bitbucket.org/ciml-ufjf/ciml-lib.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2233-z) contains supplementary material, which is available to authorized users.

IL-33 gene variants and protein expression in pediatric Tunisian asthmatic patients

Interleukin-33 (IL-33) is one of the last discovered members of the human IL-1 family. It is involved in the pathogenesis of many inflammatory diseases. This study investigates the relationship between IL33 gene variants and serum protein levels with the development of childhood asthma. We analyzed in this case-control study the distribution of two IL33 polymorphisms, rs7044343 and rs1342326, within 200 Tunisian children, using predefined Taqman genotyping assays. IL-33 serum levels were assessed by commercial sandwich Enzyme-linked immunosorbent assay (ELISA). The presence of rs1342326 polymorphism was significantly associated with a lower risk of asthma development. The CC [OR=0.20, CI (0.08-0.50)] and AC [OR=0.24, CI (0.11-0.49)] genotypes, as well as the C-allele [OR=0.40; CI: 0.26-0.61, P=0.00001] were associated significantly with a decreased asthma risk. However, the C-allele was more frequent in severe asthma patients than in milder ones. No association was found between rs7044343 variant and asthma. The level of IL-33 in sera was significantly increased in asthmatic children [1.48±0.47pg/mL] compared to controls [0.70±0.18pg/mL; P<0.001]. Furthermore, this increase of IL-33 was associated with the presence of rs1342326 C allele. The IL33 rs1342326 polymorphism was associated with a lower childhood asthma risk in the Tunisian population and a higher IL-33 protein expression.

Polymorphisms in DENND1B gene are associated with asthma and atopy phenotypes in Brazilian children

Asthma is a heterogeneous disease associated with a complex basis involving environmental factors and individual variabilities. The DENN Domain Containing 1B (DENND1B) gene has an important role on T cell receptor (TCR) down-regulation on Th2 cells and studies have shown that mutations or loss of this factor can be associated with increased Th2 responses and asthma. The aim of this work is to evaluate the association of polymorphisms in the DENND1B with asthma and allergy markers phenotypes in Brazilian children. Genotyping was performed using a commercial panel from Illumina (2.5 Human Omni bead chip) in 1309 participants of SCAALA (Social Change, Asthma, Allergy in Latin American) program. Logistic regressions for asthma and atopy markers were performed using PLINK software 1.9. The analyzes were adjusted for sex, age, helminth infections and ancestry markers. The DENND1B gene was associated with different phenotypes such as severe asthma and atopic markers (specific IgE production, skin prick test and IL-13 production). Among the 166 SNPs analyzed, 72 were associated with asthma and/or allergy markers. In conclusion, polymorphisms in the DENND1B are significantly associated with development of asthma and atopy and these polymorphisms can influence DENND1B expression and consequently, asthma.

Effect of dietary consumption as a modifier on the association between FTO gene variants and excess body weight in children from an admixed population in Brazil: the Social Changes, Asthma and Allergy in Latin America (SCAALA) cohort study

Previous studies have shown associations of variants of the FTO gene with body weight, but none of these have involved Latin American populations with a high level of miscegenation, as is seen in the north-eastern Brazilian population. This study evaluated the association between SNP in the FTO gene and excess weight in Salvador, Bahia, Brazil. In addition, the effect of diet as a modifier on this association was also investigated. This cross-sectional study included 1191 participants aged 4-11 years, who were genotyped for 400 variants of the FTO gene. Direct anthropometric measures were made and dietary data were obtained by 24-h food recall. Multivariate logistic regression analyses were used to assess the associations of interest. Overall, 11·2 % of the individuals included in the study were overweight/obese. Interactions were identified between the percentage energy intake from proteins and obesity risk linked to the rs62048379 SNP (P interaction=0·01) and also between fat intake (PUFA:SFA ratio) and obesity risk linked to the rs62048379 SNP (P interaction=0·01). The T allele for the variant rs62048379 was positively associated with overweight/obesity in individuals whose percentage energy intake from protein was above the median (OR 2·00; 95 % CI 1·05, 3·82). The rs62048379 SNP was also associated with overweight/obesity in individuals whose PUFA:SFA ratio was below the median (OR 1·63; 95 % CI 1·05, 2·55). The association between FTO gene variants and excess body weight can be modulated by dietary characteristics, particularly by fatty acid distribution and dietary protein intake in children.

Suggestive association between variants in IL1RAPL and asthma symptoms in Latin American children

Several genome-wide association studies have been conducted to investigate the influence of genetic polymorphisms in the development of allergic diseases, but few of them have included the X chromosome. The aim of present study was to perform an X chromosome-wide association study (X-WAS) for asthma symptoms. The study included 1307 children of which 294 were asthma cases. DNA was genotyped using 2.5 HumanOmni Beadchip from Illumina. Statistical analyses were performed in PLINK 1.9, MACH 1.0 and Minimac2. The variant rs12007907 (g.29483892C>A) in IL1RAPL gene was suggestively associated with asthma symptoms in discovery set (odds ratio (OR)=0.49, 95% confidence interval (CI): 0.37-0.67; P=3.33 × 10^-6). This result was replicated in the ProAr cohort in men only (OR=0.45, 95% CI: 0.21-0.95; P=0.038). Furthermore, investigating the functional role of the rs12007907 on the production a Th2-type cytokine, IL-13, we found a negative association between the minor allele A with IL-13 production in the discovery set (P=0.044). Gene-based analysis revealed that NUDT10 was the most consistently associated with asthma symptoms in discovery sample. In conclusion, the rs12007907 variant in IL1RAPL gene was negatively associated with asthma and IL-13 production in our study and a sex-specific association was observed in one of the validation samples. It suggests an effect on asthma susceptibility and may explain differences in severe asthma frequency between women and men.

Admixture in Latin America

Latin Americans arguably represent the largest recently admixed populations in the world. This reflects a history of massive settlement by immigrants (mostly Europeans and Africans) and their variable admixture with Natives, starting in 1492. This process resulted in the population of Latin America showing an extensive genetic and phenotypic diversity. Here we review how genetic analyses are being applied to examine the demographic history of this population, including patterns of mating, population structure and ancestry. The admixture history of Latin America, and the resulting extensive diversity of the region, represents a natural experiment offering an advantageous setting for genetic association studies. We review how recent analyses in Latin Americans are contributing to elucidating the genetic architecture of human complex traits.

Prebiotics: Definition and protective mechanisms

The increase in chronic metabolic and immunologic disorders in the modern society is linked to major changes in the dietary patterns. These chronic conditions are associated with intestinal microbiota dysbiosis where important groups of carbohydrate fermenting, short-chain fatty acids-producing bacteria are reduced. Dietary prebiotics are defined as a selectively fermented ingredients that result in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health. Application of prebiotics may then restore the gut microbiota diversity and activity. Unlike the previously accepted prebiotics definition, where a limited number of bacterial species are involved in the prebiotic activity, new data from community-wide microbiome analysis demonstrated a broader affect of the prebiotics on the intestinal microbiota. These new findings require a revision of the current definition. In addition, prebiotics may exert immunomodulatory effects through microbiota-independent mechanisms that will require future investigations involving germ-free animal disease models.