Etiology Distribution Of Nonspecific Chronic Cough In Children And Its Relationship With TRPV1Gene Polymorphism At Position Rs222748, Rs8065080

Objective:To evaluate the causes of nonspecific chronic cough in children and investigate the predictors for risk of wheezing onset from cough variant asthma (CVA). To investigate the relationship between transient receptor potential vanilloid1(TRPV1) gene polymorphisms and non-specific chronic cough in children.Methods:The follow-up study was conducted in Asthma Center of Children’s Hospital between June2008and October2010.451children with a chronic cough for more than4weeks were recruited into this study. The children were followed up at the second week, the fourth week and the twelfth week after study enrollment.105children with CVA presenting to Asthma Center of Children’s Hospital between June2008and September2009had been studied for two years to ascertain whether wheezing developed or not. Bronchial provocation tests with methacholine were performed to measure the provocative concentration of methacholine causing a20%fall in FEV1from prechallenge values (PC20). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were used to analyze the polymorphisms of the TRPV1gene in children with non-specific chronic cough (n=195) and healthy controls (n=205).Results:1. Of all the451children, there were172(38.1%) children with diagnosis of CVA,136(30.2%) children were diagnosed cough variant asthma combined with upper airway cough syndrome(CVA+UACS),77(17.1%) children with postinfectious cough,57(12.6%) children with upper airway cough syndrome (UACS),3(0.7%) children with psychogenic cough, the diagnoses were uncertain in6(1.3%) of the children.2. After2years of follow up assessment,24(22.9%) of the105children with CVA developed wheezing (identify as wheezing-developed children). Results of logistic analysis showed that allergic to pollen (adjusted OR6.78,95%CI1.24-37.20,P=0.028) was a risk factor for wheezing onset from cough variant asthma.3. Three genotypes were detected in chronic cough children and healthy controls at position rs222747(CC、GC、GG); rs222748(CC、TC、TT); rs8065080(CC、 TC、TT). The frequencies of genotype and allele at position rs222747does not accord with the law of Hardy-Weinberg. There were no significant differences between children with nonspecific chronic cough and those in healthy controls in frequencies of genotype and allele at position rs222748、 rs8065080. Conclusion:1. Cough variant asthma (CVA), upper airway cough syndrome (UACS), postinfectious cough were the three most common causes in children with nonspecific chronic cough.2. Sensitive to pollen may be a risk factor for the development of wheezing in children with CVA.3. Transient receptor potential vanilloid1(TRPV1) gene polymorphisms at position rs222748、rs8065080may unrelated with nonspecific chronic cough in children.