Objective: The main aim of this study was to investigate the prevalence and risk factors of adult self-reported allergic rhinitis and asthma in plain lands and hilly areas of Shenmu City in China, and analyze the differences between regions.Methods: The multi-stage stratified random sampling was applied in a cross-sectional survey of adult residents in Shenmu City, from September to December 2019. The unconditional logistic regression analysis was used to screen the influence factors of allergic rhinitis and asthma.Results: 4,706 adults participated in the survey, and 99% (4,655 in 4,706) completed the questionnaires. The prevalence of allergic rhinitis was 25.4%, and the prevalence of asthma was 9.4%. The prevalence of the allergic rhinitis without asthma, asthma without allergic rhinitis, and the combined allergic rhinitis with asthma were 18.9, 2.9, and 6.5%, respectively. The prevalence of allergic rhinitis and asthma existed regional differences. The prevalence of adult self-reported allergic rhinitis was 41.5% in plain lands areas and 22.1% in hilly areas. The prevalence of adult self-reported asthma was 12.8% in plain lands and 8.8% in hilly areas. The prevalence of allergic rhinitis and asthma existed seasonal differences, with the highest prevalence from July to September. The analysis of risk factors showed that higher education [middle and high school (OR 1.72, 95%CI 1.42–2.07); college and above (OR 2.67, 95%CI 1.99–3.59)], comorbidities of other allergic diseases (OR 3.90, 95%CI 3.23–4.70), family history of allergies (OR 2.89, 95%CI 2.36–3.53), and plain lands areas (OR 2.51, 95%CI 2.06–3.05) were the risk factors for the allergic rhinitis without asthma. Aging [40–49 years old (OR 4.29, 95%CI 1.02–18.13); 50–59 years old (OR 5.89, 95%CI 1.40–24.76); ≥60 years old: (OR 6.14, 95%CI 1.41–26.71)], never-smokers (OR 1.66, 95%CI 0.99–2.80), comorbidities of other allergic disorders (OR 2.17, 95%CI 1.42–3.32), and family history of allergies (OR 2.20, 95%CI 1.40–3.47) were the risk factors for the asthma without allergic rhinitis. Advanced age [30–39 years (OR 2.16, 95%CI 1.23–3.82); 40–49 years (OR 2.86, 95%CI 1.56 to 5.25); 50–59 years (OR 2.95, 95%CI 1.58–5.51); ≥60 years old (OR 2.27, 95%CI 1.09–4.72)], higher education [middle and high school (OR 2.23, 95%CI 1.62–3.07); college and above (OR 4.28, 95%CI 2.72–6.74)], non-agricultural workers (OR 1.70, 95%CI 1.18–2.43),never-smokers (OR 2.26, 95%CI 1.51–3.39), comorbidities of other allergic diseases (OR 4.45, 95%CI 3.37–5.88), family history of allergies (OR 5.27, 95%CI 3.98–6.97), and plain lands areas (OR 2.07, 95%CI 1.51–2.86) were the risk factors for the combined allergic rhinitis with asthma.Conclusions: The prevalence of allergic rhinitis and asthma in Shenmu City was relatively high, with regional differences. Genetic and environmental factors were the important risk factors associated with allergic rhinitis and asthma. Our research would provide data support for preventing and controlling allergic rhinitis and asthma in this region in the future, and appropriate prevention and control programs should be formulated according to the characteristics of different regions.

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Background Allergic rhinitis (AR) is a common allergic disease in otolaryngology. Its pathogenesis is still unclear. PLC1 plays a key role in calcium homeostasis and immune response, which is potentially related to AR. We aimed to explore the association between PLCL1 genetic loci and susceptibility to AR. Methods We recruited 1975 volunteers to perform an association analysis through SNPStats online software. False-positive report probability (FPRP) analysis was used to detect whether the positive findings were worth noting. Linkage disequilibrium and haplotype analysis were completed through Haploview and SNPStats. The influence of SNP-SNP interaction on AR susceptibility was evaluated through multifactor dimensionality reduction (MDR). Results The results showed that four genetic loci in PLCL1 (rs2139049, rs212164068, rs2228135, and rs6738825) are associated with AR susceptibility under multiple genetic models. Allele “A” of PLCL1 -rs2139049 (OR = 0.85, p = 0.031) or of -rs212164068 (OR = 0.85, p = 0.030), and allele “G” of PLCL1 -rs6738825 (OR = 0.84, p = 0.022) are significantly associated with reduced AR risk. PLCL1 -rs2228135 is associated with an increased risk of AR in males or participants older than 43 years of age. FPRP analysis showed that most of positive results are noteworthy findings. Three loci model composed of rs2139049, rs2164068, and rs2228135 is the best model for predicting AR risk ( p = 0.0022). In addition, the haplotype “G rs2139049 A rs6738825 A rs2164068 A rs2228135 ” (OR = 0.50, p = 0.033) can reduce the AR risk. Conclusion Allele “A” of PLCL1 -rs2139049, allele “A” of -rs212164068, and allele “G” of PLCL1 -rs6738825 are protective factors of AR in Han population from northern Shaanxi, China.