***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The purpose of this study was to estimate the national prevalence of childhood asthma and other allergic diseases in Korea , and to determine potential risk factors for the diseases . Stratified r and om sample s of 42,886 were selected from 34 elementary ( 6 - 12 yr olds ) and 34 middle schools ( 12 - 15 yr olds ) nationwide , and 38,955 were in the final analysis . The Korean-translated modified version of the International Study of Asthma and Allergies in Childhood question naire was used in this cross-sectional survey . Twelve-month prevalences of the symptoms of asthma , rhinoconjunctivitis , and flexural eczema were 8.7 % , 10.5 % , 7.3 % in 6 - 12 yr olds , and 8.2 % , 10.0 % , 3.9 % in 12 - 15 yr olds , respectively . For allergic conjunctivitis , food allergy , and drug allergy , the prevalences in 6 - 12 yr olds were 11.2 % , 6.5 % , and 1.5 % , respectively . Asthma and flexural eczema decreased significantly with age . Other significant risk factors were also noted . For 6 - 12 yr-old asthma , adjusted odds ratio ( aOR ) of body mass index was 1.21 with 95 % confidence interval ( CI ) 1.0 - 1.48 , aOR of passive smoking was 1.37 with 95%CI 1.24 - 1.51 , aOR of carpet use was 1.28 with 95%CI 1.10 - 1.49 . For 6 - 12 yr-old eczema , aOR of affluence was 1.22 with 95%CI 1.07 - 1.39 . The control of obesity and passive smoking would be the most important preventive measures of allergic diseases The chemokine ( C-X-C motif ) receptor 3 ( CXCR3 ) gene , on chromosome Xq13 , is known to have critical roles in inflammatory and immune responses . In an effort to discover polymorphisms have been implicated in asthma , we investigated the genetic polymorphisms in CXCR3 to evaluate it as a potential c and i date gene for a host genetic study of asthma . Statistical analysis revealed that one SNP in intron 1 , c.12 + 234 G > A , showed significant association with the risk of asthma development ( P = 0.007 , OR = 0.81 ) . By subgroup analyses stratified by gender and atopic status , the genetic effect of c.12 + 234 G > A on asthma was more apparent among male atopic subjects ( P = 0.0009 , OR = 0.61 ) . Our findings suggest that polymorphisms in CXCR3 might be one of the genetic factors for the risk of asthma development , especially in male atopic subjects . CXCR3 variation/haplotype information identified in this study will provide valuable information and insight into strategies for the control of asthma and its subgroup , atopy BACKGROUND It is important to diagnose asthma at an early stage as early treatment may improve the prognosis in the long term . However , many patients do not present at an early stage of the condition so the physician may have difficulty with the diagnosis . A study was therefore undertaken to compare the proportion of patients who underpresented their respiratory symptoms with the proportion of underdiagnosed cases of asthma by the general practitioner ( GP ) . A secondary aim was to investigate whether bad perception of dyspnoea by the patient was a determining factor in the underpresentation of asthma symptoms to the GP . METHODS A r and om sample of 1155 adult subjects from the general population in the eastern part of the Netherl and s was screened for respiratory symptoms and lung function and the results were compared with the numbers of asthma related consultations registered in the medical files of the GP . In subjects with reduced lung function the ability to perceive dyspnoea was investigated during a histamine provocation test in subjects who did and did not report their symptoms to their GP . RESULTS Of the r and om sample of 1155 subjects 86 ( 7 % ) had objective airflow obstruction ( forced expiratory volume in one second ( FEV1 ) below the reference value corrected for age , length , and sex minus 1.64SD on two occasions ) and had symptoms suggestive of asthma . Of these 86 subjects only 29 ( 34 % ) consulted the GP , which indicates underpresentation by 66 % of patients . Of all subjects with objective airflow obstruction who presented to their GP with respiratory symptoms , 23 ( 79 % ) were recorded in the medical files as having asthma , indicating underdiagnosis by the GP in 21 % of cases . Of the subjects with objective airflow obstruction who visited the GP with respiratory symptoms 6 % had bad perception of dyspnoea compared with 26 % of those who did not present to the GP in spite of airflow obstruction ( χ2 = 3.02 , p = 0.08 ) . CONCLUSIONS Underpresentation to GPs of respiratory symptoms by asthmatic patients contributes significantly to the problem of underdiagnosis of asthma . Underdiagnosis by the GP seems to play a smaller role . Furthermore , there are indications that underpresentation of symptoms by the patient is at least partly explained by a worse perception of dyspnoea Background Recent investigations have demonstrated that spider mites are important allergens in the development of asthma in fruit‐cultivating farmers 
    Output:
    
Disease severity , level of control , and symptom state were all found to negatively impact the quality of life of asthmatics .