Cockroach is a major cross-reactive allergen source in shrimp-sensitized rural children in southern China.

BACKGROUND: Little is known about the prevalence of food allergy (FA) in China. The aim of this study was to investigate the disparity of FA between urban and rural areas in southern China. METHODS: EuroPrevall questionnaire responses were obtained from 5542 school-age children in urban Guangzhou and 5319 in rural Shaoguan. A case-control study enrolled 190 children with adverse reactions (ARs) after food intake as cases and 212 controls in Guangzhou, whereas 116 cases and 233 controls in Shaoguan. These subjects underwent skin prick test (SPT) and serum IgE measurements to food and inhalant allergens. Allergen extracts from shrimp, house dust mite (HDM), and cockroach were prepared for IgE cross-reactivity testing in 23 Guangzhou and 20 Shaoguan shrimp-sensitized subjects. RESULTS: The prevalence of ARs to shrimp was higher in Guangzhou than in Shaoguan children (3.5% vs 1.4%, P < .001). However, sensitization rate to shrimp (SPT: 3.7% vs 11.2%, P = .015; IgE: 12.6% vs 36.2%, P < .001) and cockroach (SPT: 5.3% vs 33.5%; IgE: 2.6% vs 27.6%, P < .001) was lower in Guangzhou. A significant correlation between shrimp and HDM/cockroach IgE was found in Shaoguan children. The proportions of positive IgE to tropomyosin (Pen a 1, Der p 10) were lower than 7.4% in both areas. Cockroach allergen has a significantly higher inhibition rate of binding to IgE to house dust mite allergens in Shaoguan sera. CONCLUSION: Shrimp is a common allergic food in southern China. Higher proportion of shrimp sensitization in rural subjects could be explained by cross-reactivity to cockroach. Tropomyosin was not a major allergen responding to the cross-reactivity.

Prevalence of vitamin D insufficiency among adolescents and its correlation with bone parameters using high-resolution peripheral quantitative computed tomography.

UNLABELLED: Vitamin D deficiency and insufficiency are highly prevalent among adolescents in Hong Kong, which is a sub-tropical city with ample sunshine. Vitamin D level is significantly correlated with key bone density and bone quality parameters. Further interventional studies are warranted to define the role of vitamin D supplementation for improvement of bone health among adolescents. INTRODUCTION: The relationship between bone quality parameters and vitamin D (Vit-D) status remains undefined among adolescents. The aims of this study were to evaluate Vit-D status and its association with both bone density and bone quality parameters among adolescents. METHODS: Three hundred thirty-three girls and 230 boys (12-16 years old) with normal health were recruited in summer and winter separately from local schools. Serum 25(OH) Vit-D level, bone density and quality parameters by Dual Energy X-ray Absorptiometry (DXA) and High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT), dietary calcium intake, and physical activity level were assessed. RESULTS: Sixty-four point seven percent and 11.4 % of subjects were insufficient [25 ≤ 25(OH)Vit-D ≤ 50 nmol/L] and deficient [25(OH)Vit-D < 25 nmol/L] in Vit-D, respectively. The mean level of serum 25(OH)Vit-D in summer was significantly higher than that in winter (44.7 ± 13.6 and 35.9 ± 12.6 nmol/L, respectively) without obvious gender difference. In girls, areal bone mineral density (aBMD) and bone mineral content (BMC) of bilateral femoral necks, cortical area, cortical thickness, total volumetric bone mineral density (vBMD), and trabecular thickness were significantly correlated with 25(OH)Vit-D levels. In boys, aBMD of bilateral femoral necks, BMC of the dominant femoral neck, cortical area, cortical thickness, total vBMD, trabecular vBMD, BV/TV, and trabecular separation were significantly correlated with 25(OH)Vit-D levels. CONCLUSION: Vit-D insufficiency was highly prevalent among adolescents in Hong Kong with significant correlation between Vit-D levels and key bone density and bone quality parameters being detected in this study. Given that this is a cross-sectional study and causality relationship cannot be inferred, further interventional studies investigating the role of Vit-D supplementation on improving bone health among adolescents are warranted.

Frequency of food group consumption and risk of allergic disease and sensitization in schoolchildren in urban and rural China.

BACKGROUND: Diet is a potential determinant of allergic diseases. OBJECTIVE: To examine in schoolchildren the association between food intake and allergic diseases and determine whether there is effect of environment - rural vs. urban. METHODS: A questionnaire survey was performed in 11 473 children aged 7-12 years in 20 schools from urban Guangzhou and rural Shaoguan, China. A nested case-control group, 402 from Guangzhou and 349 from Shaoguan, was recruited. Food ingestion frequency data were collected. Serum-specific IgE to 34 food and airborne allergens was determined. Associations between food ingestion frequency and clinical outcomes were sought by logistic analyses. RESULTS: The prevalence of self-reported asthma (6.6% vs. 2.5%), rhinitis (23.2% vs. 5.3%) and eczema (34.1% vs. 25.9%) was significantly higher in Guangzhou subjects compared to Shaoguan, whereas prevalence of food hypersensitivity (9.7% vs. 9.2%) and food allergy (4.0% vs. 3.5%) was not significantly different. In this case-control study, seafood and fruits were two major food groups causing food hypersensitivity. Urban children consumed more milk, egg, chocolate, fruits, vegetable and cereals compared to rural children. Significantly higher percentage of Guangzhou children was sensitized to egg and milk, whereas more Shaoguan children were sensitized to seafood, nuts and seeds, fruit, vegetables, legumes and cereals. High consumption of milk (OR 2.604, 95 CI% 1.569-4.322, P < 0.001) and vegetables (OR 0.382, 95% CI 0.180-0.809, P = 0.012) were positively and reversely associated with asthma, respectively. CONCLUSION: Difference in prevalence of asthma but not food allergy was observed. Diets of schoolchildren are affected by disease-related modification and country's urbanization. High vegetable intake and low milk intake might protect against asthma.

House dust mite sensitization is the main risk factor for the increase in prevalence of wheeze in 13- to 14-year-old schoolchildren in Guangzhou city, China.

BACKGROUND: Little is known about time trend of prevalence of asthma and the association between the changing prevalence and allergen sensitization in Chinese children. OBJECTIVE: To determine the changes in prevalence of asthma and allergen sensitization in schoolchildren over a period of 15 years. METHODS: A total of 6928 schoolchildren aged 13-14 years in 2009 were recruited for the study using the Phase III Protocol of the International Study of Asthma and Allergic disease in Childhood (ISAAC) and 2531 of them underwent skin prick test for seven common aeroallergens. The results were compared with those obtained in the Phase I (1994/95) and III (2001/02) ISAAC studies. RESULTS: The prevalence of asthma ever and current wheeze increased from 3.9% and 3.4% in 1994, to 4.6% and 4.8% in 2001 (P<0.001), and to 6.9% and 6.1% in 2009 (P ≤ 0.008). The prevalence of higher degree of skin response to house dust mites (HDMs) and cat, and atopic index increased significantly in all children in 2010 when compared with those in 2002 (P<0.001). Prevalence of wheeze remained unchanged in subjects without sensitization to any tested allergen including HDMs (P > 0.05). Sensitization to HDMs, especially Dermatophagoides Pteronyssinus was associated with increase in prevalence of wheeze. CONCLUSION: The prevalence of wheeze and sensitization to common aeroallergens in secondary schoolchildren in Guangzhou China has increased significantly since 1994. Sensitization to HDMs is an important risk factor associated with the increase in prevalence of wheeze in this group of population in Guangzhou city.

Pediatric asthma control in Asia: phase 2 of the Asthma Insights and Reality in Asia-Pacific (AIRIAP 2) survey.

BACKGROUND: We conducted Phase 2 of the Asthma Insights and Reality in the Asia-Pacific (AIRIAP 2) survey in 2006 to determine the level of asthma control in this region and the validity of the Asthma Control Test (ACT) and childhood ACT (C-ACT) in relation to asthma control. METHODS: Pediatric participants (0 to <16 years; N = 988) with diagnosed asthma and current asthma symptoms or taking anti-asthma medications were recruited from 12 geographic areas in Asia. The survey consisted of the AIRIAP 2 questionnaire (asthma symptoms, use of urgent healthcare services and anti-asthma medication) and the ACT or C-ACT (English or Chinese translations only), both administered in the participant's preferred language. A symptom control index based on the Global Initiative for Asthma criteria (except lung function) was used to classify asthma control status. RESULTS: Most participants had inadequately controlled asthma ('uncontrolled' = 53.4%, 528/988; 'partly controlled' = 44.0%, 435/988). Only 2.5% (25/988) had 'controlled' asthma. Demand for urgent healthcare services (51.7%, 511/988) and use of short-acting beta-agonists (55.2%, 545/988) was high. The optimal ACT and C-ACT cutoff score for detecting uncontrolled asthma (compared with controlled or partly controlled asthma) was determined to be ≤19 (receiver operating characteristic analysis) with good agreement between the ACT and C-ACT and the symptom control index. CONCLUSIONS: Findings from this survey show that asthma control is suboptimal in many children in the Asia-Pacific region. Practical tools, such as the ACT or C-ACT, may help clinicians assess asthma control and facilitate adjustment of asthma medication.

Spirometric reference standards for preschool children in Hong Kong.

1. Prediction equations and normograms are established using incentive spirometry in a community cohort of 770 Hong Kong Chinese children aged 2 to 6 years. 2. All spirometric parameters depend mainly on standing height. Boys have higher values than girls. 3. Forced expiratory volumes depend on birth weight, place of birth, history of wheezing, and environmental tobacco smoke (ETS) exposure. 4. High urinary cotinine level as a biomarker of ETS exposure is noted in about one tenth of the children. 5. Urinary cotinine level is inversely associated with all spirometric parameters. This supports implementation of the smoking cessation programme.

Respiratory viruses and atypical bacteria triggering severe asthma exacerbation in children.

1. Respiratory viruses and atypical bacteria were detected in 51.0% of Hong Kong children with asthma exacerbations, which was significantly higher than the detection rate of 27.3% in children with chronic stable asthma. 2. Co-infections of two or more respiratory pathogens were more commonly found in children with asthma exacerbations (10.7%) than in patients with stable asthma (2.6%). 3. Human rhinovirus infection was a significant risk factor for asthma exacerbations. 4. There was no significant association between the severity of asthma exacerbations and respiratory viral or atypical bacterial infections. 5. Routine use of macrolide antibiotics in the treatment of childhood asthma exacerbations should be discouraged.

Circulating LL-37 is a biomarker for eczema severity in children.

BACKGROUND: Eczema lesions are characterized by impaired expression of antimicrobial peptides such as cathelicidin, which play crucial roles in the innate immune defence against cutaneous infections. LL-37 corresponds to amino acids 134-170 of human cathelicidin and is a multifunctional host defence molecule essential for normal immune responses to infection and tissue injury. OBJECTIVES: The aim of this study was to investigate the relationship between childhood eczema and circulating LL-37 levels. METHODS: One hundred and forty-four eczema children and 36 controls were recruited. Eczema severity was assessed by SCORing Atopic Dermatitis (SCORAD) and serum LL-37 concentration measured using enzyme immunoassay. Patients' skin hydration and transepidermal water loss at forearms were measured using Corneometer and Tewameter. RESULTS: Patients' mean SCORAD was 49.2 and their disease was classified as mild (n=28; 12.8%), moderate (n=95; 43.6%) and severe (n=95; 43.6%). Serum LL-37 concentrations did not differ between eczema patients and controls (mean: 832 pg/mL vs. 952 pg/mL, P=0.471). However, serum LL-37 concentrations increased with increasing eczema severity among the patients (P=0.005 for trend). This biomarker shows weakly positive correlation with patients' objective SCORAD (r=0.207, P=0.013) and age (r=0.170, P=0.041), but not skin hydration or transepidermal water loss (P>0.09). Linear regression confirmed significant association between objective SCORAD and serum LL-37 when adjusted for age and gender as covariates (ß=0.171, P=0.038). On the other hand, serum LL-37 did not differ between patients with and without heavy growth of staphylococci (P=0.151). CONCLUSIONS: Circulating LL-37 may be a biomarker for severity of childhood eczema, which supports the importance of innate immunity in eczema pathogenesis.

The EuroPrevall-INCO surveys on the prevalence of food allergies in children from China, India and Russia: the study methodology.

BACKGROUND: Very little is known regarding the global variations in the prevalence of food allergies. The EuroPrevall-INCO project has been developed to evaluate the prevalence of food allergies in China, India and Russia using the standardized methodology of the EuroPrevall protocol used for studies in the European Union. The epidemiological surveys of the project were designed to estimate variations in the prevalence of food allergy and exposure to known or suspected risk factors for food allergy and to compare the data with different European countries. METHODS: Random samples of primary schoolchildren were recruited from urban and rural regions of China, Russia and India for screening to ascertain possible adverse reactions to foods. Cases and controls were then selected to answer a detailed questionnaire designed to evaluate the possible risk factors of food allergies. Objective evidence of sensitisation including skin-prick test and serum specific IgE measurement was also collected. RESULTS: More than 37 000 children from the three participating countries have been screened. The response rates for the screening phase ranged from 83% to 95%. More than 3000 cases and controls were studied in the second phase of the study. Further confirmation of food allergies by double blind food challenge was conducted. CONCLUSIONS: This will be the first comparative study of the epidemiology of food allergies in China, India, and Russia using the same standardized methodology. The findings of these surveys will complement the data obtained from Europe and provide insights into the development of food allergy.

Associations of insulin-like growth factor binding protein-3 gene polymorphisms with IGF-I activity and lipid parameters in adolescents.

OBJECTIVE: Childhood obesity is a growing global epidemic. Recent studies indicate that obesity and related metabolic traits are highly heritable. Increasing evidence suggests that growth hormone (GH) and the insulin-like growth factor-I (IGF-I) axis have important functions in regulating adiposity and insulin sensitivity. Five single-nucleotide polymorphisms (SNPs) at IGF-binding protein-3 (IGFBP3) were genotyped to find their associations with IGF-1 activity level and common clinical metabolic traits. PATIENTS AND METHODS: We examined the associations of five SNPs at IGFBP3 with serum IGF-I and IGFBP-3 levels, as well as with obesity-related metabolic traits in 981 Hong Kong Chinese adolescents. Factor analysis was used to reduce the intercorrelated variables to five factor scores indicating body composition, blood pressure, IGF-I activity, triglyceride (TG)+high-density lipoprotein cholesterol (HDL-C) and total cholesterol (TC)+low-density lipoprotein cholesterol (LDL-C) factor scores. RESULTS: There was a strong association between the -202A/C polymorphism (rs2854744) and IGF-I activity (P=1.2 x 10(-6)) and TC+LDL-C factor scores (P=0.0085), corrected for age and sex. The C allele was associated with decreased IGFBP-3 levels (P=1.21 x 10(-13)), increased IGF-I/IGFBP-3 molar ratio (P=5.22 x 10(-6)) and decreased LDL-C (P=0.020). There was also a significant association between a G/A polymorphism at the 3' flanking sequence (rs13223993) of the IGFBP3 gene and the TG+HDL-C factor score (P=0.0013). The minor A allele carriers of rs13223993 had a lower HDL-C (P=0.0067) level and a tendency toward a high TG level. Haplotype analysis did not increase the significance of associations between single SNPs and phenotypes. CONCLUSION: Our results support the function of IGFBP3 gene polymorphisms in modulating IGF-I activity and lipid levels in adolescents. Given the prognostic significance of IGF-I, IGFBPs and lipids on risk of diabetes, obesity and cancer, long-term studies are required to clarify the clinical meaning of these findings.

Quality-of-life assessment in Chinese families with food-allergic children.

BACKGROUND: Caucasian families with food-allergic children have a compromised quality of life (QoL) for fear of life-threatening food reactions. Such data are limited in Asian children. Based on our recent questionnaire-based survey, 8.1% of young children recruited from local nurseries and kindergartens had parent-reported adverse food reactions (AFRs). OBJECTIVE: This study tested the robustness of the Chinese Food Allergy Quality of Life-Parental Burden questionnaire (FAQL-PB) and assessed QoL in families with childhood AFR. The correlations among FAQL-PB items were evaluated by factor analysis. METHODS: Two hundred and ninety-eight of 3677 children aged 2-7 years had parent-reported AFR, and 197 (66.1%) of them completed the 17 items of our self-administered FAQL-PB. Six hundred and thirty-nine (18.9%) children without AFR returned this questionnaire. Factor analysis was used to delineate the inter-relationship among the FAQL-PB items. RESULTS: Cronbach alpha for our Chinese FAQL-PB was 0.976, and the median (interquartile range) FAQL-PB scores of children with and without parent-reported AFR were 0.10 (0.02-0.32) and 0 (0-0.18), respectively (P < 0.001). Factor analysis confirmed excellent correlations between FAQL-PB items. The 17 items were clustered into two factors, which explained 79.7% of the total variance. Among children with AFR, FAQL-PB scores increased with increasing numbers of foods that caused AFRs (P < 0.001 for trend). Thirty (15.2%) children had impaired QoL, defined as average item FAQL-PB score > or = 0.5. Impaired QoL was associated with AFR that was caused by >3 foods (P = 0.001), current food avoidance (P = 0.005) and AFR caused by peanut (P = 0.003), egg (P = 0.011) and cow's milk (P = 0.028), and current flexural dermatitis (P = 0.011). CONCLUSIONS: FAQL-PB is a robust measure of AFR-specific parental QoL, which is impaired in Chinese children with parent-reported AFR. Flexural dermatitis, current food avoidance and AFR caused by multiple foods are independent risk factors for lower parental QoL.

A multi-centre study of candidate genes for wheeze and allergy: the International Study of Asthma and Allergies in Childhood Phase 2.

BACKGROUND: Common polymorphisms have been identified in genes suspected to play a role in asthma. We investigated their associations with wheeze and allergy in a case-control sample from Phase 2 of the International Study of Asthma and Allergies in Childhood. METHODS: We compared 1105 wheezing and 3137 non-wheezing children aged 8-12 years from 17 study centres in 13 countries. Genotyping of 55 candidate single nucleotide polymorphisms (SNPs) in 14 genes was performed using the Sequenom System. Logistic regression models were fitted separately for each centre and each SNP. A combined per allele odds ratio and measures of heterogeneity between centres were derived by random effects meta-analysis. RESULTS: Significant associations with wheeze in the past year were detected in only four genes (IL4R, TLR4, MS4A2, TLR9, P<0.05), with per allele odds ratios generally <1.3. Variants in IL4R and TLR4 were also related to allergen-specific IgE, while polymorphisms in FCER1B (MS4A2) and TLR9 were not. There were also highly significant associations (P<0.001) between SPINK5 variants and visible eczema (but not IgE levels) and between IL13 variants and total IgE. Heterogeneity of effects across centres was rare, despite differences in allele frequencies. CONCLUSIONS: Despite the biological plausibility of IgE-related mechanisms in asthma, very few of the tested candidates showed evidence of association with both wheeze and increased IgE levels. We were unable to confirm associations of the positional candidates DPP10 and PHF11 with wheeze, although our study had ample power to detect the expected associations of IL13 variants with IgE and SPINK5 variants with eczema.

Asthma and atopy are associated with chromosome 17q21 markers in Chinese children.

BACKGROUND: Single-nucleotide polymorphism (SNP)-based genome-wide association study revealed that markers on chromosome 17q21 were linked to childhood asthma but not atopy in Caucasians, with the strongest signal being detected for the SNP rs7216389 in the ORMDL3 gene. Such association was unknown in Chinese. This study delineated the allele and genotype frequencies of 10 SNPs at chromosome 17q21, and investigated the relationship between these SNPs and asthma and plasma IgE in southern Chinese children. METHODS: Asthmatic children and non-allergic controls were recruited from pediatric clinics. Their plasma total and aeroallergen-specific IgE concentrations were measured by immunoassay. Ten SNPs on 17q21 region were genotyped by multiplex SNaPshot, and their genotype associations with asthma traits analyzed using multivariate regression. RESULTS: 315 patients and 192 controls were enrolled. The allele frequency for C allele of rs7216389 varied significantly from 0.232 in our controls, 0.389 in Han Chinese to 0.536 in Caucasians. Asthma diagnosis was associated with rs11650680 and five other SNPs including rs7216389 (P = 0.019-0.034), whereas atopy was associated only with rs11650680 (P = 0.0004). Linear regression revealed the covariates for plasma total IgE to be significant for rs11650680 (P = 0.008-0.0002). Haplotypic associations were found with atopy and increased plasma total IgE, with the respective odds ratios and 95% confidence intervals for TTTCCGTT haplotype to be 0.21 and 0.09-0.52 (P = 0.0002) and 0.41 and 0.18-0.90 (P = 0.025). CONCLUSION: Childhood asthma and atopy are associated with chromosome 17q21 in Chinese, but such association may involve genes other than ORMDL3 in this region.

How well do questionnaires perform compared with physical examination in detecting flexural eczema? Findings from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two.

BACKGROUND: Questionnaires are widely used in epidemiological studies to measure eczema symptom prevalence, but there are concerns regarding their accuracy if used as a diagnostic tool. OBJECTIVES: To compare the performance of a validated eczema symptom questionnaire and a standardized skin examination protocol employed in the second phase of the International Study of Asthma and Allergies in Childhood (ISAAC). METHODS: A total of 30,358 schoolchildren aged 8-12 years from 18 countries were examined for flexural eczema. Parents also completed an eczema symptom questionnaire. We compared prevalence estimates at the population level based on the questionnaire vs. physical examination. We also compared the skin examination and the ISAAC questionnaire in making a diagnosis of flexural eczema. RESULTS: The point prevalences for flexural eczema at centre level based on a single examination were lower than the questionnaire-based 12-month period prevalences (mean centre prevalence 3.9% vs. 9.4%). Correlation between prevalences of both outcome measures was high (r = 0.77, P < 0.001). At the individual level, questionnaire-derived symptoms of 'persistent flexural eczema in the past 12 months' missed < 10% of cases of flexural eczema detected on physical examination. However, between 33% and 100% of questionnaire-based symptoms of 'persistent flexural eczema in the past 12 months' were not confirmed on examination. CONCLUSIONS: ISAAC questionnaire-derived symptom prevalences are sufficiently precise for comparisons between populations. Where diagnostic precision at the individual level is important, questionnaires should be validated and potentially modified in those populations beforehand, or a standardized skin examination protocol should be used.

Identifying uncontrolled asthma in young children: clinical scores or objective variables?

OBJECTIVE: Several international asthma guidelines emphasize the importance of assessing asthma control. However, there is limited data on the usefulness of available assessment tools in indicating disease control in young asthmatics. This study investigated the ability of Chinese version of Childhood Asthma Control Test (C-ACT) and other disease-related factors in identifying uncontrolled asthma (UA) in young children. METHODS: During the same clinic visit, asthma patients 4 to 11 years of age completed C-ACT and underwent exhaled nitric oxide and spirometric measurements. Blinded to these results, the same investigator assigned Disease Severity Score (DSS) and rated asthma control according to Global Initiative for Asthma. RESULTS: The mean (SD) age of 113 recruited patients was 9.1 (2.0) years, and 35% of them had UA. C-ACT, DSS and forced expiratory volume in 1 second (FEV(1)) differed among patients with different control status (p < 0.001 for C-ACT and DSS; p = 0.014 for FEV(1)). Logistic regression confirmed that UA was associated with DSS (p < 0.001), PEF (p = 0.002), C-ACT (p = 0.011), and FEV(1) (p = 0.012). By ROC analysis, C-ACT and DSS were the best predictors for UA (p < 0.001), followed by PEF (p = 0.006) and FEV(1) (p = 0.007). When analyzed by the Classification and Regression Tree (CART) approach, the sequential use of DSS and C-ACT had 77% sensitivity and 84% specificity in identifying UA. CONCLUSIONS: C-ACT is better than objective parameters in identifying young Chinese children with UA.

Study of gene-gene interactions for endophenotypic quantitative traits in Chinese asthmatic children.

BACKGROUND: Asthma is a complex disease resulting from interactions between multiple genes and environmental factors. Study of gene-gene interactions could provide insight into the pathophysiology of asthma. METHODS: We investigated the interactions among 18 single-nucleotide polymorphisms in eight candidate genes for plasma total immunoglobulin E (IgE) concentration and peripheral blood (PB) eosinophil count in 298 Chinese asthmatic children and 175 controls. Generalized multifactor dimensionality reduction and generalized linear model were used to analyze gene-gene interactions for the quantitative traits. RESULTS: A significant interaction was found between R130Q in IL13 and I50V in IL4RA for plasma total IgE concentration, with a cross-validation (CV) consistency of nine of 10 and a prediction error of 41.1% (P = 0.013). Plasma total IgE concentration was significantly higher in the high-risk than the low-risk groups (P < 0.0001). For PB eosinophil count, significant interaction was found between C-431T in TARC and RsaI_in2 in FCERIB, with a CV consistency of nine of 10 and a prediction error of 40.2% (P = 0.009). PB eosinophil count was significantly higher in the high-risk group than the low-risk groups (P < 0.0001). Generalized linear model also revealed significant gene-gene interaction for the above two endophenotypes with P = 0.013 for plasma total IgE concentration and P = 0.029 for PB eosinophil count respectively. CONCLUSIONS: Our data suggest significant interactions between IL13 and IL4RA for plasma total IgE concentration, and this is the first report to show significant interaction between TARC and FCERIB for PB eosinophil count in Chinese asthmatic children.

Environmental determinants associated with the development of asthma in childhood.

Asthma is a common chronic respiratory disease, and many epidemiological studies have documented an increasing trend over the past few decades. Comparative studies have shown that asthma is more prevalent in Westernised societies than in rural or developing regions. Environmental factors are likely to be important in explaining such disparities and increasing trends. Although allergen exposure and atopic sensitisation have been thought to be important in the pathogenesis of asthma, recent cross-sectional and longitudinal studies suggest that allergic sensitisation is likely a marker rather than a causative factor for asthma. There is accumulating evidence confirming the role of early exposure to infections in altering the regulation of cytokine production and reduction of subsequent development of atopic disorders. The consistent finding of a lower prevalence of asthma in subjects brought up in a farming environment and the inverse relationship between microbial exposure and asthma symptoms further support the importance of early environmental exposure affecting the risk of subsequent development of asthma. Confirmation of the pathogenetic role of these environmental determinants may allow us to develop primary preventive strategies against the development of asthma and related atopic diseases.