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PubMed2002

Risk factors for onset and remission of atopy, wheeze, and airway hyperresponsiveness.

BACKGROUND: Although many children with asthma may have a remission as they grow and other children who did not have asthma may develop asthma in adult life, knowledge about the factors that influence the onset and prognosis of asthma during adolescence and young adulthood is very limited. METHODS: A cohort of 8-10 year old children (n=718) living in Belmont, New South Wales, Australia were surveyed six times at 2 yearly intervals from 1982 to 1992, and then again 5 years later in 1997. From this cohort, 498 subjects had between three and seven assessments and were included in the analysis. Atopy, airway hyperresponsiveness (AHR), and wheeze in the last 12 months were measured at each survey. Late onset, remission, and persistence were defined based on characteristics at the initial survey and the changes in characteristics at the follow up surveys. RESULTS: The proportion of subjects with late onset atopy (13.7%) and wheeze (12.4%) was greater than the proportion with remission of atopy (3.2%) and wheeze (5.6%). Having atopy at age 8-12 years (OR 2.8, 95% CI 1.5 to 5.1) and having a parental history of asthma (OR 2.0, 95% CI 1.02 to 4.13) were significant risk factors for the onset of wheeze. Having AHR at age 8-12 years was a significant risk factor for the persistence of wheeze (OR 4.3, 95% CI 1.3 to 15.0). Female sex (OR 1.9, 95% CI 1.01 to 3.60) was a significant risk factor for late onset AHR whereas male sex (OR 1.9, 95% CI 1.1 to 2.8) was a significant risk factor for late onset atopy. CONCLUSIONS: The onset of AHR is uncommon during adolescence, but the risk of acquiring atopy and recent wheeze for the first time continues during this period. Atopy, particularly present at the age of 8-10 years, predicts the subsequent onset of wheeze.

Age of Onset↗
PubMed1997

Absence of genetic linkage of chromosome 5q31 with asthma and atopy in the general population.

BACKGROUND: Clinical asthma is associated with increased serum total immunoglobulin E (IgE), atopy (skin prick test positivity to common aeroallergens), and bronchial hyperreactivity (BHR) to non-specific stimuli (positive methacholine challenge test). A region on chromosome 5q31-33 has been linked with increased total serum IgE and BHR. A study of the genetic linkage of this region with clinical asthma and atopy was therefore undertaken. METHODS: A polymorphic microsatellite marker in chromosome 5q31 (D5S399) was studied in 119 sibling pairs recruited from the general population who shared asthma, atopy, and/or BHR. Based on our population distribution of 13 different alleles, it was expected that by chance alone sibling pairs would share on average 1.24 alleles and that a significant excess would indicate genetic linkage. RESULTS: No evidence of linkage was found in 45 siblings concordant for asthma (shared alleles = 1.09, p = 0.95), in 103 sibling pairs with atopy (shared alleles = 1.18, p = 0.82), in 51 sibling pairs with BHR (shared alleles = 1.22, p = 0.62), or in 68 sibling pairs who shared atopy in the absence of BHR (shared alleles = 1.22, p = 0.61). A slight non-significant excess of shared alleles (1.44, p = 0.11) was observed in siblings who shared BHR without atopy. CONCLUSIONS: No evidence of genetic linkage of chromosome 5q31 with either clinical asthma or atopy was therefore detected in the population studied. Linkage between chromosome 5q and BHR needs further investigation.

Adult↗
PubMed2000

[Natural history of atopy].

Atopy is defined by an individual propensity to develop IgE-dependent reactions against environmental allergens. It could be now defined by a propensity to develop a Th2 response against such allergens, which takes into account not only the IgE production but also the eosinophil activation and the pivotal role of T lymphocytes in this process. A number of factors are determinants of atopy: some of them precede birth, such as genetic factors and some peculiarities of the immune system during pregnancy, in relation to maternal atopy, to in utero allergen exposure or to pregnancy itself. After birth, car pollution could modify the response to allergens by enhancing the IgE production. Food habits, by favoring intake of omega-6 polyunsaturated fat acids contained in some vegetal fat instead of omega-3 polyunsaturated acids from fish, could facilitate IgE dependent sensitization. Viral infections could, depending on their nature and their circumstances of occurrence protect from atopy inversely induce some sensitizations. Finally the degree of exposure to allergens themselves is proportional to the probability of sensitization. Together, these determinants of atopy could account for the higher prevalence of atopy in developed countries. The clinical expression of atopy varies during life from atopic dermatitis to rhinitis and asthma. Infancy is the time for dermatitis and sensitization to food allergens. Sensitization to airborne allergens occurs thereafter. Asthma, sometimes introduced by one or several bronchiolitis episodes follows to dermatitis or can be associated to it. Rhinitis appears in children or young adults. Seasonal, it is due to pollens and is rarely associated with asthma. In contrast, perennial, it is due to indoor allergens and leads to bronchial hyperreactivity and asthma.

Adult↗
PubMed1998

[European study of asthma. Prevalence of atopy in young adults of 5 areas in Spain. Spanish Group of European Asthma Study].

BACKGROUND: The aim of the current study is to show the prevalence of atopy in five Spanish areas, and its variability according to area, age and gender. PATIENTS AND METHODS: From a populational based sample of 16,884 individuals aged 20 to 44 years-old, we obtained a randomized 20% subsample (n = 3,310). Participants performed specific IgE measurements, skin prick tests, forced spirometries and metacholine challenges to measure bronchial hyperresponsiveness. The response rate was 40%, and 1,313 individuals were finally included in the study. Specific atopy to the following aeroallargens was determined: cat dander, Cladosporium, Dermatophagoides, Phleum, Parietaria, birch, Alternaria, ambrosia, olive, rye grass and dog dander. RESULTS: The global prevalence of atopy (detectable specific antibodies IgE in serum and/or skin reactivity) widely varied by area, skin reactivity ranking in males from a minimum in Albacete (24.6%; 95% CI: 18-33) to a maximum in Huelva (39.6%; 95% CI: 30-53), and in females ranking from a minimun in Galdakao (10.3%; 95% CI: 6-17) to a maximum in Barcelona (28.8%; 95% CI: 19-43). Considering separately seropositivity and skin reactivity we observed a similar trend. Males showed a higher prevalence of global atopy (40.1%) than females (29.4%). Our data indicate that there is a decrease in the prevalence of atopy according to age in the general population, but only significant in men. Dermatophagoides pteronyssinus is the most common allergen in all ares but Albacete, where the most common allergen is the olive pollen. CONCLUSIONS: By means of a standard methodology, we report population data of the prevalence of atopy in five Spanish areas. The distribution of the prevalence of atopy varies widely in the five areas surveyed, according to the composition of the most common environmental allergens.

Adult↗
PubMed2001

Triangle test statistic in discordant sib pairs: test of genetic heterogeneity of asthma and atopy in CSGA families.

The purpose of our study was to detect genetic heterogeneity (i.e., different genotype relative risks of genetic factor) between atopic and non-atopic asthma and between atopy associated or independent of asthma. Genetic heterogeneity was tested in the Caucasian Collaborative Study on the Genetics of Asthma families using the TTS (triangle test statistic) and the predivided sample test. The TTS was proposed to detect both linkage and intra-sib-pair genetic heterogeneity; such heterogeneity may exist if the sibs differ for a factor on which the penetrances of the putative linked gene depend. The TTS has been applied to asthmatic pairs discordant for atopy and atopic sib pairs discordant for asthma. To confirm genetic heterogeneity detected by the TTS, the predivided sample test was also applied among concordant and discordant sib pairs. The analyses detected a genetic factor on chromosome 8p that could be involved in atopy with different genotype relative risks according to whether asthma is present. This would suggest a pleiotropic effect of this genetic factor in asthma and atopy. Two other regions located on chromosomes 8q and 20p were detected for genetic heterogeneity with asthma and atopy, respectively, but the factor of heterogeneity could be independent from the presence of atopy or asthma, respectively. It could be a characteristic of the disease such as the severity or the presence of an environmental factor.

Adult↗
PubMed1989

The relationships between atopy, bronchial hyperresponsiveness, and a family history of asthma: a cross-sectional study of migrant Tokelauan children in New Zealand.

We have examined age-related changes in the association between nonspecific bronchial hyperresponsiveness (BHR) and atopy in 494 second-generation Polynesian migrant children, aged 5 to 15 years. BHR (provocative dose of methacholine, less than or equal to 7.8 mumol, causing a 20% fall in FEV1) was present in 125 children (25.3%). Atopy (skin wheal, greater than or equal to 4 mm diameter) was present in 157 children (32%). BHR associated with atopy demonstrated a constant age-related frequency in the 7- to 15-year-old children that was influenced by a family history (FH) of asthma (FH, 50%; no FH, 34%; p = 0.051). BHR not associated with atopy demonstrated a marked decreasing frequency with age from 25% in 5- to 7-year-old children to 3% in 13- to 15-year-old children and was uninfluenced by an FH of asthma. We conclude that the differences in the frequency of BHR with age, together with the genetic influence on BHR associated with atopy, compared with the findings in nonatopic children, indicate distinct heterogeneity in the pathogenesis of BHR in these Tokelauan children. These differences may be important for understanding the relationships between nonspecific BHR, atopy, and asthma in children.

Adolescent↗
PubMed1992

Genetic analysis using DNA polymorphism of the linkage between chromosome 11q13 and atopy and bronchial hyperresponsiveness to methacholine.

Previous studies have suggested that there is a genetic predisposition for the development of asthma and atopy. A recent study has also demonstrated that there is a striking link between chromosome 11q and the IgE response underlying asthma and rhinitis. To assess the linkage between chromosome 11q (region D11S97) and atopy or bronchial hyperresponsiveness (BH), we have studied nine families of two and, in many instances, three generations with the index case having asthma and/or atopy. With variable number of tandem repeat analysis with the probe, p lambda-MS.51, we have been unable to confirm a significant link between region D11S97 of chromosome 11q and either atopy or BH to methacholine. We have demonstrated that atopy and BH produce similar log of odds scores with linkage analysis at each recombination fraction from 0.001 to 0.5 with both Hinf1 and Taq1 restriction digests and that the use of either a positive skin prick test or positive RAST as a definition of atopy does not significantly alter the log of odds score.

Adolescent↗
PubMed1993

Localisation of atopy and beta subunit of high-affinity IgE receptor (Fc epsilon RI) on chromosome 11q.

Atopy, a common familial syndrome underlying allergic asthma and rhinitis, is characterised by sustained immunoglobulin E (IgE) responses to common allergens. We have previously shown genetic linkage of atopy to the chromosome 11q13 marker D11S97 (pms51) through maternally derived alleles, but no likely candidate genes were known to lie near this marker. We have analysed maternally derived alleles from 155 sibling-pairs affected by atopy to seek evidence of linkage between the gene predisposing to atopy and other markers on chromosome 11q13. We found that the beta subunit of the high-affinity receptor for IgE (Fc epsilon RI-beta) also lies on chromosome 11q13, and that it is in close genetic linkage with the gene for atopy. The known roles of Fc epsilon RI in antigen-induced mast-cell degranulation and in the release of cytokines that enhance IgE production make the gene for its beta subunit a candidate for the chromosome 11 atopy locus.

Chromosome Mapping↗
PubMed2004

Geographic variations in the effect of atopy on asthma in the European Community Respiratory Health Study.

BACKGROUND: Atopy has long been related to asthma. The prevalences of both atopy and asthma have shown substantial variation. OBJECTIVE: We sought to assess geographic variations in the fraction of asthma attributable to IgE sensitization to specific allergens in the European Community Respiratory Health Survey. METHODS: A cross-sectional study was undertaken during the years 1991 and 1992 on 13,558 individuals in 36 centers in 16 countries. Asthma was defined in several ways, variously incorporating reported symptoms, bronchial responsiveness to methacholine, and physician diagnosis. Specific IgE against house dust mite (Dermatophagoides pteronyssinus), cat, timothy grass, Cladosporium herbarum , and a local allergen (birch, Parietaria judaica , or ragweed) were measured. RESULTS: The overall attributable fraction (AF) of asthma symptoms caused by atopy was 30% but varied widely between centers, ranging from 4% to 61%. The overall AF increased to 43% when asthma was based on wheezing and bronchial responsiveness, to 45% with a physician diagnosis of asthma, and to 48% when the patient reported more than 12 attacks in the last year. Between centers, the AF for atopy was significantly correlated with the prevalence of atopy among the asthmatic patients ( r = 0.91) and with the sensitization to house dust mite ( r = 0.64), as well as with the prevalence of asthma among atopic individuals ( r = 0.43) and the prevalence of asthma among nonatopic individuals ( r = -0.51). CONCLUSION: The effect of atopy on the prevalence of asthma varies widely between centers, probably because of variations in factors related to the expression of asthma and to the prevalence of sensitization, particularly to house dust mite.

Allergens↗
PubMed2005

Antibiotic exposure in early infancy and risk for childhood atopy.

BACKGROUND: The increase in pediatric allergy and asthma parallels the increase in use of antibiotics. Antibiotics disturb the flora of the gastrointestinal tract, possibly perturbing the developing immune system. OBJECTIVE: We evaluated whether antibiotic use during early infancy increased the risk for atopy. METHODS: Antibiotic prescriptions documented in medical records were collected from a birth cohort born from 1987 through 1989 (n = 725). At 6 to 7 years of age, 448 were followed by means of examination, including skin prick tests and serum IgE measurements to common allergens. RESULTS: Adjusted odds ratios (aORs) and 95% CIs were calculated comparing children with any versus those with no antibiotic use in the first 6 months and the outcomes of atopy (any positive skin test response), seroatopy (any positive specific IgE test result), either atopy or seroatopy, and both atopy and seroatopy. Atopy increased with antibiotic use approaching statistical significance (aOR, 1.48; 95% CI, 0.94-2.34; P = .09); however, the risk was concentrated among children with less than 2 pets in the home (aOR, 1.73; 95% CI, 1.07-2.80; P = .024) and children breast-fed for 4 or more months (aOR, 3.02; 95% CI, 1.27-7.17; P = .013). The aORs were generally in the same direction for seroatopy and the combined categories. CONCLUSION: Antibiotic use in early life appears to contribute to increased risk for atopy in certain subgroups of children.

Animals↗
PubMed2000

[Factors associated with the development of atopy in young adults].

BACKGROUND: To determine the risk factors for the development of atopy in Spanish young adults. SUBJECTS AND METHODS: Case-control study over prevalent cases. Carried out in general population between the ages of 20 to 44 years old. Spanish participants of the ECRHS, a random representative sample of Spanish young adults (n = 16,884), and a 20% randomised subsample made by those who answered to a short respiratory questionnaire and had atopy assessed, was studied. Atopy was defined as having serum specific IgE positivity to the following aeroallergnes: cat dander, Cladosporium herbarum, Dermatophagoides pteronyssinus, Parietaria judaica and Phleum pratense. RESULTS: Several factors had a statistically significant effect. In addition to male gender and lower age, maternal allergy (OR = 1.63; 95% CI = 1.11-2.40), having allergic siblings (OR = 1.40; 95% CI = 1.06-1.90) and a higher educational level (OR = 1.69; 95% CI = 1.22-2.34) were associated with the presence of high levels of specific IgE in our sample. Moreover, having had older siblings, especially older brothers appears to be a protective factor to the development of atopy but not in a statistically significant way, while having had pet birds during childhood appears to enhance the risk. CONCLUSIONS: In addition to the familial variables that indicates both environmental and genetic factors, educational level seems to have low degree of association with atopy; this feature shows that variables related with life style are involved in atopy development.

Adult↗
PubMed1999

Atopy in children of families with an anthroposophic lifestyle.

BACKGROUND: Increased prevalence of atopic disorders in children may be associated with changes in types of childhood infections, vaccination programmes, and intestinal microflora. People who follow an anthroposophic way of life use antibiotics restrictively, have few vaccinations, and their diet usually contains live lactobacilli, which may affect the intestinal microflora. We aimed to study the prevalence of atopy in children from anthroposophic families and the influence of an anthroposophic lifestyle on atopy prevalence. METHODS: In a cross-sectional study, 295 children aged 5-13 years at two anthroposophic (Steiner) schools near Stockholm, Sweden, were compared with 380 children of the same age at two neighbouring schools in terms of history of atopic and infectious diseases, use of antibiotics and vaccinations, and social and environmental variables. Skin-prick tests were done for 13 common allergens, and we took blood samples from children and their parents for analysis of allergen-specific serum IgE-antibodies. FINDINGS: At the Steiner schools, 52% of the children had had antibiotics in the past, compared with 90% in the control schools. 18% and 93% of children, respectively, had had combined immunisation against measles, mumps, and rubella, and 61% of the children at the Steiner schools had had measles. Fermented vegetables, containing live lactobacilli, were consumed by 63% of the children at Steiner schools, compared with 4.5% at the control schools. Skin-prick tests and blood tests showed that the children from Steiner schools had lower prevalence of atopy than controls (odds ratio 0.62 [95% CI 0.43-0.91]). There was an inverse relation between the number of characteristic features of an anthroposophic lifestyle and risk of atopy (p for trend=0.01). INTERPRETATION: Prevalence of atopy is lower in children from anthroposophic families than in children from other families. Lifestyle factors associated with anthroposophy may lessen the risk of atopy in childhood.

Adolescent↗
PubMed1993

Atypical ocular atopy.

BACKGROUND: Atopic keratoconjunctivitis (AKC) is defined as a chronic keratoconjunctivitis associated with atopic dermatitis, but severe progressive keratoconjunctivitis as a sole manifestation of atopy also may occur. The authors report three patients with a longstanding history of chronic conjunctivitis with bilateral pannus formation. These patients denied any history of major atopy at the time of presentation. METHODS: All patients were evaluated for collagen vascular disease and for evidence of atopy. Conjunctival biopsy was obtained in each case and was analyzed by light microscopy and by immunohistochemical techniques. RESULTS: Systemic evaluation for collagen vascular disease was negative. Serum IgE levels were elevated in one patient. Conjunctival biopsy suggested atopy in all patients with characteristic histopathologic findings. Referral to an allergist showed wheal and flare reactions to multiple ubiquitous environmental allergens. Two patients then disclosed a history of atopic dermatitis and another confessed a history of asthma. Each patient responded well to environmental control of allergens, topical cromolyn sodium 4%, and systemic antihistamine therapy with subsequent resolution of the chronic conjunctivitis. The corneal complications were managed with pannus resection and postoperative mitomycin C drops in two patients. CONCLUSION: These patients suffered from the progressive blinding consequences of a chronic keratoconjunctivitis, which we believe is an atypical form of AKC. In this report, it is suggested that atopy should be considered in some cases of external ocular inflammation, even in the absence of the characteristic findings of systemic atopy. Conjunctival biopsy is a valuable diagnostic tool in such cases.

Adult↗
PubMedDate not supplied

Genetic variants of FcepsilonRIbeta and Il-4 and atopy in a Polish population.

BACKGROUND: Atopy results from the interaction between genetic and environmental factors. The aim of our study was to clarify the association between the FcRIint2 polymorphic variant, the Glu237Gly mutation in exon 7 of FcepsilonRIbeta and (-590 C/T) Il-4 gene promoter polymorphism with atopy in a randomized Polish sample. SUBJECTS AND METHODS: Unrelated subjects aged 18-45 years who were residents of an urban area (Lodz, Poland) were included in the study: 98 patients with asthma and/or allergic rhinitis, and 87 non-atopic, non-asthmatic controls. We used common criteria for atopy and asthma. Atopic status was determined by positive skin prick tests (SPT) and IgE levels. The severity of asthma was assessed in spirometric measurements; SPTs to house dust mite (HDM) and mixed grass pollen (MGP) were performed. Total and specific IgE were measured in each subject. Genotypic analysis was performed by PCR for FcRIint2 and (590 C/T) Il-4 gene promoter polymorphism and ARMS-PCR was performed for the Glu237Gly mutation. RESULTS: We found a statistically significant association between atopy and FcRIint2 variant polymorphism (OR = 2.96), a correlation between positive skin prick tests to MGP and raised MGP-specific IgE concentrations in patients bearing this variant (OR = 4.0). We did not observe that the FcRIint2 variant was associated with positive SPTs to HDM or high levels of HDM-specific IgE (OR = 1.0). The intronic variant of FcepsilonRIbeta was strongly correlated with elevated total serum IgE (OR = 4.74). No statistically significant association was found between atopy and the Glu237Gly mutation of FcepsilonRIbeta(OR = 1.36) or (-590 C/T) Il-4 gene promoter polymorphism (OR = 0.88). CONCLUSIONS: The results suggest that FcRIint2 polymorphism is related to atopy and may influence its development.

Adolescent↗
PubMed2000

Predictors of atopy in HIV-infected patients.

BACKGROUND: Some studies have reported an increase of atopy in HIV-infected (HIV+) patients, but the cause still remains unclear. OBJECTIVE: To determine the prevalence of atopy in HIV+ patients and to investigate its predictors. METHODS: Seventy-four HIV+ hospitalized patients (46 of them with AIDS) were studied prospectively for the presence of atopy, based on immediate hypersensitivity to common allergens by prick test. Serum immunoglobulins, specific IgE, lymphocyte subsets, and the expression of low affinity IgE receptor (CD23) on B cells were determined. RESULTS: Thirty-one percent of patients presented IgE values greater than 150 ku/L (39% of patients without AIDS and 26% of AIDS patients; P = .23) and 47% showed an increase (> or = 2%) in the percentage of CD23+ B cells. Non-AIDS patients had higher IgE values than AIDS patients (346 +/- 605 versus 175 +/- 276; P = .16). Atopy prevalence was higher in non-AIDS than in AIDS patients (28% versus 11%; P = .06). Specific IgE agreed with positive prick test in 58% of cases. Multivariate analysis showed that a personal history suggestive of allergic disease and IgE > 150 ku/L were predictors of atopy, while gender, risk group, CD4+ T cells, CD23 expression on B cells, and AIDS were not associated. CONCLUSIONS: HIV+ patients present a higher prevalence of atopy in early stages of HIV infection than general population. Since allergic reactions could accelerate HIV-infection by increasing type 2 cytokines, it is important to evaluate the atopic state in HIV+ patients with IgE > 150 ku/L or with suggestive allergic history in order to prevent it.

Adult↗
PubMed2001

Genetic susceptibility to asthma and atopy among Chinese in Singapore--linkage to markers on chromosome 5q31-33.

BACKGROUND: Asthma and atopy are complex genetic traits, influenced by the interaction of multiple genes and environmental factors. Linkage of these traits to chromosome 5q31-33 has been shown in other populations, but has not been well studied in the Chinese. We studied linkage between asthma and atopy with markers on chromosome 5q31-33 in the Singapore Chinese. This region contains many candidate genes, including the cytokine gene cluster. METHODS: We recruited 88 Chinese families with at least two affected offspring, totaling 373 subjects, with 125 and 119 sib-pairs for atopy and asthma, respectively. All individuals were genotyped with 19 polymorphic microsatellite markers spanning a distance of 41 cM along chromosome 5q31-33. Affected sib-pair and multipoint linkage analysis was performed. RESULTS: There was evidence for linkage of the asthma and atopy phenotypes with three markers, D5S2110, D5S2011, and D5S412 (P values of 0.001 to 0.00001). Multipoint analysis further substantiated this (nonparametric linkage scores of 1.8-2.9). These findings suggest that susceptibility genes for asthma and atopy are found in this region in the Chinese. CONCLUSION: This study has shown linkage of atopy and asthma to chromosome 5q31-33 in a heterogeneous Chinese population. These findings further substantiate the notion that chromosome 5q31-33 contains "universally" important susceptibility genes for these traits.

Adolescent↗
PubMed2002

Atopy in children in relation to BCG vaccination and genetic polymorphisms at SLC11A1 (formerly NRAMP1) and D2S1471.

The influence of the SLC11A1 (formerly NRAMP1) gene on the association between BCG vaccination and atopy in children was studied in 179 children, BCG vaccinated in infancy, and 307 children without BCG vaccination, all 3 to 8 years of age and with atopic heredity. DNAs were genotyped for a functional repeat polymorphism (designated GTn) in the promoter of SLC11A1 and a linked microsatellite D2S1471. Associations between genotype, atopic symptoms and allergen-specific IgE-antibodies in relation to the BCG status of the children were assessed. Atopy in relation to SLC11A1 GTn-alleles was similarly distributed between the two groups. In BCG vaccinated children, genotype associations were observed for D2S1471 and atopy, with carriage of allele 5 conferring increased risk of atopy (odds ratio (OR) 2.6; 95% confidence interval (CI) 1.3-5.5; P = 0.01), and particularly IgE responses to airborne allergens (OR = 4.3; 95% CI 1.7-10.7; P = 0.002). No linkage disequilibrium was found between the SLC11A1 GTn repeat and the microsatellite D2S1471, and therefore no haplotype associations were observed for atopy in BCG- or non-BCG vaccinated children. Stratification by BCG vaccination unmasked a potential genetic risk factor for atopy in the region of the SLC11A1 locus, and point to the importance of genotype by environment interactions in determining disease susceptibility.

BCG Vaccine↗
PubMed2004

Determinants of atopic sensitization in Turkish school children: effects of pre- and post-natal events and maternal atopy.

Emergence of new environmental risk factors, and/or loss of protective factors of a traditional lifestyle may explain the increase, or variations in prevalence of allergic diseases. The aim of this study was to delineate the prevalence and spectrum of, and to reveal the causal and/or protective factors for atopic sensitization among a heterogeneous cohort of Turkish children, for the first time in our country. The study design adhered to International Study of Asthma and Allergies in Childhood (ISAAC) phase II protocol. A self-administered parental questionnaire about demographic characteristics and detailed risk factors, and skin-prick test with 13 allergens were employed in a clustered random sample of 8-11-yr-old Turkish school children. Atopy was defined as the presence of at least one positive skin reaction to any allergen tested. The association between a total of 78 risk factors and different aspects of atopy were analyzed in 1144 children with multivariate logistic regression analysis. The overall prevalence of atopy was 20.6%. Most common sensitizations were to grass pollens, Dermatophagoides pteronyssinus and Blatella germanica. Day care attendance, high paternal education level, male gender and maternal asthma were significant risk factors for atopy. Breastfeeding more than 6 months (compared with 0-6 months), maternal smoking during pregnancy and a birth weight under 2500 g were inversely related to (or protective factors for) atopic sensitization. Maternal atopic disease had significant effects on risk factors pattern. In children with a maternal atopy history a low birth weight, day care attendance and maternal smoking during the first year of life independently increased the risk of atopic sensitization. Gender, breastfeeding and paternal education did not show any association with atopy in this group of children. A history of measles and low gestational age were significant protective factors for mite sensitization. This study showed that children of atopic mothers showed a different profile of risk factors associated with atopic sensitization, when compared with other children. Prenatal and early childhood events had important associations with atopic sensitization.

Case-Control Studies↗